Monthly Archives: June 2020

Pick & Mix 48 – wildflowers, sinistral snails, slaves, Charles Dickens, medieval insect lore, conservation and teaching in a virtual world

Rob Yorke on insects

On the importance of ‘real’ wildflowers and the rise of plant blindness

Do you remember Jeremy the left-handed snail?  Sadly, he is now no longer with us but he has been immortalised in print 🙂 See the published paper here.

Sickening and sobering visualisation of the slave trade 😦

Interesting analysis of some of Charles Dickens’ characters

Insects and other arthropods in medieval manuscripts – some remarkable illustrations

The role of arthropods in medieval medicine

One, two, more or less? How many metres apart will keep us safe?

Teaching tips for a virtual world

If you are interested in UK nature and conservation, then this is an interesting on-line news round-up

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Natural History learning should be compulsory for all, not just an option for a niche few

One of the few benefits of the Covid-19 pandemic is that I have been able to spend a lot more time outdoors roaming the country lanes around my lockdown prison*.  Prior to my move to Harper Adams University, I had, from 1992-2012, spent two days a week doing fieldwork at Silwood Park. When I moved  from there to Harper Adams, I resisted the temptation to set up yet another long-term field study, and decided to concentrate (not very successfully) on analysing my data backlog and getting the MSc courses well and truly established at their new location. At the time I hadn’t realised how much I had benefited, physically and mentally, from my Silwood transects until I started my lunchtime lockdown treks. I have over the past eleven weeks, added four new aphid species to my personal list, plus a couple of beetles (including one notable species), counted butterflies, seen a hare, reacquainted myself with lots of grasses and herbaceous plants, talked to trees, fumbled a few fungal identifications, and even taken a passing interest in birds :-).  I mention all this because I am a great believer in fieldwork and the benefits that accrue in terms of ideas if you keep your eyes open to all the other things that are happening around your study organisms. Given the vast number of insect species and the close relationships most of them have with plants, it behoves a field entomologist to have more than a passing interest in natural history.

This past week has seen a flurry of interest in the study of natural history in the UK. One of the national exam boards (OCR), after a lot of lobbying from the author Mary Colwell and organisations such as the UK Plant Science Federation, has set out a consultation document about the launch of a new GCSE** qualification in Natural History. As someone who has been bemoaning the lack of natural history training at all levels for many years, this, on the face of it, seems a great idea.

Learning the basics

This is their proposed statement on the purpose of studying Natural History: (so lack of appropriate punctuation is not due to me)

“Natural history offers a unique opportunity to observe and engage with the natural world to develop a deeper understanding of the flora and fauna (life on Earth) within it. It is a study of how the natural world has been shaped and has evolved as well as how humans (as part of that natural world) influence, conserve and protect it. It is vital that we continue to develop our understanding of the natural world in order to safeguard the future.

To fully appreciate the complexities of the natural world it is important to study it closely and interact with it through field research and measurement. Natural history provides opportunities to develop skills out in the field as well as in a classroom and/or laboratory. Studying natural history makes an important contribution to understanding the relationship between the natural world and culture, policy decisions, scientific research and technology.

Study of science, geography, history and the arts at key stages 3 and 4 provides a variety of complementary skills and knowledge which support the study of Natural history. This subject supports the development of unique skills and knowledge which give a sharper focus and depth to the complexities of the natural world. The progression pathway for this subject at key stage 5 and beyond could be scientific, geographical, environmental, ecological or natural history itself.”

 

This is all very laudable and something I think that all of us interested in natural history would support wholeheartedly.  In the UK, the problem is particularly acute and is something that has been recognised for some time (Leather & Quicke, 2010).  Natural history training at all levels has been appalling over the last couple of decades, and has been aided and abetted by the way in which research councils have awarded funding over that period (Clark & May, 2002; Leather, 2009, 2013).  This, and the typical media coverage, see us living in a world where ecology and conservation, is largely perceived to be vertebrate biased, and insects, with the exception of honeybees, portrayed as the enemies of humankind.

Typical reporting of the biodiversity crisis in the UK

Vertebrate bias not just confined to the UK

A very natural (and to me fascinating) phenomenon provoking hysterical reactions on Twitter. Most of the replies were similar to these “Just RUN,  RUN, Ew, Look for a spaceship – it’s an alien, we’re doomed, we’re all doomed”

Yet another harmless insect vilified

This is a problem and something one would hope that a pre-university qualification in natural history would seek to address.  Now, although I very much like and support the idea of a secondary school qualification in Natural History, I can see a couple of problems looming ahead.  First,  I may be biased, but looking at how the macro-species are represented globally, one would justifiably expect the study of natural history to focus on plants, insects and other invertebrates.

