Tag Archives: Lepidoptera

Not all moths have wings

Insects really took off when they developed flight (Alexander, 2015), so it is perhaps surprising that so many have lost the ability subsequently.  Nearly all the winged Orders have developed flightless members, with beetles of course, topping the list (Wagner & Liebherr, 1992).  A number of reasons for why flightlessness made a reappearance have been put forward. The eminent coloepterist, Thomas Vernon Wollaston, noted that the island of Madeira had an unusually high number of wingless (apterous) beetles. His friend, Charles Darwin, suggested that for island dwelling animals, it was a disadvantage to be winged especially if you were small or subjected to high winds (Darwin, 1859). Many years later, Derek Roff reviewed the literature, and found that there was no difference in the proportion of non-winged insects on islands compared with those on continental areas (Roff, 1990).  Winglessness is also common in insects living at high altitudes, in cold climates or in those that are autumn or winter active (Hackman, 1966).  It might be that wings are energetically costly in those environments (Mani, 1962), but why then is it that in many cases, it is only the females that are wingless?  To explain this we can hypothesise that eggs are energetically more expensive than sperm (Hayward & Gilooly, 2011), so that males can ‘afford’ to be winged and travel to find a mate. For this to work, the females need to be able to attract males from a distance, something moths are renowned for (Greenfield, 1981).

Male Thyridopteryx ephemeraeformis – note the well-developed antenna – ideal for picking up female sex pheromones. https://upload.wikimedia.org/wikipedia/commons/4/4d/-_0457_%E2%80%93_Thyridopteryx_ephemeraeformis_%E2%80%93_Evergreen_Bagworm_Moth_%2814869905567%29.jpg By Andy Reago & Chrissy McClarren [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)%5D, via Wikimedia Commons

We also know that in those insects with wing dimorphism, the apterous forms are more fecund compared with those with wings (Dixon, 1972; Mackay & Wellington, 1975). In those insects that retain their wings, many resorb their wing muscles once they have found suitable egg laying sites (Stjernholm et al., 2005; Tan et al., 2010), further proof that wings are costly. Winglessness is also common in those insects that are parasitic on vertebrates, bedbugs, fleas and lice for example.  Those that do start with wings, such as the Hippoboscid flies, lose their wings once they have found a suitable host. Finally, winglessness is often associated with stable and extensive habitats, such as forests, or surprisingly to me at any rate, mountains, where dispersal is not a high priority (Roff, 1990).

Thyridopteryx ephemaeraeformis https://ideastations.org/sites/default/files/storage/secondary-images/bagworm-case.jpg  

I first saw bagworms as a child in Jamaica but of course at the time had no idea what species they were. I was however, fascinated by the sight of the cunningly constructed cases in which the larvae lived and eventually pupated within.  To me, case bearer moths and caddisflies were the insect equivalent of hermit crabs, which were and are one of my favourite non-insect animals*.  Little did I know that one day I would write about these very same bagworms (Rhainds et al., 2008). Bagworms, of which just over half have wingless females, immediately contradict the cold climate hypothesis of winglessness, as many of them are tropical and there are just as many wingless species in the tropics as there are elsewhere (Rhainds et al., 2009). The bagworms belong to the family Pyschidae, which contain a 1000 species or so.  Not only do over half of these have wingless females, some also have females which are legless and never leave their pupal case, even mating in it.

Male Thyridopteryx ephemeraeformis bagworm mating with bag-enclosed female (Jones, 1927)

Even though the more primitive (less derived) members of the Psychidae have wings, the winged females are less active than the males (Rhainds et al. 2009).  As you might expect, host plant selection is by the larval stage, which on hatching, throw out a silk thread and float off with great expectations (Moore & Hanks, 2004).  Once they find a suitable host plant, which is not as difficult as you might expect, as they extremely polygamous, they begin to feed and construct their cases.  Some of the larval cases that Psychids construct are truly magnificent.  A great example is Eumeta crameri, the large faggot worm, so called because it looks like it is carrying a pile of firewood on its back 🙂

Eumeta crameri, the large faggot worm, so called because of the twigs its carries around on its back Melvyn Yeo

In case you are wondering about the ornate cases, they are not decorative, but more likely to be anti-predator devices (Khan, 2020).

Although the Psychids have the largest number of species with wingless females, there are 18 other moth families with species with wingless females.  Species that are found at high altitudes and northern latitudes have the most flightless species (Hackmann, 1966) or, like the Psychids, inhabit stable forest and woodland habitats (Barbosa et al., 1989).  Another characteristic of wingless moth species is that they overwinter as eggs or first instar larvae (Barbosa et al., 1989, although there are of course, many moths that have similar habits and are not wingless, such as the small ermine moths (Leather, 1986a).

After the Psychids, the families with the greatest number of species with wingless females are the Geometridae (loopers) and the Lymantridae (tussock moths). In the Lymantridae some are wingless and many have non-functional wings (Hackman, 1966).  The Arctidae and the Lasiocampidae also have some flightless species, the genus Chondrostega, endemic to the Iberian Peninsula having some notable examples, (Hackman, 1966). An oddity, as they are not strictly flightless, are females of the tortricid Choristoneura fumiferana, which have functional wings, but are behaviourally flightless, only taking flight under particular environmental conditions (Barbosa et al., 1989).

Moth species that have flightless females all have one thing in common, they aren’t picky about their diet, they are polyphagous and live in forests and woodlands. They also tend to have larvae that can disperse by ballooning, although not all moths with ballooning larvae have flightless females.  First instar larvae of the pine beauty moth, Panolis flammea, which readily balloon in outbreak situations, and usefully, can survive several days without food (Leather, 1986b).

In the UK there are two very common moths with wingless females, the winter moth, Operphthera brumata and the Vapourer moth, Orgyia antiqua, the former a Geoemtrid, the latter, a Lymantrid. Both are extremely polyphagous, usually feeding on broadleaf trees and shrubs, but both have recently added conifer species to their diets.  The Vapourer moth ‘decided’ that the introduced lodgepole pine, Pinus contorta growing in Sutherland and Caithness, would make a suitable alternative food plant (Leather, 1986) and the winter moth opted for another introduced conifer, Sitka spruce, Picea sitchensis, in the Scottish Borders (Hunter et al., 1991). Why both these host shifts happened in the early 1980s and in Scotland, remains a mystery, although it is possible that they moved onto conifers via heather (Hewson & Mardon, 1970; Kerslake et al., 1996).

