Vive La France! The BES crosses La Manche

This year the AGM of the British Ecological Society  (BES) was a joint affair with the Société Française d’Écologie (SFE) and was held in Lille in northern France just over an hour away from London by Eurostar.  Given our love of France and in my wife’s case, Christmas markets, there was no way I was not going to attend this landmark meeting especially as the BES were willing to pay my registration fee in recognition of my role as an Associate Editor of the Journal of Animal Ecology.   My mother-in-law is also a keen fan of Christmas markets so she decided to come along and keep Gill company.

We left London on a later train than originally planned (strike action in Brussels) and arrived in Lille mid –afternoon Monday to find that our hotel was a good 4 km away from the railway station and almost as far away from the Grand Palais where the conference was being held.  Luckily my mother-in-law, although almost 86, is very spry and took the longish walk in her stride.  We eventually found the hotel, on the way being amused by an Irish pub with a very non-Irish name ;-)

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An unusual name for an Irish Pub

Being a Monday in France, not much was open but we eventually found somewhere to eat for a reasonable price, and amusingly were served by an English waiter!

As the conference registration didn’t start until Tuesday evening we spent most of the day sight-seeing and bumping into fellow delegates.

 

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The Christmas market was, however, somewhat disappointing, especially for those of us who were at the BES Birmingham meeting a couple of years ago.

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The very small Christmas Market

The damp weather was also a bit off-putting.  This was when I started to regret my decision to opt for a comfortable well-worn pair of Desert Boots with holes in the soles instead of a new pair.

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Wet, cold feet

The state of my feet inspired me to tweet an appropriate Haiku ;-)

 

Wet Pavements in Lille

Desert boots are great,

except when soles are holey;

then rain means wet feet

 

The BES and SFE did a great job – a very full programme kept us occupied from Wednesday 10th until late afternoon of Friday 12th December.  (Gill and my mother-in-law managed to get to Brussels and Arras for their Christmas markets).  My only gripe was that because it was such a popular meeting (over 1100 delegates) that there were a huge number of sessions (62) so I missed a lot of talks that I wanted to hear.  This is why in some ways I much prefer smaller conferences such as the Royal Entomological Society annual meetings where there are generally only two parallel sessions.  I have long ago given up trying to session- hop, so confined myself to the plenaries and complete sessions such as the Agricultural Ecology, Pest & Pesticides session, where one of my favourite talks was given by Victoria Wickens from the University of Reading on local and landscape effects on aphids and their natural enemies; she was supported in the audience by her identical twin, Jennifer (also a PhD student at Reading and who spoke later in the Plant-Pollinator Interactions session).  I first meet Jennifer and Victoria at the BES AGM in Leeds when they were MSc students and student helpers.  It was only towards the end of that conference that I realised that there were actually two of them ;-)

With careful planning I managed to fit in the Urban Ecology session, the Ecology & Society session, the symposium session on plant-insect-microbe interactions, and a session on herbivory.  There were a lot of really good talks and I learnt a lot. I made sure that I attended the Friday morning talk by Grrl Scientist who spoke about the use of social media and crowd funding in ecology.  I was somewhat embarrassed (and flattered) to have my blog publicly cited as an example of what other ecologists should be doing.  It was lucky that it was dark in the auditorium as I was blushing rather a lot.

The influence of the SFE was definitely felt; the catering was much, much better than we normally get at the normal BES meetings and it was great to see so many French ecologists.

Cakes DSCF4848 DSCF4850

and the free beer at lunch time was a welcome innovation that went down very well with the English delegates ;-)

Free beer

The organisers of the meeting next year in Edinburgh must be feeling somewhat nervous ;-)

 

Very many thanks to the BES and SFE and their local organisers for putting on such a splendid meeting; a veritable scientific and gastronomic delight.

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The infamous Desert boots – back home and ready to be  put to rest!

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Entomological Classics – Southwood 1961 – The number of insect species associated with various trees

 

Nineteen-Sixty-One  was a momentous  year for entomology and ecology, although at the time I suspect few realised it.  Skip forward to 2013 when The British Ecological Society published a slim volume celebrating  the 100 most influential papers published in the Society’s journals.  The papers included in the booklet were selected based on the opinions of 113 ecologists from around the world, who were then asked to write a short account of why they thought that paper influential.  I was disappointed not to be asked to write about my nomination but instead asked to write about Maurice Solomon’s 1949 paper in which he formalised the term functional response.

The paper I had wanted to write about was included, but John Lawton had the privilege of extolling its virtues, and given the word limits did a pretty good job.  I do, however, feel that given its importance to ecology and entomology it deserves a bit more exposure, so I am taking the opportunity to write about it here.  I could have included this post in a series I have planned, called Ten Papers that Shook My World, but given the impact that this paper has had on entomologists I felt it deserved an entry in my Entomological Classics series.

