Ten papers that shook my world – watching empty islands fill up – Simberloff & Wilson (1969)

Sadly this is the tenth and last in my series of the ten papers that had a great influence on my life as an ecologist.  I’m going to cheat somewhat and actually discuss three papers. In my defence they are extremely closely linked and I am pretty certain that in today’s publishing world they would all have had to have been combined anyway.  That aside, I really liked this experiment the first time I read about it and still rate it very highly.  I would, however, love to be able to travel back in time and give them a couple of hints with the benefit of hind-sight, although as the authors are two of the greatest living ecologists, Dan Simberloff and E O Wilson, I might be a bit apprehensive doing so 🙂 In any case, much of what I would have said was addressed a few years later (Simberloff, 1976).

Wilson and Simberloff wanted to practically test the island biogeography theory famously described by McArthur and Wilson a few year earlier (MacArthur & Wilson, 1967).  To do this they travelled to the Florida Keys and after due reconnaissance decided that the many mangrove “tree islands” would be ideal study sites (Figure 1).  Then came the really cool bit.

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Figure 1.  Two of the experimental ‘islands’ from Wilson & Simberloff (1969)

They set about removing the arthropod animal life from nine of the islands (Figure 2), or as much as they could, by fogging with methyl bromide; not something we could do now.  They then monitored the islands at frequent intervals for the next year.  They had of course surveyed the islands before they fumigated them.

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Figure 2.  What a cool project; defaunation in progress – from Wilson & Simberloff (1969)

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Figure 3. Island equilibria – from Simberloff & Wilson (1970)

The major finding from their study was that recolonization happened quite quickly and that a year later had pretty much reached an equilibrium position (Figure 3).  Another important finding and one that has important implications for restoration and conservation strategies was that two years after the defaunation event, although the islands were well populated, the species composition, except for one island was less than 40% similar to the original inhabitants (Simberloff & Wilson (1970).  Most species present were new to those islands.  The analysis of the data presented in the two data papers is rather basic, some of the key island biogeographical premises are not addressed at all and I wondered why they had not done so.  Their data are all shown in some detail so it is possible to do some more analysis, which I took the liberty of doing.  The extra analysis shows why they did not discuss area effects per se .  The only significant relationship that I could find was that between the number of species and the distance from the ‘mainland’ source (Figure 4), which as predicted by MacArthur & Wilson (1967) was negative. Sadly, island size did not correlate with species number (Figure5).   Finally, there was a positive, but not significant relationship between the initial number of species found on an island and the number a year later (Figure 6).

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Figure 4.  Relationship between distance from ‘mainland’ source and the number of arthropod species present (R2 = 0.65, P <.0.05) Data from Simberloff & Wilson (1970).

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Figure 5.  Island diameter and number of arthropod species (not statistically significant, r2 = 0.19, although I am sure many politicians would view this as a positive trend). Data from Simberloff & Wilson (1970)

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Figure 6.  Initial number of species on an island and number of species present one year later. Although it looks convincing (r2 = 0.54), there are too few observations to reach statistical significance.  Data from Simberloff & Wilson (1970)

Although this work was extremely influential, (my Bracknell roundabouts study owes a lot to it), there were two major flaws in the original experimental design.  Firstly the number of islands was very low, but of course this is understandable, given the effort and complex logistics required to remove the arthropods safely (Figure 2).  The other flaw was that the islands did not cover a large enough range of sizes, thus making it less likely for the species-area pattern to be detected which was a great shame.

As I mentioned earlier, these short-comings were not ignored by the authors, and a few years later Sinberloff (1976) reported the results of an enhanced study, again in the Florida Keys, where he was able to convincingly demonstrate the species-area effect.   I guess that this was pretty satisfying as it tied up a number of loose strings.  He also managed to get the phrase “flogging a dead horse” into his introduction 🙂

Of the three papers, Simberloff & Wilson (1969) is the most highly cited (according to Google Scholar, 618 to date) and became a “citation classic”* in 1984 at which time it had accumulated 164 citations.  Simberloff & Wilson (1970) has attracted 252 cites with Wilson & Simberloff (1969) trailing in third with a mere 158 cites.  As a point of interest, Simberloff (1976) has so far received 313 cites.  To reiterate, the original mangrove island study, despite its flaws was a fantastic piece of work and Sinberloff and Wilson won the Mercer Award of the Ecological Society of America for this work in 1971.

