Category Archives: EntoNotes

Green Islands – mining cytokinins

A little while ago I wrote about the phenomenon of  “green islands” caused by ants keeping insect herbivores away from trees.   If, however, you work on leaf miners, the term green islands means something else entirely.  Instead of referring to a feature of the landscape, it refers to a feature of the leaf, which unless you are Toby*, is definitely not a landscape-level phenomenon 😊

While some insects, aphids for example, induce senescence to improve the quality of their host plant and some plants induce senescence and early leaf-fall in those leaves that have been colonised by gall aphids in order to reduce their infestation load (Williams & Whitham, 1986), there are other insects that try desperately to prevent senescence so as to prolong their feeding life on what would otherwise be a dead leaf.

Green island leaf mine of the moth, Stigmella atricapatella – Many thanks to Mike Shurmer for the photographs.

The phenomenon of the green islands in autumn leaves associated with leaf mining Lepidoptera has been known about for some time (Hering, 1951), but although the adaptive value of this was easy to see, the causal mechanism remained unknown for some time. Similarly, plant pathologists had also noticed that one of the symptoms of powdery mildew infections is the appearance of a green ring around the necrotic spot caused by the fungus (von Tubeuf, 1897); if not a green island, a green atoll 😊

Green island or green atoll? Powdery mildew on wheat https://slideplayer.com/slide/9073461/27/images/14/Green+island+on+wheat+infected+with+wheat+powdery+mildew.jpg

That fungi produced secretions containing plant growth substances such as the auxin (plant hormones) indole acetic acid has been known since the 1930s (Thimann, 1935) and it was later hypothesised that the levels present in the surrounding leaf tissue were associated with the resistance or lack thereof, to the fungal agent (e.g. Shaw & Hawkins, 1958). A further class of plant growth substances, initially termed kinins because of their similarity to kinetin (a cell growth promoting plant hormone, but later renamed cytokinins** (Skoog et al., 1965)) were discovered by Folke Skoog and co-workers (Miller et al., 1956) and linked to the production of green islands by plant pathogens (reviewed by Skoog & Armstrong, 1970).

“What about the leaf miners?” I hear you ask. You will be pleased to know that entomologists were not too far behind. Lisabeth Engelbrecht working on Nepticulid leaf miners on birch (Betula pendula) and Aspen (Populus tremula) set up a study (Engelbrecht, 1968) to test her hypothesises that the green islands were caused as a result of insect saliva or by the larvae physically cutting the leaf veins that would otherwise have delivered the chemical signal responsible for beginning leaf senescence. She discovered that the green islands contained large concentrations of cytokinin  (Engelbrecht, 1968) and working with other colleagues discovered that the labial glands of leaf mining larvae also contained cytokinin, but was unsure as to whether the cytokinin originated from the larvae or were formed in the leaf in response to chemicals in the saliva or frass of the larvae (Engelbrech et al., 1969), although if you read the paper it is quite clear that she is convinced that the source of the cytokinin is from the larvae and not the plant.

After all this excitement about insect produced cytokinin and green islands things seemed to go a bit dead.  I found a couple of passing references to the possibility that leaf mining Lepidopteran larvae use cytokinin to produce a green island to extend larval life after leaf abscission (Miller, 1973; Faeth, 1985) and an opinion piece discussing the possible adaptive role of using green islands to prolong larval life after leaf fall (Kahn & Cornell, 1983), but, surprisingly, nothing experimental to test this hypothesis. Oddly, I did find a paper testing the idea that early leaf abscission was an induced defence against leaf miners, where green islands were mentioned in the introduction but not mentioned again (Stiling & Simberloff, 1989).

Don’t get me wrong, plant pathologists and entomologists working on insect galls were still writing about the role of cytokinin (e.g. Murphy et al., 1997: Mapes & Davies, 2001), but leaf miner green island research seemed to have died.  Suddenly, however, in the mid-2000s the French ‘discovered’ leaf miners and David Giron and colleagues, showed how the leaf miner Phyllonorycer blancardella manipulates the nutritional quality of their host leaves by increasing the levels of cytokinin in the surrounding leaf tissue (Giron et al., 2007).

‘Green island’ formed by Phyllonorycter blancardella (From Giron et al., 2007).

 

As we know from aphids, where insects play, bacterial symbionts are never far away, and sure enough it wasn’t long before it was shown that Wolbachia ‘infections’ were helping the leaf miners produce their ‘green islands’. Wilfried Kaiser and colleagues treated leaf miner larvae with antibiotics to remove the symbiont and found that the ‘cured’ larvae, although still able to feed and form leaf mines, were unable to produce ‘green islands’ and the levels of cytokinin were much lower than that found in the ‘green islands’ formed by untreated leaf miners (Kaiser et al., 2010).

Influence of Wolbachia on green island formation. To the left, infected leaf miners (Phyllonorycter blancardella) happily surrounded by nutritious plant tissue; to the right, ‘cured’ by antibiotics, the leaf miner soon runs out of food (Kaiser et al., 2010)

The same group have also documented the mechanism by which the leaf miners and their symbionts work together (Body et al., 2013) and also, using molecular phylogenies and ecological trait data, shown that the existence of the ‘green island’ phenotype and Wolbachia infections are associated with the evolutionary diversification of the Gracillarid leaf miners (Gutzwiller et al., 2015).

You might expect that these findings would have stimulated renewed interest in the ‘green island’ phenomenon, but you would be wrong.  Despite the fact that at the time of writing this article (September 10th 2019) Kaiser et al. (2010) had, according to the Web of Science, been cited 105 times, only three papers dealing with this phenomenon have been published, the most recent appearing in early 2018 (Zhang et al., 2018) and, incidentally, by the same group that published the Kasier et al. (2010) study. It would appear that as with ‘green islands’, the study of the phenomenon is also very localised.

References

Allen, P.J. (1942) Changes in the metabolism of wheat leaves induced by infection with powdery mildew. American Journal of Botany, 42, 425-435.

Body, M., Kaiser, W., Dubreuil, G., Casas, J. & Giron, D. (2013) Leaf-miners co-opt microorganisms to enhance their nutritional environment. Journal of Chemical Ecology, 39, 969-977.

Engelbrecht, L. (1968) Cytokinin in den ,,grunen Inseln” des Herbstlauibes. Flora oder Allgemeine botanische Zeitung. Abt. , Physiologie und Biochemie, 159, S, 208-214.

Englebrecht , L., Orban, U. & Heese, W. (1969) Leaf-miner caterpillars and cytokinins in the “green islands” of autumn leaves. Nature, 223, 319-321.

Faeth, S.H. (1985) Host leaf selection by leaf miners: interactions among three trophic levels. Ecology, 66, 870-875.

Gutzwillner, F., Dedeine, F., Kaiser, W., Giron, D., & Lopez-Vaamonde, C. (2015) Correlation between the green-island phenotype and Wolbachia infections during the evolutionary diversification of Gracillariidae leaf-mining moths. Ecology & Evolution, 5, 4049-4062.

Hering, E.M. (1951) Biology of the Leaf Miners, Dr W Junk, The Hague, Netherlands

Herrick, G.W. (1922) The Maple Case-Bearer Paraclemensia Acerifoliella Fitch. Journal of Economic Entomology, 15, 282-288.

