Tag Archives: Acer pseudoplatanus

On rarity, apparency and the indisputable fact that most aphids are not pests

I am willing to bet that when most entomologists are out for a walk spend most of their time looking at the ground or the vegetation between the ground and head height. Lepidopterists and odonatologists may be the exceptions that prove the rule, but most of us spend a lot of time looking for things lurking in dung, hiding under stones or bark, scurrying around in the undergrowth or making holes in leaves 🙂

Tell-tale signs for an entomologist that something is or has been enjoying a meal

I’m an entomologist, I’m trained to look out for signs of insect infestations; curled leaves as in the above picture tell me that almost certainly an aphid and her offspring have been at work, sticky leaves alert me to the fact that there are aphids above me in the canopy of a tree. Leaves with holes tell me that a beetle or caterpillar has been at work. Leaves spun together with a silk web tell me a similar story. Plants with their stems and leaves stripped right back inform me that sawfly, lepidoptera and beetle larvae have been at work. A fancy spiral of brown or white on a leaf tells me that a leafminer has been, or is at work. In some cases the insect may not be there when I see the damage, the curled leaves caused by an aphid or psyllid infestation remain there until leaf fall, the chances of finding a caterpillar feeding on the very obviously shot-holed leaves of a plant are slim.  Like all sensible herbivores, the culprit will be in hiding closer to the stem, only sporadically popping out to feed.  On the other hand it may have fallen victim to a visually acute predator (bird) that was attracted to the leaf by the tell-tale feeding signs, or been eaten by a predatory insect or  have been parasitized by an ichneumonid wasp.  Plants are a lot less passive than people think. By producing the equivalent of an immune response they cause the insects to move to different feeding sites to make more holes effectively advertising their presence to potential predators.  Simultaneously, the plant sends out chemical signals telling insect predators and parasites that there is a meal or host available.  An herbivore’s lot is not an easy one.

The Covid-19 crisis means that I have been working from home in a hamlet on the Staffordshire/Shropshire border.  To keep myself reasonably sane and moderately physically healthy I have been treating myself to a lunchtime walk along the bridleways, footpaths and public roads within a 5 km radius of my house. As a result I have become much more familiar with the area. One of the things that has been very obvious, apparent even, is that some plants dominate the roadside verges, cow parsley Anthricus sylvestris being one that really stands

Cow parsley – very common and abundant, occurring in huge swathes around Forton and Sutton and in this case and in many other sites along my walks, backed by the equally apparent hawthorn (Crataegusus monogyna) hedge.

out from the crowd at this time of the year. Not only is it very apparent, but it provides a great source of nectar for the spring butterflies such as the Orange Tip and the assorted bumblebees, solitary bees and hoverflies, that despite the anthropogenic pressures put upon them, still manage to make an appearance.  Nettles, as I particularly noticed when having to social distance myself from the sweaty joggers and cyclists taking advantage of the virtually deserted country lanes, also play a prominent role in the roadside plant community. Also very common, but showing a much patchier distribution and occurring in clumps, including in my garden, is the ribwort plantain, Plantago lanceolata, which is yet another so called weed*, that is perfect for pollinators.

Ribwort plantain – common but patchy and clumped – this clump in my garden where it is safe from forks and herbicides.

Although both the cow parsley and plantain were buzzing with pollinators, they were, and still are at time of writing, singularly devoid of herbivores, including my favourite aphids. Conversely, the odd scattered bird cherries (Prunus  padus) and the solitary self-seeded wild cherry (Prunus avium) in my garden are proudly sporting the characteristic leaf rolls caused by the bird cherry aphid, Rhopaloisphum padi and the cherry black fly, Myzus cerasi respectively.

Note that both these trees were not growing near any of their relatives and were surrounded and overtopped by other plant species, so as far as humans are concerned not very apparent.

This got me to wondering why it was, that, the to me, and presumably other humans, the very obvious cow parsley and plantains, were not covered in plant feeding insects, while the less apparent cherries were heavily infested by their respective aphids.  After all, according to Richard Root, large swathes of monocultures are likely to be easily found and colonised by pests. Plant apparency was first defined by the British born, American based ecologist Paul Feeny in the mid-1970s.