I can think of no better person to explain why Simberloff & Wilson (1969) deserves its place in the Ecological Hall of Fame than Simberloff himself who in the commentary to the 1984 citation classic article wrote “I think the main reason it is cited, however, and its lasting contribution, is not so much that it supports the [equilibrium] theory, as that it reported a field experiment on ecological communities, and thus seemed dramatically different from the correlative approach that dominated this field

 

References

MacArthur, R.H. & Wilson, E.O. (1967) The Theory of Island Biogeography Princeton University Press, Princeton.

Simberloff, D. (1976)  Experimental zoogeography of islands: effects of island size.  Ecology, 57, 629-648.

Simberloff, D. & Wilson, E.O. (1969) Experimental zoogeography of islands: the colonization of empty islands. Ecology, 50, 278-296.

Simberloff, D. & Wilson, E.O. (1970) Experimental zoogeography of islands: a two-year record of colonization. Ecology, 51, 934-937.

Wilson, E.O. & Simberloff, D. (1969) Experimental zoogeography of islands: defaunation and monitoring techniques. Ecology, 51, 267-278.

 

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

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

mind-the-gap

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

 

References

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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A Roundabout Review of the Year – highlights from 2016

Welcome to my traditional, well it is the fourth after all, annual review of my social media and science communication activities.  I have had another enjoyable year blogging and tweeting, and as I wrote last year, I have absolutely no plans to stop either.   You may also be pleased to know that pictures of roundabouts will continue to appear at irregular intervals 🙂

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Roundabout on the edge of Prades, 2016, complete with the author 🙂

 

Impact and reach

I have continued to post at about ten-day intervals; this is my 142nd post.  The more I write the easier it seems to become. I also did my first jointly authored post, teaming up with Anne Hilborn (@AnneWHilborn) to ask if naming study animals introduced observational bias which generated a fair bit of interest and was published in a slightly modified form in the on-line magazine Biosphere.  Another of my blog articles was converted into a discussion piece for the journal Agricultural & Forest Entomology  (see February 2017 issue) and my blogging activities resulted in me being asked to do an article about roundabouts and their biodiversity for the summer newsletter of the International Association for Landscape Ecology.  For those of you who think that social media has no place in science, I feel that this is pretty convincing evidence that science communication via social media is a  very worthwhile use of our time.

I had visitors from 164 countries (150 last year) and received 34 036 views (29 385 last year).  As last year, the majority of my readers

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The top ten countries for views in 2016

came form the UK and USA, although Sweden and The Netherlands made it into the top ten, pushing Spain into the wilderness.

 

Top reads

My top post (excluding my home page) in 2016 was one of my entomological classics, the Moericke Trap, closely followed by  A Winter’s Tale – Aphid Overwintering,  although my all-time winner is still Not All Aphids are Vegans with over 5 000 views.  My top ten posts tend to be either about aphids or entomological techniques/equipment which I guess means that I am filling an entomological niche.  I was however, disappointed to see that one of my favourite posts about (to me at any rate) the inspirational paper by Mike Way and Mike Cammell on using aphid egg counts to predict crop damage is languishing in the bottom ten, despite being published in September 2015 😦

 

Comparative statistics

One of the things that I find somewhat frustrating with blogging is the difficulty of gathering comparative data.  It may be the scientist in me or perhaps I am just too competitive, but as WordPress kindly supply their users with personal statistics, I feel the need to know how others are doing.  It is surprisingly hard to get these sort of data although this site is useful if you are hoping to use your blog for generating an income.  I was very excited a few weeks ago when my blog reached over 100 000 views at beginning of December.  Just a few days later Dynamic Ecology announced their 1 00 000 unique visitor which certainly put me in my place!   They have, however, been around a while and post much more frequently than I do, so are perhaps not the best yardstick, although of course something to aspire to.  Luckily, Jeff Ollerton who has been blogging about a year longer than me and in a similar subject area, is as obsessed with blogging statistics as I am and very kindly gave me access to his data.  Looking at the data it seems that we arrived at the same point