Estimated number of species globally within the macro-world (invertebrates other than insects number approximately 300 000 species).

Where are the invertebrates? Surely rather than the rise of the mammals, it should be mammals gain a precarious claw hold?  The invertebrates were, and continue to be the dominant animal life from on Earth, but don’t get a mention.  Then in another part of the consultation document, under topics to be considered, we see yet another anti plant and insect bias creeping in and a pro-vertebrate slant.

  • Effects of introducing non-native species (e.g. harlequin ladybirds, Rhododendron)
  • Species reintroduction (e.g. wolves, beavers, red kites)

There are lots of vertebrate non-native species that could be named (Eatherley, 2019) and many notable insect reintroductions (e.g. Andersen, 2016)..but where are they?

Despite the fact that the much respected book series The New Naturalist,and the equally respected journal, The American Naturalist, proudly include the word naturalist in their titles, sometime in the last thirty years or so, natural history and naturalist became words that were regarded with some scorn and suspicion within the hallowed halls of academia. Whereas in the past, to be an ecologist necessitated an understanding and knowledge of the living world (Travis, 2020), the ability to produce mathematical models and run complex statistical analyses became the route to tenure and laboratories chock a block with postdocs and PhD students.  In universities, computers and molecular biology labs replaced plant and animal based practical classes. Ecology field courses based around insect, and plant identification disappeared, to reappear rebadged as conservation courses and moved to exotic climes with a focus on the large and easily seen furry, feathered and scaled vertebrates. (OK, I’m being a bit hyperbolic here but you know what I mean; and this is a true story, when I was at Imperial College and it was very obvious that we were running out of entomologists to teach the subject, my Head of Department on me drawing this to his attention, suggested that we could do more modelling).  At the same time, biology teaching in secondary schools was also changing in scope, moving away from the outdoors and whole organisms, to molecules, genetics and humans.  The age of plant blindness, entomyopia, entoalexia and nature deficit disorder (Louw, 2005) was well and truly established by the beginning of the 21st Century.

This brings me to my biggest concern.  Insects and plants dominate the natural world, but, as we know, entomologists and botanists are in very short supply. In the UK, Botany and Zoology departments have mostly been subsumed into BioScience and Life Sciences departments to the detriment of whole organism teaching. There are no Botany Departments per se, and in the few remaining Zoology Departments, entomologists, make up at the most, half of the tenured staff, so where are the teachers going to come from?

Who will teach Natural History?

 

Finally, even if we find the teachers and the curriculum is appropriately balanced to reflect the natural world, unless we make it compulsory to all, as is the case with English and Mathematics, it will only ever remain a niche subject taken by relatively few students.  Consequently, elephant hawk moth caterpillars will continue to be beaten to death by suburban parents afraid of snakes, the press will continue to vilify harmless wood wasps, bumbling beautiful cockchafers will be swatted to death and hoverflies squashed by rolled up newspapers for no good reason.

 

References

Andersen, A. , Simcox, D.J., Thomas, J.A. & Nash, D.R. (2016) Assessing reintroduction schemes by comparing genetic diversity of reintroduced and source populations: A case study of the globally threatened large blue butterfly (Maculinea arion). Biological Conservation, 175, 34-41.

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

Eatherley, D. (2019) Invasive Aliens, William Collins, London.

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

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.

Louw, R. (2005)  Last Child in the Woods, Atlantic Books, London.

Purvis, A. (2020) A single apex target for biodiversity would be bad news for both nature and people. Nature Ecology & Evolution, 4, 768-769.