“The susceptibility of an individual plant to discovery by its enemies may be influenced not only by its size, growth form and persistence, but also by the relative abundance of its species within the overall community. To denote the interaction of abundance, persistence and other plant characteristics which influence likelihood of discovery, I now prefer to describe “bound to be found” plants by the more convenient term “apparent”, meaning “visible, plainly seen, conspicuous, palpable, obvious” (Shorter Oxford English Dictionary, 3rd, edition; Webster’s Concise English Dictionary). Plants which are “hard to find” by their enemies will be referred to as “unapparent”, the antonym of apparent (O.E.D. and Webster, loco cit.). The vulnerability of an individual plant to discovery by its enemies may then be referred to as its “apparency”, meaning “the quality of being apparent; visibility” (O.E.D. and Webster, loco cit.). Since animals, fungi and pathogens may use means other than vision to locate their host-plants, I shall consider apparency to mean “susceptibility to discovery” by whatever means enemies may employ” Feeny (1976).

So, even though cow parsley is highly visible and apparent to us humans, and their pollinators, because it is an annual and thus ephemeral within the landscape, it is not necessarily apparent to the herbivores that want to feed on it. Conversely, trees, such as bird cherry, although not necessarily apparent to us, are apparent to insect herbivores because they are large and long-lived. How does this affect the way in which plants avoid being found and eaten by insect herbivores?

Peter Price, another British born American based ecologist very neatly summarised Paul’s hypothesis as follows

Long-lived trees which are bound to be found by herbivores, invest heavily in costly chemical defence with broad-spectrum efficacy.   These quantitative defences are expensive but the cost is tolerable for a long-lived plant.  Short-lived plants are less easily detected by herbivores, and their best defence is being hard to find in patchy and ephemeral sites.  Low cost defences are effective against generalist herbviores should plants be found.  Instead of tannins and other digestibility reducers found as defences in long-lived plants, short-lived plants have evolved with mustard oils (glucosinolates) in crucifers, for example, alkaloids in the potato family, furanocoumarins in the carrot family (Price, 2003).

All I can say is that the quantitative defences of the trees don’t seem to be doing as good a job as the less expensive ones of the cow parsley, plantains and nettles.  As an aside, it turns out that although both cow parsley and plantain have a lot of medicinal uses, their chemistry does include some insecticides (Adler et al., 1995; Milovanovic et al., 1996). Cheap and cheerful seems to be the answer for an herbivore-free life in this case 🙂 Earlier I referred to cow parsley and plantains as being common.  What does that mean? According to Wikipedia (where else would I go?),

 “Common species and uncommon species are designations used in ecology to describe the population status of a species. Commonness is closely related to abundance. Abundance refers to the frequency with which a species is found in controlled samples; in contrast, species are defined as common or uncommon based on their overall presence in the environment. A species may be locally abundant without being common.

However, “common” and “uncommon” are also sometimes used to describe levels of abundance, with a common species being less abundant than an abundant species, while an uncommon species is more abundant than a rare species.”

In the UK we have a conservation designation, Sites of Special Scientific Interest, the criteria for selection which can be found here. To save you the trouble of reading the whole document, the way in which rarity and scarcity are defined is as follows.

Nationally Rare (15 or fewer UK hectad (10 km squares) records)

Nationally Scarce – Notable A (31-100 UK hectad records),

Nationally Scarce – Notable B (16-30 hectad records.

Local – (101-300 UK hectad records)

Okay, so what has all this to do with aphids and their pest status? As you all probably know by now I love aphids; as far as I am concerned, where insects are concerned, they are the bee’s knees**.

Unfortunately, aphids get a terrible press, most of it, in my opinion, undeserved.

Just a couple of examples of aphids getting a biblically bad press.

A few years ago, I wrote a short piece about the fact that only a minority of the so far 5600 or so aphids described, are pests, and many are very rare. The cover of this issue of New Scientist from 1977, which appeared a few months after I joined the group, very nicely sums up the question that we really ought to be asking. Here I have to confess that the article from our lab (McLean et al., 1977), made the case for aphids being pests, and it was the late Denis Owen who defended aphids (Owen, 1977).

Tony Dixon’s cereal aphid research group (of which I was proud to be a member) got more than just a mention in this issue.