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Comparative statistics between my blog and that of Jeff Ollerton’s Biodiversity Blog.

after the same amount of time but in different ways.  Jeff had a much slower start than me and his stats are best described using a curvilinear relationship whereas my line is still a straightforward linear relationship.  I guess that as I was on Twitter when I launched my blog that I immediately picked up more views than Jeff who only joined the Twitter fraternity a month or so ago.  It will be interesting to see if his readership curve steepens in the coming months and if mine continues to rise linearly, plateau or (hopefully) take-off as Jeff’s did.

Tweeting for entomology

In terms of Tweeting I had a really great experience curating the Real Scientists Twitter account @realscientists.  It kept me very busy but I interacted with a whole new set of people and had some really interesting conversations.  I can heartily recommend it to anyone who is considering volunteering.  I had hoped to hit the 5 000 follower milestone before the end of the year but didn’t quite make it, ending the year with 4 960 instead which is according to my children, pretty good for a normal person 🙂

Many thanks to all my readers and especially to those who take the time to comment as well as pressing the like button.  My top commenters, as indeed they were last year, were Emma Maund, Emily Scott, Emma Bridges, Jeff Ollerton, Amelia from A French Garden and Philip Strange.  I look forward to interacting with you all in 2017.  A Happy and Prosperous New Year to you all.

 

 

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Merry Christmas and a Happy New Year

Just to wish all my readers a Merry Christmas and a Happy and productive New Year.  I am especially grateful to all of you who took the time to comment on my posts and/or press the like button.  Many thanks to those who shared my posts; your thoughtfulness is much appreciated.  I hope that you will continue to support my blog and follow me on Twitter in 2017.

merry-christmas-from-entoprof

 

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Entomologists – hirsutely stereotyped? — Don’t Forget the Roundabouts

There is a general perception that entomologists* are bearded, eccentric elderly men, with deplorable dress sense, something I must confess I probably do little to dispel. Beard and entomologically-themed clothing – living the stereotype🙂 Whilst it is certainly true that many Victorian entomologists fitted this description, it was and is not, a universal requisite for […]

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Entomologists – hirsutely stereotyped?

There is a general perception that entomologists* are bearded, eccentric elderly men, with deplorable dress sense, something I must confess I probably do little to dispel.

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Beard and entomologically-themed clothing – living the stereotype 🙂

Whilst it is certainly true that many Victorian entomologists fitted this description, it was and is not, a universal requisite for entomologists, although the images below may suggest otherwise.

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Two views of the same beard

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Two famous (and bearded coleopterists) Charles Darwin and David Sharp – two great examples of an elderly entomological beard.

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Alfred Russel Wallace – often overlooked so have not paired him with Darwin 🙂

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Two examples of the weird (to me at any rate) under the chin beard.

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Elegant (?) entomologists; note not all are bearded 🙂  From the Aurelian’s Fireside Companion

 

To return to the proposition that male entomologists are facially hirsute, we need to answer the question, were, and are male entomologists different from the general population?  Up until the 1850s beards were fairly uncommon and usually associated with radical political views (Oldstone-Moore, 2005).  Entomologists were no exception, those from the 18th and early 19th centuries, being in the main, clean-shaven, well-dressed gentlemen, or so their portraitists would have us believe.

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Entomologists also remained relatively clean-shaven up to the 185os, as these pictures of two entomologists who became famously bearded in later life show.

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Charles Darwin, fairly clean-shaven, but sporting fashionable side boards, 1854, pre-Crimean War, and a youthful, clean-shaven Alfred Russel Wallace.

After the 1850s, beards and bushy side boards began to be seen as a sign of masculinity (Oldstone-Moore, 2005).  This was further reinforced as a result of the conditions during the Crimean War where due to the freezing conditions and lack of shaving soap, beards became commonplace among the soldiers.  Beards were then seen as a sign of the hero, hence the adoption by many civilian males of the time (Oldstone-Moore, 2005).  This sporting of facial hair was not just confined to entomologists, as the pictures of my great-great-grandfather and his cousin show.

