Tag Archives: UK

An unintended consequence – Maris Huntsman: A great choice for entomological careers but not so good for farmers

I could have used Sod’s Law or Murphy’s Law as the lead in for this article, but as you will see (if you keep on reading), this story isn’t all doom and gloom 😊. During the 1960s, cereal growers in the UK and on mainland Europe, were subjected to onslaughts on two fronts, yellow rust* ((Puccinia striiformis) (Doling & Doodson, 1968) and cereal aphids (Fletcher & Bardner, 1969; Kolbe, 1969).  Although cereal aphids had been a sporadic problem in Europe for several decades previously (Kolbe, 1969,1973; Rautapää, 1976) and even earlier than that (e.g. Marsham, 1798), 1968 was an exceptional year for them (Fletcher & Bardner, 1969; Kolbe, 1969).  Presaging  Richard Root’s seminal work on crop apparency and pest occurrence, the Dutch agronomist Willem Feekes predicted that changes in agricultural practice, in particular cereal production, would lead to increased pest and disease problems (Feekes, 1967). This was further emphasised by Wilhelm Kolbe of Bayer, who suggested that the big increase in cereal production in Europe between 1950 and 1970 and the switch from oats to wheat was the cause of the cereal aphid problem (Kolbe, 1973).   Similarly, in the UK, where oats were 51% of the cereal crop in 1930, they had fallen to 11% by 1965 (Marks & Britton, 1989).

Cereal production UK

The shift in cereal crops may indeed have been a contributory factor, but I think, certainly in the UK, that we can add another factor to the equation. Over at Maris Lane**, where the Plant Breeding Institute was based at Trumpington, Cambridge, a new variety of wheat, Maris Huntsman, with good resistance to both powdery mildew and yellow rust (Ruckenbauer, 1975) had been developed and introduced as a recommended variety to farmers in 1972 (Hughes & Bodden, 1978).  By 1977 it accounted for almost 40% of the wheat sold in the UK (Hughes & Bodden, 1978), although a mere two years later, it had fallen to just over 20% (Johnson, 1992).  Based at Trumpington, entomologist Henry Lowe, had, since the late1960s been investigating the resistance of crop plants to aphids, first beans (e.g. Lowe, 1968) was at the time, investigating the resistance of varieties of wheat to aphids (Lowe, 1978, 1980). He found, as one might expect that not all cereal species and varieties were equally susceptible to aphids, and if given a free choice, the grain aphid Sitobion avenae, showed a preference for Maris Huntsman.

So what does this have to do with launching the careers of a couple of dozen entomologists? Well, back in the late 1960s Tony Dixon, then based in Glasgow, got interested in the bird cherry-oat aphid, Rhopalosiphum padi  (Dixon, 1971; Dixon & Glen, 1971), a minor pest of cereals in the UK, mainly because of its great ability to transmit Barley Yellow Dwarf Virus (Watson & Mulligan, 1960. In those countries, such as Finland and Sweden, where spring sown cereals are the norm, it is a pest in its own right, able to cause yield reduction without the help of a virus (Leather et al., 1989). Tony moved to the University of East Anglia as Professor of Ecology in 1975 and started his new career there by appointing six new PhD students. Three of these were looking at aspects of cereal aphid ecology, Allan Watt researching the biology of S. avenae and Metoplophium dirhodum, Ian McLean looking at the predators and Nick Carter modelling their populations in order to develop a forecasting system.  Research groups at Imperial College and at the University of Southampton also began to work on the problem.  Fortuitously although cereal aphid numbers had fallen since the  

Numbers of Sitobion avenae caught in the Brooms Barn suction trap (data from Watson & Carter, 1983)

populations picked up in 1974 and then rose to outbreak levels again in 1976, just as the new PhD students started their field work. I joined the group in 1977 to work on R. padi, followed in subsequent years by Keith Walters (now a colleague at Harper Adams University), John Chroston, Sarah Gardner, Nigel Thornback, Ali Fraser, Shirley Watson, Trevor Acreman, Dave Dent, and after I left for pastures new, Alvin Helden (now Head of School at Anglia Ruskin University). Similar numbers of students were appointed at Southampton, including Nick Sotherton, now Director of Research at the Game and Wildlife Conservation Trust.  There were also groups started at Imperial College and the University of Reading. There was a certain element of rivalry between the groups, Steve Wratten for example, was an ex-student of Tony’s and there was a certain degree of animosity between Roy Taylor (of Taylor’s Power Law fame) at Rothamsted and Tony Dixon, we had mini-conferences to exchange findings and generally got on well.  Allan Watt for example went to work for Steve Wratten as a post-doc before moving up to Scotland to work on the pine beauty moth alongside me.  It was a great time to be working on aphids and I think we all benefitted from the experience and I for one, am very grateful to the plant breeders for developing a  variety of wheat, that although resistant to rust and powdery mildew, is very attractive to the grain aphid 🙂

Having fun in a Norfolk cereal field; me, Allan Watt and Ian McLean (Nick Carter had the good sense to stand behind the camera).

You may be wondering why I penned this reminiscence. Well, last year, my colleague Tom Pope and I were discussing cereal aphids at coffee time (as you do), and I mentioned how Maris Huntsman had launched my career.  It just so happened that Tom had access to old, ancient and modern varieties of cereals to hand and a final year project student keen on aphids so it doesn’t take a genius to guess what happened next 🙂

Host preferences of Sitobion avenae (Dan Hawes & Tom Pope). Can you guess which is Maris Huntsman?

So, Maris Huntsman, a great choice for attracting aphids and producing entomologists 🙂 and of course a great big vote of thanks to the PBI



Dean, G.J.W. & Luuring, B.B. (1970) Distribution of aphids on cereal crops. Annals of Applied Biology, 66, 485-496.

Dixon, A.F.G. (1971) The life cycle and host preferences of the bird cherry-oat aphid, Rhopalosiphum padi (L) and its bearing on the theory of host alternation in aphids. Annals of Applied Biology, 68, 135-147.

Dixon, A.F.G. & Glen, D.M. (1971) Morph determination in the bird cherry-oat aphid, Rhopalosiphum padi (L). Annals of Applied Biology, 68, 11-21.

