Category Archives: Science writing

Data I am never going to publish – A tale of sixty trees

In 1981 I spent a lot of time trudging through snow, cross-country skiing and snow-shoeing my way across the snowy wastes of Finland to snip twigs off bird cherry trees.  This was part of my post-doc which was to develop a forecasting system for the bird cherry-oat aphid, Rhopalosiphum padi.  On returning to the lab I then spent many a happy hour counting how many aphid eggs were nestled in between the buds and the stem on each twig.  It was while doing this that I noticed that some of the twigs were infested with the overwintering larval shields of the bird cherry ermine moth, Yponomeuta evonymellus.  Of course I then started counting them as well 🙂  I noticed that trees with lots of aphid eggs didn’t have very many larval shields and I wondered why. Some later observations from marked trees in Scotland appeared to provide evidence that the aphids and the moths tended to either prefer different trees or perhaps excluded each other.

Negative correlation between moths and aphids – more moths equals fewer aphids and vice versa

Based on these data I hypothesised that the two insects were indirectly competing for resources by altering plant chemistry and/or architecture thus making the trees less or more suitable for egg laying in the autumn (Leather, 1988).  I tested this experimentally when I was working for the Forestry Commission in Scotland using potted bird cherry trees that I defoliated to a lesser or greater extent to see if I could induce changes in foliar quality and tree growth rates that might influence subsequent colonisation by the aphids and moths. As predicted, those trees that had been defoliated, albeit by me and not by moth larvae, were less attractive to aphids in the autumn (Leather, 1993).  These effects were still apparent five years after the beginning of the experiment (Leather, 1995) when I had to desert my trees as I moved to a new position at Imperial College’s Silwood Park campus.

Given that apart from the location, the SE of England, this was my idea of a dream job for life (colleagues at the time included John Lawton, Mike Hassell, Bob May, Stuart McNeill, Mike Way, Brad Hawkins, Shahid Naeem, Mike Hochberg, Chris Thomas to name but a few), I decided to start up two long-term projects to see me through the next 30 years, one observational (my 52 sycamore tree project), the other experimental, a follow up to my bird cherry defoliation experiment.

I went for a simplified design of my earlier experiments, just two defoliation regimes, one to mimic aphid infestation (50%), the other to mimic bird cherry ermine moth defoliation (100%) and of course a non-defoliated control.  I also planted the trees in the ground to better simulate reality.  Using potted plants is always a little suspect and I figured that I would need to do rather a lot of re-potting over the next 30 years 🙂

The grand plan!

I sourced my trees from a Forestry Commission nursery thinking that as the national organisation responsible for tree planting in the UK I could trust the provenance of the trees.  Things didn’t go well from the start.  Having planted my trees in autumn 1992 and established the treatments in the spring of 1993 I discovered that my bird cherry, rather than being from a native provenance (seed origin) were originally from Serbia! Hmm 🙂  It was too late to start again, so I decided to carry on.  After all, bird cherry although widely planted in the SE, has a native distribution somewhat further north and west, which meant I was already operating close to the edge of ‘real life’, so what did an extra 1600 kilometres matter?

The mainly ‘natural’ distribution of bird cherry (left, Leather, 1996) and the current distribution including ‘introduced’ trees

Next, I discovered that my fence was neither rabbit nor deer proof.  I almost gave up at this point, but having invested a lot of time and energy in setting up the plot I once again decided to carry on. On the plus side, the trees most heavily defoliated and bitten back were mainly from the 100% defoliation treatment, but did give me some negative growth rates in that year.

My original plan was to record height (annually), bird cherry egg numbers (every December), bird cherry ermine moth larval shields (annually), bud burst and leaf expansion once a week, leaf-fall (annually), and once a month, defoliation rates in two ways, number of damaged leaves and an overall estimation of percentage defoliation.  This was a personal project, so no grant funding and no funding for field assistants.  It soon became clear, especially when my teaching load grew, as Imperial started replacing whole organism biologists with theoretical and molecular biologists, and I was drafted in to take on more and more of the whole organism lecturing, that I would not be able to keep both of my long term projects going with the same intensity.  Given the ‘problems’, associated with the bird cherry project, I decided  that I would ditch some of my sampling, bud burst was scored on 21st March every year and defoliation only measured once, in late summer and egg sampling and height recording came to a halt once the trees grew above me (2005)!  This allowed me to carry on the sycamore project as originally intended*.

I kept an eye on the trees until I left Silwood Park in 2012, but by 2006 I was only monitoring bud burst and leaf fall feeling that this might be useful for showing changes in phenology in our ever-warming world.  One regret as I wandered between the then sizeable trees in the autumn of 2012 was that I had not taken a before and after photograph of the plots.  All I have are two poor quality photos, one from 2006, the other from 2012.

The Sixty Tree site April 2006.

The Sixty Tree site April 2010 with a very obvious browse line


So, after all the investment in time, and I guess to a certain extent money (the trees and the failed fencing, which both came out of my meagre start-up funding**), did anything worthwhile come out of the study?

The mean number of Rhopalosiphum padi eggs per 100 buds in relation to defoliation treatment

As a long-time fan of aphid overwintering it was pleasing to see that there was a significant difference not only between years (F= 8.9, d.f. = 9/29, P <0.001), but also between treatments with the trees in the control treatment having significantly more eggs laid on them than the 100% defoliation treatment (F= 9.9, d.f. = 2/ 29, P <0.001 with overall means of 1.62, 1.22 and 0.65 eggs/100 buds).  This also fitted in with the hypothesis that trees that are defoliated by chewing herbivores become less suitable for aphids (Leather, 1988).  I must admit that this was a huge surprise to me as I had thought that as all the trees were attacked by deer the year after the experimental treatments they would all respond similarly, which is why I almost gave up the experiment back in 1994.

Bud burst stage of Prunus padus at Silwood Park on March 21st 1996-2012; by treatment and combined

When it came to budburst there was no treatment effect, but there was a significant trend to earlier budburst as the trees became older which was strongly correlated with warmer springs, although as far as spring temperatures were concerned there was no significant increase with year.

Mean spring temperature (Silwood Park) 1993-2012 and relationship between mean spring temperature and bud bust stage on 21st March.

Mean date of final leaf fall of Prunus padus at Silwood Park 1995-2012; by treatment and combined

At the other end of the year, there was a significant difference between date of final leaf fall between years but no significant difference between treatments.  In retrospect I should have adopted another criterion.  My date for final leaf fall was when the last leaf fell from the tree.  Those of you who have watched leaves falling from trees will know that there are always a few who are reluctant to make that drop to the ground to become part of the recycling process.  Even though they are very obviously dead, they hang there until finally dislodged by the wind.   I should really have used a measure such as last leaf with any pigment remaining.  I am sure that if I could be bothered to hunt down the wind speed data I would find that some sort of correlation.

Mean height (cm) of Prunus padus trees at Silwood Park 1993-2005 and Diameter at Breast Height (DBH) (cm) at the end of 2012

Except for the year after the deer attack, the trees, as expected, grew taller year by year.  There was however, no significant difference between heights reached by 2005 or in DBH at the end of 2012 despite what looked like a widening gap between treatments.

Defoliation scores of Prunus padus at Silwood Park 1993-2004; % leaves damaged and overall defoliation estimates

My original hypothesis that trees that were heavily defoliated at the start of their life would be more susceptible to chewing insects in later life, was not supported.  There was no significant difference between treatments, although, not surprisingly, there was a significant difference between years.  Average defoliation as has been reported for other locations was about 10% (Kozlov et al., 2015; Lim et al., 2015).

Number of Prunus padus trees with severe deer damage

That said, when I looked at the severity of deer attack, there was no effect of year but there was a significant effect of treatment, those trees that had been 100% defoliated in 1993 being most attractive to deer.   In addition, 20% of those trees were dead by 2012 whereas no tree deaths occurred for the control and less severely defoliated treatments.

I confess to being somewhat surprised to find as many significant results as I did from this simple analysis and was momentarily tempted to do a more formal analysis and submit it to a journal.  Given, however, the number of confounding factors, I am pretty certain that I would be looking at an amateur natural history journal with very limited visibility.  Publishing it on my blog will almost certainly get it seen by many more people, and who knows may inspire someone to do something similar but better.

The other reason that I can’t be bothered to do a more formal analysis is that my earlier work on which this experiment was based has not really hit the big time, the four papers in question only accruing 30 cites between them.  Hardly earth shattering despite me thinking that it was a pretty cool idea;  insects from different feeding guilds competing by changing the architecture and or chemsitry of their host plant.  Oh well.  Did anything come out of my confounded experiment or was it a total waste of time?  The only thing published from the Sixty Trees was a result of a totally fortuitous encounter with Marco Archetti and his fascination with autumn colours (Archetti & Leather, 2005), the story of which I have related in a previous post, and which has, in marked contrast to the other papers, had much greater success in the citation stakes 🙂

And finally, if anyone does want to play with the data, I am very happy to give you access to the files.


Archetti, M. & Leather, S.R. (2005) A test of the coevolution theory of autumn colours: colour preference of Rhopalosiphum padi on Prunus padus. Oikos, 110, 339-343. 50 cites

Kozlov, M.V., Lanta, V., Zverev, V., & Zvereva, E.L. (2015) Global patterns in background losses of woody plant foliage to insects. Global Ecology & Biogeography, 24, 1126-1135.

Leather, S.R. (1985) Does the bird cherry have its ‘fair share’ of insect pests ? An appraisal of the species-area relationships of the phytophagous insects associated with British Prunus species. Ecological Entomology, 10, 43-56.  14 cites

Leather, S.R. (1988) Consumers and plant fitness: coevolution or competition ? Oikos, 53, 285-288. 10 cites

Leather, S.R. (1993) Early season defoliation of bird cherry influences autumn colonization by the bird cherry aphid, Rhopalosiphum padi. Oikos, 66, 43-47. 11 cites

Leather, S.R. (1995) Medium term effects of early season defoliation on the colonisation of bird cherry (Prunus padus L.). European Journal of Entomology, 92, 623-631. 4 cites

Leather, S.R. (1996) Biological flora of the British Isles Prunus padus L. Journal of Ecology, 84, 125-132.  14 cites

Lim, J.Y., Fine, P.V.A., & Mittelbach, G.G. (2015) Assessing the latitudinal gradient in herbivory. Global Ecology & Biogeography, 24, 1106-1112.



*which you will be pleased to know, is being analysed as part of Vicki Senior’s PhD project, based at the University of Sheffield.

**£10 000 which even in 1992 was not overly-generous.


Filed under EntoNotes, Science writing, Uncategorized

Arthropod orchids – who’s fooling who?

A few weeks ago I read the first volume of Jocelyn Brooke’s Orchid trilogy, The Military Orchid. I have never been a great fan of orchids, my main experience of them being as ornamental house plants in which context I have always found them ugly, ungainly and obtrusive.

My colleague Lucy’s orchid ‘brightening up’ our communal office kitchen area

‘Artistically displayed’ for sale by an on-line florist – still just as ugly

Jocelyn Brooke’s account of his search for the Military Orchid was however a bit of a revelation.  His obsession with the eponymous orchid reminded me of how I quite liked seeing the first emerging spikes of the common spotted orchid, Dactylorhiza fuchsii appearing in Heronsbrook Meadow at Silwood Park as I returned from my lunchtime run.  A little bit later Jeff Ollerton posted an interesting article about orchid pollination myths and this got me thinking about the common names of our native UK orchids, especially those named after arthropods.