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Two Victorian civil engineers – my great-great grandfather John Wignall Leather and his cousin, John Towlerton Leather.

Entomologists were however, still very much bearded at the end of the century.

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A group of entomologists from the north-west of England in the 1890s.  Some impressive beards and moustaches; from the Aurelian’s Fireside Companion

So during the latter half of the 19th century, it would seem that male entomologists were no different from any other male of the time.

The full beard, except for those associated with the Royal Navy, started to disappear soon after the beginning of the 20th Century; the Boer Wars and the First World War hastening its departure.  Moustaches were still common however, and many entomologists remained resolutely bearded until the 1920s, although perhaps not as luxuriantly so as some of their 19th century predecessors.

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A group of entomologists from 1920 https://en.wikipedia.org/wiki/Percy_Ireland_Lathy#/media/File:BulletinHillMuseum1923.jpg

It is surprisingly difficult to find group photographs of entomologists on the internet, so I have been unable to do a robust analysis of the proportions of bearded entomologists through the ages.  Two of the most influential entomologists of the first half of the last century were however, most definitely clean-shaven.

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Sir Vincent Wigglesworth (1899-1994) and A D Imms (1880-1949), the authors of my generation’s two entomological ‘bibles’.  Definitely clean shaven.

The 1960s and 1970s were renowned for the hairiness of males in general (at least those in the West) and this especially spread into the world of students, many of whom were entomologists.  My memories of those times of attending meetings of the Royal Entomological Society and the British Ecological Society are of a dominance of beards among the male delegates and not just those in their twenties, but then memory is a funny thing.  I was, for example, lucky enough to attend the Third European Congress of Entomology held in Amsterdam in 1986.  My memory is of many bearded entomologists, but looking at the photograph of the delegates only 30% of the male delegates are bearded.

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The third European Congress of Entomology, Amsterdam 1986 – I am there, suitably bearded 🙂  The eagle-eyed among you may be able to spot a young John (now Sir John) Lawton, also bearded.

More shocking is the fact that the photograph shows that less than 20% of the delegates were female.  Times have changed since then, and as the two recent photos below show, we now have more female entomologists and fewer beards, the former a very positive trend, that I heartily endorse, the latter, something I am less happy about 🙂

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IOBC Meeting 2015 https://www.iobc-wprs.org/images/20151004_event_wg_field_vegetables_Hamburg_group_photo.jpg

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Entomological Society of America 2016

Generally speaking, it seems that beards are in decline and female entomologists are on the rise, something that I have, in my position as the Verrall Supper Secretary of the oldest extant entomological society in the world been at pains to encourage.

As to the matter of entomological eccentricity, that is another thing entirely.  As far as most non-entomologists are concerned anyone who loves insects and their allies is somewhat eccentric, and if that is indeed the case then I am happy to be considered eccentric.

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Me, happy with my head in a net

Eccentricity is not just confined to those of us in our dotage.

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A modern day eccentric?  Josh Jenkins-Shaw ex-MSc Entomology Harper Adams University, now pursuing a PhD at the Natural History Museum of Denmark at the University of Copenhagen resolving the biogeography of Lord Howe Island using beetle phylogenetics, mostly the rove beetle subtribe Amblyopinina.

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A selection of entomologist from our Department at Harper Adams University – not all bearded but we are all wearing antennae!

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Perhaps Santa Claus is an entomologist!

Merry Christmas to all my readers 🙂

 

References

Oldstone-Moore, C. (2005) The beard movement in Victorian Britain.  Victorian Studies, 48, 7-34.

Salmon, M.J. & Edwards, P.J. (2005) The Aurelian’s Fireside Companion.  Paphia Publishing Ltd. Lymington UK.

 

*That is of course if they know the meaning of the word.  I am constantly being surprised by the number of people who ask what an entomologist is and as for the ways in which entomology is spelt by the media, words fail me 🙂

 

 

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Insects in flight – whatever happened to the splatometer?