Two plants that I have a particular interest in are sycamore and bird cherry, mainly because of their aphids, but in the case of the bird cherry, I love its flowers.  Now, although both have very similar distributions and occurrences to cow parsley and ribwort plantain, ubiquitous, they are much easier

Distribution of cow parsley, ribwort plantain, and sycamore and bird cherry in the British Isles (Atlas of the British Flora)

to find aphids on than both cow parsley and plantain.  On my daily walks during which I pass countless cow parsley and plantain plants, I have, so far, only found one cow parsley with aphids on and not a single plantain has shown any signs of aphid infestation . I have also, only found one nettle plant with Microlophium carnosum on it.  Cow parsley has a number of aphid species that use it as a secondary host migrating there from willows or hawthorns. Plantains also serve as host plants to aphids, some such as Dysaphis plantaginea host alternate, others such as Aphis plantaginis, do not. The latter species, if present, is almost always ant attended (Novgorodova & Gavrilyuk, 2012), which, if you know what you are looking for, makes it easy to spot.  I know what to look for and so far, have not found any! Nettles are also very common in the roadside verges, and they too have aphids that love them, Microlophium carnosum and Aphis urticata, the former a favourite prey of ants, the latter, farmed by the ants.  So far this year I have only found one small colony of M. carnosum, and believe me, I have been looking.

So what about the trees? Sycamores are a common sight on my walks, occurring both as hedges and as solitary trees or sometime in small groups. Almost all the large trees have sycamore aphids, Drepanosiphum platanoidis feeding on their leaves, and many have dense colonies of the maple aphid, Periphyllus testudinaceus, some with ants in attendance. Bird cherry is not as common on my walks and where I have found it, they have been small trees or shrubs usually on their own, and surrounded by other woody plants. Without exception, all have been conspicuously infested by the bird-cherry oat aphid.  To summarise, we have common plants that support aphids that are not regarded as rare, but find startlingly different levels of abundance of them here in Staffordshire, and in my experience, elsewhere.  At the same time that I have been actively searching for aphids, six species of butterfly that the Woodland Trust lists as common, have been hard to miss.  In order of sightings these are the Orange Tip, the Peacock, the Small Tortoiseshell, the Speckled Wood, the Holly Blue and the Brimstone, two of which, the Peacock and the Small Tortoiseshell, being nettle feeders as larvae. Despite the abundance of nettles in the hedgerows, So far I have only seen one small colony of Small Tortoiseshell larvae on the of nettles. I am, at this juncture, unable to resist mentioning that adults of the Holly Blue feed on aphid honeydew J Going back to my original point, the fact that I have seen more butterflies than aphids doesn’t necessarily mean that the aphids are less abundant, just less apparent.

There are at least 614 species of aphid in the UK (Bell et al., 2015). I am not sure how many I have seen, I stopped keeping a personal tick list many years ago, but I would guess that I have seen about half of them.  I like aphids, I look for aphids, but there are many ‘common’ species that I have never seen. I have, however, seen some of the rare ones. Four that stand out in my memory are Monaphis antnenata, Stomapahis graffii, Myzocallis myricae and Maculolachnus submacula. The first feeds on the upper surface of birch leaves (Hopkins & Dixon, 1997) and was shown to me by the late Nigel Barlow, when he was on a sabbatical at Silwood Park. Stomaphis graffii which feeds under the bark of sycamores and maples and is ant attended, was shown to me by an MSc student, Andrew Johnson, also at Silwood Park.  Myzocallis myricae, the bog myrtle aphid, only found on bog myrtle (Myrica gale) (Hopkins et al., 2002), I saw in the Highlands of Scotland, when Tony Dixon asked me to stop the car so he could go and look at a clump of bog myrtle he had spotted as we drove along between field sites. The giant rose aphid, Maculolachnus submacula, I saw in my garden in Norwich (84 Earlham Road) when I was a PhD student at the University of East Anglia.  I only found it because I wondered why there was an ant nest reaching halfway up one of my roses.  When I looked, I found that they were farming the aphids that were feeding on the lower stems.

It is important to remember that most aphids are host-specific, some feeding only on a single plant species, others being confined to a single genus with only a minority having a wide host range*** and considered pests (Dixon, 1998). Given this, it is obvious that aphids with rare host plants are also going to be rare (Hopkins et al., 2002).  Many aphids are also very fussy about their niche, either feeding on a very particular part of a plant or having a very close association with a particular species of ant.  Looking at the aphids that the two Bobs (Influential Points it seems that aphids that are rare  are also ant-attended.  Given, that many ant-attended aphids aren’t rare it would seem an interesting area to pursue. Perhaps it is the degree of ant-attendance, i.e. facultative versus obligate that is the key factor?