It turns out that there are fewer than I thought; Bee, some varieties of which seem to be called the wasp orchid, the Fly, Lesser butterfly, Greater butterfly, Early spider and Late spider orchid being the lot.  My self-imposed mission was to first find a suitable photograph of each species to see if it did look like its namesake and secondly to identify the main pollinators.  Or to put it another way, exactly what are they mimicking and what or who are they really fooling?  Orchids generally speaking are honest brokers, providing nectar as a resource for pollination services (Nilsson, 1992).  About a quarter of orchid species are however frauds or cheats (Nilsson, 1992), either pretending to be a food source or a receptive female insect, nutritive deceptive or sexually (reproductive) deceptive as the jargon has it (Dafni, 1984).  Ophrys orchids are sexually deceptive (Nilsson 1992).

The Bee Orchid, Ophrys apifera, is pollinated by a solitary mining bee, Eucera longicornis  (Kullenberg, 1950) belonging to a group commonly known as long horned bees, which in the UK is rather uncommon meaning that the Bee Orchid is generally self-pollinated.

The Bee Orchid, Ophrys apifera with pollinator Eucera longicornis

If you look at the female bee, which is what we suppose the flower is mimicking, you can just about convince yourself that there is a slight resemblance between the two.  Insects of course do not see things the same way humans do (Döring et al., 2012) so what we think is almost certainly irrelevant.  That said, it doesn’t actually have to be a particularly good visual mimic for the insects either, as it is the smell that really matters and as long as the flower is the right shape to enable the deceived male to copulate in such a way that the flower is fertilized that is all that matters.   To quote Dafni (1984) “The olfactory specificity allows a high degree of morphological variability because the selective pressures leading to uniformity-as a means for better recognition-are relaxed. When odors become the main means of attraction, they efficiently serve as isolating agents among closely related species

The fly orchid, Ophrys insectiflora, is also sexually deceptive, but despite its common name is pollinated by digger wasps and bees (Kullenberg, 1950; Wolff 1950).

Ophrys insectifera   Fly orchid  By Jörg Hempel, CC BY-SA 3.0 de,  with pollinator Argogorytes mystaceus (formerly Gorytes)

Oddly, despite being sexually deceptive it does, at least in my opinion, resemble its pollinators fairly well.

Next up (alphabetically), we have the Lesser Butterfly Orchid, Planthera bifolia, which despite its name is pollinated by night-flying hawk moths,


The Lesser Butterfly Orchid, Planthera bifolia.  By © Hans Hillewaert, CC BY-SA 4.0, and the two leading pollinators Hyloicus pinastri and Deilephila elpenor.

most commonly by the Pine Hawk Moth, Hyloicus pinastri and the Elephant Hawk Moth, Deilephila elpenor  (Nilsson (1983). These orchids provide a nectar reward, and attract their pollinators by producing a strong scent (Nilsson, 1978) easily detected by humans even at a distance (Tollsten & Bergström, 1989).  As an added extra, the flowers are very light-green and also highly light-reflecting, giving the moths a visual as well as an olfactory signal (Nilsson, 1978).  In terms of shape the flower more closely resembles H. pinastri.

The closely related Greater Butterfly Orchid, Planthera chlorantha is also pollinated by night-flying moths, the two Elephant hawk moths  Deiliphila porcellus and D.elpenor, 

Platanthera chlorantha,  The Greater Butterfly  Orchid with hawk moth and Noctuid pollinators.

but mainly by Noctuid moths, most commonly, Apame furva (The Confused) and  A. monoglypha (the Dark Arches) Nilsson (1983).  Although recent video evidence has shown that the Pine Hawk moth also pollinates it (Steen, 2012).  Like the Lesser Butterfly Orchid, the flower only vaguely resembles its pollinators.  The chemicals responsible for the characteristic and intense fragrances of these two closely related orchids differ between the species and is probable that they are linked to the preferences of the different pollinator species (Nilsson, 1978).

Despite its name and suggested resemblance to its namesake, the Early Spider Orchid, Ophrys sphegodes is pollinated by a solitary bee,

Ophrys sphegodes, The Early Spider Orchid

Andrena nigroaenea (Schiestl et al. 2000).  The scent of the nectarless flower, closely resembles the female sex pheromone of the bee and fools the male into ‘mating’ with it (Schiestl et al., 2000).  If you allow your imagination to run riot you could possibly just about see the flower as a giant female bee which might act as an extra stimulus for an excited male bee (Gaskett, 2011).

The final arthropod orchid is the Late Spider, Ophrys fuciflora; do be careful how you pronounce it, a soft c might be advisable 🙂

Ophrys fuciflora, the Late Spider orchid and two of its documented pollinators, Eucera longicornis (originally tuberculata) and Phyllopertha horticola.  Orchid Photo by © Pieter C. Brouwer and his Photo Website

As with all Ophrys orchids, they are sexually deceptive and attract male insects to their nectar-free, but highly scented flowers, with the promise of a good time Vereecken et al., 2011).  Most pollination is by solitary bees (Kullenberg, 1950) although the Garden Chafer, Phyllopertha horticola has been recorded as pollinating it in northern France (Tyteca et al., 2006).  Again both pollinators could be said to resemble the flowers to some extent

That concludes my tour of UK arthropod orchids.  Having learnt a lot about other orchids in the last couple of weeks while researching this article it seemed a shame to waste it.  So, as an added bonus, I’m going to finish with a few imaginatively named orchids, the names of which do not refer to their pollinators but rather to the imagination of their human namers.

Orchis anthropophora, The Man Orchid.  Photo by Erwin Meier

This not usually pollinated by sexually-deceived humans but by two beetles, Cantharis rustica (soldier beetle) and Cidnopus pilosus (click beetle) and also by two species of sawfly Tenthredopsis sp. and Arge thoracia (Schatz, 2006).

Orchis simia, The Monkey Orchid. Photo Dimìtar Nàydenov

Again, as with the Man Orchid, the Monkey Orchid, is not pollinated by cruelly deceived anthropoids.  There are, as far as I can discover, only a few confirmed pollinators of O. simia.  They include the beetle C. pillosus, the moth Hemaris fuciformis and some hymenopterans such as honeybees (Schatz, 2006).  According to PlantLife, hybrids of the Man Orchid and Monkey Orchid are called the Missing Link Orchid.

My fellow blogger Jeff Ollerton and his colleagues (Waser et al., 1996), point out that pollination systems are not as specialist as many might think, and even in sexually-deceptive orchids that use pheromone mimics, many of their pollinators can get ‘confused’ and pollinate closely related orchid species.  Hence the existence of what are termed ‘natural hybrids’ such as the Missing Link Orchid and the interesting hybrid between the Fly Orchid and the Woodcock Orchid pictured below.

The hybrid, Fly x Woodcock  Orchid.  Photo Karen Woolley‏ @Wildwingsand

It looks like a belligerent penguin to me, but is of course pollinated by insects.

Often regarded as one of the most bizarrely flowered orchids is the Flying Duck Orchid, Caleana major from Australia.

Flying duck orchid Caleana major (from Australia) sawfly pollinated (Adams & Lawson, 1993).

I was intrigued to notice what appears to be a Cantharid beetle, species of which are known to pollinate other orchids (Schatz, 2006), lurking in the background. There are a number of Cantharids noted as being pollinators in Australia, some of which have been recorded pollinating orchids, although not specifically on Calaena (Armstrong, 1979) so this may be an overlooked pollinator, just waiting to be confirmed by a dedicated pollinator biologist or orchidologist.  There is also, if you wondered, a Small Duck Orchid, Paracaleana minor.

Who would have thought that reading a biography would have started me off on such an interesting paper hunt?  Perhaps the most interesting new bit of information I discovered was that male orchid bees although they attract females with scents, do not produce their own pheromones but collect flower volatiles which they mix with volatiles from other sources like fungi, plant sap and resins (Arriaga-Osnaya et al., 2017).  They use these ‘perfumes’ as part of their competitive courtship behaviour to attract females; the best perfumier wins the lady J

And then you have Dracula vampira….

Dracula vampira (Vampire orchid) – only found in Ecuador (Photo: Eric Hunt, licensed under CC by 3.0).© Eric Hunt.  I hasten to add this is not pollinated by vampires, bats or otherwise.


But to finish, here is the one that started it all…

The one that started it all, The Military Orchid, Orchis militaris



Many thanks to Manu Saunders over at Ecology is Not a Dirty Word for sending me a key reference and also to her and Jeff Ollerton for casting critical ‘pre-publication’ eyes over this post.


Armstrong, J.A. (1979) Biotic pollination mechanisms in the Australian flora — a review.  New Zealand Journal of Botany, 17, 467-508.

Adams, P.B. & Lawson, S.D. (1993) Pollination in Australian orchids: A critical assessment of the literature 1882-1992.  Australian Journal of Botany, 41, 553-575.

Arriaga-Osnaya, B.J., Contreras-Garduño, J., Espinosa-García, F.J. García-Rodríguez, Y.M.,  Moreno-García, M., Lanz-Mendoza, H., Godínez-Álvarez, H., & Cueva del Castillo, R. (2016) Are body size and volatile blends honest signals in orchid bees? Ecology & Evolution, 7, 3037–3045.

Dafni, A. (1984) Mimicry and deception in pollination.  Annual Review of Ecology & Systematics, 15, 259-278.

Döring, T.F., Skellern, M., Watts, N., & Cook, S.M. (2012) Colour choice behaviour in the pollen beetle Meligethes aeneus (Coleoptera: Nitulidae). Physiological Entomology, 37, 360-368.

Gaskett, A.C. (2011) Orchid pollination by sexual deception: pollinator perspectives. Biological Reviews, 86, 33-75.

Kullenberg, B. (1950) Investigations on the pollination of Ophrys species. Oikos, 2, 1-19.

Nilsson, L.A. (1978) Pollination ecology and adaptation in Platanthera chlorantha (Orchidaceae).  Botaniska Notiser, 131, 35-51.

Nilsson, L.A. (1983) Processes of isolation and introgressive interplay between Platanthera bifolia (L.) Rich and P. chlorantha (Custer) Reichb. (Orchidaceae). Botanical Journal of the Linnean Society, 87, 325-350.

Schatz, B. (2006)  Fine scale distribution of pollinator explains the occurrence of the natural orchid hybrid xOrchis bergoniiEcoscience, 13, 111-118.

Schiestl, F.P., Ayasse, M., Pauklus, H.F., Löfstedt, C., Hansson, B.S., Ibarra, F. & Francke, W. (2000) Sex pheromone mimicry in the eraly spider orchid (Ophrys sphegodes): patterns of hydrocarbons as the key mechanism for pollination by sexual deception.  Journal of Comparative Physiology A, 186, 567-574.

Steen, R. (2012) Pollination of Platanthera chlorantha (Orchidaceae): new video registration of a hawkmoth (Sphingidae). Nordic Journal of Botany, 30, 623-626.

Tollsten, L. & Bergström, J. (1989) variation and post-pollination changes in floral odours released by Platanthera chlorantha (Orchidaceae). Nordic Journal of Botany, 9, 359-362.

Tyteca, D., Rois, A.S. & Vereecken, N.J. (2006) Observations on the pollination of Oprys fuciflora by pseudo-copulation males of Phyllopertha horticola in northern France. Journal Europäischer Orchideen, 38, 203-214.