I have been musing about extinctions and shifting baselines for a while now; BREXIT and an article by Simon Barnes in the Sunday Times magazine (3rd September 2016) finally prompted me to actually put fingers to keyboard.  I fear that BREXIT will result in even more environmental damage than our successive governments have caused already.  They have done a pretty good job of ignoring environmental issues and scientific advice (badgers) even when ‘hindered’ by what they have considered restrictive European legislation and now that we head into BREXIT with a government not renowned for its care for the environment I become increasing fearful for the environment. Remember who it was who restructured English Nature into the now fairly toothless Natural England, because they didn’t like the advice they were being given and whose government was it who, rather than keep beaches up to Blue Flag standard decided to reclassify long-established resort beaches as not officially designated swimming beaches?  And, just to add this list of atrocities against the environment, we now see our precious ‘green belt’ being attacked.

My generation is liable to wax lyrical about the clouds of butterflies that surrounded us as we played very non PC cowboys and Indians outside with our friends in the glorious sunshine.  We can also fondly reminisce about the hordes of moths that used to commit suicide in the lamp fittings or beat fruitlessly against the sitting room windows at night.  The emptying of the lamp bowl was a weekly ceremony in our house.  We also remember, less fondly, having to earn our pocket-money by cleaning our father’s cars, laboriously scraping the smeared bodies of small flies from windscreens, headlamps and radiator grilles on a Saturday morning.  A few years later as students, those of us lucky enough to own a car, remember the hard to wash away red smears left by the eyes of countless Bibionid (St Mark’s) flies, as they crashed into our windscreens.

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Typical Bibionid – note the red eyes; designed specially to make a mess on your windscreen 🙂 https://picasaweb.google.com/lh/photo/GBgoGHhRbj-eUUF9SxZ4s9MTjNZETYmyPJy0liipFm0?feat=embedwebsite

Are these memories real or are we looking back at the past through those rose-tinted glasses that only show the sunny days when we lounged on grassy banks listening to In the Summertime and blank out the days we were confined to the sitting room table playing board games?

We have reliable and robust long-term data sets showing the declines of butterflies and moths over the last half-century or so (Thomas, 2005; Fox, 2013) and stories about this worrying trend attract a lot of media attention. On a less scientific note, I certainly do not find myself sweeping up piles of dead moths from around bedside lamps or extricating them from the many spider webs that decorate our house.  Other charismatic groups, such as the dragonflies and damselflies are also in decline (Clausnitzer et al., 2009) as are the ubiquitous, and equally charismatic ground beetles (carabids) (Brooks et al., 2012).  But what about other insects, are they too on the way out?  A remarkable 42-year data set looking at the invertebrates found in cereal fields in southern England (Ewald et al., 2015) found that of the 26 invertebrate taxa studied less than half showed a decrease in abundance; e.g. spiders, Braconid parasitic wasps, carabid beetles, Tachyporus beetles, Enicmus (scavenger beetles), Cryptophagid fungus beetles, leaf mining flies (Agromyzids), Drosophila, Lonchopteridae (pointed wing flies), and surprisingly, or perhaps not, aphids.  The others showed no consistent patterns although bugs, excluding aphids, increased over the study period.  Cereal fields are of course not a natural habitat and are intensely managed, with various pesticides being applied, so are perhaps not likely to be the most biodiverse or representative habitats to be found in the UK.

But what about the car-smearing insects, the flies, aphids and other flying insects?  Have they declined as dramatically?  My first thought was that I certainly don’t ‘collect’ as many insects on my car as I used to, but is there any concrete evidence to support the idea of a decline in their abundance.  After all, there has been a big change in the shape of cars since the 1970s.

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Top row – cars from 1970, including the classic Morris 1000 Traveller that my Dad owned and I had to wash on Saturdays.

Bottom row the cars of today, sleek rounded and all looking the same.

 

Cars were  much more angular then, than they are now, so perhaps the aerodynamics of today’s cars filter the insects away from the windscreen to safety? But how do you test that?  Then I remembered that the RSPB had once run a survey to address this very point.  Sure enough I found it on the internet, the Big Bug Count 2004, organised by the RSPB.  I was very surprised to find that it happened more than a decade ago, I hadn’t thought it was that long ago, but that is what age does to you 🙂

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The “Splatometer” as designed by the RSPB

The idea, which was quite cool, was to get standardised counts of insect impacts on car number platesThe results were thought to be very low as the quote below shows, but on what evidence was this based?