Kahn, D.M. & Cornell, H.V. (1983) Early leaf abscission and folivores: comments and considerations. American Naturalist, 122, 428-432.

Kaiser, W., Huguet, E., Casas, J., Commin, C. & Giron, D. (2010)  Plant green-island phenotype induced by leaf-miners is mediated by bacterial symbionts. Proceedings of the Royal Society B, 277, 2311-2319.

Mapes, C.C. & Davies, P.J. (2001) Cytokinins in the ball gall of Solidago altissima and in the gall forming larvae of Eurosta solidaginis. New Phytologist, 151, 203-212.

Miller, C. O., Skoog, F., Okumura, F. S., Von Saltza, M. H., & Strong, F. M. (1956). Isolation, structure and synthesis of Kinetin, a substance promoting cell division. Journal of the American Chemical Society, 78, 1375–1380.

Miller, P.F. (1973) The biology of some Phyllonorycter species (Lepidoptera: Gracillariidae) mining leaves of oak and beech. Journal of Natural History, 7, 391-409.

Murphy, A.M., Pryce-Jones, E., Johnstone, K. & Ashby, A.M. (1997) Comparison of cytokinin production in vitro by Pyrenopeziza brassicae with other plant pathogens. Physiological & Molecular Plant Pathology, 50, 53-65.

Shaw, M. & Hawkins, A.R. (1958) the physiology of host-parasite relations V. A preliminary examination of the level of free endogenous Indoleacetic acid in rusted and mildewed cereal leaves and their ability to decarboxylate exogenously supplied radioactive indoleacetic acid. Canadian Journal of Botany, 34, 389-405.

Skoog, F. & Armstrong, D.J. (1970) Cytokinins. Annual Review of Plant Physiology, 21, 359-384.

Skoog, F., Strong, F.M. & Miller, C.O. (1965) Cytokinins. Science, 148, 532-533.

Stiling, P.D. & Simberloff, D. (1989) Leaf abscission – induced defense against pests or response to damage ? Oikos, 55, 43-49.

Thimann, K.V. (1935) On the plant growth hormone produced by Rhizopus suinus. Journal of Biological Chemistry, 109, 279-291.

Von Tubeuf, K.F. (1897) Diseases of Plants, Longmans, Green & Co, London.

Walters, D.R., McRoberts, N. & Fitt, B.D.L. (2008) Are green islands red herrings? Significance of green islands in plant interactions with pathogens and pests. Biological Reviews, 83, 79-102.

Williams, A.G. & Whitham, T.G. (1986) Premature leaf abscission: an induced plant defense against aphids. Ecology, 67, 1619-1627.

Zhang,  H., Dubreuil, G., Faivre, N., Dobrev, P., Kaiser, W., Huguet, E., Vankova, R. & Giron, D.  (2018) Modulation of plant cytokinin levels in the Wolbachia‐free leaf‐mining species Phyllonorycter mespilella. Entomologia experimentalis et applicata, 166, 428-438.

 

*Toby Alone (La Vie Suspendue) by Timothée de Fombelle, is a fantastic novel, which I only fairly recently discovered, but can heartily recommend.

** Cytokinins are a class of plant growth substances that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence. Wikipedia

 

 

Advertisements

4 Comments

Filed under EntoNotes

Sowing the seeds of virology–entomology research collaborations to tackle African food insecurity

Success!

At the end of last month (June) I had the privilege of taking part in CONNECTEDV4. In case you’re wondering, this was a two-week training event at which a group of early career researchers from 11 African countries got together in Bristol, UK. Nothing so unusual about that, you may think.

Yet, this course, run by the Community Network for African Vector-Borne Plant Viruses (CONNECTED), broke important new ground. The training brought together an unusual blend of researchers: plant virologists and entomologists studying insects which act as vectors for plant disease, as an important part of the CONNECTED project’s work to find new solutions to diseases that devastate food crops in Sub-Saharan African countries.

The CONNECTED niche focus on vector-borne plant disease is the reason for bringing together insect and plant pathology experts alongside plant breeders. The event helped forge exciting new collaborations in the fight against African poverty, malnutrition and food insecurity.  ‘V4’ – Virus Vector Vice Versa – was a fully-funded residential course which attracted great demand when it was advertised. Places were awarded by competitive application, with funding awarded to cover travel, accommodation, subsistence and all training costs. For every delegate who attended, five applicants were unsuccessful.

The comprehensive programme combined scientific talks, general lab training skills, specific virology and entomology lectures and practical work and also included workshops, field visits, career development, mentoring, and desk-based projects. Across the fortnight delegates received plenty of peer mentoring and team-building input, as well as an afternoon focused on ‘communicating your science.’

New collaborations will influence African agriculture for years to come

There’s little doubt that the June event, hosted by The University of Bristol, base of CONNECTED Network Director Professor Gary Foster, has sown seeds of new alliances and partnerships that can have global impact on vector-borne plant disease in Sub-Saharan Africa for many years to come.

In writing this, I am more than happy to declare an interest. As a member of the CONNECTED Management Board, I have been proud to see network membership grow in its 18 months to a point where it’s approaching 1,000 researchers, from over 70 countries. The project, which derived its funding from the Global Challenges Research Fund, is actively looking at still more training events.

I was there in my usual capacity of extolling the virtues of entomology and why it is important to be able to identify insects in general, not just pests and vectors.  After all, you don’t want to kill the goodies who are eating and killing the baddies.  My task was to introduce the delegates to basic insect taxonomy and biology and to get them used to looking for insects on plants and learning how to start recognising what they were looking at. Our venue was the University of Bristol Botanic Gardens as the main campus was hosting an Open Day. This did impose some constraints on our activities, because as you can see from the pictures below, we didn’t have a proper laboratory.  The CONNECTED support team did, however, do a great job of improvising and coming up with innovative solutions, so thanks to them, and despite the rain, my mission was successfully accomplished.

Me in full flow, and yes, as is expected from an entomologist, I did mention genitalia 🙂

It’s genitalia time 🙂

A hive of activity in the ‘lab’

Collecting insects in the rain

The V4 training course follows two successful calls for pump-prime research funding, leading to nine projects now operating in seven different countries, and still many more to come. Earlier in the year CONNECTED ran a successful virus diagnostics training event in Kenya, in close partnership with BecA-ILRI Hub. One result of that training was that its 19 delegates were set to share their new knowledge and expertise with a staggering 350 colleagues right across the continent.

I thoroughly enjoyed the day, despite the rain, and was just sorry that I wasn’t able to spend more time with the delegates and members of the CONNECTED team. Many thanks to the latter for the fantastic job they did. The catering and venue were also rather good.

Project background

Plant diseases significantly limit the ability of many of Sub-Saharan African countries to produce enough staple and cash crops such as cassava, sweet potato, maize and yam. Farmers face failing harvests and are often unable to feed their local communities as a result. The diseases ultimately hinder the countries’ economic and social development, sometimes leading to migration as communities look for better lives elsewhere.