Vereecken, N.J., Streinzer, M., Ayasse, M., Spaethe, J., Paulus, H.F., Stökl, J., Cortis, P. & Schiestl, F.P. (2011) Integrating past and present studies on Ophrys pollination – a comment on Bradshaw et al. Botanical Journal of the Linnean Society, 165, 329-335.

Waser , N.M., Chittka, L., Price, M.V., Williams, N.M. & Ollerton, J. (1996) Generalization in pollination systems, and why it matters. Ecology, 77, 1043-1060.

Wolf, T. (1950) Pollination and fertilization of the Fly Ophrys, Ophrys Insectifera L. in Allindelille Fredskov, Denmark. Oikos, 2, 20-59.



Filed under EntoNotes, Science writing

Mind the gap – time to make sure that scientists and practitioners are on the same page

I have deliberately used the same title for this post as my 2017 Editorial in Annals of Applied Biology and if you were to run it through Turnitin™ you would find a very high percentage similarity indeed 🙂 I had originally planned for this post and my Editorial to appear simultaneously, but thanks to modern publishing practices, the January issue of the Annals of Applied Biology, hit the virtual newsstands in mid-December and put the kibosh on my cunning plan.


Once a year I am wheeled out to do a guest lecture to the final year agriculture undergraduates on the Global Food Production module here at Harper Adams.  I start off the lecture by reminiscing about when I was an agricultural zoology undergraduate student at the University of Leeds in 1975 and was introduced to the concept of Integrated Pest Management (IPM), or as it was termed then, Integrated Pest Control.  I was very much taken by this idea and on my next visit home, approached my Uncle James, a farmer, and explained the concept to him and suggested that he might like to implement it on his farm.  To my surprise, he was not convinced by my arguments, and replied with words to the effect, “It all sounds rather tedious, and after all, I can do all my pest control much more easily using a tank mix, so why should I bother?”.  This attitude was, at the time widespread among the UK farming community and elsewhere despite the concept having been formally discussed in the scientific literature since the late 1950s and early 1960s (Stern et al., 1959; de Fluiter, 1962).  Despite the benefits of IPM being recognised and extolled IPM by researchers and agronomists for many years, take-up by growers has been much slower than expected (Kogan, 1998; Hammond et al., 2006). Resistance to the adoption of integrated pest management is not new, Benjamin Walsh writing in 1866 wrote

Let a man profess to have discovered some new patent powder pimperlimplimp, a single pinch of which being thrown into each corner of a field will kill every bug throughout its whole extent, and people will listen to him with attention and respect.  But tell them of any simple common-sense plan, based upon correct scientific principles, to check and keep within reasonable bounds the insect foes of the farmer, and they will laugh you to scorn”  Benjamin Walsh The Practical Entomologist

Why, if IPM is regarded as being of such paramount importance to sustainable crop production, the European Union for example passed a directive recently (2009/128/EC) requiring all member states to pass legislation to make sure that all professional growers at the very least adopt the principles of IPM, is its adoption so slow.  Hokkanen (2015) cites three main impediments to the adoption of IPM, science funding, political interference and economics.  As an applied entomologist I know from bitter experience, that there is a lack of willingness by the UK Research Councils to fund basic applied science i.e. grants to aid researchers to establish much-needed new economic thresholds are very unlikely to be funded.  Hokkanen (2015) also points out that whilst the political landscape now includes IPM, different governments have views, not necessarily based on science, about what are acceptable items for the IPM toolbox, genetically modified crops (GM) and neonicotinoid insecticides being just two such examples. Thirdly, as Hokkanen (2015) points out the ability of farmers to fully adopt IPM practices, is often out of their control, but is decided by market forces and social and political pressures, GM crops and neonicotinoids again serving to illustrate this point.

As Felicity Lawrence writing in the Guardian says “British farmers growing wheat typically treat each crop over its growing cycle with four fungicides, three herbicides, one insecticide and one chemical to control molluscs. They buy seed that has been precoated with chemicals against insects. They spray the land with weedkiller before planting, and again after.

They apply chemical growth regulators that change the balance of plant hormones to control the height and strength of the grain’s stem. They spray against aphids and mildew. And then they often spray again just before harvesting with the herbicide glyphosate to desiccate the crop, which saves them the energy costs of mechanical drying.

Most farmers around the world, whatever the crop, will turn to one of just six companies that dominate the market to buy all these agrochemicals and their seeds. The concentration of power over primary agriculture in such a small number of corporations, and their ability both to set prices and determine the varieties available, has already been a cause of concern among farmers. Yet by next year the competition is likely to shrink even further”.

Independent advice in the UK is not as easy to get as it once was.  The expected career outcome for my undergraduate course was either academia or to work as an advisor for the then, government funded, Agricultural Development and Advisory Service (ADAS).  ADAS was the research and advisory arm of the then Ministry of Agriculture Fisheries and Food and employed specialist advisers throughout the country to advise farmers and growers how to maximise their output.   ADAS became an agency in 1992, was privatised in 1997 and in December 2016 was taken over by RSK, a large environmental consultancy.  The first incarnation of ADAS was relatively well-staffed with truly independent advisors. The second incarnation, although still billed as independent, had far fewer offices and far fewer staff, so their traditional advisory role was largely taken over by private agronomists whose agendas and training are very varied.  This state of affairs is not unique to the UK.

As an example, this is from another of my correspondents who is also on the Editorial Board of Annals of Applied BiologyThanks for your message and interesting question.  You are correct that in the US the extension service is closely aligned with the land grant Universities.  It was the complete opposite in Australia and NZ (similar to the UK) where the government funded extension service had been cut years ago and the gap had been ‘filled’ by private consultants which were also often chemical sales representatives.

Even in the USA, traditionally very strong when it comes to entomology in universities, the situation is less than rosy as this email from another correspondent (of necessity anonymised) highlights:

“I am currently the only trained entomologist in any XX university with a position focused on commercial ornamental entomology despite nurseries in XX being our largest plant-based agricultural commodity. Between shipping out 75-80% of the nursery plants across a state or international border, thousands of cultivated varieties, several planting systems (protected and field grown), and the aesthetic thresholds with ornamental plants, I’m a bit too popular (couldn’t haven’t happened in high school when I could have used it). I don’t even have a PhD and my position is actually a regional Extension educator position versus specialist. Since we have no specialists for non-food crops, I often am asked to work off position description on other ornamental plant needs in landscapes as well. Not just entomology as this is an IPM position.  This level of demand has curtailed my ability to be involved with activities that would have been useful professionally (like publishing more and reviewing work of peers). No regrets about the new discoveries, adoption and impact of my work in many diverse areas but I will have less legacy in the published world.  

I’m retiring in less than three years. A little early but necessary as I’ve been fighting burn-out for years. And the university has taught me many times that they value my work less as a female (the stories I could tell). Women in STEM gets lots of verbiage but those of us working in these systems will tell you how far we have to go yet to be treated equitably. Perhaps they will value my work once I’m gone and people have nowhere to go. I have been fortunate to have had the privilege of excellent training and only hope that this country can maintain some of these bastions of entomology into the future”

Science is crucial to the development of IPM, be it understanding pest phenology, developing and evaluating biocontrol agents or obtaining a basic understanding of the biology and ecology of a particular pest (e.g. Webb et al., 2015; Dandurand & Knudsen, 2016; Karley et al., 2016; Rowley et al. 2016).  Basic science is important, but funding needs to be mainly allocated to more immediately applicable research than to the more academic end of the spectrum which is where it tends to go more often than not (Hokkanen, 2015).   I recently attended a conference organised by AgriNet, whose mission statement is “AGRI-net is an Agri-science Chemical Biology network which aims to stimulate the development and facilitate the translation of novel tools and technologies to key end-users in the Agri-sciences”, the title of which was  Bridging the gap between Physical sciences & Agri-sciences research.  Although the science presented was excellent it was hard to see how it could be translated to the relevant end-users in their lifetimes.

Don’t get me wrong, basic science is needed as there will be a time when the technology is available for it to be relevant.  As an example, Winer et al. (2001) convincingly demonstrated that planting spring wheat at extremely high densities (up to 600 seeds m2) in a grid pattern, significantly reduced weed density and significantly increased yield when compared with planting at conventional seed rates and in the traditional row pattern.  Fifteen years ago this may not have been very attractive to farmers as it would have meant modifying their already expensive machinery.  With the advent of precision farming this is perhaps now a viable strategy, but so far is little taken up by growers.  Is this a lack of communication from the scientists to the end-user or a reluctance to adapt new ways by the farmer?  I would suggest the former.

The recent State of Nature report (Hayhow et al., 2016) caused dismay amongst UK ecologists and raised the hackles of the UK farming community.  The data were very convincing and much of the decline in wildlife in agricultural systems was attributed to the intensification of agriculture post World War 2. The UK farming community reacted quickly and angrily (Midgely, 2016), pointing out that farming practices have changed greatly over the last half century and that the report was overlooking the many farmers who have willing engaged with the various environmental stewardship initiatives.  The debate was somewhat exacerbated by the fact that some trenchant exchanges on both sides of the fence are of a long-standing nature.  Although I have a great deal of sympathy for the conservation side of the argument I sometimes feel that the language used by what the farming press equally dismissively calls ‘green lobby’ does not help. Michael McCarthy for example, an author whom I greatly admire, is in his recent book, The Moth Snowstorm, is extremely scathing about the practices of farmers, whom he mockingly calls “Farmer Giles” (McCarthy, 2016)

Similarly, there has been for some time, a debate within the scientific community as to whether it is better to farm intensively to maximize yields while conserving and protecting natural habitats (land sparing), or to use wildlife-friendly farming methods (land sharing) that integrate biodiversity conservation with food production (e.g. Tscharntke et al., 2012; Bommarco et al., 2013; Fischer et al., 2014; Kremen, 2015).  Due, however, to the pressures imposed by academic institutions and state funding bodies, the scientists concerned publish in ‘high impact’ conservation journals unlikely to be read by agronomists let alone farmers.

Sue Hartley (2016) “…working in Malawi on a Christian Aid funded project on improving crop resilience to drought.  I thought I had the answer: farmers should stop growing maize and grow the much more drought tolerant millet instead.  Consternation amongst the farmers greeted that suggestion! “But, they exclaimed in horror, Dr Sue, we can’t we are married to maize!  Hopelessly naïve, I had neglected the wider cultural and socioeconomic context; I’d focussed on the physiology of the plants, my discipline, and not on the sociology of farmer behaviour, someone else’s discipline

There are ways to bridge the gap, although it may mean some scientists having to step outside their laboratories and comfort zones. A recent experiment in China where academic staff and their postgraduate students lived in farming communities and worked alongside local farmers resulted in significant increases in crop yields (Zhang et al., 2016).  Whilst not suggesting that all scientists involved in basic science with potential agricultural applications, adopt a similar approach, I would encourage them to spend some time speaking to farmers on their farms and not in workshops away from the agricultural environment.   Similarly, I would exhort ecologists with an interest in agriculture to either publish in journals more likely to be read by agronomists and farmers and not in journals that only their peers will read. Arguments in journals such as Biological Conservation, no matter how well presented or reasoned, reach a very limited audience of peers and undergraduates writing assignments. The people who make the decisions and grow our food do not read those journals. Failing that, in these days of ‘research impact’ it would make sense to take steps to summarise their findings in a more popular format such as the farming press. The workshops often mentioned in grant applications under the “pathways to impact” section will only have a limited reach and the proposed web sites, another favourite of the grant writer, unless extensively advertised and scrupulously kept up to date, again will remain largely unread.