Doling, D.A. & Doodson, J.K. (1968) The effect of yellow rust on the yield of spring and winter wheat. Transactions of the British Mycological Society, 51, 427-434.

Feekes, W. (1967) Phytopathological consequences of changing agricultural methods. II Cereals. Netherlands Journal of Plant Pathology, 73 Supplement 1, 97-115.

Fletcher, K.E. & Bardner, R. (1969) Cereal aphids on wheat. Report of the Rothamsted Experimental Station 1968, 200-201.

Hughes, W. G., & Bodden, J. J. (1978). An assessment of the production and performance of F1 hybrid wheats based on Triticum timopheevi cytoplasm. Theoretical and Applied Genetics, 53, 219–228.

Janson, H.W. (1959) Aphids on cereals and grasses in 1957. Plant Pathology, 8, 29.

Johnson R. (1992) Past, present and future opportunities in breeding for disease resistance, with examples from wheat. [In] Johnson R., Jellis G.J. (eds) Breeding for Disease Resistance. Developments in Plant Pathology, vol 1. Springer, Dordrecht

Kolbe, W. (1969) Studies on the occurrence of different aphid species as the cause of cereal yield and quality. Pflanzenschutz Nachrichten Bayer, 22, 171-204.

Kolbe, W. (1973) Studies on the occurrence of cereal aphids and the effect of feedingdamage on yields in relation. Pflanzenschutz Nachrichten Bayer, 26, 396-410.

Latteur, G. (1971) Evolution des populations aphidiennes sur froments d’hiver.  Mededelingen van de Faculteit Landbouwwetenschappen, Rijksuniversiteit Gent, 36, 928-939.

Leather, S.R., Walters, K.F.A., & Dixon, A.F.G. (1989) Factors determining the pest status of the bird cherry-oat aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae), in Europe: a study and review. Bulletin of Entomological Research, 79, 345-360.

Leather, S.R., Carter, N., Walters, K.F.A., Chroston, J.R., Thornback, N., Gardner, S.M., & Watson, S.J. (1984) Epidemiology of cereal aphids on winter wheat in Norfolk, 1979-1981. Journal of Applied Ecology, 21, 103-114.

Lowe, HJ.J.B. (1967) Interspecific differences in the biology of aphids (Homoptera: Aphididae) on leaves of Vicia faba I. Feeding behaviour. Entomologia experimentalis et applicata, 10, 347-357.

Lowe, H.J.B. (1974) Effects of Metopolophium dirhodum on Spring wheat in the glasshouse.  Plant Pathology, 23, 136-140.

Lowe, H.J.B. (1978) Detection of resistance to aphids in cereals.  Annals of Applied Biology, 88, 401-406.

Lowe, H.J.B. (1980) Resistance to aphids in immature wheat and barley. Annals of Applied Biology, 95, 129-135.

Macer, R.C.F. (1972) The resistance of cereals to yellow rust and its exploitation by plant breeding.  Proceedings of the Royal Society London B., 181, 281-301.

Marks, H.F. & Britton, D.K. (1989)  A Hundred  Years of British Food and Farming: A Statistical Survey. Taylor & Francis.

Marsham, T. (1798) Further observations on the wheat insect, in a letter to the Rev. Samuel Goodenough, L.L.D. F.R.S. Tr.L.S. Transactions of the Linnaean Society London, 4, 224-229.

Rautapää, J. (1976) Population dynamics of cereal aphids and method of predicting population trends. Annales Agriculturae Fenniae, 15, 272-293.

Rogerson, J.P. (1947) The oat-bird cherry aphis Rhopalosiphum padi (L.) and comparison with R. crataegellum Theo. Bulletin of Entomological Research, 38, 157-176.

Ruckenbauer, P.  (19 75) Photosynthetic and translocation pattern in contrasting winter wheat varieties. Annals of Applied Biology, 79, 351-359.

Watosn, M.A. & Mulligan, T. (1960) The manner of transmission of some Barley Yellow‐Dwarf Viruses by different aphid species. Annals of Applied Biology, 48, 711-720.

Watson, S.J. & Carter, N. (1983) Weather and modelling cereal aphid populations in Norfolk (UK). EPPO Bulletin, 13, 223-227.

Zayed, Y. & Loft, P. (2019) Agriculture: Historical Statistics. House of Commons Briefing paper 3339


*Yellow rust is still a  still a major problem for cereal growers worldwide

**an address that is immortalised in the names of several cultivars of crops developed by the PBI


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Global Insect Extinction – a never ending story

I have had an unexpectedly busy couple of weeks talking about declines in insect populations.  Back in November of last year I wrote a blog about the sudden media interest in “Insect Armageddon” and followed this up with a more formal Editorial in Annals of Applied Biology at the beginning of the year (Leather, 2018).  I mused at the time if this was yet another media ‘storm in a teacup’ but it seems that the subject is still attracting attention.  I appeared on television as part of TRT World’s Roundtable programme and was quoted quite extensively in The Observer newspaper on Sunday last talking about insect declines since my student days 🙂 At the same time, as befits something that has been billed as being global, a similar story, featuring another veteran entomologist appeared in the New Zealand press.

The TV discussion was quite interesting, the panel included Nick Rau from Friends of the Earth, Lutfi Radwan, an academic turned organic farmer, Manu Saunders from Ecology is Not a Dirty Word and me.  If they had hoped for a heated argument they were out of luck, we were all pretty much in agreement; yes insects did not seem to be as abundant as they had once been, and this was almost certainly a result of anthropogenic factors, intensive agriculture, urbanisation and to a lesser extent climate change.  Unlike some commentators who firmly point the finger at the use of pesticides as the major cause of the declines reported, we were more inclined to towards the idea of habitat degradation, fragmentation and loss.  We also agreed that a big problem is a lack of connection with Nature by large sections of the population, and not just those under twenty.  We also felt very strongly that governments should be investing much more into research in this area and that we desperately need more properly replicated and designed long-term studies to monitor the undeniable changes that are occurring.  I had, in my Editorial and an earlier blog post, mentioned this point and lamented the paucity of such information, so was pleasantly surprised, to receive a couple of papers from Sebastian Schuh documenting long-term declines in Hemiptera and Orthoptera in Germany (Schuh et al., 2012ab), although of course sad, to see yet more evidence for decreasing insect populations.