For those of you who haven’t come across this paper before, this was an astonishingly influential paper.  Basically, Southwood, who despite his later reputation as one of the ecological greats, was an excellent entomologist, (in fact he was a Hemipterist), wanted to explain why some tree species had more insect species associated with them than others.  He made comparisons between trees in Britain, Russia and Cyprus and demonstrated that those trees that were more common and had a wider range had more insect species associated with them (Figure 1).

Southwood 1961 Fig 1

From Southwood 1961.  I was surprised to see that he had committed the cardinal error in his Figure caption of describing it as Graph and also including the regression equation in the figure pane; two things that I constantly reprimand students about!

Importantly he also showed that introduced trees tended to have fewer insects than native species.  He thus hypothesised that the number of insects associated with a tree species was proportional to its recent history and abundance and was a result of encounter rates and evolutionary adaptation.  He then tested this hypothesis using data on the Quaternary records of plant remains from Godwin (1956) making the assumption that these were a proxy for range as well as evolutionary age.

He commented on the outliers above and below the line suggesting that those above the line were a result of having a large number of congeners and those below the line either as being taxonomically isolated and/or very well defended.

He then went on to test his ideas about the evolutionary nature of the relationship by looking at trees and insects in Hawaii, (ironically this appeared in print (Southwood, 1960), before the earlier piece of work (Journal of Animal Ecology obviously had a slower turnaround time in those days than they do now).

Hawaiin figure

Figure 2.  Relationship between tree abundance and number of insect species associated with them (drawn using data from Southwood 1960).

Considering the research that these two papers stimulated over the next couple of decades, what I find really odd, is that Southwood, despite the fact that he was dealing with data from islands and that Darlington (1943) had published a paper on carabids on islands and mountains in which he discussed species-area relationships and further elaborated on in his fantastic book (Darlington, 1957), did not seem to see the possibility of using the species-area concept to explain his results.  It was left to Dan Janzen who in 1968 wrote

It is unfortunate that the data on insect-host plant relationships have not in general been collected in a manner facilitating analysis by MacArthur and Wilson’s methods (as is the case as well with most island biogeographical data). What we seem to need are lists of the insect species on various related and unrelated host plants, similarity measures between these lists (just as in Holloway and Jardine’s 1968 numerical taxonomic study of Indo- Australian islands), knowledge of the rates of buildup of all phytophagous insect species on a host plant new to a region, where these species come from, etc. Obviously, the insect fauna must be well known for such an activity. The English countryside might be such a place; it has few “islands” (making replication difficult) but a very interesting “island” diversity, with such plants as oaks being like very large islands and beeches being like very small ones, if the equilibrium number of species on a host plant (Elton, 1966; Southwood, 1960) is any measure of island size.”

 

In 1973 Dan Janzen  returned to the subject of trees as islands and cited Paul Opler’s 1974 paper in relation to the fact that the number of  herbivorous insects associated with a plant increases with the size of the host plant population (Figure 3), and further reiterated

Opler Figure

Figure 3.  Opler’s 1974 graph showing relationship between range of oak trees in the USA and the number of herbivorous insect species associated with them.

 his point about being able to consider trees as ecological islands.  Opler’s 1974 paper is also interesting in that he suggested that this approach could be used for predicting pest problems in agricultural systems, something that Don Strong and colleagues did indeed do (Strong et al., 1977; Rey et al., 1981), and that the concept of habitat islands and the species-area relationship could be used when designing and evaluating nature reserves, something which indeed has come to pass.

Again in 1974 but I think that Strong has precedence because Opler cites him in his 1974 paper, Don Strong reanalysed Southwood’s 1961 data using tree range (based on the Atlas of the British Flora)  as the explanatory variable  (figure 4) to explain the patterns seen.

Strong Figure

Figure 4Strong’s reworking of Southwood’s 1961 insect data using the distribution of British trees as shown in Perring & Walters1 (1962).

The publication of this paper opened the floodgates, and papers examining the species-area relationships of different insect groups and plant communities proliferated (e.g  leafhoppers (Claridge & Wilson, 1976); bracken (Rigby & Lawton, 1981); leaf miners (Claridge & Wilson, 1982); rosebay willow herb (McGarvin, 1982), with even me making my own modest contribution in relation to Rosaceous plants   (Leather, 1985, 1986).

Although not nearly as popular a subject as it was in the 1980s, people are still extending and refining the concept  (e.g. Brändle & Brandl, 2001; Sugiura, 2010; Baje et al., 2014).