Most importantly, use language that everyone can understand.  The farmer representing Innovate UK at the Agri-futures meeting was particularly scathing about the presentations, slickly and smoothly delivered by the obviously keen and excited scientists, remarking that most farmers would not know the word heterogeneity; keep it simple, avoid jargon, but don’t speak down to practitioners just because they don’t have the same vocabulary you do.   Emma Hamer the Senior Plant Health advisor for the National Farmers Union was just one of the many speakers from industry at the Advances in Integrated Pest Management Conference that I attended in November, who pointed out that many farmers were still unaware of exactly IPM was, even though they were practicing it to some extent.

There are agricultural scientists who do their best to step down from their ivory towers and try to make their work easily accessible.  Rothamsted Research for example, where the scientists are under immense pressure to publish in high impact journals, are doing their best to provide an effective extension service despite the swingeing cuts that have been made to their staff who work with whole organisms.  Their advocacy of the IPM concept via their app Croprotect is innovative and useful.  The UK of course is not alone in these types of ventures.  My Editorial sparked this response via email:  “I read with interest your editorial in the Annals of Applied Biology.  Our research group works strongly with State Government to convert our research into practical tools for fire management, but we struggle at the interface because each agency things that it is the responsibility of the other to do the extension work!  A better example comes from my colleagues in the crop sciences who have a very workable model in the southern hemisphere (see ).” On the other hand, we have scientists who extol the virtues of extension but publish in journals that are non-accessible to many academics and certainly beyond the ken of agronomists and farmers (Kremen, 2015).  Important commentaries on pollinators aimed at farmers and politicians (Dicks et al., 2016) are too often hidden behind ‘high impact’ paywalls and if not revealed by helpful bloggers such as Jeff Ollerton, would remain hidden away from the very people who need to know.  Other bloggers such as Manu Saunders are also on the case, debunking and/or publicising the debates surrounding sustainable agriculture, but this is not enough.  Scientists who put themselves forward as working in the agricultural sciences need to pay more heed to the ways in which farmers work, understand the farming year* and actually talk to farmers whilst in their own environment.  Perhaps not so much as being on the same page but standing in the same field.


Pleased to see that a Wordle analysis of this post puts farmers centre stage.



Bommarco, R., Kleijn, D. & Potts, S.G. (2013) Ecological intensification: harnessing ecosystem services for food security. Trends in Ecology and Evolution, 28, 230–238

Dandurand, L.M. & Knudsen, G.R. (2016) Effect of the trap crop Solanum sisymbriifolium and two biocontrol fungi on reproduction of the potato cyst nematode, Globodera pallida. Annals of Applied Biology, 169, 180-189

De Fluiter, H.J. (1962) Integrated control of pests in orchards. Entomophaga, 7, 199-206.

Dicks, L.V., Viana, B., Bommarco, R., Brosi, B., del Coro Arizmendi, M., Cunningham, S.A., Galetto, L., Hill, R.,  Lopes, A.V., Pires, C., Taki, H., & Potts, S.G. (2016) Ten policies for pollinators.  Science, 354, 975-976.

Fischer, J., Abson, D.J., Butsic, V., Chappell, M.J., Ekroos, J., Hanspach, J., Kuemmerle, T., Smith, H.G. & von Wehrden, H. (2014) Land sparing versus land sharing: moving forward. Conservation Letters, 7, 149–157

Hammond, C.M., Luschei, E.C., Boerboom, C.M. & Nowak, P.J. (2006) Adoption of integrated pest management tactics by Wisconsin farmers.  Weed Technology, 20, 756-767

Hartley, S. (2016) In praise of interdisciplinarity.  The Bulletin, 47, 5-6.

Hayhow, D.B., Burns, F., Eaton, M.A., Al Fulaij, N., August, T.A., Babey, L., Bacon, L., Bingham, C., Boswell, J., Boughey, K.L., Brereton, T., Brookman, E., Brooks, D.R., Bullock, D.J., Burke, O., Collis, M., Corbet, L., Cornish, N., De Massimi, S., Densham, J., Dunn, E., Elliott, S., Gent, T., Godber, J., Hamilton, S., Havery, S., Hawkins, S., Henney, J., Holmes, K., Hutchinson, N., Isaac, N.J.B., Johns, D., Macadam, C.R., Mathews, F., Nicolet, P., Noble, D.G., Outhwaite, C.L., Powney, G.D., Richardson, P., Roy, D.B., Sims, D., Smart, S., Stevenson, K., Stroud, R.A., Walker, K.J., Webb, J.R., Webb, T.J., Wynde, R. and Gregory, R.D. (2016) State of Nature 2016. The State of Nature partnership.

Hokkanen, H.M.T. (2015) Integrated pest management at the crossroads: science, politics or business (as usual)?  Arthropod-Plant Interactions, 9, 543-545

Karley, A.J., Mitchell, C., Brookes, C., McNicol, J., O’Neill, T., Roberts, H., Graham, J. & Johnson, S.N. (2016) Exploiting physical defence traits for crop protection: leaf trichomes of Rubus idaeus have deterrent effects on spider mites but not aphids.  Annals of Applied Biology, 168, 159-172

Kogan, M. (1998) Integrated pest management: historical perspectives and contemporary developments.  Annual Review of Entomology, 43, 243-270

Kremen C. (2015) Reframing the land-sparing/land-sharing debate for biodiversity conservation. Annals of the New York Academy of Sciences, 1355, 52–76.

McCarthy, M. (2016) The Moth Snowstorm, Hodder & Stoughton, London.

Midgely, O. (2016) Industry’s work overlooked by UK green lobby. Farmer’s Guardian, September 16, 2

Rowley, C., Cherrill, A., Leather, S., Nicholls, C., Ellis, S. & Pope, T. (2016) A review of the biology, ecology and control of saddle gall midge, Haplodiplosis marginata (Diptera: Cecidomyiidae) with a focus on phenological forecasting.  Annals of Applied Biology, 169, 167-179

Stern, V.M., Smith, R.F., Van Den Bosch, R., & Hagen, K.S. (1959) The integrated control concept. Hilgardia, 29, 81-101.

Tscharntke, T., Clough, Y., Wanger, T.C., Jackson, L., Motzke, I., Perfecto, I., Vandermeer, J. & Whitbread, A. (2012) Global food security, biodiversity conservation and the future of agricultural intensification. Biological Conservation, 151, 51–59

Webb, K.M., R.M. , Harveson, R.M. & West, M.S. (2015)  Evaluation of Rhizoctonia zeae as a potential biological control option for fungal root diseases of sugar beet.  Annals of Applied Biology, 167, 75-89

Winer, J., Griepentrog, H.W. & Kristensen, L. (2001) Suppression of weeds by spring wheat Triticum aestivum increases with crop density and spatial uniformity.  Journal of Applied Ecology, 38, 784-790.

Zhang, W., Cao, G., Li, X., Zhang, H., Wang, C., Liu, Q., Chen, X., Cui, Z., Shen, J., Jiang, R., Mi, G., Miao, Y., Zhang, F. & Dou, Z. (2016) Closing yield gaps in China by empowering smallholder farmers. Nature, 537, 671-674


Filed under Bugbears, Science writing, Uncategorized

Ideas I had and never followed up

“When I was younger, so much younger than before” I never needed any help to come up with ideas for research topics or papers.   When I was doing my PhD and later as a post-doc, I used to keep a note pad next to my bed so that when I woke up in the middle of night with an idea (which I often did) I could scribble it down and go back to sleep.  (These days sadly, it is my bladder and not ideas that wake me up in the wee small hours 🙂*)

On waking up properly, these ideas, if they still seemed sensible, would  move onto Stage 2, the literature search.  In those days, this was much more difficult than it is now, no Google Scholar or Web of Science then, instead you had to wade though the many hard-copy Abstract series and then get hard copies of the papers of interest.  Once in my hands, either via Inter-library loans or direct from the author, or even photocopied from the journal issue (we did have photocopiers in those days), the papers would be shoved into a handy see-through plastic folder (Stage 3).  Depending on how enthusiastic I was about the idea, I would then either mock-up a paper title page or put the folder in the ‘to deal with later’ pile (Stage 4).   Many of these eventually led on to Stage 5, experiments and published papers.  Others have languished in their folders for twenty or thirty years.

As part of my phased run up to retirement (2021), I have started farming out my long-term publishable (hopefully) data-sets to younger, more statistically astute colleagues and ‘publishing’ less robust, but possibly useful data on my blog site.  I have also, somewhat halfheartedly since the task is monumental, started to go through my old field and lab books that


A monumental collection of data.  The top right picture is my 20-year sycamore data set.  I estimate that there are about 7 million data points in it; of which to date only 1.6 million, give or take a million, are computerised.  I also have a ten-year bird cherry aphid data set from Scotland, waiting to go on the computer, any volunteers?

are not yet computerised.  Whilst doing this I came across some Stage 3 folders, which as you can see from the colour of the paper have languished for some time.


The Forgotten Nine


There were nine forgotten/dismissed proto-papers, the oldest of which, judging by the browning of the paper and my corresponding address, dates from the early 1980s, and is simply titled “What are the costs of reproduction?”.  This appears to have been inspired by a talk given by Graham Bell at a British Ecological Society, Mathematical Ecology Group meeting in 1983.  In case you are wondering, this was one of those meetings supposed to bring theorists and empiricists together.   It didn’t work, neither group felt able to talk to each other 🙂  The idea, inevitably based on aphid data, didn’t bear any fruit, although I do have this graph as a souvenir.  If anyone wants


In those days we used graph paper 🙂

 the data, do let me know.

Slightly later, we find the grandly titled, “Size and phylogeny – factors affecting covariation in the life history traits of aphids”.  This had apparently been worked up from an earlier version of a paper, less grandly, but no less ponderously, titled, “Size and weight: factors affecting the level of reproductive investment in aphids”.  This is based on some basic dissection data from eight aphid species and presents the relationships, or lack of, between adult weight (or surrogate measure), ovariole number, potential fecundity and the number of pigmented embryos.  As far as I can remember these are data that Paul Wellings** and I collected as a follow-up to work we had published from a side project when we were doing our PhDs at the University of East Anglia (Wellings et al., 1980).  The second title was inspired by a paper by Stephen Stearns (Stearns, 1984), who was something of a hero of mine at the time, and was, I guess, an attempt to publish pretty simple data somewhere classier than it deserved 🙂  So this one seems to be a Stage 4, almost Stage 5 idea, and may, if I have time or someone volunteers, actually get published, although I suspect it may only make it to a very minor journal under its original title.

Then we have a real oddity, “Aphids, elephants and oaks: life history strategies re-examined”.  This one as far as I remember, is based on an idea that I had about r- and k-selection being looked at from a human point of view and not the organism’s point of view.  My thesis was that an oak tree was actually r-selected as over its life-time it was more fecund than an aphid 🙂  I suspect this was going to be aimed at the Forum section of Oikos.

The next one, dates from the late-1980s, “Protandry versus protogyny: patterns of occurrence within the Lepidoptera”, and reflects the fact that females of the pine beauty moth, Panolis flammea, on which I was then working, emerge before the males (Leather & Barbour, 1983; Leather, 1984), something not often reported in Lepidoptera.  I wondered what advantage (if any) this gave P. flammea.  I planned this one as a review or forum type paper but never got beyond the title and collecting two references (Robertson, 1987; Zonneveld & Metz, 1991).  I still think this is an interesting idea, but do feel free to have a go yourselves, as again, I suspect that I won’t actually get round to it.