The idea that insects are in terminal decline has been rumbling on for some time; more than a decade ago Kelvin Conrad and colleagues highlighted a rapid decline in moth numbers (Conrad et al., 2006) and a few years later, Dave Brooks and colleagues using data from the UK  Environmental Change Network revealed a disturbing decline in the numbers of carabid beetles across the UK (Brooks et al., 2012).   In the same year (2012) I was asked to give a talk at a conference organised by the Society of Chemical Industry. Then, as now, I felt that pesticides were not the only factor causing the biodiversity crisis, but that agricultural intensification, habitat loss and habitat degradation were and are probably more to blame.  In response to this quote in the media at the time:

“British Insects in Decline

Scientists are warning of a potential ecological disaster following the discovery that Britain has lost around 7% of its indigenous insect species in just under 100 years.

A comparison with figures collected in 1904 have revealed that around 400 species are now extinct, including the black-veined white butterfly, not seen since 1912, the Essex emerald moth and the short-haired bumblebee. Many others are endangered, including the large garden bumblebee, the Fen Raft spider, which is only to be found in a reserve on the Norfolk/Suffolk border, and the once common scarlet malachite beetle, now restricted to just three sites.

Changes to the insects’ natural habitats have been responsible for this disastrous decline in numbers. From housing and industrial developments to single-crop farming methods, Britain’s countryside has become increasingly inhospitable to its native insects.”

I chose to talk about “Forest and woodland insects: Down and out or on the up?” I used data from that most valuable of data sets, the Rothamsted Insect Survey to illustrate my hypothesis that those insects associated with trees were either doing better or not declining, because of increased tree planting over the last fifty years.  As you can see from the slides from my talk, this does indeed seem to be the case with moths and aphids that feed on trees or live in their shade.  I also showed that the populations of the same species in northern Britain, where agriculture is less intensive and forests and woodlands more prevalent were definitely on the up, and this phenomenon was not just confined to moths and aphids.

Two tree aphids, one Drepanosiphum platanoidis lives on sycamore, the other Elatobium abietinum, lives on spruce trees; both are doing rather well.

Two more tree-dwelling aphids, one on European lime, the other on sycamore and maples, both doing very well.  For those of you unfamiliar with UK geography, East Craigs is in Scotland and Newcastle in the North East of England, Hereford in the middle and to the west, and Starcross in the South West, Sites 2, 1, 6 and 9 in the map in the preceding figure.

Two conifer feeding moth species showing no signs of decline.

On the up, two species, a beetle, Agrilus biguttatus perhaps due to climate change, and a butterfly, the Speckled Wood Pararge aegeria, due to habitat expansion and climate change?

It is important however, to remember that insect populations are not static, they vary from year to year, and the natural fluctuations in their populations can be large and, as in the case of the Orange ladybird, Halyzia sedecimguttata, take place over a several years, which is yet another reason that we need long-term data sets.

The Orange ladybird Halyzia sedecimguttata, a mildew feeder, especially on sycamore.

It is obvious, whether we believe that an ecological catastrophe is heading our way or not, that humans are having a marked effect on the biodiversity that keeps our planet in good working order and not just through our need to feed an ever-increasing population.  A number of recent studies have shown that our fixation with car ownership is killing billions of insects every year (Skórka et al., 2013; Baxter-Gilbert et al.,2015; Keilsohn et al., 2018) and that our fear of the dark is putting insects and the animals that feed on them at risk (Eccard et al.,  2018; Grubisic et al., 2018).  We have a lot to answer for and this is exacerbated by our growing disconnect from Nature and the insidious effect of “shifting baselines” which mean that succeeding generations tend to accept what they see as normal (Leather & Quicke, 2010, Soga & Gaston, 2018) and highlights the very real need for robust long-term data to counteract this dangerous and potentially lethal, World view (Schuh, 2012; Soga & Gaston, 2018).  Perhaps if research funding over the last thirty years or so had been targeted at the many million little things that run the World and not the handful of vertebrates that rely on them (Leather, 2009), we would not be in such a dangerous place?

I am, however, determined to remain hopeful.  As a result of the article in The Observer, I received an email from a gentleman called Glyn Brown, who uses art to hopefully, do something about shifting baselines.  This is his philosophy in his own words and pictures.



Baxter-Gilbert, J.H., Riley, J.L., Neufeld, C.J.H., Litzgus, J.D. & Lesbarrères, D.  (2015) Road mortality potentially responsible for billions of pollinating insect deaths annually. Journal of Insect Conservation, 19, 1029-1035.

Brooks, D.R., Bater J.E., Clark, S.J., Monteith, D.T., Andrews, C., Corbett, S.J., Beaumont, D.A. & Chapman, J.W. (2012)  Large carabid beetle declines in a United Kingdom monitoring network increases evidence for a widespread loss in insect biodiversity. Journal of Applied Ecology, 49, 1009-1019.

Conrad, K.F., Warren. M.S., Fox, R., Parsons, M.S. & Woiwod, I.P. (2006) Rapid declines of common, widespread British moths provide evidence of an insect biodiversity crisis. Biological Conservation, 132, 279-291.

Eccard, J.A., Scheffler, I., Franke, S. & Hoffmann, J. (2018) Off‐grid: solar powered LED illumination impacts epigeal arthropods. Insect Conservation & Diversity, https://onlinelibrary.wiley.com/doi/full/10.1111/icad.12303

Estay, S.A., Lima, M., Labra, F.A. & Harrington, R. (2012) Increased outbreak frequency associated with changes in the dynamic behaviour of populations of two aphid species. Oikos, 121, 614-622.

Grubisic, M., van Grunsven, R.H.A.,  Kyba, C.C.M.,  Manfrin, A. & Hölker, F. (2018) Insect declines and agroecosystems: does light pollution matter? Annals of Applied Biology,   https://onlinelibrary.wiley.com/doi/full/10.1111/aab.12440

Keilsohn, W., Narango, D.L. & Tallamy, D.W. (2018) Roadside habitat impacts insect traffic mortality.  Journal of Insect Conservation, 22, 183-188.