“Using a cardboard counting-grid dubbed the “splatometer”, they recorded 324,814 “splats”, an average of only one squashed insect every five miles. In the summers of 30-odd years ago, car bonnets and windscreens would quickly become encrusted with tiny bodies.”  “Many people were astonished by how few insects they splatted,” the survey’s co-ordinator Richard Bashford, said.

Unfortunately despite the wide reporting in the press at the time, the RSPB did not repeat the exercise.  A great shame, as their Big Garden Birdwatch is very successful and gathers useful data.   So what scientific evidence do we have for a decline in these less charismatic insects?  Almost a hundred years ago, Bibionid flies were regarded as a major pest (Morris, 1921) and forty years ago it was possible to catch almost 70 000 adults in a four week period from one field in southern England (Darcy-Burt & Blackshaw, 1987).   Both these observations suggest that in the past Bibionids were very common.  It is still possible to pluck adult Bibionids out of the air (they are very slow, clumsy fliers) in Spring, but if asked I would definitely say that they are not as common as they were when I was a student.  But as Deming once said, “Without data, you’re just another person with an opinion.”  In the UK we are fortunate that a long-term source of insect data exists, courtesy of Rothamsted Research, the longest running agricultural research station in the world.  Data have been collected from a nationwide network of suction and light traps for more than 50 years (Storkey et al., 2016).   Most of the publications arising from the survey have tended to focus on aphids (Bell et al., 2015) and moths (Conrad et al., 2004), although the traps, do of course, catch many other types of insect (Knowler et al., 2016).  Fortuitously, since I was interested in the Bibionids I came across a paper that dealt with them, and other insects likely to make an impact on cars and splatometers (Shortall et al., 2009).  The only downside of their paper was that they only looked at data from four of the Rothamsted Suction Traps, all from the southern part of the UK, which was a little disappointing.

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Location and results of the suction traps analysed by Shortall et al. (2009).

Only three of the trap showed downward trends in insect biomass over the 30 years (1973-2002) analysed of which only the Hereford trap showed a significant decline.  So we are really none the wiser; the two studies that focus on a wider range of insect groups (Shortall et al., 2009; Ewald et al., 2015) do not give us a clear indication of insect decline.   On the other hand, both studies are limited in their geographic coverage; we do not know how representative the results are of the whole country.

What a shame the RSPB stopped collecting ‘splatometer’ data, we would now have a half-decent time series on which to back-up or contradict our memories of those buzzing summers of the past.

Post script

After posting this I came across this paper based on Canadian research which shows that many pollinators, possibly billions are killed by vehicles every year.

References

Bell, J.R., Alderson, L., Izera, D., Kruger, T., Parker, S., Pickup, J., Shortall, C.R., Taylor, M.S., Verrier, 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.

Brooks, D.R., Bater, J.E., Clark, S.J., Montoth, D.J., 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 of insect biodiversity. Journal of Applied Ecology, 49, 1009-1019.

Clausnitzer, V., Kalkman, V.J., Ram, M., Collen, B., Baillie, J.E.M., Bedjanic, M., Darwall, W.R.T., Dijkstra, K.D.B., Dow, R., Hawking, J., Karube, H., Malikova, E., Paulson, D., Schutte, K., Suhling, F., Villaneuva, R.J., von Ellenrieder, N. & Wilson, K. (2009)  Odonata enter the biodiversity crisis debate: the first global assessment of an insect group.  Biological Conservation, 142, 1864-1869.

Conrad, K.F., Woiwod, I.P., Parsons, M., Fox, R. & Warren, M.S. (2004) Long-term population trends in widespread British moths.  Journal of Insect Conservation, 8, 119-136.

Darcy-Burt, S. & Blackshaw, R.P. (1987) Effects of trap design on catches of grassland Bibionidae (Diptera: Nematocera).  Bulletin of Entomological Research, 77, 309-315.

Ewald, J., Wheatley, C.J., Aebsicher, N.J., Moreby, S.J., Duffield, S.J., Crick, H.Q.P., & Morecroft, M.B. (2015) Influences of extreme weather, climate and pesticide use on invertebrates in cereal fields over 42 years. Global Change Biology, 21, 3931-3950.