Finishing off my time in Scotland, is a paper simply entitled, “Egg hatch in the bird cherry aphid, Rhopalosiphum padi.” I have ten years of egg hatch data from eight trees waiting to be analysed.  This is almost certainly not worth more than a short note unless I (or a willing volunteer) tie it in with the ten years data on spring and autumn populations on the same trees 🙂 Aphid egg data although not very abundant, is probably not in great demand.  My first published paper (Leather, 1980) was about egg mortality in the bird cherry aphid and 36 years later has only managed to accrue 32 citations, so I guess not an area where one is likely to become famous 🙂

I then have four papers dating from my time as an Associate Member of the NERC Centre for Population Biology at Silwood Park.   The first is titled, “The suitability of British Prunus species as insect host plants” and was definitely inspired by my foray into counting host plant dots as exemplified by the late great Richard Southwood (Leather, 1985, 1986).  I think I was going to look at palatability measures of some sort.

The next is called ‘Realising their full potential: is it important and how many insects achieve it?”  I’m guessing that this was a sort of follow-up to my second most-cited paper ever (Leather, 1988), the story of which you can read here, if at all interested.  Most insects, even those that are pests, die before achieving anywhere near their full reproductive potential, but then so do we humans, and our population continues to grow.  So in answer to the question, I guess not and no it doesn’t matter 🙂

Also linked to insect reproduction is the next paper, which I have followed up with the help of a PhD student, and do hope to submit in the near future, “Queue positions, do they matter”.  As this one may actually see the light of day, I won’t say anything further about it.

And finally, another one about aphid eggs, “Bud burst and egg hatch synchrony in aphids”.  This one was going to be based on my then ten-year sycamore aphid data but is now based on my twenty-year data set and is now in the very capable hands of a PhD student and hopefully will see the light of day next year.

There are also a number of other folders with no titles that are just full of collections of reprints.  I can only guess at what these ideas were so won’t burden you with them.

I mentioned at the beginning of this piece that I don’t wake up in the middle of the night with ideas any more.  As we get older I think there is a tendency to worry that we might run out of ideas, especially when, as we do in the UK, suffer from ludicrously underfunded research councils with very high rejection rates that don’t allow you to resubmit failed grant applications.  It was thus reassuring to see this recent paper that suggests that all is not lost after you hit the grand old age of 30.  That said, I do believe that as you move away from the bench or field, the opportunity to be struck by what you see, does inevitably reduce.  As a PhD student and post-doc you are busy doing whatever it is you do, in my case as an ecological entomologist, counting things, and inevitably you see other things going on within and around your study system, that spark off other ideas.  It was the fear of losing these opportunities as I moved up the academic ladder, which inevitably means, less field and bench time and more time writing grant applications and sitting on committees, that I specifically set aside Monday mornings (very early mornings) to my bird cherry plots and even earlier Thursday mornings to survey my sycamore trees.   Without those sacrosanct mornings I am pretty certain I would have totally lost sight of what is humanly possible to do as a PhD student or post-doc.  This, thankfully for my research group, means that I had, and have, realistic expectations of what their output should be, thus reducing stress levels all round.   As a side benefit I got to go out in the fresh air at least twice a week and do some exercise and at the same time see the wonderful things that were going on around and about my study areas and as a bonus had the chance to get some new ideas.



Leather, S.R. (1984) Factors affecting pupal survival and eclosion in the pine beauty moth, Panolis flammea (D&S). Oecologia, 63, 75-79.

Leather, S.R. (1985) Does the bird cherry have its ‘fair share’ of insect pests ? An appraisal of the species-area relationships of the phytophagous insects associated with British Prunus species. Ecological Entomology, 10, 43-56.

Leather, S.R. (1986) Insect species richness of the British Rosaceae: the importance of host range, plant architecture, age of establishment, taxonomic isolation and species-area relationships. Journal of Animal Ecology, 55, 841-860.

Leather, S.R. (1988) Size, reproductive potential and fecundity in insects: Things aren’t as simple as they seem. Oikos, 51, 386-389.

Leather, S.R. & Barbour, D.A. (1983) The effect of temperature on the emergence of pine beauty moth, Panolis flammea Schiff. Zeitschrift fur Angewandte Entomologie, 96, 445-448.

Robertson, H.G. (1987) Oviposition and site selection in Cactoblastis cactorum (Lepidoptera): constraints and compromises. Oecologia, 73, 601-608.

Stearns, S.C. (1984) The effects of size and phylogeny on patterns of covariation inthe life history traits of lizards and snakes. American Naturalist, 123, 56-72.

Wellings, P.W., Leather , S.R., & Dixon, A.F.G. (1980) Seasonal variation in reproductive potential: a programmed feature of aphid life cycles. Journal of Animal Ecology, 49, 975-985.

Zonneveld, C. & Metz, J.A.J. (1991) Models on butterfly protandry – virgin females are at risk to die. Theoretical  Population Biology, 40, 308-321.


*I hasten to add that I do still have new ideas, they just don’t seem to wake me up any more 🙂

**Now Vice-Chancellor of the University of Wollongong



Filed under Science writing, Uncategorized

Red, green or gold? Autumn colours and aphid host choice

“The falling leaves
Drift by my window
The falling leaves
Of red and gold”


Red, green and gold, all on one tree

When Frank Sinatra sang Autumn Leaves he was almost certainly not thinking of aphids and I am pretty certain that the English lyricist, Johnny Mercer, who translated the words from the original French by Jacques Prévert wasn’t either 🙂

The colours we see in autumn are mainly due to two classes of pigment, the carotenoids (yellow-orange; think carrot) and the anthocyanins (red-purple).  Carotenoids are present in the leaves all year round but are masked by the green chlorophyll.  Chlorophyll breaks down in autumn, leaving the yellow carotenes visible.  The anthocyanins on the other hand are not formed until autumn (Sanger, 1971; Lee & Gould, 2002) and this mixture of pigments give us the colours that have inspired so many artists.


Autumn Leaves Georgia O’Keeffe (1924) Tate Modern

To many, autumn starts with the appearance of the first turning leaves, to me it is the arrival of gynoparae* of the bird cherry-oat aphid (Rhopalosiphum padi) on my bird cherry (Prunus padus) trees.


Bird cherry, Prunus padus, leaves on the turn.

Little did I know when I started my PhD in 1977 that almost thirty years later I would be part of a raging debate about the function of autumn colouration in woody plants. At the time I was interested in the colonisation patterns (or as I pretentiously termed it in my thesis ‘remigration’) of bird cherry aphids from their secondary grass and cereal host plants to their primary host bird cherry.  My study system was 30 bird cherry saplings divided between two cold frames in the Biology Compound at the University of East Anglia (Norwich).  Every day from the middle of August until leaf fall I checked every leaf of each tree, for gynoparae, males and oviparae, carefully noting the position of each leaf, its phenological stage and giving it a unique number. I repeated this in the autumns of 1978 and 1979.  The phenological stage was based on the leaf colour: green, mature; yellow, mature to senescent; red, senescent.  What I reported was that more gynoparae landed on green and yellow leaves than on red and that the gynoparae on green and yellow leaves survived for longer and produced more offspring (oviparae), than those on red leaves (Leather, 1981).   The gynoparae of the bird cherry aphid are quite special in that although as adults they do not feed (Leather, 1982), they do not land on bird cherry trees at random (Leather & Lehti, 1982), but choose trees that not only do their offspring (the oviparae) do better on, but that also favour those aphids hatching from eggs in the spring (Leather, 1986).  It should not have come as a surprise then, that when I analysed some of the data I had collected all those years ago, their preference for green and yellow leaves over red ones, is linked to how long those


Figure 1. Length of time leaves remained on tree after first colonisation by gynoparae of Rhopalosiphum padi (F = 30.1 df 2/77, P <0.001)

leaves have left to live (Figure 1). The timing of events at this time of year, has, of necessity, got to be very precise. The egg-laying females (oviparae) are unable to develop on mature bird cherry leaves (Leather & Dixon, 1981), but it seems that the bird cherry aphid has this under control, making its decisions about the timing of the production of autumn forms (morphs) sometime in August (Ward et al., 1984).  All very sensible as far as I was concerned and that was as far as I took things.  Subsequent work by Furuta (1986) supported this in that he showed that maple aphids settled on and reproduced on green-yellow and yellow-orange leaves but avoided red leaves which had shorter life spans.

Jump forward fifteen years or so, and in a paper, that at the time, had somehow passed me by, the late great Bill Hamilton and Sam Brown (Hamilton & Brown, 2001) hypothesised that trees with an intense autumn display, similarly to those brightly coloured animals that signal their distastefulness with yellows, blacks and reds, were signalling their unsuitability as a host plant to aphids.  Like the costs imposed on insects that sequester plant toxins to protect themselves against predators, the production of anthocyanins responsible for the red autumn colouration is expensive, especially when you consider that the leaves have only a short time left to live (Hoch et al., 2001).  In autumn, trees and woody shrubs are normally mobilising resources in the leaves and moving them back into themselves ready to be used again the following spring (Dixon, 1963). Ecologists and evolutionary biologists were thus keen to explain the phenomenon in terms of trade-offs, for example, fruit flags that advertise the position of fruits for those trees that rely on seed dispersal by vertebrates (Stiles, 1982) or as ultra-violet screens to prevent tissue damage (Merzlyak & Gittelson, 1995).  Hamilton & Brown felt that these hypotheses were either, in the case of the fruit flag, only applicable to trees with fruit present and, in the latter, untenable. Instead they advocated the ‘signalling hypothesis’ which was based on the premise that trees that suffer from a lot of aphids (attacked by more than one species rather than by large numbers of a single species), invest in greater levels of defence and in autumn advertise this using bright warning colours.   The premise being, that although it is metabolically expensive for the plants to produce these colours, it is worth the investment if they result in a reduction in aphid attack.

This hypothesis was not without its detractors. Others suggested, that far from avoiding red colours, aphids were attracted to yellow or green as an indicator of host nutrition (Wilkinson et al., (2002).  Holopainen & Peltonen (2002) also suggested that birch aphids use the onset of autumn colours to pick out those trees where nutrient retranslocation was happening, and thus with higher levels of soluble nitrogen in the leaves.  This was of course, what I was trying to confirm back when I was doing my PhD.  Conversely, supporters of the signalling hypothesis, argued that trees (birch again) that could ‘afford’ to produce bright autumn colours were fitter, so more resistant in general and that they were warning potential herbivores of this by a bright autumn display (Hagen et al 2004).

Round about this time (2002), I was approached by a young Swiss researcher, Marco Archetti, who knew that I had a plot of sixty bird cherry trees that I had planted up when I arrived at Silwood in 1992, originally designed to follow-up some work that I had begun whilst at the Forestry Commission looking at the effects of early season defoliation on subsequent tree growth (Leather, 1993, 1995).  Marco convinced me that I had the ideal set-up to test the ‘signalling hypothesis’ and what was to be a very fruitful collaboration began.