They do, however, have some striking differences in their approach to life. Larvae of the Winter moth are spring flush feeders, and very dependent on egg hatch coinciding with bud burst (Wint, 1983), Vapourers are summer foliage feeders so are adapted to feeding on mature leaves. The adults of the Winter moth, as its name suggests are active in the winter months, laying their eggs on the bark or in crevices of their host trees in November and December and even January. Vapourer adults on the other hand are summer active, the eggs being laid on their pupal cases on the leaves of their host trees from July to September.

Female Vapourer moth and her egg mass – note the short legs and much reduced wings

 

Long legged female winter moth Operphtera brumata https://butterfly-conservation.org/sites/default/files/styles/large/public/2019-01/8179909985_76865dd047_o.jpg

Hackman (1966) distinguishes two types of wingless females, those with reduced locomotion, very heavy, filled with eggs and what I describe in class as splurgers, i.e. all their eggs laid in one go.  The female Vapourer with short legs and much-reduced wings is an ideal example.  The female winter moth is a good example of the second type, those possessing good strong legs which after copulation seek out suitable egg-laying sites.  Despite the difference in oviposition tactics, the first instar larvae of both species are adept ballooners, and it is they who ‘decide’ whether to stay or go (Tikkanen et al., 1999).

First instar Vapourer moth larvae in the process of dispersing.

Understandably, they have very little control of where they land, although presumably, they can reject the plant they land on and launch themselves into space again. How many times they can do this and how long they can live for without feeding, is something that needs research, but given that the first instar larvae of the pine specialist P. flammea can live several days without feeding, I would expect that the Winter moth and Vapourer moth larvae are equally capable of resisting starvation.

Moths without wings, but highly successful and many are pests, so not such a dumb approach to life after all?

And while we’re at it, here is the lymantriid Teia anartoides. With hamsterlike apterous females! AinsleyS @americanbeetles

References

Alexander, D.E. (2015) On the Wing, Oxford University Press. (This is an excellent book).

Barbosa, P., Krischik, V. & Lance, D. (1989) Life history traits of forest-inhabiting flightless lepidoptera. American Midland Naturalist, 122, 262-274.

Darwin, C. (1859) 0n the Origin of Species, JohnMurray, \lodnon.

Dixon, A.F.G. (1972) Fecundity of brachypterus and macropterous alatae in Drepanosiphum dixoni (Callaphididae, Aphididae). Entomologia experimentalis et applicata, 15, 335-340.

Greenfield, M.D. (1981) Moth sex pheromones: an evolutionary perspective. Florida Entomologist, 64, 4-17.

Hackman, W. (1966) On wing reduction and loss of wings in Lepidoptera. Notulae Entomologicae, 46, 1-16.

Hayward, A. & Gillooly, J.F. (2011) The cost of sex: quantifying energetic investment in gamete production by males and females. PLoS One, 6, e16557

Hewson, R. & Mardon, D.K. (1970) Damage to heather moorland by caterpillars of the vapourer moth Orgyia antiqua L. (Lep., Lymantridae). Entomologist’s Monthly Magazine, 106, 82-84.

Hunter, M.D., Watt, A.D. & Docherty, M. (1991) Outbreaks of the winter moth on Sitka spruce are not influenced by nutrient deficiencies of trees. Oecologia, 86, 62-69.

Jones, F.M. (1927) Mating of the Psychidae (Lepidoptera). Transactions of the Entomological Society of America, 53, 293-312.

Kerslake, J.E., Kruuk, L.E.B., Hartley, S.E. & Woodin, S.J. (1996) Winter moth (Operophtera brumata (Lepidoptera: Geometridae)) outbreaks on Scottish  moorlands; effects of host plant and parasitoids on larval survival and development. Bulletin of Entomological Research, 86, 155-164.

Khan, M.K. (2020) Bagworm decorations are an anti-predator structure.  Ecological Entomology https://onlinelibrary.wiley.com/doi/epdf/10.1111/een.12876

Leather, S.R. (1986a) Insects on bird cherry I The bird cherry ermine moth, Yponomeuta evonymellus (L.). Entomologist’s Gazette, 37, 209-213.

Leather, S.R. (1986b) The effect of neonatal starvation on the growth, development and survival of larvae of the pine beauty moth Panolis flammea. Oecologia, 71, 90-93.

Leather, S.R. (1986c) Keep an eye out for the vapourer moth. Forestry & British Timber, 15, 13.

Mackay, P.A. & Wellington, W.G. (1975) A comparison of the reproductive patterns of apterous and alate virginoparous Acyrthosiphon pisum (Homoptera: Aphididae). Canadian Entomologist, 107, 1161-166.

Mani, M.S. (1962) Introduction to High Altitude Entomology: Insect Life above the Timber-line in the Northwest Himalaya. Methuen, London.

Moore, R.G. & Hanks, L.M. (2004) Aerial dispersal and host plant selection by neonate Thyridopteryx ephemeraeformis (Lepidoptera: Psychidae). Ecological Entomology, 29, 327-335.

Rhainds, M., Leather, S.R. & Sadoff, C. (2008) Polyphagy, flightlessness and reproductive output of females: a case study with bagworms (Lepidoptera: Psychidae). Ecological Entomology, 33, 663-672.

Rhains, M., Davis, D.R. & Price, P.W.(2009) Bionomics of Bagworms (Lepidoptera: Psychidae). Annual Review of Entomology, 54, 209-226.

Roff, D.A. (1990) The evolution of flightlessness in insects. Ecological Monographs, 60, 389-422.

Stjernholm, F., Karlsson, B. & Boggs, C.A. (2005) Age-related changes in thoracic mass: possible reallocation of resources to reproduction in butterflies. Biological Journal of the Linnean Society, 86, 363-380.

Tan, J.Y., Wainhouse, D.W., Day, K.R. & Morgan, G. (2010) Flight ability and reproductive development in newly-emerged pine weevil Hylobius abietis and the potential effects of climate change. Agricultural and Forest Entomology, 12, 427-434.

Tikkanen, O.P., Carr, T.G. & Roininen, H. (1999) Factors influencing the distribution of a generalist spring-feeding moth, Operophtera brumata (Lepidoptera: Geometridae), on host plants. Environmental Entomology, 28, 461-469.

Wagner, D.L. & Liebherr, J.K. (1992) Flightlessness in insects. Trends in Evolution & Ecology, 7, 216-219.

Watt, A.D., Evans, R. & Varley, T. (1992) The egg-laying behaviour of a native insect, the winter moth Operophtera brumata (L.) (Lep., Geometridae), on an introduced tree species, Sitka spruce, Picea sitchensis. Journal of Applied Entomology, 114, 1-4.