The CONNECTED network project is funded by a £2 million grant from the UK government’s Global Challenges Research Fund, which supports research on global issues that affect developing countries. It is co-ordinated by Prof. Foster from the University of Bristol School of Biological Sciences, long recognised as world-leading in plant virology and vector-transmitted diseases, with Professor Neil Boonham, from Newcastle University its Co-Director. The funding is being used to build a sustainable network of scientists and researchers to address the challenges. The University of Bristol’s Cabot Institute, of which Prof. Foster is a member, also provides input and expertise.

Did I mention that it rained? 🙂

1 Comment

Filed under EntoNotes

Insectageddon, Ecological Armageddon, Global insect Apocalypse – why we need sustained long-term funding

“To him that countryside, largely unspoiled in his early days, was an inexhaustible source of delight and a subject of endless study and mediation…And as the years passed and the countryside faded away under the withering touch of mechanical transport, that knowledge grew more and more precious. Now, the dwindling remnants had to be sought and found with considered judgement and their scanty material eked out with detail from the stores of the remembered past”  R Austin Freeman The Jacob Street Mystery (1942)

The recent release of the IPBES report highlighting the significant global declines in biodiversity has prompted me to revisit the “Insectageddon” debate, some of the ramifications of which I wrote about earlier this year.

 

Summary from the IPBES report – note that even a well-known group like dragonflies is quite data deficient*.

Insects may be in decline, but papers about their decline have been around for almost twenty years and even more are appearing as we entomologists begin to hope that people may at last be beginning to listen to us.

A selection of some of the many papers that have documented insect declines over the last several years.

Using the now infamous search term “insect decline” in the Google Trends function I was not surprised to see the steep increase since 2016, as 2017 was the year in which the paper reporting  the 75% decline in flying insect biomass appeared (Hallmann et al., 2017), but I was intrigued by what appeared to have been a peak in mentions since 2004.

Google Trends using the phrase insect decline – last data point is 2019 at the time of writing

I wondered what caused the peak in 2004, so using the same key words as Sánchez-Bayo & Wyckhuys (2019), checked Google Scholar and Web of Science to see if I could track down a paper that might have caused a media splash at the time.  I also checked 2003, in case there was a delay in reporting. To my surprise I couldn’t find anything relevant in 2004, but 2003 threw up three papers (Hopkins & Freckleton, 2002; Kotze & O’Hara, 2003; Shreeve & Dennis, 2003).  The first was about the decline of taxonomists, which although a serious problem is unlikely to have generated that much attention, the other two were about long-term declines in Carabid beetles (Kotze & O’Hara, 2003) and the third about the decline of French butterflies (Shreeve & Dennis, 2003) which again, I suspect were probably not high enough profile to generate a big splash.  I was puzzled but then I thought, why not just put it into Google with the date 2004, and sure enough it directed me to a Nature News item with the headline Insect deaths add to extinction fears, which in turn led me to Thomas et al., (2004) which I am pretty certain generated the peak in interest and also highlights the fact that ecologists and entomologists have been worrying about this problem for some time.

Since the appearance of the, now, infamous paper, that sparked the most recent round of Armageddon stories (Sánchez-Bayo & Wyckhuys, 2019), a lot has been, quite justifiably, written about the short-comings of the study both in scientific journals (e.g. Komonen et al., 2019, Simmons et al., 2019; Thomas et al, 2019, Wagner, 2019) and in blog posts, such as this thoughtful piece from Manu Saunders.

What does need to be stressed, is that although these commentators recognise the shortcomings of the paper, none of them, including the most scathing of commentators (Mupepele et al., 2019) dispute the fact, that insects, in general, are in decline. Unfortunately, the climate change deniers and their ilk, have, of course, used the criticisms to try and spread a message of “nothing to fear folks”.

Hopefully a failed attempt at downplaying the insect decline stories, but a great example of how climate change deniers are keen to muddy the waters

For humans with our relatively short lifespans, shifting baselines can be a problem (Leather & Quicke, 2010; Tree, 2018), in that people accept what they have known in their childhoods as the natural state of nature.  It can of course work the other way. I can remember the late great Miriam Rothschild telling me in the early 1990s, how as a “gel” in the 1920s a particular butterfly species that was currently at very low numbers compared with the 1970s which was what I and similar aged colleagues were remarking upon, was 50 years before that, also very low, her message being “populations cycle”.  It is because of this propensity, which is nicely illustrated by some of my 20-year data sets, all from the same 52 trees, that we need access to long-term funding to monitor insect populations.  Chop my data sets into three-year concurrent periods, the time-span of a typical PhD study or research grant, and you end up with some very different pictures of the populations of three common insect species.

The Silwood Park Winter moth, Operophtera brumata – dramatic shifts in population levels

Twenty years of the Sycamore aphid, Drepanosiphum platanoidis, at Silwood Park.  First five years versus last five years – what happened? Does this fit with the recent paper by Stephen Heard and colleagues that species chosen for study because they are common or easy to find, are almost certainly to show declines over the long-term?

 

The Maple aphid, Periphyllus testudinaceus – twenty-year data run from Silwood Park

Given the above, and the fact that most of the evidence for insect declines is largely based on studies from Europe, the UK heading the list (Wagner, 2019) and on top of that, the evidence from tropical locations is open to different interpretations (e.g.  Willig et al, 2019), there is an urgent need for something to be done.  So, what do we need to do?  I think there are three things that need addressing, sooner, rather than later.

Monitoring

First, we need to build on the work that has been done in Germany (Hallmann et al., 2017) and the UK via the Rothamsted Insect Survey (Bell et al., 2015) and establish active insect monitoring networks using repeatable sampling methods, but on a global scale. New monitoring programs will not help establish past baselines, but they can help us determine trends from this point forward. We can make this truly global by engaging the public through community science. These programs will need to use standardized methods, such as Malaise traps, pitfall traps, light traps, and effort-based counts, with species diversity, abundance and biomass being primary measures. Although biomass is an imperfect estimator because it can be sensitive to changes in abundances of large species, it is still a valuable metric from the ecosystem perspective. Determining biomass trends also does not require fine-scale taxonomic knowledge, which is often lacking in citizen science initiatives. It would, even if it were possible, be incredibly expensive, to try to monitor all insect species from any community with appreciable diversity.  A much better option, and one that will certainly appeal to a wide range of citizen scientists would be to monitor taxa like butterflies, macro-moths, dragonflies, bees, and some beetle groups.  All these can serve as indicator species for other insect groups and, tongue in cheek, many can be observed using binoculars, thus encouraging ornithologists and mammalologists to join in 😊

Innovative use of past data

At national levels, a few long-term monitoring schemes already exist, for example, the UK Environmental Change Network (http://www.ecn.ac.uk/ ) collects biotic and abiotic data, including many insect groups, from 57 different sites across the UK using identical protocols (Rennie, 2016).   Multiple Long-Term Ecological Research projects track different facets of ecosystems in different ways (Magurran et al., 2010). In fact, the LTER network, if expanded to a global scale, could be the natural framework to make a global network proposal feasible, possibly through a targeted step change in funding (Thomas et al., 2019).  This is great for the future, but unfortunately, all the active long-term monitoring schemes are younger than modern agricultural intensification.  A way forward would be to use museum collections and to construct data sets by going through back numbers of those entomological journals that pre-date the 1940s.  There are some long-term historical long-term data that are already accessible, for example the 150 year record pine beauty moth infestations in Germany dating from 1810 (Klimetzek, 1972) and I am sure that others must exist.