Southwood (1961) inspired at least two generations of entomologists and ecologists, including me, and is still relevant today.  It is truly an entomological (and ecological) classic.

References

Baje, L., Stewart, A.J.A. & Novotny, V. (2014)  Mesophyll cell-sucking herbivores (Cicadellidae: Typhlocybinae) on rainforest trees in Papua New Guinea: local and regional diversity of a taxonomically unexplored guild.  Ecological Entomology 39: 325-333

Brändle, M. &Brandl, R. (2001). Species richness of insects and mites on trees: expanding Southwood. Journal of Animal Ecology 70: 491-504.

Claridge, M. F. &Wilson, M. R. (1976). Diversity and distribution patterns of some mesophyll-feeding leafhoppers of temperate trees. Ecological Entomology 1: 231-250.

Claridge, M. F. &Wilson, M. R. (1982). Insect herbivore guilds and species-area relationships: leafminers on British trees. Ecological Entomology 7: 19-30.

Darlington, P. J. (1943). Carabidae of mountains and islands: data on the evolution of isolated faunas and on atrophy of wings. Ecological Monographs 13: 37-61.

Darlington, P. J. (1957). Zoogeography: The Geographical Distribution of Animals. New York: John Wiley & Sons Inc.

Elton, C. S. (1966). The Pattern of Animal Communities. Wiley, New York.

Holloway, J. D., & Jardine, N. (1968). Two approaches to zoogeography: a study based on the distributions of butterflies, birds and bats in the Indo-Australian area. Proceedings of the Linnaean Society. (London) 179:153-188.

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

Janzen, D. H. (1968). Host plants as islands in evolutionary and contemporary time. American Naturalist 102: 592-595.

Janzen, D. H. (1973). Host plants as islands II.  Competitive in evolutionary and contemporary time. American Naturalist 107: 786-790.

Kennedy, C.E.J. & Southwood, T.R.E. (1984) The number of species of insects associated with British trees: a re-analysis. Journal of Animal Ecology 53: 455-478.

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 hostrange, plant architecture, age of establishment, taxonomic isolation and species-area relationships. Journal of Animal Ecology 55: 841-860.

Macgarvin, M. (1982). Species-area relationships of insects on host plants: herbivores on rosebay willowherbs. Journal of Animal Ecology 51: 207-223.

Opler, P. A. (1974). Oaks as evolutionary islands for leaf-mining insects. American Scientist 62: 67-73.

Perring, F.J. & Walters, S.M. (1962) Atlas of the British Flora BSBI Nelson, London & Edinburgh.

Preston,  C.D., Pearman, D.A. & Tines, T.D. (2002) New Atlas of the British and Irish Flora: An Atlas of the Vascular Plants of Britain, Ireland, The Isle of Man and the Channel Islands. BSBI, Oxford University Press

Rigby, C. & Lawton, J. H. (1981). Species-area relationships of arthropods on host plants: herbivores on bracken. Journal of Biogeography 8: 125-133.

Solomon, M. E. (1949). The natural control of animal populations. Journal of Animal Ecology 18: 1-35

Southwood, T. R. E. (1960). The abundance of the Hawaiian trees and the number of their associated insect species. Proceedings of the Hawaiian Entomological Society 17: 299-303.

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

Sugiura, S. (2010). Associations of leaf miners and leaf gallers with island plants of different residency histories.  Journal of Biogeograpgy 37: 237-244

Rey, J.R.M.E.D. & Strong, D.R. (1981) Herbivore pests, habitat islands, and the species area relation. American Naturalist 117: 611-622.

Strong, D. R. (1974). The insects of British trees: community equilibrium in ecological time. Annals of the Missouri Botanical Gardens 61: 692-701.

Strong, D.R., D., M.E., & Rey, J.R. (1977) Time and the number of herbivore species: the pests of sugarcane. Ecology 58: 167-175

 

1Postscript

The Atlas of the British Flora by Perring and Walters (1962) was an iconic piece of work, although not without its flaws.  As with many distribution atlases it is based on a pence or absence score of plant species within one kilometre squares.  So although it is a good proxy or range it does not necessarily give you an entirely reliable figure for abundance.  A dot could represent a single specimen or several thousand specimens.   Later authors attempted to correct for this by using more detailed local surveys e.g. tetrads.  It must have been particularly galling for  Southwood that the Atlas didn’t appear until after he had published his seminal papers, but he later made up for it by reanalysing and extending his data from that original 1961 paper (Kennedy et al., 1984).