Wint, W. (1983) The role of alternative host-plant species in the life of a polyphagous moth, Operophtera brumata (Lepidoptera, Geomtridae). Journal of Animal Ecology, 52, 439-450.

Wollaston, T.V. (1854) Insecta Maderensia, John van Voorst, London.

 

 

 

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Snouts, pugs, daggers and leaf eating wainscots – and all because of the sharks!

I joined Twitter seven years ago,  and I was, and continue to be amazed by how many people out there run moth traps*. One of the many side-effects of the Covid-19 crisis is an increase in the number of trappers; every day my Twitter feed is filled with pictures of their more notable specimens.  The other day in response to this deluge of moths, I remarked on the fact that the common names of moths range from the extremely prosaic, to completely lyrical flights of fancy. Take for example, the baldly descriptive Orange Underwing and the gloriously named Merveille du Jour.  To these I could add the beautiful, but literally named, Green Silver Lines and the bizarrely named Purple Thorn.

Orange Underwing and the Merveille de Jour.

Green Silver Lines and a Purple Thorn. I see no purple 🙂

Now, I have seen a mouse moth in action, so I totally get its name. On the other hand, while browsing Paul Waring and Martin Townsend’s excellent Field Guide (I was trying to identify a Yellow Shell I had come across in the garden), I noticed a mention to the sharks. Intrigued, I skipped down to the species notes to see why they were called sharks. The answer was simple; Paul and Martin say it is the way their wings are folded at rest to give the appearance of  a dorsal fin. Looking at the picture, I could live with that, and it also gave me an idea.

As loyal readers will know, I have a penchant for delving into insect names.  Who could forget my in-depth investigation into the naming of thrips or the mystery of the wheat dolphin? I figured that here was yet another subject for a blog. I had, however, been beaten to the punch!  Naturalist Extraordinaire, Peter Marren has written a whole book about the often, gnomic names of Lepidoptera :-). Having discovered it, I had, of course, to buy it. You will be glad to know, that even though it cost me the princely sum of £20, and although as a Yorkshireman, I toyed with the idea of getting a second hand copy, I don’t regret the purchase one iota.

Peter Marren (2019) Little Toller Books £20

It is a lovely little book. It is amusingly written, brimming with history and filled with factoids over which any entomologist setting a Pub Quiz will drool.  Take my word for it, well worth the investment.  My only complaint is that there aren’t enough colour plates, but that is only a minor quibble. I don’t want to stop you buying Peter’s book so I am only treating you to a few of the gems contained therein.

I’ll start with the more obvious ones. There is a group of moths within the Erebidae (they were Noctuids when I was student) known as the snouts.  When you look at them from above it is obvious why. They have long palps that protrude very noticeably, forming a very distinctive snout. Just to confuse you, some pyralid moths are also known as snout moths, but their snouts are feeble affairs.

Hypena proboscidalis – The Snout

In the Noctuidae proper, we have the one that started it all, the shark, Cucullia umbratica, so called because it is sleek, grey and from above has a pointed shark like nose and a dorsal fin.

Cucullia umbratica – the shark.  yes, it is quite shark-like, but also a bit like a bit of bark. Perhaps it should be called the wood chip 🙂

 

Also within the Noctuidae we find the wainscots, so named because their pale grainy wings resemble wood panelling.

Mythimna pallens –  common wainscot and would definitely be able to hide in a wood panelled study

The three examples above definitely fit their common names.  The next two I feel have been somewhat misnamed.

Yet another Noctuid, this time Acronicta psi, the Grey Dagger.  According to Peter Marren, the markings on the wings look like daggers.  Personally I don’t see them, but I do see something that resembles pairs of of scissors 🙂

Daggers – the grey dagger wing markings suggest daggers, but look more like scissors to me

And finally, a Geometrid, a pug.  Supposedly the resting posture is reminiscent of the head of a pug dog with its drooping jaws.

Pug anyone? I don’t see it myself – someone must have had an overactive imagination!

 

If you want to know about the brocades, shoulderknots, carpets, quakers, prominents, rustics, eggars, thorns, sallows, and all the others, you’re going to have have to buy his book

Reference

Waring, P. & Townsend, M. (2003) Field Guide to the Moths of Great Britain and Ireland. British Wildlife Publishing, Dorset, UK.

Acknowledgements

Thanks to the Butterfly Conservation Trust for allowing me to use the moth photographs.

*it always amuses me how many of them are vertebrate ecologists 🙂

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The Last Butterflies – book review

Book and cover both fantastic!

My review of Nick Haddad’s excellent book was published recently in Oryx.  If you want to read the review, follow this link.  If you don’t, then all you need to know is that my responses to the following questions were all very positive 🙂

  1. Would I buy it?
  2. Would I recommend a colleague to buy it?
  3. Would I recommend it to students as worth buying?
  4. Would I ask the library to buy it?
  5. Would I recommend it to anyone else?

Enjoy!

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Shocking News – the truth about electroperception – insects can ‘feel’ electric fields

Static electric fields are common throughout the environment and this has been known for some time (e.g Lund (1929) and back in 1918, the great Jean-Henri Fabre, writing about the dung beetle, Geotrupes stated “They seem to be influenced above all by the electric tension of the atmosphere. On hot and sultry evenings, when a storm is brewing, I see them moving about even more than usual. The morrow is always marked by violent claps of thunder

Given this, it is surprising that it was not until the 1960s that entomologists started to take a real interest in electroperception, when a Canadian entomologist decided to investigate the phenomenon further, but using flies (Edwards, 1960).  He found that if Drosophila melanogaster and Calliphora vicina exposed to, but not in contact with, an electrical field, they stopped moving. Calliphora vicina needed a stronger voltage to elicit a response than D. melanogaster, which perhaps could be related to their relative sizes. It seemed that their movement was reduced when electrical charge applied and changed, but not if the field was constant.

Responses of two fly species to electrical fields (From Edwards, 1960)

In a follow up experiment with the the Geometrid moth Nepytia phantasmaria he showed that females were less likely to lay eggs when exposed to electrical fields (Edwards, 1961), but the replication was very low and the conditions under which the experiment was run were not very realistic.

In the same year, Maw (1961) working on the Ichneumonid wasp, Itoplectis conquisitor, which is attracted to light, put ten females into a chamber with a light at one end but with parts of the floor charged at different levels.  The poor wasps were strongly attracted to the light but the electrical ‘barrier’ slowed them down; the stronger the charge, the greater the reluctance to enter the field.