If you look at the list of species of insects that are regarded as endangered and worthy of conservation in the UK, the overwhelming impression is that unless they are big and pretty they don’t get a look in.  Needless to say, despite their beauty and fascinating life styles, no aphids are included in the list L

We really should be conserving aphids, not squashing them. Many provide important nutrition for ants and other pollinators, honeydew.  They are an important source of food for insects and birds (Cowie & Hinsley, 1988).  Aphids also help plants grow by feeding mycorrhizae with their honeydew (Owen, 1980; Milcu et al., 2015). Finally, as aphids are so host specific using the presence of uncommon species in suction traps could help identify sites with rare plants.

Aphids, rare, useful and much maligned, time to rethink their role.

 

References

Adler, L.S., Schmitt, J. & Bowers, M.D. (1995) Genetic variation in defensive chemistry in Plantago lanceolata (Plantaginaceae) and its effect on the specialist herbivore Junonia coenia (Nymphalidae). Oecologia, 101, 75-85.

Bell, J.R., Alderson, L., Izera, D., Kruger, T., Parker, S., Pickup, J., Shortall, C.R., Taylor, M.S., Verier, P. & Harrington, R. (2015) Long-term phenological trends, species accumulation rates, aphid traits and climate: five decades of change in migrating aphids. Journal of Animal Ecology, 84, 21-34.

Cowie, R.J. & Hinsley, S.A. (1988) Feeding ecology of great tits (Parus major) and blue tits (Parus caeruleus), breeding in suburban gardens. Journal of Animal Ecology, 57, 611-626.

Dixon, A.F.G. (1998) Aphid Ecology. Chapman & Hall, London.

Feeny, P. (1976) Plant apparency and chemical defence. Recent Advances in Phytochemistry, 10, 1-40.

Hopkins, G.W. & Dixon, A.F.G. (1997) Enemy-free space and the feeding niche of an aphid. Ecological Entomology, 22, 271-274.

Hopkins, G.W., Thacker, J.I.T., Dixon, A.F.G., Waring, P. & Telfer, M.G. (2002) Identifying rarity in aphids: the importance of host plant range. Biological Conservation, 105, 293-307.

McLean, I., Carter, N. & Watt, A. (1977) Pests out of Control. New Scientist, 76, 74-75.

Milcu, A., Bonkowski, H., Collins, C.M. & Crawley, M.J. (2015) Aphid honeydew-induced changes in soil biota can cascade up to tree crown architecture. Pedobiologia, 58, 119-127.

Milovanovic, M., Stefanovic, M., Djermanovic, V., & Milovanovic, J. (1996). Some chemical constituents of Anthriscus sylvestris. Journal of Herbs, Spices & Medicinal Plants, 4, 17–22. Eugenol – insecticide

Novgorodova, T.A. & Gavrilyuk, A.V. (2012). The degree of protection different ants (Hymenoptera: Formicidae) provide aphids (Hemiptera: Aphididae) against aphidophages European Journal of Entomology, 109, 187-196.

Owen, D.F. (1977) Are aphids really plant pests? New Scientist, 76, 76-77.

Owen, D.F. (1980) How plants may benefit from the animals that eat them. Oikos, 35, 230-235.

Price, P.W. (2003) Macroecological Theory on Macroecological Patterns, Cambridge University Press, Cambridge.

Thacker, J.I., Hopkins, G.W. & Dixon, A.F.G. (2006) Aphids and scale insects on threatened trees: co-extinction is a minor threat. Oryx, 40, 233-236.

Uusitalo, M. (2004) European Bird Cherry (Pruns padus L). A Biodiverse Wild Plant for Horticulture. MTT Agrifood Research Finland, Jokioinen.

** https://en.wiktionary.org/wiki/the_bee%27s_knees    

***Hugh Loxdale however, would argue that all insects are specialists and that so called polyphagous species are, in reality, cryptic specialist species (Loxdale, H.D., Lushai, G. & Harvey, J.A. (2011) The evolutionary improbablity of ‘generalism’ in nature, with special reference to insects. Biological Journal of the Linnean Society, 103, 1-18.)

 

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Filed under Aphidology, Aphids

Satiable curiosity – side projects are they worthwhile?

