Category Archives: EntoNotes

Large, complex, beautiful and multi-chambered – Robin’s pincushion, rose bedeguar gall, mossy rose gall

As I wrote a little while ago, thanks to the Covid-19 lockdown I have been roaming the countryside around my rural retreat a lot more than I normally do. One of the things that I have noticed is that there seem to be a lot more of the spectacular galls caused by the gall wasp, Diplolepis rosae, than I can remember seeing in previous years. I have absolutely no empirical evidence for this observation, so it could all be down to shifting baselines (Jones et al., 2020). Nevertheless, to me they have been much more noticeable this year, perhaps confounding the insect apocalypse narrative (Leather, 2018), but then again, perhaps not.

I am, when it comes to galls, more of an expert on those caused by aphids, than on those induced by Hymenoptera, although, as it happens I am a co-author on an oak gall wasp paper (Walker et al., 2002).  Of course, that does not make me an expert. One the rose bushes in our front garden always has at least one of Robin’s spectacular pincushions clamouring for attention.  The others rarely have one and I have idly wondered about the host preferences of the wasp and the suitability of different roses for the development of the larvae.

Our front garden Diplolepis rosae gall

Having noticed that despite the relative abundance of the galls in the hedgerow roses, some bushes were totally gall-free while others supported several, sometimes in close proximity to each other, my thoughts immediately turned to possible student project.

Multiple infestations of Diplolepis rosae on hedgerow roses in the environs of Sutton, Staffordshire

A preliminary bit of research with the aid of Google Scholar quickly disabused me of that idea, but, as is the way with the internet, soon had me delving deep into the past in search of the history of this fascinating manifestation of insect activity.

My first discovery was that is also known as the rose bedeguar gall, something that had, until now, totally passed me by. According to my favourite dictionary (Gordh & Headrich, 2001),

“Bedeguar, Bedegar or Bedequar’ comes from a French word, bédégar, and is ultimately from the Persian, bād-āwar, meaning ‘wind-brought’”.

I’m guessing this meant that the first people to see them had no idea what caused them.

Not just complex galls

My next discovery was that D. rosae and the parasitoids that share its gall is a fairly well studied system (Randolph, 2005; Urban, 2018), although I am sure that it would still be possible to come up with some sort of project.  Diploelpis rosae is a member of the order Hymenoptera, so related to the larger and much more obvious bees, wasps and ants. It belongs to a family of wasps, the Cynipidae, commonly known as gall wasps.  Considering how small they are, 3.8 mm (Urban, 2018), the galls they make are spectacularly huge as are those that their relatives on oak form. Interestingly* more than 80% of gall wasps are associated with oaks, with most of the rest forming galls on members of the rose family (Shorthouse, 1973).  That in itself is, at least to me, an interesting fact; why such a restricted host range?  It is univoltine (one generation a year), overwinters as mature larva or pre-pupa in the galls, and emerges as adults in the spring when it seeks out suitable egg-laying sites. It is mainly parthenogenetic, although males are occasionally found (Callan, 1940; Stille, 1984). Despite being tiny, each wasp has the potential to lay about 500 eggs (Stille & Dävring, 1980). The adults are not very adventurous, usually laying eggs in the developing buds or flowers of the bush they emerged on, or on another close by (Bronner, 1985: Urban, 2018). That said, there must be some sort of host preference and selection going on, as in Sweden and the Czech Republic most galls are found on Rosa canina (Stille, 1984; Urban 2018). They also seem to favour younger bushes, or those that produce long vigorous stems (Stille, 1984).  The potentially high fecundity is presumably an adaptation to the high rates of parasitism that the larvae of D. rosae can experience, up to 70% in some cases (Stille, 1984).  In fact, so varied and numerous are the parasites, that many of the early papers about D. rosae pay more attention to the other inhabitants of the galls than they do the architects (Osten Sacken, 1870; Blair, 1945; Bugbee, 1951).  Females that lay a lot of eggs in the same developing bud produce bigger galls and a greater proportion of the larvae survive (Stille, 1984).

Survival of D. rosae in relation to gall weight (after Stille, 1984)

 It also appears that the closer to the ground the galls are, the lower the parasitism rate (Laszló, 2001).