We counted arriving gynoparae and their offspring (oviparae) throughout October (Marco making trips over from Oxford where he was then based**) noting leaf colour before and after each count.  As with my PhD work we found that the greener trees were preferentially colonised by the gynoparae and that more oviparae were produced on those trees and that given what I had found earlier that bird cherry aphid gynoparae chose trees that are good hosts in spring (Leather, 1986), Marco felt that we were able to support the honest signalling hypothesis (Archetti & Leather, 2005).  I was slightly less comfortable about this, as there are only two species of aphid that attack bird cherry and one of those is very rare and the original signalling hypothesis was based on the premise that it was trees that were attacked by a lot of aphid species that used the red colouration as a keep clear signal.  Anyway, it was published 🙂

That said, others agreed with us, for example, Schaefer & Rolshausen (2006) who called it the defence indication hypothesis, arguing that bright colours advertise high levels of plant defence and that the herbivores would do well to stay away from those plants displaying them. On the other hand, Sinkkonen (2006) suggested that reproductively active plants produce autumn colours early to deter insects from feeding on them and thus reduce their seed set.

Chittka & Döring (2007) on the other hand, suggested that there is no need to look further than yellow carotenoids acting as integral components of photosynthesis and protection against light damage and red anthocyanins preventing photo-inhibition (Hoch et al., 2001) as to why trees turn colourful in autumn.  In other words, nothing to do with the insects at all.  A couple of years later however, Thomas Döring and Marco got together with another former colleague of mine from Silwood Park, Jim Hardie, and changed their minds slightly.  This time, whilst conceding that red leaves are not attractive to aphids but noting that yellow leaves are even more attractive than green ones, suggested that the red colour could be being used to mask yellow (Döring et al., 2009).

Others have their own pet theories.  In recent years, veteran Australian entomologist Tom White has become interested in the concept of insect species that specifically feed on senescent plant tissue (White, 2002, 2015) and added to the debate by suggesting that aphids in general are senescence feeders and thus choose green and yellow as they have longest time to live and that the red leaves are also nitrogen depleted (White, 2009) which is supported by my PhD data (Figure 1).  This resulted in a spirited response by Lev-Yadun & Holopainen (2011) who claimed that he had misunderstood the scenario in thinking that leaves go sequentially from green to yellow to red, which they suggest is rare (I question this) and that actually in trees that go from green to red, the leaves still contain significant amounts of nitrogen, so a deterrent signal is still required.


Maple, green to yellow in this case


Spindle, Euonymus europaeus, green to red

What about those trees and other plants that have red or purple leaves in the spring or all year round and not just in autumn?


Some trees have red foliage all year

Trees like some of the ornamental cherries or copper beech? I haven’t been able to find any papers that suggest that red or purple-leaved varieties of beech and cherries are less susceptible to aphid attack.  My own observations, probably imperfectly recalled, are that copper beech is regularly infested by the beech woolly aphid, Phyllaphis fagi , and just as heavily, if not more so than the normal green-leaved  beech trees.  That of course may just be a reflection that the white waxy wool covering the aphid stands out more against the red leaves.  Perhaps someone out here might like to check this out?  Some work that my friend and former colleague, Allan Watt, (sadly unpublished) did many years ago in Scotland looking at the effect of beech species and cultivar on infestation levels by the beech leaf mining weevil, Rhynchaenus fagi, did not indicate any differences between copper and green cultivars.  It does seem however, that in cabbages, leaf colour can tell the specialist cabbage aphid, Brevicoryne brassciae, if plants are well defended or not, the bluer the cabbage, the nastier it is (Green et al, 2015).

To summarise:

  1. Red leaves are produced by the trees in autumn to reduce ultraviolet damage and protect metabolic processes in the leaf.
  2. Red leaves are deliberately produced by the tree to warn aphids that their leaves are well defended – honest signalling.
  3. Red leaves are produced by the tree to ‘fool’ the herbivores that the leaves are likely to drop soon and warn them to keep away so as to safeguard their fruit – dishonest signalling.
  4. The tree is blissfully unaware of the aphids and the aphids are exploiting the intensity of the autumn colours produced by the trees to select which are the best trees to colonise in terms of nutrition and length of time left on the tree.

As I write, the debate still goes on and we seem no nearer to arriving at a definitive answer to the riddle of why trees produce bright leaves in autumn.  If nothing else however, the debate has generated a lot of interest and enabled people to sneak some amusing titles into the scientific literature.  Do make the effort to read the titles of some of the references below.


Archetti, M. (2009) Phylogenetic analysis reveals a scattered distribution of autumn colours. Annals of Botany, 103, 703-713.

Archetti, M. & Leather, S.R. (2005) A test of the coevolution theory of autumn colours: colour preference of Rhopalosiphum padi on Prunus padus.  Oikos, 110, 339-343.

Chittka, L. & Döring, T.F. (2007) Are autumn foliage colors red signals to aphids? PLoS Biology , 5(8): e187. Doi:10.1371/journal.pbio.0050187.

Dixon, A.F.G. (1963) Reproductive activity of the sycamore aphid, Drepanosiphum platanoides (Schr) (Hemiptera, Aphididae). Journal of Animal Ecology, 32, 33-48.

Döring, T.F., Archetti, M. & Hardie, J. (2009) Autumn leaves seen through herbivore eyes.  Proceedings of the Royal Society London B., 276, 121-127.

Furuta, K. (1986) Host preferences and population dynamics in an autumnal population of the maple aphid, Periphyllus californiensis Shinji (Homoptera: Aphididae). Zeitschrift fur Angewandte Entomologie, 102, 93-100.

Green, J.P., Foster, R., Wilkins, L., Osorio, D. & Hartley, S.E. (2015) Leaf colour as a signal of chemical defence to insect herbivores in wild cabbage (Brassica oleracea).  PLoS ONE, 10(9): e0136884.doi:10.1371/journal.pone.0136884.

Hagen, S.B. (2004) Autumn coloration as a signal of tree condition. Proceedings of the Royal Society London B, 271, S184-S185.

Hamilton, W.D. & Brown, S.P. (2001) Autumn tree colours as handicap signal. Proceedings of the Royal Society London B, 268, 1489-1493.

Hoch , W.A.,  Zeldin, E.L. & McCown, B.H. (2001) Physiological significance of anthocyanins during autumnal leaf senescence. Tree Physiology, 21, 1-8.

Holopainen, J.K. & Peltonen, P. (2002) Bright colours of deciduous trees attract aphids: nutrient retranslocation hypothesis.  Oikos, 99, 184-188.

Leather, S.R. (1981) Reproduction and survival: a field study of the gynoparae of the bird cherry-oat aphid, Rhopalosiphum padi (L.). Annales Entomologici Fennici, 47, 131-135.

Leather, S.R. (1982) Do gynoparae and males need to feed? An attempt to allocate resources in the bird cherry-oat aphid Rhopalosiphum padiEntomologia experimentalis et applicata, 31, 386-390.

Leather, S.R. (1986) Host monitoring by aphid migrants: do gynoparae maximise offspring fitness? Oecologia, 68, 367-369.

Leather, S.R. (1993) Early season defoliation of bird cherry influences autumn colonization by the bird cherry aphid, Rhopalosiphum padi. Oikos, 66, 43-47.

Leather, S.R. (1995) Medium term effects of early season defoliation on the colonisation of bird cherry (Prunus padus L.). European Journal of Entomology, 92, 623-631.

Leather, S.R. & Dixon, A.F.G. (1981) Growth, survival and reproduction of the bird-cherry aphid, Rhopalosiphum padi, on its primary host. Annals of Applied Biology, 99, 115-118.

Leather, S.R. & Lehti, J.P. (1982) Field studies on the factors affecting the population dynamics of the bird cherry-oat aphid, Rhopalosiphum padi (L.) in Finland. Annales Agriculturae Fenniae, 21, 20-31.

Lee, D.W. & Gould, K.S. (2002) Anthocyanins in leaves and other vegetative organs: An introduction. Advances in Botanical Research, 37, 1-16.

Lev-Yadun, S. & Holopainen, J.K. (2011) How red is the red autumn leaf herring and did it lose its red color? Plant Signalling & Behavior, 6, 1879-1880.

Merzlyak, W.N. & Gittelson, A. (1995) Why and what for the leaves are yellow in autumn? On the interpretation of optical spectra of senescing leaves (Acer platanoides L.). Journal of Plant Physiology, 145, 315-320.

Sanger, J.E. (1971) Quantitative investigations of leaf pigments from their Inception in buds through autumn coloration to decomposition in falling leaves.  Ecology, 52, 1075-1089.

Schaefer, H.M. & Rolshausen, G. (2006) Plants on red alert – do insects pay attentionBioEssays, 28, 65-71.

Sinkkonen, A. (2006) Do autumn leaf colours serve as reproductive insurance against sucking herbivores?  Oikos, 113, 557-562.

Stiles, E.W. (1982) Fruit flags: two hypotheses. American Naturalist, 120, 500-509.

Ward, S.A., Leather, S.R., & Dixon, A.F.G. (1984) Temperature prediction and the timing of sex in aphids. Oecologia, 62, 230-233.

White, T.C.R. (2003) Nutrient translocation hypothesis: a subsect of the flush-feeding/senescence-feeding hypothesis. Oikos, 103, 217.

White, T.C.R. (2009) Catching a red herring: autumn colours and aphids. Oikos, 118, 1610-1612.

White, T.C.R. (2015) Senescence-feesders: a new trophic subguild of insect herbivore. Journal of Applied Entomology, 139, 11-22.

Wilkinson, D.M., Sherratt, T.N., Phillip, D.M., Wratten, S.D., Dixon, A.F.G. & Young, A.J. (2002) The adaptive significance of autumn colours.  Oikos, 99, 402-407.


 *for a detailed account of the wonderful terminology associated with aphid life cycles read here

**coincidentally he is now a Lecturer at the University of East Anglia in the same Department where I did my PhD


Filed under Aphidology, Aphids, Science writing

Data I am never going to publish in peer-reviewed journals

I have got to that stage in my career where retirement is no longer a distant speck on the horizon; something that 20 years ago I never even thought about, but which now I am actually looking forward to reaching. Don’t get me wrong, I have, in the main, enjoyed what I have been paid to do for the last 40 years, but I’m looking forward to a change of pace and a change of priorities. I’m not planning on leaving entomology and ecology, or putting my collecting equipment in a cupboard, throwing my field guides away and burning all my reprints in a huge bonfire. Nor do I plan on deleting my EndNote™ files and database when I retire to our house in Languedoc-Roussillon to sit next to the pool with a never-emptying glass of red wine and gently pickle myself in the sun*. I’m just looking forward to approaching it in a different way; my plan is to stop initiating the writing scientific papers, but instead to expand on the outreach, to blog more and to write books for a wider audience. I want to spread the joys and wonders of entomology to the world, and hopefully, supplement my pension a bit to make sure that I can keep that glass filled with red wine and heat the swimming pool in the winter 🙂

I’m planning a gradual retirement, a slow(ish) canter towards the day (September 30th 2020) when I finally vacate my university office and move full-time into my converted attic in the Villa Lucie surrounded by my books and filing cabinets with a superb view of the mountains.


The view from my study to be – I will have to stand up to see it, but exercise is good for you 🙂

I have already reached a number of milestones, I took on my last ever PhD student (as Director of Studies) this month (June 7th) and submitted my final grant application as a PI (June 10th).