Those of us working in this area using the original Atlas had to count the dots by hand, a real labour of love especially for those widely distributed species; the new edition (Preston et al., 2002) actually tells you how many dots there are so the task for the modern-day insect-plant species-area relationship worker is much easier ;-)

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Social media and academia do work well together – two years in and still a fan

It is now just over two years since I began tweeting and just under two years since I started blogging. My first end of year report saw me entering my second year as a fully converted Tweeter and Blogger and very happy indeed with my foray into the world of social media.  I had made new research contacts, got invitations to give talks to local conservation groups, got BBC Wildlife to acknowledge their vertebrate bias,

BBC Wildlife

been invited to give a talk on the subject at the Royal Entomological Society annual meeting and even got a publication in the journal Animal Conservation!  So I definitely finished 2013 on a high and began the New Year with an almost evangelical desire to convince all my colleagues to join in the fun.

So now here I am, two years in. Is it still working for me?  Most definitely.  I have amassed over 2300 followers on Twitter and 124 people are signed up to receive updates to my blog.  I have, including this article, written 65 blog posts.  Views on my blog have increased from a daily average of 39 to 67 and at the time of writing it has received over 22000 views compared with just over 14000 last year.  I figure that this is considerably more exposure than I get from my published scientific papers.  That said, I have as a direct result of my blogging activities had two more papers published (Leather, 2014, 2015) and been asked to submit a more formal version of my end of year report to Antenna (the house journal of the Royal Entomological Society) which will give me a chance to sway a somewhat larger entomological audience than I had at the annual meeting last September (2013)! My good-natured jibes (via Twitter) at the Journal of Animal Ecology accusing them of a vertebrate bias, resulted in me being asked to edit one of their Virtual Issues which in turn, resulted in a very interesting post on their blog by their Editor-in-Chief Ken Wilson.

As a journal editor, I have been able to find referees for papers and also new editorial board members. I have also found Twitter an invaluable way of advertising the MSc course in Entomology that I run here at Harper Adams University,  of advertising PhD and staff positions and of generally reaching and interacting with a huge number of like-minded people around the world.   It is of course not all one way traffic, I get a number of requests for help and information that I am, if able, happy to respond positively to.

My biggest buzz this year was to receive a complimentary copy of a book by Peter Smith (Smith, 2014), in which one of my blog posts,

Smith book

Are PhD Examiners really ogres? was quoted several times.   I have to confess that this gave me pretty much the same feeling that I got when I saw my first ever paper (Leather, 1980) in print ;-)

So to answer the question I posed at the start of this post. Yes, I am still as firmly, if not more so, convinced as I was a year ago, that social media is an essential part of a rounded academic life.  Of course if you are reading this I am probably preaching to the converted ;-)

References

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

Leather, S.R. (2013) Institutional vertebratism hampers insect conservation generally; not just saproxylic beetle conservation. Animal Conservation, 16, 379-380.

Leather, S.R. (2014) How Stephen Jay Gould wrote Macbeth – not giving credit where its due: lazy referencing and ignoring precedence. Ideas in Ecology & Evolution, 7, 30-40.

Leather, S.R. (2015) An entomological classic: the Pooter or insect aspirator. British Journal of Entomology and Natural History, 28, in press

Smith, P. (2014) The PhD Viva: How to Prepare for your Oral Examination.  Palgrave Macmillan, Basingstoke

 

 

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A world without Pandas – would it make a difference? OR Conservation versus eradication – do some species deserve to die?

Before you all get excited and ready to shoot me down in flames, this post is not about pandas ;-) It is about how we, as humans, have a very warped view about the value of the species with whom we share this planet – note I did not say OUR planet.

Imagine this as a newspaper headline; Scientists discover a way to eradicate Siberian tigers or this; Destroy Polar Bear menace say local residents or this, Malawi’s ”Serial Killer” Crocodiles Cause Havoc among the Blind, actually this last one is true http://www.digitaljournal.com/article/33608 ;-)

Most people on seeing headlines like those would be putting pen to paper, typing tweets, sharing links and generally making a huge fuss. Replace tigers, pandas and crocodiles with mosquitoes, aphids and spiders and the only people making a fuss would be that other endangered species,  entomologists,  as evidenced by this Twitter conversation sparked off by this article http://www.radiolab.org/story/kill-em-all/

Entodebate

I know I said this wasn’t about pandas but bear with me for a minute.

The following sentences are from the WWF site http://wwf.panda.org/what_we_do/endangered_species/giant_panda/panda/why_we_save_the_giant_panda/

“The giant panda is one of these species threatened to be wiped off the planet. Ironically, it is also one better known and loved species in the world and one of the strongest symbols of nature conservation. That is one of the main reasons why they are so important: by mobilizing people to save the panda, we are actually helping preserve the rich biodiversity, plants, landscapes, other animals that need to be there in order for the pandas to survive.