Funding

Whatever we do, it will need long-term funding. There needs to be a recognition by state research funding agencies that entomological survey and monitoring work, although appearing mundane, should receive a step-change in funding, even if it is at the expense of other taxa  Funding should reflect the diversity and abundance of taxa, not their perceived charisma (Clark & May, 2002; Leather, 2013).  Crowd-funding may draw in some funding, but what is required is stable, substantial and sustained funding that will allow existing and future international collaborations to flourish.  For this to happen and failing sustained state funding, we need to convince philanthropic donors such as the Gates Foundation to turn their attention from insect eradication to insect conservation.

We do, however, need to act quickly, stop talking to just our peers, meet the public, and, if needs be, personally, or via our learned societies, lobby governments; there is no Planet B.

 

References

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

Cordoso, P. & Leather, S.R. (2019) Predicting a global insect apocalypseInsect Conservation & Diversity, 12, 263-267.

Dennis, R.H.L. & Shreeve, T.G. (2003) Gains and losses of French butterflies: tests of predictions, under-recording and regional extinction from data in a new atlas. Biological Conservation, 110, 131-139.

Hallmann, C.A., Sorg, M., Jongejans, E., Siepel, H., Hoflan, N., Schwan, H., Stenmans, W., Muller, A., Sumser, H., Horren, T., Goulson, D., & De Kroon, H. (2017) More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PLoSONE, 12(10), :e0185809.

Hopkins, G.W. & Freckleton, R.P. (2002) Declines in the numbers of amateur and professional taxonomists: implications for conservation. Animal Conservation, 5, 245-249.

Klimetzek, D. (1972) Die Zeitfolge von Ubervermehrungen nadelfressender kiefernraupen in derPfalz seit 1810 und die Ursachen ihres Ruckanges in neuerer Zeit. Zeitschrift fur Angewandte Entomologie, 71, 414-428.

Kotze, D.J. & O’Hara, R.B. (2003) Species decline – but why?  Explanations of Carabid beetle (Coleoptera, Carabidae) declines in Europe. Oecologia, 135, 138-148.

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

Magurran, A.E., Baillie, S.R., Buckland, S.T., Dick, J.M., Elston, D.A., Scott, M., Smith, R.I., Somerfiled, P.J. & Watt, A.D. (2010) Long-term datasets in biodiversity research and monitoring: assessing change in ecological communities through time. Trends in Ecology and Evolution, 25, 574-582.

Møller, A.P. (2019) Parallel declines in abundance of insects and insectivorous birds in Denmark over 22 years. Ecology & Evolution, 9, 6581-6587.

Mupepele, A.C., Bruelheide, H., Dauber, J., Krüß, A., Potthast, T., Wägele, W. & Klein, A.M. (2019). Insect decline and its drivers: Unsupported conclusions in a poorly performed meta-analysis on trends—A critique of Sánchez-Bayo and Wyckhuys (2019).  Basic & Applied Ecology, 37, 20-23.

Rennie, S.C. (2016) Providing information on environmental change: Data management, discovery and access in the UK Environmental Change Network data.  Ecological Indicators, 68, 13-20.

Sánchez-Bayo, F. & Wyckhuys, K.A.G. (2019) Worldwide decline of the entomofauna: A review of its drivers. Biological Conservation, 232, 8-27.

Thomas, C.D., Jones, T.H. & Hartley, S.E. (2019) “Insectageddon”: a call for more robust data and rigorous analyses. Global Change Biology, 6, 1891-1892.

Thomas, J.A., Telfer, M.G., Roy, D.B., Preston, C.D., Greenwood, J.J.D., Asher, J., Fox, R., Clarke, R.T. & Lawton, J.H. (2004) Comparative losses of British butterflies, birds, and plants and the global extinction crisis. Science, 303, 1879-1881.

Tree, I. (2018) Wilding, Picador, Pan Macmillan.

Wagner, D.L. (2019) Global insect decline: comments on Sánchez-Bayo and Wyckhuys (2019). Biological Conservation, 233, 332-333.

Willig, M.R., Woolbright, L., Presley, S.J., Schowalter, T.D., Waide, R.B., Heartsill Scalley, T., Zimmerman, J.K.,  González, G. & Lugo, A.E. (2019) Populations are not declining and food webs are not collapsing at the Luquillo Experimental Forest. Proceedings of the National Academy of Sciences, 116, 12143-12144.

*

5 Comments

Filed under Bugbears, EntoNotes

Satiable curiosity – side projects are they worthwhile?

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

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

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

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

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

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

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

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

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

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

 

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

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

 

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

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

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

 

Side project 5. Sixty bird cherry trees 1993-2012

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

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

 

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

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

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

 

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

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

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

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

 

References

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

 

*

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

**

My second post-doc was only for two years.

***

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

 

9 Comments

Filed under EntoNotes, Roundabouts and more

Green islands – safe and healthy in a sea of death

Those of you whom work in forests, will, I am sure, be familiar with the term “green island”.  To a forester or forest entomologist, a green island is a clump of trees that have, for some reason or other, survived the ravages of an insect outbreak.  The earliest reference I can find to this phenomenon is in a 1927 paper by the German myrmecologist Hermann Eidmann (1897-1949), who described them as green oases, or, as the paper was written in German, more correctly, “grüne Oasen” (Eidmann, 1927).

Red wood ants helping maintain a “grüne Oasen”   green oasis” in a German pine forest (Eidman, 1927).

As well as “farming aphids” to obtain sugar from their honeydew, ants also have a similar mutualistic relationship with plants that give them a sugary reward to protect them from herbivorous insects, except those that also provide the ants with sugar (Janzen 1966; Bentley, 1977).  The mutualisms can be very sophisticated. In Michigan, the North American black cherry, Prunus serotina, times nectar production from its extra-floral nectaries to attract the ant Formica obscuripes  when the larvae of its major herbivore, the eastern tent caterpillar, Malacosoma americanum are at their most vulnerable (Tilman, 1978).  Trees that are protected have greatly reduced levels of herbivory. When more than one ant colony is involved, rather than single trees being protected, a group of trees can be saved from defoliation, and form a green island.  The areas covered by these green islands can be quite extensive, for example two ant colonies of the ant  Formica polyctena were enough to protect pine trees from the nun moth Lymantria monacha in Sweden within a 45 m diameter around the colonies (0.16 ha) (Wellenstein, 1980) and green islands of up to 3 ha have been reported (Eidmann, 1927).

Left – canopy of trees near ant nests, on the right, trees not close to ant nests Wellenstein (1980)

 

In Finland, one colony of the ant F. aquilonia is enough to create subarctic mountain birch (Betula pubescens), green islands of up to 0.12 ha in area (Laine & Niemelä, 1980).

Green islands attributed to the activity of the ant Formica aquilonia in subarctic Finland (Laine & Niemela, 1980).