On the other hand, some years later, working with the housefly, Musca domestica and the cabbage looper, Trichoplusia ni, across a range of different strength electrical fields, Perumpral et al., (1978)   found no consistent avoidance patterns in where the houseflies preferred to settle, but did find that wing beat frequency of male looper moths was significantly affected, although inconsistently.  Female moths on the other hand were not significantly affected.  This put paid to their intention to develop a non-chemical control method for these two pests.

A more promising results was obtained using the cockroach Periplaneta americana.  Christopher Jackson and colleagues at Southampton University showed that the cockroaches turned away, or were repulsed, when they encountered an electric field and if continuously exposed to one, walked more slowly, turned more often and covered less distance (Jackson et al., 2011).  As an aside, this is similar to the effects one of my PhD students found when she exposed carabid beetles exposed to sub-lethal applications of the insecticide dimethoate*.

Periplaneta americana definitely showing a reluctance to cross an electrical field (Jackson et al., 2011).

Other insect orders have also been shown to respond to electric fields.  Ants, in particular the fire ant, Solenopsis invicta, are apparently a well-known hazard to electrical fittings (MacKay et al., 1992), and a number of species have been found in telephone receivers (Eagleson, 1940), light fittings and switches (Little, 1984), and even televisions (Jolivet, 1986), causing short circuits and presumably, coming to untimely ends 🙂

Rosanna Wijenberg and colleagues at Simon Fraser University in Canada, really went to town and tested the responses of a variety of different insect pests to electric fields. They found that the common earwig, Forficula auricularia, two cockroaches, Blatta germanica, Supella longipalpa, two Thysanurans, the silverfish, Lepisma saccharina and the firebrat Thermobia domestica were attracted to, or at least arrested by electrified coils.  Periplaneta americana, on the other hand, was repulsed (Wijenberg et al., 2013).  They suggested that using electrified coils as non-toxic baits might be an environmentally friendly method of domestic pest control.  I have, however, not been able to find any commercial applications of this idea although perhaps you know better?

Although a number of marine vertebrates generate electricity and electric fields as well as perceiving and communicate using them, there was, until fairly recently, no evidence of electrocommunication within the insect world (Bullock, 1999); after all, they have pheromones 😊

When we look at the interaction between insects and electromagnetic fields there is growing evidence that bees, or at least honey bees, like some birds (Mouritsen et al., 2016) have the wherewithal and ability to navigate using magnetic fields (Lambinet et al., 2017ab).  Interestingly**, honeybees, Apis mellifera have been shown to generate their own electrical fields during their waggle dances which their conspecifics are able to detect (Greggers et al., 2013).  Bumble bees (Bombus terrestris), have also been shown to be able to detect electrical fields.  In this case, those surrounding individual plants.  The bees use the presence or absence of an electrical charge to ‘decide’ whether to visit flowers or not. If charged they are worth visiting, the charge being built up by visitation rates of other pollinating insects  (Clarke et al., 2013)

Since I’m on bees, I can’t leave this topic without mentioning mobile phones and electromagnetic radiation, although it really deserves an article of its own.  The almost ubiquitous presence of mobile phones has for a long time raised concern about the effect that their prolonged use and consequent exposure of their users to electromagnetic radiation in terms of cancer and other health issues (Simkó & Mattson, 2019). Although there is growing evidence that some forms of human cancer can be linked to their use (e.g. Mialon & Nesson, 2020), the overall picture is far from clear (Kim et al., 2016). Given the ways in which bees navigate and the concerns about honeybee populations it is not surprising that some people suggested that electromagnetic radiation as well as neonicitinoids might be responsible for the various ills affecting commercial bee hives (Sharma & Kumar, 2010, Favre, 2011). The evidence is far from convincing (Carreck, 2014) although a study from Greece looking at the intensity of electromagnetic radiation from mobile phone base stations on the abundance of pollinators found that the abundance of beetles, wasps and most hoverflies decreased with proximity to the base stations, but conversely, the abundance of bee-flies and underground nesting wild bees increased, while butterflies were unaffected (Lázaro et al., 2016). A more recent study has shown that exposure to mobile phones resulted in increased pupal mortality in honeybee queens but did not affect their mating success (Odemer & Odemer, 2019).  All in all, the general consensus is that although laboratory studies show that electromagnetic radiation can affect insect behaviour and reproduction the picture remains unclear and that there are few, if any field-based studies that provide reliable evidence one way or the other (Vanbergen et al., 2019).   Much more research is needed before we can truly quantify the likely impacts of electromagnetic radiation on pollinators and insects in general.

 

Acknowledgements

I must confess that I had never really thought about insect electroperception until I was at a conference and came across a poster on the subject by Matthew Wheelwright, then an MRes student at the University of Bristol, so it is only fair to dedicate this to him.

 

References

 

Bullock, T.H. (1999) The future of research on elctroreception and eclectrocommunicationJournal of Experimental Biology, 10, 1455-1458.

Carreck, N. (2014) Electromagnetic radiation and bees, again…, Bee World, 91, 101-102.

Clarke, D., Whitney, H., Sutton, G. & Robert, D. (2013) Detection and learning of floral electric fields by bumblebees. Science, 340, 66-69.

Eagleson, C. (1940) Fire ants causing damage to telephone equipment.  Journal of Economic  Entomology, 33, 700.

Edwards, D.K. (1960) Effects of artificially produced atmospheric electrical fields upon the activity of some adult Diptera.  Canadian Journal of Zoology, 38, 899-912.

Edwards, D.K. (1961) Influence of electrical field on pupation and oviposition in Nepytia phantasmaria Stykr. (Lepidoptera: Geometridae). Nature, 191, 976.

Fabre, J.H. (1918) The Sacred Beetle and Others. Dodd Mead & Co., New York.

Favre, D. (2011) Mobile phone induced honeybee worker piping. Apidologie, 42, 270-279.

Greggers, U., Koch, G., Schmidt, V., Durr, A., Floriou-Servou, A., Piepenbrock, D., Gopfert, M.C. & Menzel, R. (2013) Reception and learning of electric fields in bees. Proceedings of the Royal Society B, 280, 20130528.

Jackson, C.W., Hunt, E., Sjarkh, S. & Newland, P.L. (20111) Static electric fields modify the locomotory behaviour of cockroaches. Journal of Experimental Biology, 214, 2020-2026.

Jolivet, P. (1986) Les fourmis et la Television. L’Entomologiste, 42,321-323.