The region where pandas live, in the Yangtze Basin and its magnificent forests are home to a stunning array of wildlife such as dwarf blue sheep and beautiful multi-coloured pheasants; as well as a number of other endangered species, including the golden monkey, takin and crested ibis. The panda’s habitat is also home for millions of people. This is the geographic and economic heart of China. By making this area more sustainable, we are also helping to increase the quality of life of local populations”
By rewriting this very slightly and using Anopheles gambiae and mosquito instead of panda, you get this somewhat thought-provoking version;

Anopheles gambiae is one of those species threatened to be wiped off the planet by the deliberate action of man (http://synbiobeta.com/oxitec-arming-insects-eliminate/ and http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_10-6-2014-16-5-11).

The region where Anopheles gambiae live, sub-Saharan Africa, and its magnificent forests and savannahs are home to a stunning array of wildlife such as lions, elephants and giraffes; as well as a number of other endangered species, including the cheetah and black rhino.

That is one of the main reasons why they are so important: by mobilizing people to save the mosquito, we are actually helping preserve the rich biodiversity, plants, landscapes, other animals that need to be there in order for the mosquitoes to survive.

The mosquitoes’ habitat is also home for millions of people. This is the geographic and economic heart of Africa. By making this area more sustainable, we are also helping to increase the quality of life of local populations”

 

I know that this is a somewhat extreme example, and I am in NO way whatsoever saying that malaria prevention is a bad thing and that we should allow millions of people to die every year. What I am proposing is that we should look at the ways we can protect people from malaria and other fatal and debilitating diseases and our crops from the depredations of pests and diseases that don’t involve the eradication of other species on the planet.
Conservation biology teaches us that we should preserve species for a number of reasons.  Common textbook examples usually include the following:

Resource values – all species may have an economic or ecological value, some of which we do not yet appreciate e.g. Food, pharmaceuticals, watershed regulation, coastline stabilisation, reefs for fisheries, tourism, education, ecological baselines, habitat reconstruction etc.

Non-resource values – all species should be valued anyway e.g. Religion, moral codes, social/cultural values, existence values, intrinsic value, and aesthetic values

Precautionary principle – all species should be preserved just in case – the rivets and spaceship (aeroplane) theory

This latter theory comes from the preface to Paul Ehrlich’s 1981 book, Extinction, where he imagines a passenger inspecting the ‘plane he is about to fly in. The passenger notices someone popping rivets out of the wings and asks what he is doing. The rivet popper replies that the passenger shouldn’t worry because not all the rivets are necessary. The rivets represent species and the rivet popper represents humanity, and the ‘plane the planet Earth. Ehrlich predicted that continuing to pop the rivets of ecosystems would lead to “a crumbling of post-industrial society” and demanded that the rivet popping be stopped.

Michael Soulé, a pioneer conservation biologist and former PhD student of Paul Ehrlich wrote

untimely extinction of populations and species is bad, conservation biology does not abhor extinction per se. Natural extinction is thought to be either value free or good because it is part of the process of replacing less well-adapted gene pools with better adapted ones. Ultimately, natural extinction, unless it is catastrophic, does not reduce biological diversity, because it is offset by speciation”

Conservation principles have moved from the preservation of single species to an ecosystem point of view as outlines recently by Professor Georgina Mace of University College London,

Mace picture

although the concept of keystone species, a term first coined by Richard Paine in 1969 has, particularly if the keystone species is vertebrate, had a marked influence on where conservation efforts have been directed over the years.

The concept of ecosystem services where species can be assigned an economic value depending on the services they offer to humankind  is not new (e.g. Hooper, 1970; Westman, 1977), but has increasingly and unfortunately allowed politicians and research funders to make decisions about the worth of species from a purely human viewpoint. As a result, when discussing the eradication or otherwise of species there is a definite bias towards the ‘charismatic mega-fauna’ whether they are keystone species or not, and those species that cause us discomfort must argue very hard for their preservation; see for example this extract from Jennifer Fang’s (2010) article.
A stronger argument for keeping mosquitoes might be found if they provide ‘ecosystem services’ — the benefits that humans derive from nature. Evolutionary ecologist Dina Fonseca at Rutgers University in New Brunswick, New Jersey, points as a comparison to the biting midges of the family Ceratopogonidae, sometimes known as no-see-ums. “People being bitten by no-see-ums or being infected through them with viruses, protozoa and filarial worms would love to eradicate them,” she says. But because some ceratopogonids are pollinators of tropical crops such as cacao, “that would result in a world without chocolate”.

“They don’t occupy an unassailable niche in the environment,” says entomologist Joe Conlon, of the American Mosquito Control Association in Jacksonville, Florida. “If we eradicated them tomorrow, the ecosystems where they are active will hiccup and then get on with life. Something better or worse would take over.” 