It would seem that the case for the ants protecting the trees against defoliating herbivores and being the cause for the green islands is very convincing.  Tom White, never one to avoid a controversy, disagreed. He suggested that it was the nest building activities of the ants that were the cause for the green islands, the refuse dumps provide higher concentrations of nutrients that the roots of surrounding trees can access and additionally soil moisture conditions are improved, both these factors encouraging more vigorous growth in those trees close to ant nests, making them less palatable to herbivores (White, 1985).   The Finnish team responded to this with some additional data and arguments defending their hypothesis (Niemelä & Laine, 1986) and there the matter rested, for a while at least. Not satisfied with their post hoc response, the Finns came up with, to me at any rate, a very convincing field experiment where they showed that soil nitrogen did not vary significantly with distance from ant nests and that birch leaf nitrogen content and moth larval growth rates and survival were also not affected by distance from ant nests (Karhu, 1998; Karhu & Neuvonen, 1998), indicating that the green islands were indeed, due to predation by the ants and not improved tree nutrition.

Soil nitorgen in realtion to distance from ant colonies (Karhu & Neuvonen, 1998).

You might think that this would be the last word, but you would be wrong 🙂  The Karhu and Neuvonen paper, is, in the journal, followed by a “comment” paper by no less a person than Tom White (White 1998) in which he disputes in no uncertain terms, their interpretation of their new data.  Matthias Schaefer, the then Editor of Oecologia, felt that some sort of explanation was needed and added a final note to the saga, which in itself makes very interesting reading.  I get the feeling that there were some strong emotions involved 🙂

Pouring oil on troubled water – wise words from Editor-in-Chief Mathias Schaefer

 

References

Bentley, B.L. (1977) Extrafloral nectaries and protection by pugnacious bodyguards. Annual Review of Ecology & Systematics, 8, 407-427.

Eidmann, H. (1927) Weitre Beobachtungen über den Nutzen de roten Waldameise.  Anzeiger für Schädlingskunde, 3, 49-51.

Janzen D.H. (1966) Coevolution of mutualism between ants and Acacias in Central America. Evolution, 20, 249-275.

Kaiser, W., Huguet, E., Casas, J., Commin, C. & Giron, D. (2010)  Plant green-island phenotype induced by leaf-miners is mediated by bacterial symbionts. Proceedings of the Royal Society B, 277, 2311-2319.

Karhu, K.J. (1998) Effects of ant exclusion during outbreaks of a defoliator and a sap-sucker on birch. Ecological Entomology, 23, 185-194Kah.

Karhu, K.J. & Neuvonen, S. (1998) Wood ants and a geometrid defoliator of birch: predation outweighs beneficial effects through the host plant. Oecologia, 113, 509-516.

Laine, K.J. & Niemela, P. (1980) The influence of ants on the survival of mountain birches during an Oporinia autumnata (Lep., Geometridae) outbreak. Oecologia, 47, 39-42.

Niemela, P. & Laine, K.J. (1986) Green islands – predation not nutrition. Oecologia, 68, 476-478.

Tilman, D. (1978) Cherries, ants and tent caterpillars: timing of nectar production in relation in relation to susceptibility of caterpillars to ant predation. Ecology, 59, 686-692.

Wellenstein, G. (1980) Auswirkung hügelbauender Waldameisen der Formica rufa‐Gruppe auf forstschädliche Raupen und das Wachstum der Waldbäume. Zeitschrift für Angewandte Entomologie, 89, 145-157.

White, T.C.R. (1985) Green islands – nutrition not predation – an alternative hypothesis. Oecologia, 67, 455-456.

White, T.C.R. (1998) Green islands – still not explained.  Oecologia, 113, 517-518.

 

1 Comment

Filed under EntoNotes

“Insectageddon” – bigger headlines, more hype, but where’s the funding?

Unless you have been hibernating in a deep, dark cave or on another planet, you can hardly have missed the ‘insectageddon’ media frenzy that hit the UK (and elsewhere) on Monday (11th February).

This time the stimulus was a review paper outlining the dramatic decline in insect numbers, from two Australian authors (Sánchez-Bayo & Wyckhus, 2019).  Their paper, based on 73 published studies on insect decline showed that globally, 41% of insect species are in decline, which is more than twice that reported for vertebrates.  They also highlighted that a third of all insect species in the countries studied are threatened with extinction.  Almost identical figures were reported some five years ago (Dirzo et al., 2014), but somehow escaped the attention of the media.

I’m guessing that a clever press release by either the authors’ university or from the publisher of Biological Conservation set the ball rolling and the appearance of the story in The Guardian newspaper on Monday morning got the rest of the media in on the act.

The headline that lit the fuse – The Guardian February 11th  2019

The inside pages

A flurry of urgent phone calls and emails from newspapers, radio stations and TV companies resulted as the various news outlets tried to track down and convince entomologists to put their heads above the parapet and comment on the story and its implications for mankind.  I was hunted down mid-morning by the BBC, and despite not being in London and recovering from a bad cold, was persuaded to appear live via a Skype call.  A most disconcerting experience as although I was visible to the audience and interviewer, I was facing a blank screen, so no visual cues to respond to.  According to those who saw it, it was not a disaster 🙂  Entomologists from all over the country, including at least three of my former students, were lured into TV and radio studios and put through their entomological paces.

Me, former student Tom Oliver (University of Reading), Blanca Huertas (NHM) and former student Andy Salisbury (RHS Wisley), getting our less than fifteen minutes of fame 🙂

As far as I know, we all survived relatively unscathed and the importance of insects (and entomologists) for world survival was firmly established; well for a few minutes anyway 🙂

It is the ephemeral nature of the media buzz that I want to discuss first.  Looking at the day’s events you would be forgiven that the idea of an ecological Armageddon brought about by the demise of the world’s insects was something totally new.   If only that were so.

Three years of insect decline in the media

The three years before the current outbreak of media hype have all seen similar stories provoking similar reactions, a brief flurry of media attention and expressions of concern from some members of the public and conservation bodies and then a deafening silence. Most worrying of all, there has been no apparent reaction from the funding bodies or the government, in marked contrast to the furore caused, by what was, on a global scale, a relatively minor event, Ash Die Back.  Like now, I responded to each outcry by writing a blog post, so one in 2016, one in 2017 and another last year.

So, will things be different this time, will we see governments around the world, after all this is a global problem, setting up urgent expert task forces and siphoning research funding into entomology? Will we see universities advertising lots of entomologically focused PhD positions?  I am not hopeful. Despite three years of insectageddon stories, the majority of ecology and conservation-based PhDs advertised by British universities this autumn, were concerned with vertebrates, many based in exotic locations, continuing the pattern noted many years ago. In terms of conservation and ecology it seems that funding is not needs driven but heavily influenced by glamorous fur and feathers coupled with exotic field sites (Clarke & May, 2002).