I must admit that it is a bit of funny feeling, but a remarkably rewarding one in many ways. I look at my former colleagues who have already retired productively and enjoyably, and I’m envious, so I know that I am making the right decision despite the slight feeling of apprehension. I now have a dilemma. As Jeff Ollerton points out, when you have been around a while, in my case it is almost 40 years since I started my PhD**, you build up a substantial amount of data, especially, if as I have, you have supervised over 150 undergraduate research projects, an equal number of MSc research projects and over 50 PhD students. Much of these data are fragmentary, not significant or even lost (sadly when I moved from Imperial College, they threw away the hard copies of my undergraduate projects, although I can remember what some of the lost data were about). My ten year sycamore and bird cherry aphid field study from my time in Scotland (1982-1992) remains largely unpublished and my huge twenty year sycamore herbivores data set from Silwood Park (1992-2012) is in the same boat, although parts of the data are ‘out on loan’ to former students of mine and I hope will be analysed and published before I retire.

This leaves however, the data, some of it substantial, which I would like to see the light of day, e.g. a whole set of rabbit behaviour data that I collected one summer with the help of an undergraduate and MSc student, which surprisingly revealed novel insights. Other data, perhaps not as novel, may be of interest to some people and there is a whole bunch of negative and non-significant data, which as Terry McGlynn highlights over on Small Pond Science, does not necessarily mean that it is of no use.   I have, as an example of fragmentary, not entirely earth-shattering data, the following to offer. Whilst monitoring aphid egg populations on bird cherry and sycamore trees, in Scotland between 1982 and 1992, I occasionally sampled overwintering eggs of Euceraphis betulae, on some nearby birch (Betula pendula) trees and of Tuberculoides annulatus, on an oak tree (Quercus robur) in my back garden in Peebles.

As far as I know there are no published data on the overwintering egg mortality of these two aphids. Although novel for these two aphid species, the observation of the way the egg populations behave over the winter and the factors causing the mortality have already been described by me for another aphid species (Leather, 1980, 1981). I am therefore unlikely to get them published in any mainstream journal, although I am sure that one of the many predatory journals out here would leap at the chance to take my money and publish the data in the Journal of Non-Peer-Reviewed Entomology 🙂 I could of course publish the data in one of the many ‘amateur’ type, but nevertheless peer-reviewed journals, such as Entomologist’s Monthly Magazine, The Entomologist’s Record, The Entomologist’s Gazette or the British Journal of Entomology & Natural History, which all have long and distinguished histories, three of which I have published in at least once (Leather & Brotherton 1987, Leather, 1989, 2015), but which have the disadvantage of not being published with on-line versions except for those few issues that have been scanned into that great resource, The Biodiversity Heritage Library, so would remain largely inaccessible for future reference.

I thus offer to the world these data collected from four Betula pendula trees in Roslin Glen Nature Reserve in Scotland between 1982 and 1986. On each sampling occasion, beginning at the end of October, 200 buds were haphazardly selected and the number of eggs present in the bud axils recorded. Sampling continued until egg hatch began in the spring.


Figure 1. Mean number of eggs per 100 buds of the aphid Euceraphis betulae present on four Betula pendula trees at Roslin Glen Nature Reserve Scotland***.

The number of eggs laid on the trees varied significantly between years (F = 20.3, d.f. = 4/15, P <0.001) ranging from 12.75 eggs/100 buds in 1983-84 to 683 eggs/100 buds in 1986-87. Mortality occurred at a regular rate over the winter and ranged from between 60% in 1985-86 to 83 % in 1984-85, averaging out at 74% over the five-year study.

So in conclusion, no startling new insights, but just some additional data about aphid egg mortality to add to the somewhat sparse records to date (Leather, 1992). Perhaps it is time for me to write another review 🙂


Leather, S.R. (1980) Egg survival in the bird cherry-oat aphid, Rhopalosiphum padi. Entomologia experimentalis et applicata, 27, 96-97.

Leather, S.R. (1981) Factors affecting egg survival in the bird cherry-oat aphid, Rhopalosiphum padi. Entomologia experimentalis et applicata, 30, 197-199.

Leather, S.R. (1986) Insects on bird cherry I. The bird cherry ermine moth, Yponomeuta evonymellus (L.). Entomologist’s Gazette, 37, 209-213.

Leather, S.R. (1989) Phytodecta pallida (L.) (Col.,Chrysomelidae) – a new insect record for bird cherry (Prunus padus). Entomologist’s Monthly Magazine, 125, 17-18.

Leather, S.R. (1992) Aspects of aphid overwintering (Homoptera: Aphidinea: Aphididae). Entomologia Generalis, 17, 101-113.

Leather, S.R. (2015) An entomological classic – the Pooter or insect aspirator. British Journal of Entomology & Natural History, 28, 52-54.


*although in light of the recent horrific BREXIT vote this may now not be as simple as it might have been 😦

**I must confess that I haven’t actually published all the data that I collected during my PhD. I rather suspect that this will never see the light of day 🙂

***Data from 1986-87 are not shown as their inclusion makes it very difficult to see the low years. I can assure you however, that the mortality rate shows the same patterns as the other years.



Filed under EntoNotes, Science writing

Does naming your study animals introduce observer bias?

I think, that most, if not all entomologists, will confess to a bit of funding envy when talking with those of their colleagues who work with the “undeserving 3%”, the large charismatic mega-fauna and the modern dinosaurs. The terminology gives us away, although the evidence is overwhelmingly on our side (Leather, 2009).  As entomologists, particularly those of us working in the field, we are used to reporting numbers collected in the tens of thousands (Ramsden et al., 2014 ), if not the hundreds of thousands (Missa et al., 2009) and  even a short six-week study can result in the capture of thousands of ground beetles (Fuller, et al., 2008).  Naming our subjects, much as we love them, is not an option, even if we wanted to. Even behavioural entomologists counting individual flower visits by pollinators are used to dealing with hundreds of individuals.   In the laboratory, although numbers may be smaller, say tens, we still assign them alphanumeric codes rather than names, even though one might look forward to counting the number of eggs laid by the unusually fecund moth #17 or hope that aphid #23 will be dead this morning as she is becoming a pesky outlier for your mortality data 🙂

Our colleagues who work with mammals in the field, seem however to adopt a different strategy. It appears quite common for them to name their animals as the following examples from Twitter make clear.


From her dissertation field note book, Erin Kane @Diana_monkey but not yet published.

Published data in McGraw et al., (2016) are from another study where the animals are not named.


Anthropomorphic judgement values


Anne being very involved with her cheetahs, although the paper (Hillborn et al., 2012) does not mention them by name.



Another example of subjects with names Hubel et al., 2016), but this time named in the paper.


Although in the description of methodology and results animals are referred to as subjects, the Table gives it away! (Allritz et al., 2016).


Another example of named subjects (Stoinski et al., 2003).


More named subjects (Dettmer & Fragaszy, 2000), but as these were captive the names almost certainly not chosen by the observers.


In this case (Blake et al., 2016), use no human-based names either in the methods or tables, so exemplary, although of course I have not seen their field note books 🙂

My concern, highlighted by these examples, is that by naming their study animals, the observers are anthropomorphising them and that this may lead them to inadvertently bias their observations. After all, the names have not been chosen at random, and thus could influence the behaviours noted (or ignored). I say ignored, because of two very specific examples, there are more, but I have these two to hand.

Victorians used birds as examples of good moral behaviour, erroneously believing them to be monogamous, probably because of seeing the way they fed their chicks cooperatively. Tim Birkhead (2000)* quotes the Reverend Frederick Morris who in 1853 preached  “Be thou like the dunnock – the male and female impeccably faithful to each other,”  and goes on to point out that despite a hundred years of ornithological science it was not until the late 1960s that  the promiscuous behaviour of female birds was revealed, interestingly enough coinciding with the new moral code of the 1960s.

Descriptions of penguin homosexual behaviour and their penchant for acts of necrophilia so shocked George Levick’s publishers that they removed them from his 1915 report but printed them and privately distributed them to selected parties marked as “Not for Publication” (Russell et al., 2012).  He also transcribed his descriptions of this ‘aberrant’ behaviour in Greek in his notebooks, presumably to make it less accessible.

And finally from me, this recent report about ‘sacred and ritualistic’ behaviour in chimpanzees Kuhl et al (2016),   where, I feel the authors have really allowed themselves to over-anthropomorphise with their subjects, very much to the detriment of scientific  detachment.  I have yet to find an entomologist who agrees with their interpretation.

AND NOW SOMETHING NEW for my blog, an embedded comment/riposte. I thought that it would be useful to get a response from someone who works on large charismatic mega-fauna and who names their subjects.  Anne Hilborn, whom many of you will know from Twitter as @AnneWHilborn, has kindly agreed to reply to my comments.  In the spirit of revealing any possible conflicts of interest I should say that I taught Anne when she was an Ecology MSc student at Silwood Park 🙂

Over to you Anne…..

“Hello, my name is Anne and I name my study animals.”

Decades ago this might have gotten me jeered out of science, the assumption being that by naming my study animals I was anthropomorphizing them and that any conclusions I drew about their behavior would be suspect. Thankfully we (at least those of us who have the privilege of working on megafauna) have moved on a bit in our thinking and our ways of doing science.

There are two parts to Simon’s concern about naming study animals. One is that naming leads to anthropomorphization, the second is that the anthropomorphizing leads to biased science. I would argue that the naming of study animals doesn’t necessarily increase anthropomorphism. On the Serengeti Cheetah Project we don’t name cheetahs until they are independent from their mother (due to a high mortality rate).  During my PhD fieldwork I spent a lot of time following a young male known as HON752MC (son of Strudel).  Several months after I started my work he was named Boke. My interest in his behavior, my chagrin at his failures and happiness when he had a full belly didn’t change when he was named. Many of us get emotionally attached on some level to our study animals, whether they have names or numbers.

An interesting thing to ponder is that if naming does lead to anthropomorphizing, does it only happen when human names are used? What human characteristics am I likely to attach to cheetahs named Peanut, Muscat, Strudel, Fusili, or Chickpea?


As to whether anthropomorphism leads to biased science… it definitely can if, as Simon points out, certain behaviors are not recorded because they do not fit the image of the animal the researcher had in their head. I don’t have any data on this, but I suspect this is extremely rare now days. Almost all researchers have had extensive formal training and know the importance of standardized data collection. I study cheetah hunting behavior, and I record how long a cheetahs spends spend stalking, chasing, killing, and eating their prey. I record the number of animals in the herd they targeted, how many second the cheetah spends eating vs being vigilant, and at what time they leave the carcass. No matter my personal feelings or attachments to an individual cheetah, the same data gets recorded.

Research methods have advanced a lot in the past decades and we use standardized methodologies and statistics expressly to prevent bias in our results. Anthropomorphism is just one possible source of bias, others include wanting to prove a treasured hypothesis, the tendency to place plots in areas where you suspect you will get the best results, etc..

As Adriana Lowe (@adriana_lowe ) puts it “Basically, if you’ve got a good study design and do appropriate stats, you can romanticise the furry little buggers until the cows come home and it won’t have a massive effect on your work. Any over interpretation of results would get called out by reviewers when you try to publish anyway.”

Simon points out examples of people being shocked when birds didn’t follow the dictates of contemporary human morality. I would like to think that biologists no longer place human values on animals. I can admire hyenas because the females are bigger bodied and socially dominant to males, but that doesn’t mean I draw parallels or lessons from them to human society (not in the least because the females give birth through their elongated clitoris and the cubs practice siblicide). As scientists we are capable of compartmentalizing, of caring deeply for our subjects, of shedding a tear when Asti turns up with one cub when previously she had five, without that changing the way we record data. In our training as biologists, we are taught not impose our own feelings or values on our study animals. We may find infanticide in lions (Packer and Pusey 1983), extra pair copulations in birds and primates (Sheldon 1994, Reichard 1995), or siblicide in boobies (Anderson 1990) to be repugnant, but we record, analyze, and try to publish on the phenomenon all the same.