Fox, R. (2013) The decline of moths in Great Britain: a review of possible causes. Insect Conservation & Diversity, 6, 5-19.

Knowler, J.T., Flint, P.W.H., & Flint, S. (2016) Trichoptera (Caddisflies) caught by the Rothamsted Light Trap at Rowardennan, Loch Lomondside throughout 2009. The Glasgow Naturalist, 26, 35-42.

Morris, H.M. (1921)  The larval and pupal stages of the Bibionidae.  Bulletin of Entomological Research, 12, 221-232.

Shortall, C.R., Moore, A., Smith, E., Hall, M.J. Woiwod, I.P. & Harrington, R. (2009)  Long-term changes in the abundance of flying insects.  Insect Conservation & Diversity, 2, 251-260.

Storkey, J., MacDonald, A.J., Bell, J.R., Clark, I.M., Gregory, A.S., Hawkins, N. J., Hirsch, P.R., Todman, L.C. & Whitmore, A.P. (2016)  Chapter One – the unique contribution of Rothamsted to ecological research at large temporal scales Advances in Ecological Research, 55, 3-42.

Thomas, J.A. (2005) Monitoring change in the abundance and distribution of insects using butterflies and other indicator groups.  Philosophical Transactions of the Royal Society B, 360, 339-357

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Ideas I had and never followed up

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

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

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

monumental-data

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

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

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The Forgotten Nine

 

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

graph

In those days we used graph paper 🙂

 the data, do let me know.

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

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

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

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

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

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

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

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

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

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

 

References

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

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

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

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

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

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

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

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

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

 

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

**Now Vice-Chancellor of the University of Wollongong

 

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You don’t need charismatic mega-fauna to go on an exciting safari

I got very annoyed the other day; the Zoological Society of London (Institute of Zoology) released what they termed a ”landmark report”.  I guess you can all immediately see why I was annoyed.  The headline of the press release very clearly states that global wildlife populations are on course to decline by 67% by 2020.  What their report actually says is that global vertebrate populations are on course to decline.

safari-1

https://www.zsl.org/science/news/landmark-report-shows-global-wildlife-populations-on-course-to-decline-by-67-per-cent

Plants and invertebrates are a much bigger and more important part of global wildlife than the tiny fraction of the world’s species contributed by those animals with backbones. I instantly posted a Tweet pointing out that for a scientific institution this was a highly inaccurate statement to be promulgating.

safari-2

My comment (still ignored by them) at the ZSL press release

The ZSL despite being copied into the Tweet, have so far (three weeks later), not deigned to reply.  I have taken the ZSL to task before with equally little success.  To give them credit where it is due however, just over four years ago they did release Spineless, a report about the global status of invertebrates, although the press release associated with this was a much more low-key affair then the recent one that I took exception to 🙂

Dr. Ben Collen*, head of the Indicators and Assessments unit at ZSL says: “Invertebrates constitute almost 80 per cent of the world’s species, and a staggering one in five species could be at risk of extinction. While the cost of saving them will be expensive, the cost of ignorance to their plight appears to be even greater”.

ZSL’s Director of Conservation, Professor Jonathan Baillie added: “We knew that roughly one fifth of vertebrates and plants were threatened with extinction, but it was not clear if this was representative of the small spineless creatures that make up the majority of life on the planet. The initial findings in this report indicate that 20% of all species may be threatened. This is particularly concerning as we are dependent on these spineless creatures for our very survival.

Unlike Ryan Clark who was also stimulated to write a protest blog in response to the same article, I do have something against vertebrates; they suck away valuable research funding and resources away from the rest of the animal kingdom (Leather, 2009; Loxdale, 2016) and distract attention and people away from invertebrate conservation efforts (Leather, 2008; Cardoso et al., 2011).  I have highlighted two sentences in the above quotes from the Spineless press release for very obvious reasons and wish that ZSL had taken these words to heart.  If, however, you go to their research page it would seem that these were only empty promises as less than 10% of their projects deal with invertebrates.  It is at times like this that I take comfort in the knowledge that I am not alone in despairing of the unfair treatment that invertebrates and the people that work with them suffer.