 

On the plus side sometimes the ecosystem services concept can be used to highlight the benefits of the smaller and often over-looked species, but yet again only if a substantial economic value can be assigned to them http://www.theguardian.com/environment/2014/oct/05/threatened-species-cannot-afford-to-lose-age-of-extinction

 

Personally, I am a great believer in retaining as many species as we can, so the deliberate eradication of species from their natural environments because we find them a nuisance makes me uneasy. We share this world, we don’t own it, so finding a way to live with ‘nuisance’ species must be a better option than eradicating them.

As a parting thought, consider these words from Ehrlich & Mooney (1980), and also bear in mind the UK Government’s recent Biodiversity Offsetting policy.

“Although there are numerous examples of unsuccessful substitutions, successful ones are hard to identify.

At some point the costs of substitution will almost certainly become unbearable. Therefore, it seems that a conservative approach, emphasizing the careful preservation of ecosystems and thus the populations and species that function within them is absolutely essential.”

Tea pot

 

Some things once broken are very difficult to put back together and might not work in the same way that they did before they were broken

http://100percenttea.blogspot.co.uk/2007/11/how-not-to-repair-broken-teapot.htmle

 

References

Ehrlich, P. R. & Mooney, H.A. (1983) Extinction, substitution, and ecosystem services. BioScience, 33, 248-254

Fang, J. (2010) A World without mosquitoes. Nature, 466, 432-434

http://www.nature.com/news/2010/100721/full/466432a.html

Hooper, J.F. (1970) Economics, the ecosystem and conservation. Journal of Range Management, 23, 148-150

Mace, G. (2014). Whose conservation? Science, 345, 1558-1560.

Paine, R. T. (1969). A note on trophic complexity and community stability. American Naturalist,  103, 91-93.

Soulé, M. E. (1985). What is conservation biology? Bioscience 35, 727-734.

Westman, W.E. (1977) How much are nature’s services worth? Science, 197, 960-964

 

Post script

1Somewhat ironically Paine’s 1969 paper in which he coined the term keystone species dealt with two invertebrate species,  starfish.

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First steps towards an entomological career – A nostalgic reminiscence

Our new Freshers have now found their feet and most now no longer have to ask directions to buildings and lecture theatres. It came as a bit of a shock to me to suddenly realise that this time forty years ago I was in a similar position at Leeds University, although probably feeling somewhat more lost than our first year students because even then, Leeds was a big university (10 000 students; small compared with most universities now, but the biggest outside London then).   Then & Now Two weeks into term and I was experiencing my first ever entomology lectures – my degree was in a now extinct subject, Agricultural Zoology, which was essentially entomology and parasitology, with a strong agricultural slant. I still have the books that I bought in those first stumbling days (as Agrics we drank rather a lot) towards my career as a professional entomologist. Textbooks I note that I did not buy the two Entomological bibles of our day, Imms (A General Textbook of Entomology) and Wigglesworth (The Principles of Insect Physiology) until the following year; actually during the summer vacation so I must have been very keen and feeling quite rich  ;-) I drank and read my way through undergraduate life managing to fit in an entomological expedition to Trinidad in 1975 where I reacquainted myself with the Caribbean insects that had first sparked my interest in entomology as a child in Jamaica. Drink & Trinidad I also discovered that, to quote the advertising posters all over the island,  “in Trinidad a beer is a Carib”!

A beer is a carib

Despite the beer, the sunshine and the exotic flora and fauna, 1975 was the year that I decided aphids were the most fascinating of all insects and what I wanted to work on when I graduated.  I also realised that you didn’t need to travel to exotic places to do interesting fieldwork and make new discoveries. Graduation & FieldworkEven with all the distractions of student life, I did graduate and went on to do a PhD working on cereal aphid ecology. PhD work

PhD work – A good job Health & Safety hadn’t been invented ;-)

I had some great entomological lecturers as an undergraduate, all of whom helped me get to where I am today;  Brian Whittington, Noel Gibson, Edward Broadhead, Steve Sutton and the somewhat eccentric Dick Loxton who took us on our field course and introduced us to extreme sweep netting, something I still do to do this day! Extreme sweep netting References

Barnes, R.D. (1974) Invertebrate Zoology, 3rd Edition, W B Saunders & Co. Philadelphia

Barrington, E.J.W. (1967) Invertebrate Structure & Function, Nelson, London

Cox, F.E.G., Morton, J.E., Phillips Dale, R., Nichols, D., Green, J. & Wakelin, D. (1969) Practical Invertebrate Zoology, Sidgwick & Jackson, London

Grove, A.J. & Newell, G.E. (1969) Animal Biology, 8th Edition, University Tutorial Press Ltd. London Imms, A.D. (1947) Insect Natural History, Collins, London

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Entomological classics – The Malaise Trap

More years ago than I care to remember, my friends and I were playing the now, very non-PC game of Cowboys and Indians, when we saw through the trees, what we thought was a tent. On sneaking up to it we found that, if it was a tent, it wasn’t very watertight!  There were no sides, instead there was a central panel and the whole thing was made of netting.  What we had actually found, was of course a Malaise trap, although of course we did not know this at the time.  It was only later as an undergraduate that I realised what we had found all those years before.