To go on the offensive, there are ways naming study animals actually improves data collection.

Again, Adriana Lowe “If you’re doing scan sampling for instance, so writing down all individuals in a certain area every 10 minutes or so, names help. At least for me, it’s harder to remember if someone is M1 or M2 than Janet or Bob, particularly if you have a big study troop/community. So it can improve the quality of the data collected if you’re less likely to make identification errors.”

Because of our own training and peer review, assigning emotions or speculating about the intent on animals rarely makes it into scientific papers. However the situation is very different for those of us who wish to present our results outside of the ivory tower. While fellow scientists might be willing to wade through dry descriptions about how M43 contact called 3 times in 4 minutes when he was no longer in visual contact with M44, the public is not. Effective science communication needs a story and an emotional hook to draw people in. It is much easier to do that when you tell a story about Bradley and Cooper and not M43 and M44.  I will admit this does get into grey areas with the type of language we use outside of scientific papers. I tell stories about the cheetahs in my blog posts and even assign emotions to individuals. But if I am answering questions from the media or the public, I am still very careful not to make any definitive claims about behavior that haven’t been backed up by statistical analysis.


Here I use language and make assumption in tweets that I never would in a scientific paper.


There are a lot of issues that negatively affect the objectivity of science ie. the majority of funding going to well established entrenched researchers, papers being reviewed primarily by people from the same school of thought, the increasing pressure to have flashy results that generate headlines, but naming of study animals is not high on the list.


So now, over to you the readers, what do you think? Please comment and share your views or at the very least, please cast your vote.





Allritz, M., Call, J. & Borkenau, P. (2016) How chimpanzees (Pan troglodytes) perform in a modified emotional Stroop task. Animal Cognition, 19, 435-449.

Anderson, D. J. (1990) Evolution of obligate siblicide in Boobies. 1. A test of the insurance-egg hypothesis. American Naturalist, 135, 334–350.

Birkhead, T. (2000) Promiscuity: An Evolutionary History of Sperm Competition and Sexual Conflict. Faber, London.

Blake, J.G., Mosquera, D., Loiselle, B.A., Swing, K., Guerra, J. & Romo, D. (2016) Spatial and temporal activity patterns of ocelots Leopardus pardalis in lowland forest of eastern Ecuador.  Journal of Mammalogy, 97, 455-463.

Dettmer, E., and Fragaszy, D. 2000. Determining the value of social companionship to captive tufted capuchin monkeys (Cebus apella). Journal of Applied Animal Welfare Science, 3, 293-304

Fuller, R. J., Oliver, T. H. & Leather, S. R. (2008). Forest management effects on carabid beetle communities in coniferous and broadleaved forests: implications for conservation. Insect Conservation & Diversity 1, 242-252.

Hillborn, A., Pettorelli, N., Orme, C.D.L. & Durant, S.M. (2012) Stalk and chase: how hunt stages affect hunting success in Serengeti cheetah. Animal Behaviour, 84, 701-706

Hubel, T.Y., Myatt, J.P., Jordan, N.R., Dewhirst, O.P., McNutt, J.W. & Wilson, A.M. (2016) Energy cost and return for hunting in African wild dogs and cheetahs. Nature Communications, 7, 11034 DOI:doi:10.1038/ncomms11034

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Leather, S. R. (2009). Taxonomic chauvinism threatens the future of entomology. Biologist, 56, 10-13.

McGraw, W.S., van Casteren, A., Kane, E., Geissler, E., Burrows, B. & Dsaegling, D.J. (2016) Feeding and oral processing behaviors of two colobine monkeys in Tai Forest, Ivory Coast.  Journal of Human Evolution, in press.

Missa, O., Basset, Y., Alonso, A., Miller, S.E., Curletti, G., M., D.M., Eardley, C., Mansell, M.W., & Wagner, T. (2009) Monitoring arthropods in a tropical landscape: relative effects of sampling methods and habitat types on trap catches. Journal of Insect Conservation, 13, 103-118.

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Post script

I said that entomologists don’t name their study animals but they do name their pets. Some of our PhD students had an African flower


Soulcleaver; despite his name he seems quite cute when viewed side-on, perhaps even with a cheeky grin, although as an entomologist I couldn’t possibly say that 🙂

beetle, Mecynorhina ugandiensis, which they named Soulcleaver, and I know that some beekeepers name their Queens


*note that Tim Birkhead also falls into the very trap that he describes by using the word promiscuous in the title of his book, a human judgemental term relating to moral behaviour, multiple mating would have been more appropriate.





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When frustration becomes serendipitous – My second most cited paper

For most of the 1980s and the early 1990s I worked for the UK Forestry Commission as a research and advisory entomologist. As a civil servant I was subjected to a lot more rules than I am now as a university academic. The most frustrating set of rules in my mind, were those associated with publishing papers. The initial consultation with a statistician before your experiment was planned and any subsequent collaboration with the analysis was very sensible, and I had no problems with that part of the process at all. Our statisticians were very good in that they helped you decide the analysis but expected you to learn GenStat (the Forestry Commission standard statistics programme) and do it yourself unless you were really stuck.

The next bit was the frustrating part. When it came to writing papers you first submitted your paper to your line manager. They then read your paper, very frustrating indeed for me, as my immediate boss considered papers a very low priority and it could be several months before he got around to passing it back with comments and suggestions. Then it was passed to a member of one of the other department such as silviculture, tree breeding or pathology for them to read and make comments. The idea behind this being that it helped make the paper accessible to a wide audience, again a good idea. The problem at this stage was that once again your paper was likely to be a low priority, so yet more delay. Once that was done you then had to submit your paper to the Chief Research Office for him to read and comment on, so once again yet more delay. This meant that quite often it was a year before you actually were able to submit your paper to a journal, which could be deeply frustrating to say the least.


In 1986 a new journal to be published by the British Ecological Society was announced, Functional Ecology. In those days, the dreaded Impact Factors had not yet raised their ugly heads, and one tended to publish in journals relevant to your discipline, or, as in this case, the fancy took you.  I thought it would be cool to publish in the first issue of the first volume of this new journal.  I therefore set to work, with the help of one of our statisticians to produce a paper about life history parameters of the pine beauty moth, from a more ecological point of view and not from the more applied view-point of it as a forest pest (my job remit). I was very proud of the paper and confess to having got somewhat carried away in the discussion, so much so, that it was suggested by all who read it in the very lengthy internal appraisal process, that most of the discussion should be cut as being too far away from the main story. As the process had taken so long already I decided to go with the flow and eventually submitted my paper about a year after first writing it, incidentally giving my statistician a co-authorship. It was accepted and did indeed appear in the first volume of Functional Ecology, albeit the last of the year (Leather & Burnand, 1987)! It has to date (14th October 2015) being cited 53 times, by no means a disgrace, but certainly not my second-most cited paper.

I mentioned earlier that I was really proud of my discussion and I decided that I was going to publish it regardless. I reworked it slightly and submitted it to Oikos as a Forum piece, taking the calculated risk of not submitting it through the official Forestry Commission system. My reasoning was, that a), it was unlikely to be read by anyone in the Forestry Commission, being a very ecological journal, and b), if challenged I would say that it had already been seen by the powers that be, albeit not officially. To my relief it was accepted as is (Leather, 1988) and my immediate boss never mentioned it. To my surprise and delight this is now my second-most cited paper, having so far acquired 207 citations and still picks up a reasonable number of cites every year. I guess that I should actually be grateful to all those internal referees who insisted that I cut my discussion down so drastically.


Leather, S.R. (1988) Size, reproductive potential and fecundity in insects: Things aren’t as simple as they seem. Oikos, 51, 386-389.

Leather, S.R. & Burnand, A.C. (1987) Factors affecting life-history parameters of the pine beauty moth, Panolis flammea (D&S): the hidden costs of reproduction. Functional Ecology, 1, 331-338.


Post script

In case you wondered, my most cited paper is an Annual Review paper, written with one of my former PhD students, Caroline Awmack, and now has almost a thousand citations (994 as of today).


Awmack, C. S. &Leather, S. R. (2002). Host plant quality and fecundity in herbivorous insects. Annual Review of Entomology 47, 817-844.



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Journals of Irreproducible Research – downgrading reproducibility and fact checking

As far as I am concerned, good science is about communication and reproducibility, or, as Stephen Heard argues, at least being able to believe that it is reproducible.  I would argue a bit more strongly than Stephen, in that I think you should, at the very least, be able to be confident that you could reproduce the experiment without having to contact the author(s) and that you can also easily check the cited literature.   In this context, there are two things that really annoy me about some of the so-called ’high impact’ established print journals and their on-line would be rivals.  First, the way in which the methods and materials section is relegated to the end of the paper, often in smaller font, and in some cases to the supplementary material section  In other journals e.g. Nature, the methods section is also very minimal and I defy anyone to repeat those experiments!  My second bugbear is the habit that some journals have, possibly to reduce space, in making you use numbers to denote references, placing them either in parentheses or superscript in the main text.

Perhaps I am alone in this, but I do like to know whose work is being cited without having to constantly refer to the references section.  What  particularly annoys me, are those journals that not only insist on numbered references but then list them in number order and not in alphabetical order!  I once wrote a review paper for Annual Review of Entomology, which has the numbering system, but subverted it by listing my references alphabetically – the editor never noticed 😉

You may say that what all these journals are doing is merely structuring the paper in the order that people tend to read them which is, I admit, a valid point. To me however, they are saying to the scientific community, perhaps not overtly, but certainly subliminally, that methods and materials are something you don’t really need to bother about, somewhat akin to those things that you store in an attic or basement, just in case you might want them at some time in the future, but probably not often, if at all.

Hidden methods

This sends a strong and erroneous message to authors that despite the methodology being the most important part of how we do our science, as long as they report the general gist of how they did things it is fine.  To referees the subversion of the methods section sends an equally strong signal; you don’t really need to spend a lot of time reading about the methodology as long as the rationale for the work is justified and that the results are significant and well presented.

As someone who works on insect-plant interactions I constantly come across inadequate methods and materials sections both as a referee and as a reader of published work.  The thing that perhaps causes me the most annoyance are descriptions of plant phenology.   Herbivorous insects have a very intimate relationship with their host plants and the growth stage of their host plant or the age of the plant tissue that they are feeding on can have very marked effects on their development, survival and fecundity (Awmack & Leather, 2002).  I so often came across methods descriptions along the lines of “10 day-old cabbage seedling” “ 3 week old pepper plant”,  “2 week-old wheat plant”, that in desperation I wrote an editorial (Leather, 2010) explaining how important it was to use a measure that didn’t depend on the temperature,  photoperiod, nutrient or water status that the plants were grown at i.e. the BCCH scale.  I also compiled a virtual issue of Annals of Applied Biology, with relevant examples drawn from the journal which has a long and distinguished history in publishing such articles.  If you can’t find your host plant in past issues of the Annals you will find that most plants have a published version somewhere, even if only on Wikipedia.  Despite my efforts however, I still often have to remind authors to describe the phenological stage of their host plants accurately and precisely.

Methods and materials, please come back, we need you!



Awmack, C. S. & Leather, S. R. (2002). Host plant quality and fecundity in herbivorous insects. Annual Review of Entomology 47, 817-844.

Leather, S. R. (2010). Precise knowledge of plant growth stages enhances applied and pure research. Annals of Applied Biology 157, 159-161.



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