I’ve been meaning to write this one for quite a while.  It was stimulated by two posts, one from the incredibly prolific Steve Heard, the other by the not quite so prolific, but equally interesting,  Manu Saunders.  First off, what is a side project?  To me, a side project is one that is not directly funded by a research council or other funding agency or, in some cases, one that you do in your spare time, or to the horror of some line-managers, is not strictly in your job description 🙂 The tyranny of modern research funding dictates that projects must have specific research questions and be accompanied by hypotheses and very specific predictions; most proposals I referee, even contain graphs with predicted results and almost all have ‘preliminary data’ to support their applications.   This is not necessarily a bad thing but to directly quote Manu Saunders from her blog post

“Whittaker’s (1952) study of ‘summer foliage insect communities in the Great Smoky Mountains’ is considered one of the pioneer studies of modern community ecology methods. The very short Introduction starts with the sentence “The study was designed to sample foliage insects in a series of natural communities and to obtain results of ecological significance from the samples.” No “specific research questions” and the hypotheses and predictions don’t appear until the Discussion” Sounds like bliss.

The central ethos of my research career which began in 1977, can be summed up by this quotation uttered by the character ‘Doc’ in John Steinbeck’s novel Sweet Thursday “I want take everything I’ve seen and thought and learned and reduce them and relate them and refine them until I have something of meaning, something of use” (Steinbeck, 1954).* The other thing that has driven me for as long as I can remember, and why I ended up where I am,  is something I share with Rudyard Kipling’s Elephant Child, and that is a “satiable curiosity”:-) Something that has always frustrated me, is that, in the UK at least, most funded research tends to be of a very short duration, usually three years, often less than that**, and if you are very lucky, maybe five years.  If you work on real life field populations, even if you work on aphids, these short term projects are not really very useful; laboratory work is of course a different matter.

I got my first ‘permanent’ job in 1982 working for UK Forestry Commission Research based at their Northern Research Station (NRS) just outside Edinburgh.  My remit initially was to work on the pine beauty moth, Panolis flammea and finally, on the large pine weevil, Hylobius abietis.  As a committed aphidophile, I was determined, job description or not, to carry on working with aphids. I decided that the easiest and most useful thing to do was to set up a long-term field study and follow aphid populations throughout the year.  My PhD was on the bird cherry-oat aphid, Rhopalosiphum padi, a host alternating aphid, the primary host of which is the bird cherry, Prunus padus, with which  Scotland is very well supplied, and fortuitously, just down the road from NRS was Roslin Glen Nature Reserve with a nice healthy population of bird  cherry trees.  I chose ten suitable trees and started what was to become a ten-year once a week, lunch time counting and recording marathon.  I also decided to repeat a study that my PhD supervisor, Tony Dixon had done, record the populations of the sycamore aphid, Drepanosiphum platanoidis.  In the grounds of NRS were five adjacent sycamore tree, Acer pseudoplatanus, and these became my early morning study subjects, also once a week. I had no articulated hypotheses, my only aim was to count and record numbers and life stages and anything else I might see. Anathema to research councils but exactly what Darwin did 🙂

Although it was a ‘permanent’ job, after ten years I moved to Imperial College at Silwood Park and immediately set up a new, improved version of my sycamore study, this time a once weekly early morning*** walk of 52 trees in three transects and with much more data collection involved, not just the aphids, their natural enemies and anything else I found and on top of all that, the trees themselves came in for scrutiny, phenology, growth, flowering and fruiting, all went into my data sheets.  I also set up a bird cherry plot, this time with some hypotheses articulated 🙂

As a result of my weekly walk along my sycamore transects, a few years later I set up yet another side project, this time an experimental cum observational study looking at tree seedling survival and colonisation underneath different tree canopies. At about the same time, initially designed as a pedagogical exercise, I started my study of the biodiversity of Bracknell roundabouts.

One might argue that most undergraduate and MSc research projects could also come under the heading of side projects, but I think that unless they were part of a long term study they aren’t quite the same thing, even though some of them were published.  So, the burning question, apart from the benefits of regular exercise, was the investment of my time and that of my student helpers and co-researchers worth it scientifically?

Side project 1.  Sycamore aphids at the Northern Research Station, 1982-1992

I collected a lot of aphid data, most of which remains, along with the data from Side project 2, in these two notebooks, waiting to be entered into a spreadsheet.  I also collected some limited natural enemy data, presence of aphid mummies and numbers killed by entomopathogenic fungi.  Tree phenological data is limited to bud burst and leaf fall and as I only sampled five trees I’m not sure that this will ever amount to much, apart from perhaps appearing in my blog or as part of a book.  Nothing has as yet made it into print, so a nil return on investment.