So exactly what is a Malaise trap and how did it come into being? The Malaise Trap is a relatively new invention.  It was invented by the Swedish entomologist, Dr René Malaise in the 1930s (hence the name) and revealed to a more general entomological audience in 1937 (Malaise, 1937).  It was actually designed as a replacement for the traditional hand-held collecting net, which as Malaise states in the introduction to his paper ‘”Since the time of Linneaus, the technique of catching insects has not improved very much, and we are to-day using the same kind of net as then for our main instrument”.

I was amused, when reading on further, to find that my childhood gaffe of confusing a Malaise Trap with a net was fully justified. Malaise, later in the same paper writes, ”During my extensive travels I have repeatedly found that insects happened to enter my tent, and that they always accumulated at the ceiling-corners in vain efforts to escape at that place without paying any attention to the open tent door”. He then goes on to describe how he conjectured that “a trap made as invisible as possible and put up at a place where insect are wont to patrol back and forth, might catch them much better than any tent, and perhaps better than a man with a net, as a trap could catch them all the time, by night as by day, and never be forced to quit catching when it was best because dinner-time was at hand”.

He thus set about constructing a trap based on the idea of an open tent with a collecting device attached to the central end pole to take advantage of the fact that most insects when encountering an obstacle tend to fly upwards. On reaching the apex of the tent, the only way out is into the collecting device which is filled with a killing agent.  It is in effect, a flight intercept trap, but unlike window traps (subject of a later post), the insects instead of falling into a collecting device, head upwards and collect themselves. Malaise tested his first version of the trap on an expedition to Burma and found them to be a great success “every day’s catch from the traps grew larger and larger, and sorting it required more and more time”. He found the traps particularly good for Diptera and Hymenoptera but also very good for Coleoptera and Noctuid and Sphingid moths.  He also mentions catching Hemiptera.

In outward form, the Malaise Trap has remained fairly unchanged since its invention. The first versions were apparently fairly heavy, having a brass insect collecting cylinder and also only had one opening.  Malaise recognised the disadvantages of the single entrance version and suggested in the 1937 paper that a bilateral model would be more effective.  These followed in due course. Modified versions using plastic cylinders and different netting material were  invented in the 1960s (Gressit & Gressit, 1962; Townes, 1962; Butler, 1965).  Townes’s paper gives a very detailed description of the construction and use of modified Malaise traps (90 pages) in contrast to Butler’s three page description of a cheap and cheerful version made from a modified bed-net.

Nowadays, entomologists world-wide, particularly Dipterists and Hymenopterists, use Malaise traps of various designs and colours, and cost.  In the UK they are available from commercial outlets at prices ranging from £60 to £165. They are extremely effective and we use them to collect insects for our practical classes in the Entomology MSc based at Harper Adams University.

    Malaise traps

Malaise trap in operation, Harper Adams University, Shropshire, UK.

 

References

Butler, G.D. 91965) A modified Malaise insect trap. The Pan-Pacific Entomologist, 41, 51-53

Gressitt, J.L. & Gressitt, M.K. (1962) An improved Malaise Trap. Pacific Insects, 4, 87-90

Malaise, R. (1937) A new insect-trap.  Entomologisk Tidskrift, Stockholm, 58, 148-160

Townes, H. (1962) Design for a Malaise trap. Proceedings of the Entomological Society of  Washington, 64, 162-253

 

Post script

Malaise was not just an entomologist; he was an explorer and a passionate believer in the existence of Atlantis. A detailed biography of this extraordinary character can be found here, including a photograph of the original Malaise trap.

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Not all aphids have wings

Given that aphids are commonly known as green-fly or black-fly, it might be presumed that all aphids are capable of flight. Although this is almost certainly universal at the species level (but see Post script) it is not true within a species. As I have described in an earlier post aphids are possessed of extremely complex and fascinating (to me at least) life cycles. Depending on the species, either most stages of the life cycle are winged (alate) as adults, e.g. the sycamore aphid Drepanoisphum platanoidis

Holocyclic.png

Sycamore aphid

I couldn’t resist showing you this beautiful picture of an adult sycamore aphid borrowed from the best aphid web site that I know of (see http://influentialpoints.com/Gallery/Drepanosiphum_platanoidis_common_sycamore_aphids.htm)

 

Other aphid species, such as my favourite, the bird cherry-oat aphid, Rhopalosiphum padi, only produce alate morphs at specific times of year or in response to changes in host plant quality or crowding.