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Sums it up nicely, despite the focus on marine invertebrates 🙂

I had a few minutes of relief after posting my Tweet about the ZSL and their lack of scientific integrity, but I still felt frustrated and annoyed.  The need to do something further preyed on my mind, and then I had an idea. What about highlighting the charismatic mega-fauna that the ZSL and other similar bodies persist in ignoring.  I went on a quick photographic safari and in a few minutes was able to produce a little visual dig at the fans of the so-called charismatic mega-fauna.

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Going on safari as an entomologist

I thought this might raise a few appreciative likes from fellow entomologists and got back to work. I logged into Twitter a couple of hours later and was gratified, if somewhat surprised, to find that my Tweet seemed to have generated a bit of interest and not just from my followers.

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Appreciative tweets and comments from fellow invertebrate lovers – click on the image to enlarge it

I had also been translated into Spanish!

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Reaching the non-English speaking world 🙂

Then the Twitter account for the journal Insect Conservation & Diversity asked if anyone had other examples and generated a bit of a mini-Twitter storm with some great additions to the list.

 

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I particularly liked the Buffalo tree hopper.

And then something I didn’t know existed happened –

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I got a Gold Star!

This number of likes far exceeded my previous best-ever tweet, by a very long way.  Seriously though, it made me think about what makes some

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My previous best Tweet.

Tweets so much more retweetable than others.  My invertebrate safari tweet didn’t go viral, my understanding is that viral tweets are those that are retweeted thousands of times, but it certainly had an impact on people’s lives, however fleetingly.

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Having an impact, albeit not viral.

For those of you not up on Twitter analytics, what this means is that as of November 9th  2016, more than 33,000 people had seen my Tweet, of which almost 2000 had taken the trouble to click on it to make it bigger.  Of those 33,000 who saw it almost 400 went to the trouble to click the Like button and 260 re-tweeted it.  On the other hand, my serious taking the

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Not so great an impact, but at least it was read by a few people 🙂

ZSL to task tweet,  attracted much less attention, although one could argue that it was dealing with a much more serious issue.  That aside, responses like this and the other many positive outcomes I have had since I joined Twitter make me even more convinced that Tweeting and blogging are incredibly useful ways of interacting with both the scientific community and general public and getting more people to truly appreciate the little things that run the world.  Hopefully the ZSL, government funding agencies and conservation bodies will take notice of the plea by Axel Hochkirch (2016) to invest in entomologists and hence protect global biodiversity.

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A timely reminder (Hochkirch, 2016)

 

And finally, to end on a lighter note, please nominate and highlight your own favourite ‘charismatic mega-fauna invertebrates’.  There are many more out there.

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Another view of the Buffalo tree hopper  http://www.birddigiscoper.com/blogaugbug133a.jpg  photograph by Mike McDowell

 

References

Cardoso, P., Erwin, T.L., Borges, P.A.V., & New, T.R. (2011) The seven impediments in invertebrate conservation and how to overcome them. Biological Conservation, 144, 2647-2655.

Hochkirch, A. (2016) The insect crisis we can’t ignore.  Nature, 539, 141.

Leather, S.R. (2008) Conservation entomology in crisis? Trends in Ecology and Evolution, 23, 184-185.

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

Loxdale, H.D. (2016) Insect science – a vulnerable discipline? Entomologia experimentalis et applicata, 159, 121-134.

 

 

*The lead author of the report, Ben Collen was a former undergraduate student of mine, but hard as I tried, I was unable to convert him to the joys of entomology 🙂

 

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Filed under Bugbears, EntoNotes

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

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

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Red, green and gold, all on one tree

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

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

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Autumn Leaves Georgia O’Keeffe (1924) Tate Modern

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

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Bird cherry, Prunus padus, leaves on the turn.

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

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

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

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

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

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

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

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

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

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

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Maple, green to yellow in this case

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Spindle, Euonymus europaeus, green to red

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

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Some trees have red foliage all year

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

To summarise:

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

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

References

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

 

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

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

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Filed under Aphidology, Aphids, Science writing