Kim, K.H., Kabir, E. & Jahan, S.A. (2016) The use of cell phone and insight into its potential human health impacts. Environmental Monitoring & Assessment, 188, 221.

Lambinet, V., Hayden, M.E., Reigel, C. & Gries, G. (2017a) Honeybees possess a polarity-sensitive magnetoreceptor. Journal of Comparative Physiology A, 203, 1029-1036.

Lambinet V, Hayden ME, Reigl K, Gomis S, Gries G. (2017b) Linking magnetite in the abdomen of honey bees to a magnetoreceptive function. Proceedings of the Royal Society, B., 284, 20162873.

Lazáro, A., Chroni, A., Tscheulin, T., Devalez, J., Matsoukas, C. & Petanidou, T. (2016) Electromagnetic radiation of mobile telecommunication antennas affects the abundance and composition of wild pollinators.  Journal of Insect Conservation, 20, 315-324.

Little, E.C. (1984) Ants in electric switches. New Zealand Entomologist, 8, 47.

Lund, E.J. (1929) Electrical polarity in the Douglas Fir. Publication of the Puget Sound Biological Station University of Washington, 7, 1-28.

MacKay, W.P., Majdi, S., Irving, J., Vinson, S.B. & Messer, C. (1992) Attraction of ants (Hymenoptera: Formicidae) to electric fields. Journal of the Kansas Entomological Society, 65, 39-43.

Maw, M.G. (1961) Behaviour of an insect on an electrically charged surface. Canadian Entomologist, 93, 391-393.

Mialon, H.M. & Nesson, E.T. (2020) The association between mobile phones and the risk of brain cancer mortality: a 25‐year cross‐country analysis. Contemporary Economic Policy, 38, 258-269.

Mouritsen, H., Heyers, D. & Güntürkün, O. (2016) The neural basis of long-distance navigation in birds. Annual Review of Physiology, 78, 33-154.

Odemer, R., & Odemer, F. (2019). Effects of radiofrequency electromagnetic radiation (RF-EMF) on honey bee queen development and mating success. Science of The Total Environment, 661, 553–562.

Perumpral, J.V., Earp, U.F. & Stanley, J.M. (1978) Effects of electrostatic field on locational preference of house flies and flight activities of cabbage loopers. Environmental Entomology, 7, 482-486.

Sharma, V.P. & Kumar, N.R. (2010) Changes in honeybee behaviour and biology under the influence of cellphone radiation. Current Science, 98, 1376-1378.

Simkó, M. & Mattson, M.O. (2019) 5G wireless communication and health effects—A pragmatic review based on available studies regarding 6 to 100 GHz. International Journal of Environmental Research & Public Health, 16, 3406.

Vanbergen, A.J., Potts, S.G., Vian, A., Malkemper, E.P., Young, J. & Tscheulin, T. (2019) Risk to pollinators from anthropogenic electro-magnetic radiation (EMR): Evidence and knowledge gaps. Science of the Total Environment, 695, 133833.

Wijenberg, R., Hayden, M.E., Takáca, S. & Gries, G. (2013) Behavioural responses of diverse insect groups to electric stimuli. Entomoloogia experimentalis et applicata, 147, 132-140.

 

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yet another entry for my data I am never going to publish series 😊

 

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My wife really hates it when I start a sentence like this, as she says “You’re always starting sentences like that and it is rarely interesting”

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Pick & Mix 41 – some links to entertain and inform

Which species do we save – so many to choose from and not enough money

The moths of Whittingehame – following in the footsteps of Alice Blanche Balfour

The science behind prejudice – do cultures grow more prejudiced when they tighten cultural norms in response to destabilizing ecological threats?

Did bird vaginas evolve to fight invading penises?

Procrastination in academia – most of us do it – here is a scientific exploration and analysis – be warned it is riddled with jargon

What goes on inside an aphid and why Nancy Moran does what she does

James Wong examines the evidence (or lack of) for an impending “agricultural Armageddon”

Here Patrick Barkham recommends some books about Nature and muses on how we as individuals can make a difference

Overlooked and underused crops – a possible solution to the food crisis?

Great pictures and story – all about swallowtail caterpillars and their defence mechanism – another tour de force from Charlie Eiseman

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Ten more papers that shook my world – complex plant architecture provides more niches for insects – Lawton & Schroeder (1977)

Some years ago I wrote about how one of my ecological heroes, Sir Richard Southwood (later Lord Southwood), influenced my research and stimulated what has become a lifelong interest of mine, island biogeography, in particular the iconic species-area relationship. Apropos of this it seems apposite to write about another huge influence on my research, Sir John Lawton.  I first encountered John*, as he was then, at the tender age of 17, when our Sixth Form Science class were bussed from Ripon Grammar School to York University to hear a very enthusiastic arm-waving young ecologist, yes John Lawton, talking about food webs. Excellent as it was, it wasn’t, however, this talk that inspired me :-), but a paper that he and Dieter Schroeder wrote a few years later (Lawton & Schroeder, 1977), in which they showed that structurally more diverse plants potentially hosted more insect species per unit range than those plants with less complex architecture.  A couple of years later Strong & Levin (1979) showed that this also applied to fungal parasites in the USA.  The mechanism behind the finding was hypothesised to be based on apparency – the bigger you are the easier you are to find, the bigger you are, the more niches you can provide to be colonised, pretty much the same reasoning used to explain geographic island biogeography and species-area accumulation curves (Simberloff & Wilson, 1969). John Lawton, Don Strong and Sir Richard Southwood also highlighted this in their wonderful little book (Strong et al, 1984) which has provided excellent material for my lectures over the years.

As someone who is writing a book, theirs is an excellent example of how you can improve on other people’s offerings.  Staying with the theme of plant architectural complexity, Strong et al (1984) brilliantly reported on Vic Moran’s masterly study on the relationship between Opuntia growth forms and the number of insects associated with them (Moran, 1980).  Vic’s study was an advance on the previous studies because he examined one family of plants, rather than across families, so reducing the variance seen in other studies caused by phylogenetic effects. I should also point out that this paper was also an inspiration to me.

The figure as shown in Victor Moran’s paper.

The revamped Moran as shown in Strong & Lawton (1984).