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

Leather, S.R. (2018) “Ecological Armageddon” –  more evidence for the drastic decline in insect numbers. Annals of Applied Biology, 172, 1-3.

Leather, S.R. & Quicke, D.J.L. (2010) Do shifting baselines in natural history knowledge therten the environment? The Environmentalist, 30, 1-2.

Schuh, S. (2012) Archives and conservation biology. Pacific Conservation Biology, 18, 223-224.

Schuh, S., Wesche, K. & Schaefer, M. (2012a) Long-term decline in the abundance of leafhoppers and planthoppers (Auchenorrhyncha) in Central Europe protected dry grasslands. Biological Conservation, 149, 75-83.

Schuh, S., Bock, J., Krause, B., Wesche, K. & Scgaefer, M. (2012b) Long-term population trends in three grassland insect groups: a comparative analysis of 1951 and 2009. Journal of Applied Entomology, 136, 321-331.

Skórka, P., Lenda, M., Moroń, D., Kalarus, K., & Tryjanowskia, P. (2013) Factors affecting road mortality and the suitability of road verges for butterflies. Biological Conservation, 159, 148-157.

Soga, M. & Gaston, K.J. (2018) Shifting baseline syndrome: causes, consequences and implications. Frontiers in Ecology & the Environment, 16, 222-230.



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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 apiferahttps://thmcf.files.wordpress.com/2013/07/bee-orchid-imc-3702.jpg with pollinator Eucera longicornis http://www.bwars.com/bee/apidae/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, https://commons.wikimedia.org/w/index.php?curid=32968796  with pollinator Argogorytes mystaceus (formerly Gorytes) http://www.bwars.com/category/taxonomic-hierarchy/wasp/crabronidae/nyssoninae/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, https://commons.wikimedia.org/w/index.php?curid=4112191 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 https://c1.staticflickr.com/8/7795/17960863138_721033c527_b.jpg 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  https://upload.wikimedia.org/wikipedia/commons/d/d4/Orchis_militaris_110503a.jpg



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

Ten papers that shook my world – Lewis (1969) – the importance of (h)edges for natural biological control

In 1969, Trevor Lewis, of what was then the Rothamsted Research Station (now Rothamsted Research), published two landmark papers (Lewis 1969ab). These papers, in which he described the importance of hedges as habitats for insects (Lewis, 1969a) and in acting as possible sources of natural enemies able to colonise nearby fields (Lewis, 1969b) were to have a profound effect on me and generations of applied entomologists and pest mangers to the present day.

In 1976 the UK experienced what is now recognised as the warmest year of the 20th Century.  It was also the year that I started my final year as an undergraduate.  Before entering our final year we had to do a research placement or project.   I opted to do my project at home, I was making very good money as a temporary postman and as I usually finished my round by 10 am, I had plenty of time during the rest of the day to get to grips with my project.  I had come across the Lewis papers in lectures and thought that it would be interesting to do a similar study; given the weather I was also keen to spend as much time outside as possible 🙂 My Uncle James owned a local farm and was happy for me to sample some of his hawthorn hedges, so sampling hawthorn hedges was what I did during July and August of the glorious summer.

Simon summer 1976

The intrepid student entomologist; trusty bike, clipboard and a copy of Chinery*. Note the wellington boots despite the heat 🙂

The hedges

The hedges in question – three types of management

As I mentioned earlier, 1976 was the warmest year on record at the time, and I see from my report that during August I was recording temperatures in excess of 25oC, even in the hedge bottoms.

Hedges project

The report

What is interesting is that although 1976 was one of the famous ladybird outbreak years (in fact last week I was interviewed by the BBC about my memories of that very same event) I didn’t record more than a handful of ladybirds in my surveys.  Perhaps inland Yorkshire just wasn’t attractive enough 🙂

Overall my results showed that over-clipping resulted in more crop pests being present and that hedges with less clipping supported a greater diversity of insect life than the more managed ones, very similar to results being reported today (e.g Amy et al., 2015).

Sadly, although Lewis’s two 1969 papers and to a certain extent his earlier paper in a much harder to access source (Lewis, 1964), led on to the concept of conservation headlands (Sotherton et al., 1989) and ‘crop islands’ (Thomas et al., 1991), which are an integral part of European Union subsidised farm payments, it was included in an influential review article (van Emden & Williams, 1974).  As pointed out recently by Terry McGlynn over at Small Pond Science, this often rings the death knell for a paper’s citation score.  As a result,  Lewis (1969b) has only been cited 91 times since 1969 and is barely remembered at all.   I remember being invited to be a facilitator at a Populations Under Pressure conference workshop on this very subject at the NERC Centre for Population Biology at Silwood Park about fifteen years ago and being surprised that none of the participants had even heard of Trevor Lewis let alone read his papers.

Simon PUP

At the Populations Under Pressure conference brandishing my undergraduate hedgerow report!

The subject of hedgerow and crop edge management is still a highly important research area today, and you will be pleased to know that in the latest paper just submitted from my research group, we cite both of Trevor’s 1969 papers. Hopefully this will do something to redress the balance and bring Trevor some of the recognition that he deserves, however belated.



Amy, S.R., Heard, M.S., Hartley, S.E., George, C.T., Pywell, R.F. & Staley, J.T. (2015) Hedgerow rejuvenation management affects invertebrate communities through changes to habitat structure. Basic & Applied Ecology, 16: 443-451

Chinery, M. (1973) A Field Guide to the Insects of Britain and Northern Europe.  Collins, London

Lewis, T. (1964). The effects of shelter on the distribution of insect pests. Scientific Horticulture, 17: 74–84

Lewis, T. (1969a). The distribution of flying insects near a low hedgerow. Journal of Applied Ecology 6: 443-452.

Lewis, T. (1969b). The diversity of the insect fauna in a hedgerow and neighbouring fields. Journal of Applied Ecology 6: 453-458.

Sotherton, N.W., Boatman, N.D. & Rands, M.R.W. (1989) The “Conservation Headland” experiment in cereal ecosystems. The Entomologist, 108: 135-143

Thomas, M.B., Wratten, S.D., & Sotherton, N.W. (1991) Creation of ‘island’ habitats in farmland to manipulate populations of beneficial arthropods: predator densities and emigration. Journal of Applied Ecology, 28: 906-917.