The paper that caused the current media outbreak (Sánchez-Bayo & Wyckhus, 2019) although hailed by the media as new research, was actually a review of 73 papers published over the last several years.  It is not perfect, for one thing the search terms used to find the papers used in the review included the term decline, which means that any papers that did not show evidence of a decline over the last forty years were not included e.g. Shortall et al. (2009; Ewald et al. (2015), both of  which showed that in some insects and locations, populations were not declining, especially if the habitats that they favoured were increasing, e.g. forests, a point I raised in my 2018 post.  Another point of criticism is that the geographic range of the studies was rather limited, almost entirely confined to the northern hemisphere (Figure 1). Some commentators have also criticised the analysis, pointing out that it was

Figure 1. Countries from which data were sourced (Sánchez-Bayo & Wyckhus, 2019).

not, as stated by the authors, a true meta-analysis but an Analysis of Variance.  Limitations there may be, but the take home message that should not be ignored, is that there are many insect species, especially those associated with fresh water, that are in steep decline.  The 2017 paper showing a 75% reduction in the biomass of flying insects in Germany (Hallmann et al., 2017), also attracted some criticism, mainly because although the data covered forty years, not all the same sites were sampled every year.  I reiterate, despite the shortcomings of both these papers, there are lots of studies that show large declines in insect abundance and they should not be taken lightly, or as some are doing on Twitter, dismissing them as hysterical outpourings with little basis in fact.

https://www.itv.com/news/2019-02-11/insect-mass-extinction-headlines-do-not-tell-whole-story-and-risk-undermining-threat-of-declining-numbers/

It is extremely difficult, especially with the lack of funding available to entomologists to get more robust data.  The Twitter thread below from Alex Wild, explains the problems facing entomologists much more clearly and lucidly than I could.  Please read it carefully.

Masterly thread by Alex Wild – millions of insects, millions of ways to make a living and far too few entomologists

I am confident that I speak for most entomologists, when I say how frustrated we feel about the way ecological funding is directed.  Entomologists do get funding, but a lot of it is directed at crop protection. Don’t get me wrong, this is a good thing, and something I have benefited from throughout my career.  Modern crop protection aims to reduce pesticide use by ecological means, but we desperately need to train more entomologist of all hues and to persuade governments and grant bodies to fund entomological research across the board, not just bees, butterflies and dragonflies, but also the small, the overlooked and the non-charismatic ones  (Leather & Quicke, 2010).  A positive response by governments across the world is urgently needed.  Unfortunately what causes a government to take action is hard to understand as shown by how swiftly the UK government responded to the globally trivial impact of Ash Die Back but continues to ignore the call for a greater understanding of the significance of and importance of insects, insectageddon notwithstanding.

I put the blame for lack of entomological funding in the UK on the way that universities have been assessed in the UK over the last twenty years or so (Leather, 2013). The Research Excellence Framework and the way university senior management responded to it has had a significant negative effect on the recruitment of entomologists to academic posts and this has of course meant that entomological teaching and awareness of the importance of  insects to global health has decreased correspondingly.

I very much hope that this current outbreak of media hype will go some way to curing the acute case of entomyopia that most non-entomologists suffer from. I  fear however, that unless the way we teach biology in primary and secondary schools changes, people will continue to focus on the largely irrelevant charismatic mega-fauna and not the “little things that run the world”

Perhaps if publicly supported conservation organisations such as the World Wide Fund for Nature concentrated on invertebrates a bit more that would help.  A good start would be to remove the panda, an animal that many of us consider ecologically irrelevant from their logo, and replace it with an insect. Unlikely I know, but if they must have a mammal as their flagship species, how about sloths, at least they have some ‘endemic’ insect species associated with them 🙂

References

Ceballos, G., Ehrlich, P.R. & Dirzo, R. (2017) Biological annihilation via the ongoing sixth mass extinction signalled by vertebrate population losses and declines. Proceedings of the Natural Academy of Sciences, 114, E6089-E6096.

Clark, J.A. & May, R.M. (2002) Taxonomic bias in conservation research. Science, 297, 191-192.

Dirzo, R., Young, H.S., Galetti, M., Ceballos, G., Isaac, N.J.B., & Collen, B. (2014) Defaunation in the anthropocene. Science, 345, 401-406.

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.

Hallmann, C.A., Sorg, M., Jongejans, E., Siepel, H., Hofland, N., Schwan, H., Stenmans, W., Müller, A., Sumser, H., Hörren, T., Goulson, D. & de Kroon, H. (2017) More than 75% decline over 27 years in total flying insect biomass in protected areas. PLoS ONE. 12 (10):eo185809.

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

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

Sánchez-Bayo, F. & Wyckhus, K.A.G. (2019) Worldwide decline of the entomofauna: A review of its drivers. Biological Conservation, 232, 8-27.

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.

22 Comments

Filed under EntoNotes

Water butterflies and hairy wings – Caddisfly names around the world

“..great variety of cados worms.. “ Thomas Mouffet (1658)  Theatorum Insectorum

Adult Limnephilus caddisfly perched on top of its case-bearing larva.

Despite aphids being my favourite insect group, I have had rather a soft spot for caddisflies since I was about ten years old when I discovered that if I very carefully removed their larval cases and provided them with coloured sand, they would spin a technicoloured replacement 😊

A variety of caddis cases

I have, in the intervening years, moved on somewhat from those early experiments and largely left the wonderful world of freshwater entomology behind, except when I take students pond-dipping and give my once a year lecture on aquatic insects. I’m not going to say much about caddisflies because I am not an expert, but for those of you not overly familiar with these fascinating insects a little bit of background information may be useful.  Unless you are a caddisfly specialist most people don’t give them much thought and if they do know anything about them, it is probably limited to the fact that they are aquatic and live inside a case.

Most people probably wouldn’t recognise an adult caddisfly if they saw one and in my experience those people who do notice them, usually think they are some sort of moth.  This is actually a sensible guess as evolutionarily speaking Lepidoptera (moths and butterflies) and Trichoptera (caddisflies) are very closely related and are in the same Superorder, the Amphiesmenoptera.  Trichoptera literally translates as hairy wings, Lepidoptera as scaly wings and many adult caddisflies do look remarkably similar to micro-moths so it is an easy mistake to make.

Spot the difference – caddisflies on the left, Lepidoptera on the right

The majority of caddisflies have aquatic larvae, although a few have become completely terrestrial and spend their lives foraging in damp leaf litter and hiding in bark crevices.

Wingless female of the terrestrial caddisfly Enoicyla pusilla; doing her best to not look like a caddisfly. http://www.wbrc.org.uk/worcrecd/33/Green_Harry_7–Westwood_Brett–Sightings_of_adult_.html

Very generalised life cycle of a caddisfly.  The eggs are laid in water, on aquatic vegetation or nearby trees. On hatching, the larvae go through several (usual five) moults before pupating and the adults emerge in spring or early summer.

Caddisflies are probably the most successful of the aquatic insects. Data from stream surveys frequently list as many species of Trichoptera, or caddisflies, as species of Ephemeroptera (Mayflies), Odonata (dragon and Damselflies) and Plecoptera (Stonefleis) combined (Mackay & Wiggins, 1979).  Their success can be put down to their use of silk and ability to exploit a range of different aquatic habitats.  They can be described as lotic, those that live in running water, i.e. streams and rivers, or lentic, those that live in ponds and lakes.  Some of the ‘ponds’ can be very temporary, puddles for example, or contained in plants, e.g. Bromeliads. Those that live in running water are well supplied with fresh aerated water, but those living in ponds and pools have to make their own currents to pass ‘fresh’ water over their gills, to avoid suffocating.

Sedentary caddis larvae live in fixed shelters and use silk ‘fishing nets’ to catch their food.  If they live in fast flowing streams, their nets are coarse and tight.  Those living in slow flowing streams use baggy fine-grained nets.