Travis, J. (2020) Where is natural history in ecological, evolutionary and behavioral science?  The American Naturalist, 196,

 

*my wife and I managed to end up being lock-downed 250 km apart 😦

**Non UK residents see here for an explanation

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Not all aphids live on the underside of leaves

If I were to misquote Jane Austen and state “It is a truth universally acknowledged, that aphids are found on the underside of leaves” most people who know what aphids are would agree without quibbling. If natural enemies could speak, they would probably agree as this quote from an early paper by my former boss, Hugh Evans puts it  “since most aphids are found on the lower surfaces of leaves anthocorids must be wasting time in searching the upper leaf surface” (Evans, 1976). The only enemies that regularly search the upper surface of leaves are parasitoids, which use aphid honeydew as a host-findng cue (e.g. Volkl, 1994), which is where it falls if the leaves above them are infested with aphids.  We know that not all aphids feed on leaves, many using roots, flowers, stems and even tree trunks as their preferred feeding sites, but do all leaf-feeding aphids behave in the same way?

A few species of leaf-dwelling aphid buck the trend and live on the upper surface of leaves. Dogma has it that most leaf-feeding aphids prefer the underside because there are more stomata there and this makes access to the phloem easier.

Aphis grossulariae on the underside of a gooseberry leaf, – only revealed because I turned the leaf over.

Look, however, at a neat experiment that Graham Hopkins and Tony Dixon did (Hopkins & Dixon, 2000). They showed that the birch aphid Euceraphis betulae, which is normally found on the lower surface of leaves, will, if the leaves are held so that the upper surface faces the ground, move from the now facing upward lower surface to the now facing downward upper surface. The answer can’t all be to do with the stomata. That said, in grasses and other monocotyledonous plants, there are more stomata on the upper surface of the leaves andmMany grass-feeding aphids do seem to have a predilection for the upper surface. The green spruce aphid, Elatobium abietinum, another aphid that has a very strong preference for feeding through stomata, is found mainly on the upper surface of spruce needles which are where the stomata are more prevalent (Parry, 1971).

Utamophoraphora humboltdi feeding on the upper surface of Poa annua outside my office.

The Green Spruce Aphid, Elatobium abietinum feeding on the upper surface of spruce needles (Albrecht (2017)

It is possible, however, that the preference for the upper surface of grasses is not entirely due to the relative abundance of stomata there.  The grass aphid, Sipha kurdjumovi for example, although most commonly found feeding on the upper surface of grass and cereal leaves, prefers to settle on a concave ridged surface (Dixon & Shearer, 1974), a characteristic of the upper surface of many grasses  Lewton-Brain, 1904). Another advantage to living on the upper surface of grass leaves is that when grasses want to conserve water they roll inwards along the mid-vein, which has the added benefit of hiding the aphids and protecting them from their natural enemies.

Mainly, however, if you are an aphid, you feed where the stomata are plentiful, hence the tendency for aphids living on monocotyledonous plants to feed mainly on the upper surface of leaves, instead of the lower surface.  Conversely, a leaf-feeding aphid on a dicotyledonous host plant would be expected to feed on the lower surface of the leaves, where there are more stomata.  It also makes sense for those aphids to be underneath the leaf, as there is less chance of them being knocked off by the rain or being dislodged by leaves brushing against each other in the wind.

There are, however, two tree-dwelling aphids in the UK that live on the upper side of the leaves of their woody hosts, the very rare Monaphis antennata on birch (Hopkins & Dixon, 1997) and the less rare large walnut aphid, Panaphis juglandis on walnut (Heie, 1982). So what makes these aphids so contrary? According to Graham Hopkins and Tony Dixon (Hopkins & Dixon, 1997), M. antennata is taking advantage of enemy-free space and to compensate for living on top of the leaf is cryptic to avoid detection by enterprising predators, and has a flattened and contoured body shape to avoid accidental dislodgement.

When it comes to P. juglandis things are bit more conjectural.  Interestingly, despite being a pest in some parts of the world (e.g. Wani & Ahmad, 2014) we don’t know much about it. It is also hard to understand why it has adopted the upper side of the leaf as its habitat.  One very obvious downside

Panaphis juglandis – prominently lined up along the mid-vein of the upper surface of a walnut leaf and displaying their possible unpalatability by their conspicuous yellow and black colouration.  From Influential Points  https://influentialpoints.com/Images/Panaphis_juglandis_nymphs_on-vein_c2013-07-06_18-35-17ew.jpg