Van Emden, H.F. & Williams, G.F. (1974) Insect stability and diversity in agro-ecosystems. Annual Review of Entomology, 19: 455-475

*I still own that copy of Chinery which was a present for my 20th birthday – take note of the date if anyone wants to send me a present or card 🙂






Filed under Ten Papers That Shook My World

Underinvestment is not going to produce STARS – BBSRC take note

Earlier this year, the BBSRC at the stroke of a pen, deprived several strategically important and vulnerable research skills and capabilities areas in biosciences of approximately £9 000 000 per annum  by funneling iCASE funding to a number of universities already awash in cash and with little or no interest in vulnerable skill-sets. Now, the BBSRC in a feeble attempt to remedy this seriously misjudged action, has announced their new STARS programme. I quote from their website


“Our STARS programme aims to support the development of strategically important and vulnerable research skills and capabilities in the biosciences. Awards are available to develop postgraduate-level training in areas of significant need for clearly defined academic and industrial sectors”


Reasons for such additional support include, but are not restricted to:

A lack of training and/or capability in specific areas, or a need to up-skill individuals within a specific area

An identified need to attract researchers into the area

A need to build capacity in a new or emerging research area

A need to transfer technical and commercially relevant skills to/from industry


Delivery of training may be achieved by one or more of the following methods:

Research Experience Placements Summer research placements for undergraduate students in the middle years of their studies, to attract them into further research in a strategically important or vulnerable research area

Skills schools in strategically important and vulnerable research areas, including: Development of new skills schools

Expansion of existing institutional/regional activities for national reach

Expansion of existing activities for participation by BBSRC-funded researchers at any level (PhD, postdoctoral researcher, research fellow, research leader)

Development and delivery of training resources through other mechanisms, such as development of e-learning modules or other online resources



Up to £250k is available per year to support training activities through the STARS programme. There will be three calls per year. Awards are flexible and may be used to support strategic and vulnerable skills for a short, discrete period or for up to three years of recurrent funding.

According to the web site and after an incredulous email by me to the BBSRC, it turns out that this magnificent windfall is expected to fund 30 projects – do the sums and this averages out at just over a princely £8000 each! My colleagues and I felt (and still feel) that this really does not show a serious commitment by the BBSRC to vulnerable research skills and capabilities. Rather, it shows complete disdain and contempt for the areas that they claim to be concerned about;

“We welcome applications for support of any research capability within our remit, but particularly those highlighted in the Review of Vulnerable Skills and Capabilities, published in January 2015 (see downloads) and especially in relation to capabilities within the following areas:

Maths, statistics and computational biology

Physiology and pathology of plants, animals and microbes

Agriculture and food security”


Beggars, however, cannot be choosers and so my colleagues and I duly downloaded an application form and submitted an application to run a one-week summer school in crop protection (entomology, plant pathology, plant nematology and weed science) for three years for 15 undergraduate students per year. Notwithstanding the small sums of money available, the form required inputting a disproportionate  amount of information; asked for a business plan and detailed information, concerning in the case of a taught summer school, details of lecture content and delivery, and financial support or other from interested parties and the institution providing the service. In terms of person-hours the delivery of such a course far outweighs the paltry sum of money available; in fact the time taken to put together the application itself, if costed at FEC (full economic costs), would also eat substantially into the monies potentially available. I could borrow more from my bank as a personal loan with considerably more ease, less paperwork and probably with a considerably greater chance of success.

BBSRC you cannot be serious!


Post script

In case anyone wonders why I have chosen to illustrate this post with a photograph of a somewhat sceptical looking elderly gentleman, let me explain. The picture shows my late father, Robert Ikin Leather (1924-2007) who is a perfect example of one of the vulnerable skills set that our proposed summer school would highlight and attempt to remedy. He was a traditional agricultural plant pathologist who could go out into the field, recognise symptoms and diagnose diseases, as well as identifying them in the laboratory and conducting field research. He is no longer with us, as are the majority of people who shared his skills. Plant pathology in the UK is in dire straits as are weed science, plant nematology and to a slightly lesser extent, entomology. To reiterate my earlier point underinvestment in training and research in these areas is not the way to solve the problem.


Filed under Bugbears

Ten papers that shook my world – Way & Banks (1964) – counting aphid eggs to protect crops

The previous papers in this series (Southwood, 1961; Haukioja & Niemelä 1976; Owen & Weigert, 1976), were all ones that had an influence on my post-PhD career. This one in contrast, had a direct effect on my PhD as well as on my subsequent career, and was, I guess, greatly influential in the publication of the first book to deal with the ecology of insect overwintering (Leather, Walters & Bale, 1993). In 1964 Mike Way, one of the early proponents of Integrated Pest Management (in fact considered to be the father of UK IPM), was working on control methods for the black bean aphid, Aphis fabae.

Bean aphids

Mike had recently joined Imperial College from Rothamsted Research Station where he had been leading research on ways to reduce pesticide use by farmers and growers.   During his time at Rothamsted he had worked closely with a colleague, C.J. Banks on the black bean aphid including studies on the overwintering eggs. As they said in the introduction to their paper, published four years after their experiments; “During the British winter A. fabae survives almost exclusively in the egg stage. Egg mortality might therefore be important in affecting size of populations of this species and in predicting outbreaks”. They investigated the effects of temperature and predators on the mortality of the eggs on the primary host, spindle, Euonymus europaeus, and concluded that the levels of mortality seen would not affect the success of the aphids the following spring. By 1968 (Way & Banks, 1968) they had followed up on the idea and began to feel confident that aphid populations on field beans could be predicted from the number of eggs on the winter host; spindle bushes. The publication of this paper stimulated the setting up of a long-term collaborative project monitoring Aphis fabae eggs on spindle bushes at over 300 locations throughout England south of the River Humber, and monitoring aphid numbers in about 100 bean fields per year.   In 1977 the results were finally published (Way et al., 1977) and the highly successful black bean aphid forecasting system was born. This was further refined by using the Rothamsted aphid suction trap data (Way et al., 1981).