Caddisfly fishing net https://www.flickr.com/photos/janhamrsky/5979065987/in/photostream/

Some caddisfly larvae are free-living foragers with portable cases. They also use silk, leaving a thread behind them, just as many other insects do, to attach themselves to the substrate so they are not floated downstream willy-nilly.  If they live in fast flowing streams their cases are streamlined making it easier for them to move against the current and less likely to be swept downstream.

I had originally started this article as a companion piece to my articles on the naming of thrips, aphids, cockroaches, and most recently, ladybirds, so I guess I had better get on with it. The origin of the word “caddis” is unclear, but according to Wikipedia it dates to at least as far as Izaak Walton’s The Compleat Angler (1653), in which “cod-worms or caddis” are mentioned as being used as bait. Thomas Muffet (Moufet) used the term cados worm in his book Insectorum sive Minimorum Animalium Theatrum which was written earlier (he died in 1604) but not published until 1658.  The term cadyss was being used in the fifteenth century for silk or cotton cloth, and “cadice-men” were itinerant vendors of such materials, but a direct connection between these words and the insects has not yet been established.  What about other languages, what attributes of the caddisfly have non-English speakers latched on to describe these fascinating insects?

Bulgarian – ручейник (rucheinik), which Google Translate will also tell you is rhinoceros 😊

Catalan – Frigànies which also translates as frigates, an indication of the association with water?

Czech – potočníky = stream legs

Dutch – kokerjuffer – the larval form, Schietmotten (pl) Singular: Schietmot – directly translates as shooting moths. Interestingly (or not), dragonfly is waterjuffer.

Finnish – Vesiperhonen – water butterflies, again reflecting the close resemblance to Lepidoptera; Finns call moths night butterflies, yöperhoset

French – Trichoptères – surprisingly not very flowery at all, but the larvae are more satisfyingly described as  à fourreau ou porte bois which roughly translates as with a sheath or wooden door

German – die Köcherfliege – also Frühlingsfliege, Fruhlings = spring, fliege = fly, Kocher = quiver as in arrows which given the shape of some of the cases is quite apt and the larvae are known as Köcherfliegenlarven

Icelandic – Vorflugur – Spring fly, reflecting the time of year when most of the adults emerge.

Polish – Chruścik – the wording on the stamp seems to translate as swamp yellow

Portuguese – o mosca d’água, The water fly

Spanish – el frígano similar to the Catalán and perhaps reflecting their association with wáter?

Swedish – Nattsländan –Natt = night and slandan = dragonfly?

 

Caddis case jewlery – if only I had been a bit more entrepreneurially  minded….

And finally, for those of you interested in exotic cuisine, and a non poultry alternative to red meat; in Japan caddisfly larvae are called Zazamushi and eaten as a delicacy.  They are so popular that they are commercially farmed (Cesard et al., 2015).

Many thanks to Daniela Atanasova, Gia Aradottir, Hannah Davis, Luisa Ferreira Nunes and Marlies vaz Nunes for help with the Bulgarian, Icelandic, German, Portuguese and Dutch respectively. They are much more reliable than Google Translate.

References

Cesard, N., Komatsu, S. & Iwata, A. (2015)  Processing insect abundance: trading and fishing of zazamushi in Central Japan (Nagano Prefecture, Honshū Island). Journal of Ethnobiology and Ethnomedicine, 11:78.

Mackay, R.J. & Wiggins, G.B.  (1979) Ecological diversity in Trichoptera.  Annual Review of Entomology, 24, 185-208

 

9 Comments

Filed under EntoNotes

Meat eating moths

This post is dedicated with thanks to Entomology Uncensored which gave me the idea for this post.

Unless you believe that the Very Hungry Caterpillar’s diet is truly representative of what a lepidopteran larva eats, you will, if asked, almost certainly answer that caterpillars eat plants and that the adults, if they do feed, do so on nectar. Although this is true for the majority of Lepidoptera, there are a couple of exceptions that have opted for a very different life style. Some of you may already now be saying to yourselves, “Aha what about the clothes moth? That doesn’t eat plants, it eats clothes doesn’t it?”, and you would be right. The larvae of Tinea pellionella, the Case Bearing Clothes Moth, are not plant eaters, they make a living eating wool, fur and feathers among other keratinous* delicacies (Cheema, 1956).

Tinea pellionella – clearly demonstrating why it is called the case-bearing clothes moth

There are some moth species that have gone a step further in adopting an animal-based diet, feeding directly on living animals and not on their cast-off skins and horns. In 1879 the American entomologist John Comstock (1849-1931) while studying a colony of the cottony maple scale Pulvinaria innumerabilis, was one day surprised to find a caterpillar busily eating his study organisms.  Rather than losing his temper and killing the caterpillar, he reared it through to adulthood and realised that this was a species new to science, which he named Dakruma coccidivora (Constock, 1979), now renamed Laetilia coccidivora and recognised as a useful biological control agent (e.g. Goeden et al., 1967; Mifsud, 1997; Cruz-Rodriguez et al., 2016).  Perhaps it had evaded being spotted by less keen-eyed entomologists from its habit of living underneath the scale insects it eats (Howard, 1895).

The hidden life style of Laetilia coccidivora as described by Howard (1895)

Laetilia coccidivora busy eating prickly pear scale insects

Less deadly to its host, but no less of a carnivore, is the moth Epipomponia nawai.  This, and all the other members of its family, thirty-two in total, are all ectoparasites of Hemiptera, especially cicadas and planthoppers (Jeon et al., 2002).  The larvae attach themselves to the abdomen of their host and feed on the juicy flesh underneath the cuticle.  Once ready to pupate they spin a silk thread, drop off their host and spin a cocoon on the bark of the tree their host has fed on (Liu et al., 2018).  The adults do not fed and only live long enough to mate and lay eggs.  For those of you who love a mystery, no-one knows how the moth larvae find their cicada hosts. One possibility is that they might use the cicada song as a cue but this has, so far, not been proven (Liu et al., 2018).

Larva of Epipomponia nawai parasitizing an adult cicada (Liu et al., 2018).

An even more striking example of predatory behaviour in moth larvae is that shown by members of an otherwise herbivorous Genus of Geometrid (looper) moths, Eupithecia.  The Eupithecia have a worldwide distribution, but in Hawaii, all but two of the species are ambush predators Montgomery, 1983).  The caterpillars show typical looper behaviour, remaining motionless pretending to be a twig or leaf, depending on their colour.  When a potential prey item bumps into the back of the caterpillar it rears backwards and catches the victim between its elongated and spiny thoracic legs and then chomps happily on its juicy meal.  It is thought that the absence of praying mantises on the Hawaiian Islands allowed the ancestors of the original Eupithecia that colonised the islands to fill their empty niche (Montgomery, 1983; Mironov, 2014).  The caterpillars are not fussy about what they eat, as long as they can grab and keep hold of it and it doesn’t fight back.  They have been recorded as eating flies, braconid wasps, leafhoppers, other Lepidopteran larvae, crickets and even spiders and ants (Montgomery, 1983, Sugiura, 2010).

Eupithecia orichloris attacking and eating an ant (Sugiura 2010)

Last in my list of carnivorous Lepidoptera and perhaps the most surprising are the Vampire Moths.  The phenomenon of “puddling” by butterflies to obtain sodium is well-known (e.g. Boggs & Jackson, 1991) and can be a very attractive sight.