Raw data – anyone wanting to help input into a spreadsheet, let me know 🙂 Also includes the data for Side project 2

 

Side project 2.  Rhopalosiphum padi on Prunus padus at Roslin Glen Nature Reserve 1982-1992

I was a lot more ambitious with this project, collecting lots of aphid and natural enemy data and also a lot more tree phenology data, plus noting the presence and counting the numbers of other herbivores.  I have got some of this, peak populations and egg counts in a spreadsheet and some of it has made it to the outside world (Leather, 1986, 1993: Ward et al., 1998).  According to Google Scholar, Ward et al., is my 6th most cited output with, at the time of writing, 127 citations, Leather (1993) is also doing quite well with 56 citations, while Leather (1986) is much further down the list with a mere 38 citations.  I have still not given up hope of publishing some of the other aphid data.  I mentioned that I also recorded the other herbivores I found, one was a new record for bird cherry (Leather, 1989), the other, the result of a nice student project on the bird cherry ermine moth (Leather & MacKenzie, 1994).  I would, I think, be justified in counting this side project as being worthwhile, despite the fact that I started it with no clear hypotheses and the only aim to count what was there.

 

Side project 3.  Everything you wanted to know about sycamores but were afraid to ask 1992-2012

As side projects go this was pretty massive.  Once a week for twenty years, me and on some occasions, an undergraduate research intern, walked along three transects of 52 sycamore trees, recording everything that we could see and count and record, aphids, other herbivores, natural enemies and tree data, including leaf size, phenology, height, fruiting success and sex expression.  My aim was pretty similar to that of Whittaker’s i.e.   “…to sample foliage insects in a series of natural communities and to obtain results of ecological significance from the samples”  truly a mega-project.  I once calculated that there are counts from over 2 000 000 leaves which scales up to something like 10 000 000 pieces of data, if you conservatively estimate five data observations per leaf. Quite a lot of the data are now computerized thanks to a series of student helpers and Vicki Senior, currently finishing her PhD at Sheffield University, but certainly not all of it. In terms of output, only two papers so far (Wade & Leather, 2002; Leather et al., 2005), but papers on the winter moth, sycamore and maple aphids and orange ladybird are soon to be submitted.  On balance, I think that this was also worthwhile and gave me plenty of early morning thinking time in pleasant surroundings and a chance to enjoy Nature.

The sycamore project – most of the raw data, some of which still needs to be computerised 🙂

 

Side project 5. Sixty bird cherry trees 1993-2012

This project has already featured in my blog in my Data I am never going to publish series and also in a post about autumn colours and aphid overwintering site selection.  Suffice to say that so far, thanks to my collaborator Marco Archetti, two excellent papers have appeared (Archetti & Leather, 2005; Archetti et al., 2009), the latter of which is my third most cited paper with 101 cites to date and the former is placed at a very respectable 21st place.  I don’t really see any more papers coming out from this project, but I might get round to writing something about the study as a whole in a natural history journal. On balance, even though only two papers have appeared from this project, I count this as having been a very worthwhile investment of my time.

All now in a spreadsheet and possibly still worthwhile delving into the data

 

Side project 5.  Urban ecology – Bracknell roundabouts 2002-2012

This started as a pedagogical exercise, which will be the subject of a blog post in the not too distant future. The majority of the field work was done by undergraduate and MSc students and in the latter years spawned a PhD student, so a side project that became a funded project 🙂 To date, we have published seven papers from the project (Helden & Leather, 2004, 2005; Leather & Helden, 2005ab; Helden et al., 2012; Jones & Leather, 2012; Goodwin et al., 2017) and there are probably two more to come.  Definitely a success and a very worthwhile investment of my time.  The story of the project is my most requested outreach talk so also gives me the opportunity to spread the importance of urban ecology to a wider audience.

The famous roundabouts – probably the most talked and read about roundabouts in the world 🙂 Sadly Roundabout 1 i n o longer with us; it was converted into a four-way traffic light junction last year 😦

 

Side project 6.  Testing the Janzen-Connell Hypothesis – Silwood Park, 2005-2012

I mentioned this project fairly recently so will just link you to it here.  So far only one paper has come out of this project (Pigot & Leather, 2008) and I don’t really see me getting round to doing much more than producing another Data I am never going to publish article, although it does get a passing mention in the book that I am writing with former colleagues Tilly Collins and Patricia Reader.  It also gave undergraduate and MSc project students something to do.  Overall, this just about counts as a worthwhile use of my time.