This was also the year that I began my PhD at the University of East Anglia, working on the bird cherry-oat aphid, Rhopalosiphum padi. In the course of my preparatory reading I came across Way & Banks (1964) just in time to set up a plot of bird cherry saplings which I monitored for the next three winters, the first winter’s work resulting in my first publication (Leather, 1980). I subsequently went on to develop the bird cherry aphid forecasting system still used in Finland today (Leather & Lehti, 1981; Leather, 1983; Kurppa, 1989).

Finnish aphid forecasts

Sadly, despite the great success of these two systems there has not been a huge take-up of the idea, although the concept has been looked at for predicting pea aphid numbers in Sweden (Bommarco & Ekbom, 1995) and rosy apple aphids in Switzerland (Graf et al., 2006). Nevertheless, for me this paper was hugely influential and resulted in me counting aphid eggs for over 30 years!


Bommarco, R. & Ekbom, B. (1995) Phenology and prediction of pea aphid infestations on pas. International Journal of Pest Management, 41, 101-113

Graf, B., Höpli, H.U., Höhn, H. and Samietz, J. (2006) Temperature effects on egg development of the rosy apple aphid and forecasting of egg hatch. Entomologia Experimentalis et applicata, 119, 207-211

Haukioja, E. & Niemela, P. (1976) Does birch defend itself actively against herbivores? Report of the Kevo Subarctic Research Station, 13, 44-47.

Kurppa, S. (1989) Predicting outbreaks of Rhopalosiphum padi in Finland. Annales Agriculturae Fenniae 28: 333-348.

Leather, S. R. (1983) Forecasting aphid outbreaks using winter egg counts: an assessment of its feasibility and an example of its application. Zeitschrift fur Angewandte Entomolgie 96: 282-287.

Leather, S. R. & Lehti, J. P. (1981) Abundance and survival of eggs of the bird cherry-oat aphid, Rhopalosiphum padi in southern Finland. Annales entomologici Fennici 47;: 125-130.

Leather, S.R., Bale, J.S., & Walters, K.F.A. (1993) The Ecology of Insect Overwintering, First edn. Cambridge University Press, Cambridge.

Owen, D.F. & Wiegert, R.G. (1976) Do consumers maximise plant fitness? Oikos, 27, 488-492.

Southwood, T.R.E. (1961) The number of species of insect associated with various trees. Journal of Animal Ecology, 30, 1-8.

Way, M.J. & Banks, C.J. (1964) Natural mortality of eggs of the black bean aphid Aphis fabae on the spindle tree, Euonymus europaeus L. Annals of Applied Biology, 54, 255-267.

Way, M. J. & Banks, C. J. (1968). Population studies on the active stages of the black bean aphid, Aphis fabae Scop., on its winter Euonymus europaeus L. Annals of Applied Biology 62, 177-197.

Way, M. J., Cammel, M. E., Taylor, L. R. &Woiwod, I., P. (1981). The use of egg counts and suction trap samples to forecast the infestation of spring sown field beansVicia faba by the black bean aphid, Aphis fabae. Annals of Applied Biology 98: 21-34.

Way, M.J., Cammell, M.E., Alford, D.V., Gould, H.J., Graham, C.W., & Lane, A. (1977) Use of forecasting in chemical control of black bean aphid, Aphis fabae Scop., on spring-sown field beans, Vicia faba L. Plant Pathology, 26, 1-7.


Post script

Michael Way died in 2011 and is greatly missed by all those who knew him well. He examined my PhD thesis, and to my delight and relief, was very complimentary about it and passed it without the need for corrections. I was greatly honoured that a decade or so later I became one of his colleagues and worked alongside him at Silwood Park. He was a very modest and self-deprecating man and never had a bad word to say about anyone. He had a remarkable career, his first paper published in 1948 dealing the effect of DDT on bees (Way & Synge, 1948) and his last paper published in 2011 dealing with ants and biological control (Seguni et al., 2011), a remarkable 63 year span. His obituary can be found here http://www.telegraph.co.uk/news/obituaries/science-obituaries/8427667/Michael-Way.html


Filed under Aphidology, Aphids, Ten Papers That Shook My World

How ready is the UK to combat current and future threats to our forests and woodlands?

Almost exactly two years ago (February 2012) a consignment of ash trees sent from a nursery in the Netherlands to one in Buckinghamshire, were confirmed to be infected by the fungus causing ash dieback, Chalara fraxinea.  By October of that year, it had been confirmed by Food & Environment Research Agency (FERA) scientists to be present in a number of woodland sites within the natural environment.  The story was quickly picked up by the national press http://www.telegraph.co.uk/earth/earthnews/9660538/Ash-dieback-now-beyond-containment.html and other media http://www.bbc.co.uk/news/science-environment-20079657 and articles about the severity of the disease and our inability to control it spread proliferated at  a fantastic rate.  Partly as a result of this, the Tree Health and Plant Biosecurity Expert Taskforce was convened by the Government’s Chief Scientific Advisor in November 2012.  I was invited to be a member of the Taskforce which was an independent, multi-disciplinary group of members of the academic community, https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/200428/tree-taskforce-tor.pdf and very willingly, agreed to serve on it.   Our remit was to “provide advice on the current threats to tree health and plant biosecurity in the UK and make recommendations about how those threats could be mitigated”.   What surprised me and other members of the Task Force was the interest and emotional responses that ash dieback generated among the general public.  After all, a few years earlier another one of our iconic tree species, oak, was under threat by another fungal disease, Phytopthora ramorum, somewhat misleadingly known as Sudden Oak Death, which despite its potential threat to cause landscape level changes comparable with those caused by Dutch Elm Disease (Potter et al., 2011) failed to cause the same  level of media hysteria.  Our best guess for why there was such an outburst of press and media coverage and subsequent public concern about ash dieback, was that the Chalara outbreak was the straw that broke the camel’s back.  People, had perhaps become sensitised to forestry due to what seemed to be a constant stream of stories of threats, both man-made, such as the proposed sell-off of parts of the Forestry Commission’s estate by the UK government in 2010 http://www.telegraph.co.uk/earth/countryside/8082756/Ministers-plan-huge-sell-off-of-Britains-forests.html and natural, such as Sudden Oak Death and other pests and diseases.

For the record, although Chalara  fraxinea is now being treated as a quarantine pest under national emergency measures and is widespread across the  United Kingdom and Northern Ireland, it no longer makes the front pages of our national newspapers.