A sight to enjoy – mud puddling https://www.earthtouchnews.com/in-the-field/backyard-wildlife/mud-puddling-the-butterflys-dirty-little-secret/

Somewhat less attractive behaviour is seen in a number of moth species from the Noctuid, Geometrid and Pyralid families which satisfy their desire for Sodium by feeding as adults from the tears and pus of mammals, including humans (Bänziger & Büttiker, 1969).

The Noctuid moth Lobocraspis griseifusa sucking lachrymal fluid (tears) from a human’s eye.  The author, whose eye this is, rather gruesomely asks us to “note the deep penetration of the proboscis between eye and eye lid” Bänziger & Büttiker (1969).

Some Noctuid moths have taken this a step further, perhaps a step too far. Moths of the Genus Calyptra, have very strong proboscises which allow them to feed through the skin of fruit, even oranges, hence their common name, fruit-piecing moths.  A few species however, have adopted a somewhat more interesting diet and have developed a taste for fresh mammalian blood, again, including that of humans, which they suck directly from their victims (Bänziger, 1968).  They are, of course, known as the Vampire Moths!

Calyptra thalictri Vampire Moth in action – note the barbed proboscis

Happy Halloween!

References

Bänziger, H. (1968) Prelimnary observations on a skin-piercing blood-sucking moth (Calyptra eustrigata) (Hmps.) (Lep., Noctuidae)) in Malaya.  Bulletin of Entomological Research, 58, 159-165.

Bänziger, H. & Büttiker, W. (1969) Records of eye-frequenting Lepidoptera from man. Journal of Medical Entomology, 6, 53-58.

Boggs, C.L. & Jackson, L.A. (1991) Mud puddling by butterflies is not a simple matter. Ecological Entomology, 16, 123-127.

Cheema, P.S. (1956) Studies on the Bionomics of the Case-bearing Clothes Moth, Tinea pellionella(L.). Bulletin of Entomological Research, 47, 167-182.

Comstock, J.H. (1879) On a new predaceous Lepidopterous insects.  The North American Entomologist, 1, 25-30.

Cruz-Rodriguez, J.A., Gonzalez-Machoro, E., Gonzales, A.A.V., Ramirez, M.L.R. & Lara, F.M. 92016) Autonomous biological control of Dactylopius opuntia (Hemiptera: Dactlyliiopidae) in a prickly pear plantation with ecological management.  Environmental Entomology, 45, 642-648.

Goeden, R.D., Fleschner, C.A. & Ricker, D.W. (1967) Biological control of prickly pear cacti on Santa Cruz Island, California. Hilgardia, 38, 579-606.

Howard, L.O. (1895) An injurious parasite.  Insect Life, 7, 402-404.

Jeon, J.B., Kim, B.T., Tripotin, P. & Kim, J.I. (2002) Notes on a cicada parasitic moth in Korea (Lepidoptera: Epipyropidae). Korean Journal of Entomology, 32, 239-241.

Liu, Y., Yang, Z., Zhang, G., Yi, Q. & Wei, C. (2018) Cicada parasitic moths from China (Lepidoptera: Epipyropidae): morphology, identity, biology, and biogeography.  Systematics & Biodiversity, 16, 417-427.

Mifsud, D. (1997) Biological control in the Maltese Island – past initaitives and future programmes.  Bulletin OEPP/EPPO Bulletin, 27, 77-84.

Mironov, V.G. (2014) Geometrid moths of the Genus Eupithecia Curtis, 1825 (Lepidoptera, geometridae): prerequisites and characteristic features of high species diversity. Entomological Review, 94, 105-127.

Montgomery, S.L. (1983) Carnivorous caterpillars: the behaviour, biogeography and conservation of Eupithecia (Lepidoptera: Geometridae) in the Hawaiian Islands. GeoJournal, 7, 549-556.

Sugiura, S. (2010) Can Hawaiian carnivorous caterpillars attack invasive ants or vice versa? Nature Precedings

Leave a comment

Filed under EntoNotes

Little and Large – ENTO18 at Edgehill University

This year ENTO18 was hosted by Edgehill University, which until I met Anne Oxbrough at INTECOL in 2013, I had thought was in London 🙂 It is actually in Ormskirk, for those of you not familiar with the geography of the North of England, about 19 km as the crow flies, or 26 km by road from Liverpool. I drove up with my colleague Heather Campbell and we were both immediately impressed by the campus; even the extremely large car park took on an eerie beauty at night.

Edgehill University Campus – water features and greenery and a very large car park

The greenery, much of it just planted, also meant that there were some interesting insects to find such as the Alder beetle Agelastica alni, which up until a few years ago was considered extinct in the UK.  There was also very obvious vine weevil damage around the campus.

The Alder Leaf Beetle – very much not extinct

As you might expect with the large amount of water present, there were also a lot of ducks and other water birds which meant that one had to be careful where one trod.  The campus also boasted some interesting sculptures including pig and a goat, the significance of which escaped me.

Zoological sculptures, sadly not insects 🙂

The theme of the conference was “The Good, the Bad and the Ugly” and sessions were based around the Royal Entomological Society’s journals.

A great set of journals, especially the one with the red cover

The talks were varied and almost without exception, excellent.  Anne Oxbrough and her team had obviously done a great job in attracting a stellar cast both in the choice of keynote speakers and the shorter, but no less important, talks.

As usual, events like this don’t need a lot of text, the pictures tell the story.

Just some of the great keynote talks – note the presence of honorary insects

Some of my favourite short talks, including a couple by former students and another honorary insect subject

An unsolved conference mystery – why was this vine weevil wearing a coat? Photo by one of my former MSc students, Katy Dainton

One of my favourite talks

 

Entomological fashion icons

The traditional ceilidh – there are always some who sit and watch

Our new President, Chris Thomas FRS, never short of words especially with a glass of wine in his hand

Great to see one of my former MSc students, Liam Crowley, win the prize for the best student talk. Archie Murchie handing over the cheque.

Congratulations to two of the student essay winners, James Fage and Maggie Gill, both on the Harper Adams University MSc course.

 

 

An excellent conference dinner, although the vegetable terrine starter  did not receive universal approbation 🙂

The very large deck chair!  Entomologists never really grow up 🙂

Some personal highlights – meeting my beard twin, Mike Kaspari, a garish contribution to the entomological tee-shirt competition (I’m not sure there actually was one) and succumbing to the lure of the chair 🙂

I missed this but it looks fantastic – one of the post-conference workshops

Many thanks to Anne Oxbrough and her team and of course the Royal Entomological Society team, Kirsty Whiteford, Luke Tilley and my former student Fran Sconce – it was a great conference.

And finally, please support this great initiative organised by another of my former MSc students, Ashleigh Whiffin with the help of Matthew Esh and Richard Wright.

 

 

1 Comment

Filed under EntoNotes, Uncategorized

Global Insect Extinction – a never ending story

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

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

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

“British Insects in Decline

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

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

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

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

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

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

Two conifer feeding moth species showing no signs of decline.

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

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

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

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

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

 

References

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

 

8 Comments

Filed under EntoNotes