is that by so doing it has opened Itself up to competition from the other common walnut aphid, Chromaphis juglandicola, the honeydew of which falls from the leaves like acid rain on to P. juglandis and prevents them living on the same trees (Olson, 1974; Wani & Ahmad, 2014).  In the absence of C. juglandicola it is, however, very successful with a number of life history traits that presumably ensure its survival, although no one has quantified this. First, it is striped yellow and black, a clear warning sign.  Bob Dransfield and Bob Brightwell who run that fantastic site, Influential Points, suggest that perhaps P. juglandis sequesters juglone from its walnut host as a defence against predators. It therefore makes sense to advertise it by being conspicuously coloured.  Second, they also, point out that the way in which the nymphs line up along the mid-vein might act as a form of masquerade mimicry or disruptive camouflage, by looking from certain angles like a blemish caused  by a fungal disease or injury. Neither of these suggestions answer the question as to why it lives on the upper side of leaves. For M. antennata, escape from natural enemies and competition are cited as the reason why it lives where it does.  Neither seem to explain P. juglandis, as it is not, at least according to Olson (1974), safe from predation and parasitism, although there is some indication that it might be ant-attended (Fremlin, 2016), nor is it able to share its host plant with the other walnut specialist, Chromaphis juglandicola. On the other hand, unlike M. antennata, it is most definitely not a rarity.

As they used to say when I was young, “answers on a postcard please”. In the meantime, until someone has the time and inclination to delve into this intriguing conundrum, I guess we should add it to Ole Heie’s list of unsolved aphid mysteries 🙂

 

References

Albrecht, A. (2017) Illustrated identification guide to the Nordic aphids feeding on conifers (Pinophyta) (Insecta, Hemiptera, Sternorhyncha, Aphidomorpha). European Journal of Taxonomy, 338, 1-160.

Dixon, A.F.G. & Shearer, J.W. (1974) Factors determining the distribution of the aphid, Sipha kurdjumovi on grasses. Entomologia experimentalis et applicata, 17, 439-444.

Evans, H.F. (1976) The searching behaviour of Anthocoris confusus (Reuter) in relation to prey density and plant surface topography. Ecological Entomology, 1, 163-169.

Fremlin, M. (2016) The large walnut aphid (Panaphis juglandis Goeze) – A few observations. Nature in North-East Essex, 2016, 68-76.

Heie, O.E. (1982) Fauna Entomologia Scandinavia, Vol. 11. The Aphidoidea (Hemiptera) of Fennoscandia and Denmark. II. The family Drepanosiphidae. Scandinavian Science Press, Klampenbourg, Denmark.

Heie, O.E. (2009) Aphid mysteries not yet solved/Hemiptera:Aphidomorpha./. Monograph Aphids and Other Hemipterous Insects, 15, 31-48.

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

Hopkins, G.W. & Dixon, A.F.G. (2000) Feeding site location in birch aphids (Sternorrhyncha: Aphididae): the simplicity and reliability of cues. European Journal of Entomology, 97, 279-280.

Lewton-Brain, L. (1904). VII. On the anatomy of the leaves of British grasses. Transactions of the Linnaean Society of London, Botany, Series 2, 6, 312-359.

Olson, W.H. (1974) Dusky-veined walnut aphid studies. California Agriculture, 28, 18-19.

Parry, W.H. (1971) Differences in the probing behaviour of Elatobium abietinum feeding on Sitka and Norway spruces. Annals of Applied Biology, 69, 177-185.

Volkl, W. (1994) Searching at different spatial scales: the foraging behaviour of the aphid parasitoid Aphidius rosae in rose bushes. Oecologia, 100, 177-183.

Wani, S.A. & Ahmad, S.T. (2014). Competition and niche-partitioning in two species of walnut aphids. International Journal of Scientific Research and Reviews 3, 120 – 125.

Willmer, C. & Fricker W (1996)  Stomata, Springer, Berlin.

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Pick & Mix 47 – Captain Cook, coffee, tea, moths and bees

Follow Captain Cook on his Pacific voyages – nice interactive experience

Buried under colonial concrete – the lost botany of Botany Bay

Coffee, not just a pick you up, but a knock you down (if you’re an insect that is)

Did you know that there is an international tea day? All about tea for those of you who prefer tea to coffee

Beautifully written and equally beautifully illustrated essay by the aptly named Linden Hawthorne  (@Haggewoods onTwitter) on the Latin names of plants and animals

Gwen Pearson gives good advice on how to talk to a reporter about entomology

Moths – the mostly unseen and definitely unappreciated pollinators

Some cool bee videos from Jeff Ollerton

The bees are the stars – a novel about bees

For the non-entomologists (and entomologists) -urban fantasy novels: why they matter and which ones to read first – some good suggestions here

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