Okay, so how did this shake my world? As I have mentioned before, my PhD and first two post-docs were on the bird cherry-oat aphid, Rhopalosiphum padi, a host-alternating aphid that uses bird cherry, Prunus padus, as its primary host.  Never being one to stick to one thing, I inevitably got interested in bird cherry in general and as well as eventually writing a paper about it (Leather, 1996) (my only publication in Journal of Ecology), I also, in due course, set up a long term experiment on it, the outcome of which I have written about previously. But, I digress, the first world shaking outcome of reading Lawton & Schroeder, was published in Ecological Entomology (incidentally edited by John Lawton at the time), in which I analysed the relationships between the insects associated with UK Prunus species and their distribution and evolutionary history, and showed that bird cherry had a depauperate insect fauna compared with other Prunus species (Leather, 1985).

I’m not working with very many points, but you get the picture (from Leather, 1985). Bird cherry (and also Gean, the common wild cherry. Prunus avium) hosts fewer insect species than would be expected from its range and history.

This in turn led me on to an even more ambitious project.  Inspired by a comment in Kennedy & Southwood (1984) that a better resolution of the species-plant range relationship would result if the analysis was done on a taxonomically restricted group of plants and by the comment in Southwood (1961) that the Rosaceae were a very special plant family, I spent several months wading through insect host lists to compile a data set of the insects associated with all the British Rosaceae.  Once analysed I submitted the results as two linked papers to the Journal of Animal Ecology.  Having responded to Southwood’s demand that “this manuscript be flensed of its too corpulent flesh” it was eventually published (Leather, 1996).  My somewhat pompous introduction to the paper is shown below.

“This relationship is modified by the structure or complexity of the plant, i.e. trees support more insect species than shrubs, which in turn support more species than herbs (Lawton & Schroder 1977; Strong & Levin 1979; Lawton 1983).”

“Kennedy & Southwood (1984) postulated that if taxonomically restricted groups of insects and/or plants were considered, the importance of many of these variables would increase. Few families of plants cover a sufficiently wide range of different growth forms ranging from small herbs to trees in large enough numbers to give statistically meaningful results. The Rosaceae are a notable exception and Southwood (1961) commented on the extraordinary number of insects associated with Rosaceous trees. It would thus appear that the Rosaceae and their associated insect fauna provide an unparalleled opportunity to test many of the current hypotheses put forward in recent years concerning insect host-plant relationships.”

Cutting the long story short (I am much better at flensing nowadays), I found  that Rosaceous trees had longer species lists than Rosaceous shrubs, which in turn had longer lists than herbaceous Rosaceae.

Rather messy, but does show that the more architecturally complex the plant, the more insect species it can potentially host (from Leather, 1986).

Flushed by the success of my Prunus based paper, I started to collect data on Finnish Macrolepidoptera feeding on Prunus to compare and contrast with my UK data (I can’t actually remember why this seemed a good idea).  Even if I say so myself, the results were intriguing (to me at any rate, the fact that only 19 people have cited it, would seem to suggest that others found it less so), in that host plant utilisation by the same species of Macrolepidoptera was different between island Britain and continental Finland (Leather, 1991).

 

 

From Leather (1991) Classic species-area graph from both countries but some intriguing differences in feeding specialisation.

Despite the less than impressive citation index for the UK-Finland comparison paper (Leather, 1991), I would like to extend the analysis to the whole of Europe, or at least to those countries that have comprehensive published distributions of their Flora.  I offer this as a project to our Entomology MSc students, every year, but so far, no luck ☹

Although only four of my papers can be directly attributed to the Lawton & Schroeder paper, and taking into account that the insect species richness of Rosacea paper, is number 13 in my all-time citation list, I feel justified in counting it as one of the papers that shook my World.

References

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

Lawton, J.H. & Schroder, D. (1977) Effects of plant type, size of geographical range and taxonomic isolation on numbers of insect species associated with British plants. Nature, 265, 137-140.

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

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

Leather, S.R. (1991) Feeding specialisation and host distribution of British and Finnish Prunus feeding macrolepidoptera. Oikos, 60, 40-48.

Leather, S.R. (1996) Biological flora of the British Isles Prunus padus L. Journal of Ecology, 84, 125-132.

Moran, V.C. (1980) Interactions between phytophagous insects and their Opuntia hosts. Ecological Entomology, 5, 153-164.

Simberloff, D. & Wilson, E.O. (1969) Experimental zoogeography of islands: the colonization of empty islands. Ecology50, 278-296.

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

Strong, D.R. & Levin, D.A. (1979) Species richness of plant parasites and growth form of their hosts. American Naturalist, 114, 1-22.

Strong, D.R., Lawton, J.H. & Southwood, T.R.E. (1984) Insects on Plants – Community Patterns and Mechanisms. Blackwell Scientific Publication, Oxford.

 

 

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Twisted, hairy, scaly, gnawed and pure – side-tracked by Orders

I’m supposed to be writing a book, well actually two, but you have to be in the right mood to make real progress. Right now, I’m avoiding working on one of the three chapters that I haven’t even started yet* and I really should be on top of them by now as I have already spent the advance, and have less than a year to go to deliver the manuscript 😦 Instead of starting a new chapter I’m tweaking Chapter 1, which includes an overview of Insect Orders.  While doing that I was side tracked by etymology. After all, the word is quite similar to my favourite subject and a lot of people confuse the two. Anyway, after some fun time with my Dictionary of Entomology, (which is much more of an encyclopaedia than a dictionary), and of course Google, I have great pleasure in presenting my one stop shop for those of you who wonder how insect orders got their names.  Here they are, all in one easy to access place with a few fun-filled facts to leaven the mixture.

Wings, beautiful wings (very much not to scale)

First, a little bit of entomological jargon for those not totally au fait with it.  Broadly speaking we are talking bastardised Greek and Latin. I hated Latin at school but once I really got into entomology I realised just how useful it is.  I didn’t do Greek though 😊, which is a shame as Pteron is Greek for wing and this is the root of the Latin ptera, which features all over the place in entomology.

Since I am really only talking about insects and wings, I won’t mention things like the Diplura, Thysanura and other Apterygota.  They don’t have wings, the clue being in the name, which is derived from Greek; A = not, pterygota, derived from the Greek ptérugos = winged, which put together gives us unwinged or wingless. In Entojargon, when we talk about wingless insects we use the term apterous, or if working with aphids, aptera (singular) or apterae (plural).   I’m going to deal with winged insects, the Exopterygota and the Endopterygota. The Exopterygota are insects whose wings develop outside the body and there is a gradual change from immature to adult.  Think of an aphid for example (and why not?); when the nymph (more Entojargon for immature hemimetabolus insects) reaches the third of fourth instar (Entojargon for different moulted stages), they look like they have shoulder pads; these are the wing buds, and the process of going from egg to adult in this way is called incomplete metamorphosis.