Ash dieback distribution


We in the Tree Health Taskforce did not just consider ash dieback; we reviewed the whole range of biotic threats, both current and future, and highlighted a number of reasons that we felt had contributed to the problems and made recommendations about how these could be rectified.  In essence, how could we stop yet another ash dieback scenario occurring. Our joint report was published in May 2013 https://www.gov.uk/government/publications/tree-health-and-plant-biosecurity-expert-taskforce-final-report.  One of our major findings was that the UK as a whole lacked, or would shortly lack, enough trained personnel able to recognise and respond to threats to our forests and woodlands from native and alien pests and diseases.  One of the more immediate outcomes of our report was the rapid commissioning of some research to determine just how serious the situation actually was.

The results of this report were published by Defra on February 5 of this year,  TH0115 Strategic Analysis of Capability and Capacity to undertake Tree Health Research and Evidence Activity in the UK.  The report highlighted research and evidence themes identified by key policy stakeholders and forest researchers from the university sector, research institutes and forest industry.

Ten themes were identified – Horizon scanning, Pathways and trade, Pest and pathogen biology and epidemiology, Detection and surveillance, Ecological patterns, Control and Management, Adaptation and resilience in forests and forestry, Governance and contingency planning, Economic evaluation and analysis and finally Public engagement, communication and citizen science.

Three of the themes – Pest and pathogen biology and epidemiology, Control and management and Adaptation and resilience in forests and forestry, were identified as areas where existing research providers lack current capability and/or capacity in one or more types of expertise.

The report also highlighted that there are serious skills shortages in the UK in mycology, plant pathology and entomology, especially in relation to forest health. Even in those disciplines where universities still run undergraduate degree courses, tree specific expertise such as silviculture, the care and cultivation of forest trees, was also noted as being in short supply.

So how did we get into this mess?  Why are we seeing what appears to be an unprecedented assault on the UK by invasive forest pests and diseases (Defra 2013).  Exotic and invasive insects are not a new phenomenon in the UK; the European spruce sawfly, Gilpinia hercyniae was first recorded in 1906, the Douglas fir woolly aphid Gilleteela (Adelges) cooleyi) in 1913, the web spinning larch sawfly Cephalcia lariciphila in 1953, Megastigmus spermotrophus, the Douglas fir seed wasp since at least the late 1940s,  Ips cembrae, the large larch bark beetle, since at least 1955

Ips cembrae

Ips cembrae  http://www.padil.gov.au/pests-and-diseases/Pest/Main/135614

and the great spruce bark beetle, Dendroctonus micans since at least 1973 (Crooke & Bevan, 1957; Bevan 1987).  Apart from Dendroctonus, none of these insects has however, had landscape level effects or for that matter, made the headlines to the same extent that ash dieback did.   Since the beginning of the current century the situation has changed dramatically, the influx of tree pathogens has continued to rise at an almost exponential rate and the number of potentially landscape changing insect pests has also seen an increase e.g. the horse chestnut leaf miner, Cameraria ohridella, first seen in London in 2002  (Straw & Williams,  2013) is now found as far north as Liverpool in the West and North Yorkshire in the East (personal observation); the pine tree lappet moth Dendrolimus pini, established in Scotland since 2004.  The oak processionary moth, Thaumetopoea processionea, has been firmly established in London since at least 2006 and looks set to spread further north and west (Townsend, 2013); it is probably only the bizarre weather we have had the last couple of years that has slowed it down slightly.  The Asian longhorn beetle, Anoplophora glabripennis, caused some concern when an outbreak was found in 2012 in Kent; the eradication of which resulted in the felling of several hundred healthy trees.


Anopolophora glabripennis  (source USDA)

A related species, the Citrus longhorn beetle A. chinensis, is often intercepted but so far is not known to have established in the UK (Nigel Straw personal communication.)

Given the time that it takes for an exotic insect to reach noticeable population levels, all these insects may have actually established four or five years earlier and it could already be too late to eradicate these pests.  Attempts to eradicate the Oak processionary moth from London have, for example, now ended and been replaced by a policy of containment and eradication is only attempted in the case of new outbreaks outside London (Forestry Commission 2013).  Another species which has often been intercepted since the 1970s, is Ips typographus, a severe pest of spruce.  Other possible invaders include the pine processionary moth Thaumetopoea pityocampa, other Ips species attacking pine and spruce, and of great, and increasing concern, the emerald ash borer, Agrilus planipennis, a native of Asia which is now spreading rapidly outwards from Moscow (Straw et al., 2013).


Agrilus planipennis  (source Pennsylvania Department of Conservation and Natural Resources – Forestry Archive)

So what may have caused this flood of new forestry pests in the UK?  The most obvious change to forestry practice in the UK which undoubtedly influenced the rise of the exotic conifer pests of the first half of the 20th Century was the large-scale afforestation programmes of many non-native tree species, brought about by the formation of the Forestry Commission in 1919.  This rapid afforestation of sites, many of which had not had trees on them for centuries,  provided new hosts for native pests and pathogens and inadvertently allowed the introduction of non-native insects.  The other major change over the last 50 years or so is in global trade patterns; the world is a much smaller place, goods travel extremely quickly, come from much further afield and in greater volumes.  The ability to transport living plant material has also much improved.  In pre-container and pre-bulk air transport days, goods that were packed with unprocessed or poorly processed timber (pathways exploited by many bark beetles) took many weeks to make the long sea voyages and the insect pests often did not survive to make it to land and a new host plant.  Long sea-voyages also meant that the transport of living plant material and their accidental insect passengers also had less chance of surviving to reach the UK.  Another major change to our trade habits is the “instant tree/garden syndrome” where developers and the general public are no longer willing to wait several years for their trees to grow; rather they plant semi-mature trees, many of which come from outside the UK and which come with very large root-balls.  It is impossible for the Plant Health and Seed Inspectorate (PHSI) service to check the huge volume of soil associated with these roots and many organisms must be entering the UK unbeknownst to the very over-stretched PHSI.