Most of this is safely in a spreadsheet but the data in the notebooks still needs inputting

According to my data base I have published 282 papers since 1980 which given that I have supervised 52 PhD students, had 5 post-docs, and, at a rough estimate, supervised 150 MSc student projects and probably 200 undergraduate student projects doesn’t seem to be very productive 😦 Of the 282 papers, 125 are from my own projects, which leaves 139 papers for the post-docs and PhD students and 17 from the side projects.  Three of the papers published from the side projects were by PhD students, so if I remove them from the side projects that gives an average of 2.3 papers per side project and 2.4 papers per post-doc and PhD student.   So, in my opinion, yes, side projects are definitely worth the investment.

 

References

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.

Archetti, M., Döring, T.F., Hagen, S.B., Hughes, N.M., Leather, S.R., Lee, D.W., Lev-Yadun, S., Manetas, Y., Ougham, H.J., Schaberg, P.G., & Thomas, H. (2009) Unravelling the evolution of autumn colours: an interdisciplinary approach. Trends in Ecology & Evolution, 24, 166-173.

Goodwin, C., Keep, B., & Leather, S.R. (2017) Habitat selection and tree species richness of roundabouts: effects on site selection and the prevalence of arboreal caterpillars. Urban Ecosystems, 19, 889-895.

Helden, A.J. & Leather, S.R. (2004) Biodiversity on urban roundabouts – Hemiptera, management and the species-area relationship. Basic and Applied Ecology, 5, 367-377.

Helden, A.J. & Leather, S.R. (2005) The Hemiptera of Bracknell as an example of biodiversity within an urban environment. British Journal of Entomology & Natural History, 18, 233-252.

Helden, A.J., Stamp, G.C., & Leather, S.R. (2012) Urban biodiversity: comparison of insect assemblages on native and non-native trees.  Urban Ecosystems, 15, 611-624.

Jones, E.L. & Leather, S.R. (2012) Invertebrates in urban areas: a review. European Journal of Entomology, 109, 463-478.

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

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. (1993) Overwintering in six arable aphid pests: a review with particular relevance to pest management. Journal of Applied Entomology, 116, 217-233.

Leather, S.R. & Helden, A.J. (2005) Magic roundabouts?  Teaching conservation in schools and universities. Journal of Biological Education, 39, 102-107.

Leather, S.R. & Helden, A.J. (2005) Roundabouts: our neglected nature reserves? Biologist, 52, 102-106.

Leather, S.R. & Mackenzie, G.A. (1994) Factors affecting the population development of the bird cherry ermine moth, Yponomeuta evonymella L. The Entomologist, 113, 86-105.

Leather, S.R., Wade, F.A., & Godfray, H.C.J. (2005) Plant quality, progeny sequence, and the sex ratio of the sycamore aphid, Drepanoisphum platanoidis. Entomologia experimentalis et applicata, 115, 311-321.

Pigot, A.L. & Leather, S.R. (2008) Invertebrate predators drive distance-dependent patterns of seedling mortality in a temperate tree Acer pseudoplatanus. Oikos, 117, 521-530.

Steinbeck, J. (1954) Sweet Thursday, Viking Press, New York, USA.

Wade, F.A. & Leather, S.R. (2002) Overwintering of the sycamore aphid, Drepanosiphum platanoidis. Entomologia experimentalis et applicata, 104, 241-253.

Ward, S.A., Leather, S.R., Pickup, J., & Harrington, R. (1998) Mortality during dispersal and the cost of host-specificity in parasites: how many aphids find hosts? Journal of Animal Ecology, 67, 763-773.

Whittaker, R.H. (1952) A Study of summer foliage insect communities in the Great Smoky Mountains. Ecological Monographs, 22, 1-44.

 

*

I was so impressed by this piece of philosophy that it is quoted in the front of my PhD thesis 🙂

**

My second post-doc was only for two years.

***

You may wonder why I keep emphasising early morning in relation to surveying sycamore aphids.  Sycamore aphids are very easy to disturb so it is best to try and count them in the early morning before they have a chance to warm up and become flight active.

 

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