Fourth instar alatiform nymph of the Delphiniobium junackianum the Monkshood aphid.  Picture from the fantastic Influential Points site https://influentialpoints.com/Images/Delphiniobium_junackianum_fourth_instar_alate_img_6833ew.jpg (Any excuse for an aphid pciture)

In the Endopterygota, those insects where the wings develop inside the body, e.g butterflies and moths, the adult bears no resemblance to the larva and the process is described as complete metamorphosis and the life cycle type as holometabolous. It is also important to note that the p in A-, Ecto- and Endopterygota is silent.

Now on to the Orders and their names.  A handy tip is to remember is that aptera means no wings and ptera means with wings.  This can be a bit confusing as most of the Orders all look and sound as if they have wings.  This is in part, due to our appalling pronunciation of words; we tend to make the syllables fit our normal speech patterns which doesn’t necessarily mean breaking the words up in their correct component parts. Diptera and Coleoptera are two good examples – we pronounce the former as Dip-tera and informally as Dips.  From a purist’s point of view, we should be pronouncing the word Di-tera – two wings, and similarly, Coleoptera as Coleo-tera, without the p 🙂 Anyway, enough of the grammar lessons and on with the insects.

Exopterygota

Ephemeroptera The Mayflies, lasting a day or winged for a day J The oldest extant group with wings. They are also a bit weird, as unlike other Exopterygota they have a winged sub-adult stage

Odonata              Dragonflies and Damselflies – think dentists, toothed, derived from the Greek for tooth, odoús. Despite their amazing flight capability, the name refers to their toothed mandibles.  The wings do get a mention when we get down to infraorders, the dragonflies, Anisoptera meaning uneven in that the fore and hind wings are a different shape and the damselflies, Zygoptera  meaning even or yoke, both sets of wings being pretty much identical.

Dermaptera       Earwigs, leathery/skin/hide, referring to the fore-wings which as well as being leathery are reduced in size.  Despite this, the much larger membranous hind wings are safely folded away underneath them.

A not very well drawn (by me) earwig wing 😊

Plecoptera          Stoneflies, wickerwork wings – can you see them in the main image?

Orthoptera         Grasshoppers and crickets, straight wings, referring to the sclerotised forewings that cover the membranous, sometimes brightly coloured hind wings.  Many people are surprised the first time they see a grasshopper flying as they have been taken in by the hopper part of the name and the common portrayal of grasshoppers in cartoons and children’s literature; or perhaps not read their bible “And the locusts went up over all the land of Egypt, and rested in all the coasts of Egypt”. I think also that many people don’t realise that locusts are grasshoppers per se.

Grasshopper wings

Dictyoptera        Cockroaches, termites and allies, net wings

Notoptera           The order to which the wingless Ice crawlers (Grylloblattodea) and Gladiators Mantophasmatodea) belong. Despite being wingless, Notoptera translates as back wings. It makes more sense when you realise that the name was coined when only extinct members of this order were known and they were winged.

Mantodea           Mantids, the praying mantis being the one we are all familiar with, hence the name which can be translated as prophet or soothsayer

Phasmotodea    Phasmids, the stick insects and leaf insects – phantom, presumably referring to their ability to blend into the background.

Psocoptera         Bark lice and book lice, gnawed or biting with wings. In this case the adjective is not in reference to the appearance of the wings, but that they are winged insects that can bite and that includes humans, although in my experience, not very painful, just a little itchy. They are also able to take up water directly from the atmosphere which means that they can exploit extremely dry environments.

Embioptera        Web spinners, lively wings. Did you know that Janice Edgerly-Rooks at Santa Clara University has collaborated with musicians to produce a music video of Embiopteran silk spinning? https://www.youtube.com/watch?v=veehbMKjMgw

Zoraptera            Now this is the opposite of the Notoptera, the Angel insects, Zora meaning pure in the sense of not having any wings.  Unfortunately for the taxonomists who named this order, winged forms have now been found 🙂

Thysanoptera    Thrips and yes that is both the plural and singular, thysan meaning tassel wings, although I always think that feather would be a much more appropriate description.

Feathery thrips wing – Photo courtesy of Tom Pope @Ipm_Tom

Hemiptera          True bugs – half wings.  The two former official suborders were very useful descriptions, Homoptera, e.g. aphids, the same. Heteroptera such as Lygaeids, e.g. Chinch bugs, which are often misidentified by non-entomologists as beetles where the prefix Hetero means different, referring to the fact that the fore wings are hardened and often brightly coloured in comparison with the membranous hind wings.

Coreid bug – Gonecerus acuteangulatus – Photo Tristan Banstock https://www.britishbugs.org.uk/heteroptera/Coreidae/gonocerus_acuteangulatus.html

Phthiraptera      The lice, the name translates as wingless louse. I guess as one of the common names for aphids is plant lice they felt the need to make the distinction in the name.

Siphonaptera     Fleas – tube without wings, referring to their mouthparts

 

Endopterygota

Rhapidioptera   Snakeflies – needle with wings, in this case referring to the ovipositor, not to the wings, which are similar to those of dragonflies.

The pointy end of a female snakefly

Megaloptera      Alderflies, Dobsonflies – large wings

Neuroptera        Lacewings – veined wings

Coleoptera         Beetles – sheathed wings, referring to the hardened forewings, elytra, that cover the membranous hind wings. The complex process of unfolding and refolding their hind wings means that many beetles are ‘reluctant’ to fly unless they really need to.

Strepsiptera       These are sometimes referred to as Stylops.  They are endoparasites of other insects. The name translates as twisted wings. Like flies, they have only two pairs of functional wings the other pair being modified into halteres.  Unlike flies, their halteres are modified fore wings.  Their other claim to fame is that they feature on the logo of the Royal Entomological Society.

The Royal Entomological Society Strepsipteran

Mecoptera         Scorpionflies, hanging flies – long wings.  Again, not all Mecoptera are winged, but those that are, do indeed have long wings in relation to their body size.

Male Scorpionfly, Panorpa communis.  Photo David Nicholls https://www.naturespot.org.uk/species/scorpion-fly

Siphonaptera     Fleas – tube no wings. The tube part of the name refers to their mouthparts.

Diptera                 Flies, two wings, the hind pair are reduced to form the halteres, which are a highly complex orientation and balancing device.

Trichoptera         Caddisflies, which are, evolutionarily speaking, very closely related to the Lepidoptera.  Instead of scales, however, their wings are densely cover with small hairs, hence the name hairy wings.  Some species can, at first glance, be mistaken for small moths. If you want to know more about caddisflies I have written about them here.