Heteroecious

 RhopalosiphumPadi  Rhopalosiphum padi on leaf

Winged (alate) and non-winged (apterous) morphs of Rhopalosiphum padi.

In species such as the sycamore aphid, the only apterous morph tends to be the sexual female or ovipara, which has no need to disperse and after mating lives only long enough to develop and lay its eggs on the bark of sycamore trees.

Sycamore ovip on bark

Ovipara of the sycamore aphid searching for an oviposition site

In those species such as the bird cherry-oat aphid, the winged forms are very different from the non-winged forms, not just in terms of their wings but in their physiology, behaviour and life history traits (Dixon, 1998). The role of the winged morphs is to find new host plants and to start new colonies. They have long antenna, long legs and well-developed and many, sensory organs (rhinaria). They are the dispersal stage, or in the case of winged males, the mate seekers. They respond more readily to host odours; they need to be able to find new host plants at a suitable physiological stage and preferably free of natural enemies. A well-developed olfactory system is thus called for.

If you cut them open (preferably anaesthetizing them first), and remove their ovaries, you will find that they have ovarioles with only a few embryos in each chain and that most of the embryos are not mature i.e. without eye spots. In addition, if you cut open a number of individuals from the same clone you will find that they will not all have the same number of ovarioles. For example, the alate exules (winged forms produced on the secondary host plants )of Rhoaplosiphum padi, the number of ovarioles can range from four to ten (Wellings et al, 1980). This variability of ovariole number in the dispersal morphs of aphids that spend much of their life cycle on ephemeral host plants is quite common (Leather et al 1988).  So why do so many aphid species have variable numbers of ovarioles in their alate morphs?

Shaw (1970), showed that there appeared to be three types of black bean aphid (Aphis fabae) alate exules; migrants, those that flew before depositing nymphs, flyers, those that deposited a few nymphs before flying, and non-flyers, those that stayed and reproduced on their host plant. He postulated that this was an adaptation in response to host quality, the worse state the plant was in the more likely the migrant morph would be produced. Many years later Keith Walters and Tony Dixon (Walters & Dixon, 1983) were able to show that there was a very strong relationship between reproductive investment (number of ovarioles) and flight willingness and ability. The more ovarioles an aphid had, the less likely it was to want to take off and fly, and in addition those with more ovarioles could not fly for as long or as far as those with fewer.

Ovarioles and flight

In other words a trade-off between fecundity and migration. As long distance aphid migration is very costly (very few survive, Ward et al, 1998) it makes sense to have members of your clone spreading the load (risk), from short-distance hops (trivial flights), with the chance that the next door plant might be just as bad as the one left behind and within easy reach of natural enemies, but with a higher chance of survival and reproduction, to long distance migratory flights, with the reduced probability of finding a host plant but with the chance that it will be high in nutrition and low in natural enemies.

What clever beasts aphids are ;-)

 

References

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

Leather, S.R., Wellings, P.W., & Walters, K.F.A. (1988) Variation in ovariole number within the Aphidoidea. Journal of Natural History, 22, 381-393.

Shaw, M.J.P. (1970) Effects of population density on the alienicolae of Aphis fabae Scop.II The effects of crowding on the expression of migratory urge among alatae in the laboratory. Annals of Applied Biology, 65, 197-203.

Walters, K.F.A. & Dixon, A.F.G. (1983) Migratory urge and reproductive investment in aphids: variation within clones. Oecologia, 58, 70-75.

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.

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.

 

Post script

It is possible that there are some aphids that never fly – Aphids from the genus Stomaphis have incredibly long mouthparts (they all feed through tree bark), and as far as I can tell from perusal of

Stomaphis query aceris

Roger Blackman and Vic Eastop’s monumental work, alate morphs have never been described (or seen) and even males are apterous.

Blackman, R.L. & Eastop, V.F. (1994) Aphids on the World’s Trees. CABI, Wallingford.

 

Post post script

For a very detailed and thoughtful review of the ‘decisions’ and costs involved in aphid reproductive and dispersal biology see Ward, S.A. & Dixon, A.F.G. (1984) Spreading the risk, and the evolution of mixed strategies: seasonal variation in aphid reproductive strategies. Advances in Invertebrate Reproduction, 3, 367-386.

 

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