An often overlooked change that I am certain has contributed to the large-scale invasion of tree pests and diseases, is a result of re-organisation of the Forestry Commission.  Prior to 1990, the Forestry Commission had a localised approach to forest management.  Most forest blocks or amalgamations of them had a Chief Forester or Head Forester in charge of them.  He (very rarely she), lived in the near vicinity and much like the old village Bobby, walked his beat regularly.  Changes in forest health were thus much more likely to be spotted early and a forest pathologist or entomologist from either The Northern Research Station (NRS) or Alice Holt called in to make an assessment as to the cause of the problem.  I worked at NRS during the 1980s and early 1990s so have had personal experience of the effectiveness of this system.  By 1990, the Forestry Commission had amalgamated many forests and the number of District Offices was much reduced with a consequent reduction in the number of foresters living in near to individual forest blocks.  Forest health problems were thus much less likely to be noticed at an early stage.

The other major change was the decision to shift research to amenity forestry and away from commercial production forestry leading to a reduction in the number of entomologists and pathologists employed by the Forestry Commission as budgets were redirected.  There are now no longer enough key personnel in these disciplines to cope adequately with current problems, let alone those likely to arise.  At the same time within the university sector, the way in which government-funded universities was changed  to a system based on the outcome of the notorious publication metric based Research Assessment Exercise.  This disadvantaged academics specialising in niche applied disciplines such as entomology and plant pathology whose research output rarely, if ever, made it into the hallowed pages of Nature and Science.  Recruitment of staff in these areas in the research intensive universities was severely curtailed and retirees replaced by molecular biologists or vertebrate ecologists publishing in so-called ‘high-impact’ journals (Leather, 2009).  Universities have also replaced many specialist niche degrees with more broadly based subjects perceived to be more attractive to students.  As a result, teaching in these areas has also suffered and very few biology undergraduates in the UK today have any experience with whole organismal biology or the field and taxonomic skills needed be able to recognise forest health problems outside in the real world (Leather & Quicke, 2010).  The situation is now very critical, with, as far as I know only two forest entomologists (if you count me) and one forest pathologist teaching in UK universities today.  This is not a healthy situation for the country and we in the Tree health and Plant Biosecurity Expert Taskforce highlighted the need to address key skills shortages in this area as an urgent priority (Defra, 2013).

Worryingly, the problems do not just lie with exotic and invasive pests.  There are a number of long-established native pest species that still need research into their control and management.  The large pine weevil Hylobius abietis, which in the words of the


Hylobius abietis adults

first Forestry Commission entomologist J W Munro writing just ten years after the formation of the Forestry Commission stated “The pine weevil (Hylobius abietis) problem still occupies the attention of the Forestry Commissioners” (Munro, 1929).  The same statement is still as pertinent today although control measures for this insect have evolved greatly from the early use of DDT and organophosphates to more sophisticated, but possibly no more effective, biological control options (Torr et al., 2007).  The pine beauty moth, once a harmless indigenous moth species, rose to become a notorious pest of the introduced Lodgepole pine during the 1970s and still continues to pose a threat to Scottish plantations today (Hicks et al., 2008).   The often over-looked pine looper moth, Bupalus piniarius, may yet cause problems to our native Scots pine (Straw et al., 2002a). The green spruce aphid, Elatobium abietinum  has never gone away (Straw et al., 2002b) and may, if climate change predictions  are correct, make Sitka spruce a non-viable crop in the UK (Straw et al., 2009).

This is a problem we ignore at our peril.  Action needs to be taken, sooner, rather than later. As conventional chemicals are withdrawn and fewer chemicals approved for use in forestry, the emphasis must inevitably shift to biological control methods using classical natural enemies or biopesticide approaches with entomopathogenic fungi or nematodes or microbially derived pesticides such as Bt which was used against the Oak processionary moth in Berkshire in 2013.  We may even be able to develop even more specific methods such as pheromone disruption combined with improved tree resistance (Leather & Knight, 1997).   We need to improve quarantine measures, develop better detection methods and urgently provide more funding to enable the employment and maintenance of an expanded Plant Health Inspectorate as recommended by the Tree Health and Plant Biosecurity Expert Taskforce (Defra, 2013) and by TH0115.  The latter report highlighted the widespread concerns about the lack of undergraduate and even more critically, the lack of MSc and PhD opportunities in forestry and tree health in particular.

A key recommendation of the report is that funding needs to be put in place to support postgraduate level teaching and training support. This is to make sure a new generation of people capable of working in the tree health area, assisting a smoother and more efficient transition from broad-based undergraduate biology degrees to PhD level research.

To staff the proposed new inspectorate and to make sure we have a new cohort of well-trained forest health experts, we need to encourage newly qualified undergraduates to take up the existing training opportunities at post-graduate level, such as the MSc courses run in Entomology, Integrated Pest Management and Conservation & Forest Protection at Harper Adams University by offering government bursaries.  We are planning to launch new MSc courses in Plant Pathology, Plant Nematology and Forestry Management from September 2014.  We also offer undergraduate degrees in Countryside and Environmental Management and Wildlife Conservation and Natural Resource Management, both of which have significant woodland and forest-related elements

In addition, we need to persuade UK universities to employ forest entomologists and pathologists in academic posts by increasing the amount of appropriate whole organism research funding in these areas.  The Forestry Commission’s Forest Research arm also needs to be able to expand its staff in entomology and pathology to enable it to cope with existing and future threats to our forest estate.  Without such capacity building the future of forestry in the UK is uncertain to say the least.

Post Script

At the risk of seeming to blow our own trumpet still louder, another recommendation from the recent Defra report is that a virtual Centre for Tree Health Science should be created. This would be created by linking together those organisations currently active in the field and with appropriate training provision available.  A number of recent key appointments and the newly launched multidisciplinary Centre for Integrated Pest Management (CIPM) mean that we at Harper Adams University are also in an excellent position to undertake research in this area.  We are, as I write, involved in projects on Oak Processionary Moth and Acute Oak Decline.


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Crooke, M & Bevan, D (1957) Notes on the first occurrence of Ips cembrae (Heer) (Col., Scolytidae). Forestry 30, 21-28

Defra (2013) Tree Health and plant Biosecurity Expert Taskforce Final Report.  https://www.gov.uk/government/publications/tree-health-and-plant-biosecurity-expert-taskforce-final-report

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