Lepidoptera       Moths and butterflies, scaly wings; you all know what happens if you pick a moth or butterfly up by its wings.

Moth wing with displaced scales

 

Hymenoptera    Wasps, bees, ants – membrane wings

Wing of a wood wasp, Sirex noctilio

 

And there you have it, all 30 extant insect orders in one easy location.

 

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Ten more papers that shook my world – Plant growth formulae for entomologists – Radford (1967) and Wyatt & White (1977)

Plant growth formulae for entomologists, what a great title for a paper or even a book J These two papers, separated by a decade had a great influence on my PhD and subsequent entomological career, or at least the lab based part of it. I started my PhD at the University of East Anglia on October 2nd 1977, where I was lucky enough to be supervised by that doyen of the aphid world, Professor Tony Dixon.  I was, and still am, convinced that the sooner you get started on practical work the better and that is what I tell my students.  Yes, reading is important but getting to know your organism early on, is just as, if not more, important. You can catch up on your in-depth reading later, but that early ‘hands on’ experience, even if what you first do is not publishable, is invaluable.  I see from my lab notebooks that my first experiments* were examining the effects of host plant on the fecundity and longevity of my study aphid, Rhopalosiphum padi.

My first experiment as a PhD student!

It was doing these very simple experiments, collecting development, survival and reproductive data that introduced me to the idea of measuring life history parameters in the round,

One of my first data sheets – not used in my thesis but gave me invaluable experience for later on.

rather than as single factors, akin to how ecologists move from measuring species diversity as a simple species count to using diversity indices that combine other attributes and describe the community more holistically. So it was with me and growth and reproductive rates. I wanted to be able to infer what my laboratory results might mean in the field and to develop faster methods of screening for host plant effects.  I came across, or was pointed in the direction of, two papers that had great influence on my research, Radford (1967)** about measuring growth rates, albeit of plants, and Wyatt & White (1977) on how to measure intrinsic rates of increase rm without having to go through the very laborious and time-consuming methods devised by Birch (1948); working on aphids makes you do things in a hurry 😊

Ian Wyatt and his colleague Peter White did a series of painstaking laboratory experiments to obtain reproductive figures for aphids and mites and came up with a simplified version of the Birch equation such that

rm = 0.738(lnMd)/d

 where Md = the number of offspring produced over a period of time equal to the pre-reproductive period D and 0.738 is a constant (Wyatt & Wyatt, 1977)

The Radford paper, reinforced by reading a paper by another great aphidologist, Helmut van Emden, Professor of Horticulture at the University of Reading (van Emden, 1969) convinced me that Mean Relative Growth Rate (MRGR) was the way to go to obtain comparative measures of host plant suitability for my aphids.  To save you looking it up, MRGR is calculated as follows:

The beauty of this, especially if you are working with very small animals such as aphids, is that you don’t need to weigh them at birth, you can if you want, just measure weights between two time periods.

Screening plants for resistance to aphids is an integral part of developing sustainable and environmentally friendly ways of protecting your crops.  At the time I started my PhD several methods were in use, ranging from measuring direct fecundity and developmental time (Dean, 1974), to short cuts such as counting the number of mature embryos at adult moult (Dewar, 1977) and of course Mean Relative Growth Rate (van Emden, 1969).  Although I tended to measure life-time fecundity and longevity for almost all my experiments, having the short cut of MRGR and in many cases the fecundity achieved in the first seven days of reproduction*** (e.g. Leather & Dixon, 1981) were useful tools to have.  What was the world shaking discovery for me, and something that in retrospect, I find surprising that no one else cottoned on to, was that MRGR was highly correlated with fecundity and that this meant that MRGR was correlated with the intrinsic rate of increase (Leather & Dixon, 1984).  This means that you can screen host plants and predict population trajectories with experimental observations that take less than half the time using the traditional measurements.  That paper proved very popular and is Number 7 in my citation list, with, at the time of writing, 80 citations.   A few years later, when I had moved on to working with other insect orders, I found that the relationship between MRGR and rm applied to Lepidoptera and that different insect orders followed the same rules (Leather, 1994).

Lepidoptera and aphids, singing from the same data sheets (Leather, 1994).

So truly, a paper that shook my world.

References

Birch, L.C. (1948) The intrinsic rate of natural increase of an insect population.  Journal of Animal Ecology, 48, 15-26.

Dean, G.J.W. (1974) Effect of temperature on the cereal aphids, Metopolphium dirhodum (Wlk.), Rhoaplosiphum padi (L.) and Macrosiphum avenae (F.) (Hem., Aphididae).  Bulletin of Entomological Research, 63, 401-409.

Dewar, A.M. (1977) Assessment of methods for testing varietal resistance to aphids in cereals.  Annals of Applied Biology, 87, 183-190.

Fisher, R.A. (1921) Some remarks on the methods formulated in a recent article on ‘The quantitative analysis of plant growth’. Annals of Applied Biology, 7, 367-372.

Leather, S.R. & Dixon, A.F.G. (1981) The effect of cereal growth stage and feeding site on the reproductive activity of the bird cherry-oat aphid, Rhopalosihum padiAnnals of Applied Biology, 97, 135-141.

Leather, S.R. & Dixon, A.F.G. (1984) Aphid growth and reproductive rates. Entomologia experimentalis et applicata, 35, 137-140.  80 cites number 7 in my list

Leather, S.R. (1994) Insect growth and reproductive rates. In Individuals, Populations and Patterns in Ecology (ed. by S.R. Leather, A.D. Watt, N.J. Mills & K.F.A. Walters), pp. 35-43. Intercept, Andover.

Radford, P.J. (1967) Growth analysis formulae – their use and abuse. Crop Science, 7, 171-175.

van Emden, H.F. (1969) Plant resistance to Myzus persicae induced by a plant regulator and measured by aphid relative growth rate. Entomologia experimentalis et applicata, 12, 125-131.

Wyatt, I. J. & White, P. F. (1977) Simple estimation of intrinsic increase rates for aphids and tetranychid mites. Journal of Applied Ecology 14, 757-766.

 

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and boy was I quick off the mark.  I started my PhD on October 2nd and here I am 24 days later with cereal plants at GS 12 ready to receive aphids J

**

it is only fair to point out that Radford owed his inspiration to the work of that great statistician, Ronald Fisher (Fisher, 1921)

***

aphids like many insects produce over half their progeny in the first week or so

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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

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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.

 

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