The ideal strategy would then be for female D. rosae to lay big galls as low down on the plants as possible, but from personal observation this is not always the case , so as is often the case with the “Mother knows best” hypothesis there is something we humans are missing that the insects aren’t (Awmack & Leather, 2002).

Those darned taxonomists!

So, as so much is already known about this tiny wasp and its spectacular gall, I thought I would do a little bit of entomological archaeology and trace the entomological history of this little insect. Now I think taxonomists are wonderful people and have a huge respect for the very often unacknowledged work that they do, and am a great supporter of the campaign to make sure that people cite them in their papers (Packer et al., 2018), but they are a contentious bunch :-).  I mention this because inputting Diplolepis rosae into Google Scholar didn’t get me very far back in time, 1951 to be precise (Bugbee, 1951).  This paper justifies my good-natured jibe at the argumentative nature of taxonomists as he explains his renaming of what was then Rhodites rosae, by citing a 1917 paper (Rohwer & Fagan, 1917) who argued that the French entomologist Étienne Geoffroy (1725-1810) who raised the Genus Diplolepis in 1762, should take precedence over Theodor Hartig’s (1805-1880) 1840 Genus Rhodites. This pointed me back to the 1940s and the discovery that the mossy rose gall was then known as Rhodites rosae and I quote “I have recently published an epitome of  my own experience e in rearing from galls of R. rosae” (Blair, 1945). A bit more delving and I found that in France in the 1930s and in the USA in the 1920s, it was still known as R. rosae (Weld, 1926; da Silva  Tavares, 1930). Wending my back via citations I arrived in 1903 to find it listed as Cynips rosae (Ashmead, 1903).

Historical insights – Monsieur Wirey was ahead of his time

Armed with this knowledge, my journey back into the history of D. roase was much simplified and introduced me to a gem of a book, Insect Architecture by James Rennie  (1787-1867) (Rennie, 1851). Here I found an interesting account of galls in general but a detailed exposition of the Bedeguar gall of rose as he described it, including this rather nice drawing.

Professor Rennie presents some hypotheses on the formation of insect galls in general;

Many of the processes which we have detailed bear some resemblance to our own operations of building with materials cemented together; but we shall now turn our attention to a class of insect-architects, and who cannot, so far as we know, be matched in prospective skill by any of the higher orders of animals. We refer to the numerous family which have received the name of gall-flies,

  1. Wirey says, the gall tubercle is produced by irritation, in the same way as an inflamed tumor in an animal body, by the swelling of the cellular tissue and the flow of liquid matter, which changes the organization, and alters the natural external form. This seems to be the received doctrine at present in France. “

As you can see from the above he has little time for the French explanation (typical English exceptionalism) and puts forward his own idea that the galls are formed because the egg laying process blocks the vessels of the plant and the fluid that would normally flow unimpeded blows up the tissue surrounding the egg like a balloon.  Of course he was wrong and M. Wirey was correct :-).  Considering that he had no access to the sophisticated techniques we have he pretty much hit the nail on the head.

That aside, his book introduced me to an entomologist I had never heard of, Priscilla Wakefield (1751-1832), yet another overlooked and forgotten female scientist.

Possible projects?

Although my plans for lots of great MSc projects were reduced somewhat I have had a lot of educational fun and I think that there are still some things that could usefully be looked at, long term recording across multiple sites which I hope the British Plant Gall Society is doing would be interesting.  On my walks I noticed a lot of variability in size and phenology of gall formation.  At the end of August I was coming across small very fresh looking galls at the same time as I was seeing larger more advanced galls.

A very fresh looking Bedeguar gall, August 26th 2020, Sutton

As far as I can tell, the timing of gall formation and its effect on final size of the galls has not been looked at in detail; do early galls enter winter larger than later formed galls, or is it entirely due to the number of eggs laid?  Given the huge number of other inhabitants of the galls, at least fourteen different species (Laszló, 2001, there is probably a viable project in looking at the timing of invasion by the different gall parasites and the outcome this may or may not have on the final composition of the gall fauna.

Feel free to suggest additional projects in the comments.

References

Ashmead, W.H. (1903) Classification of the gall-wasps and the parasitic cynipoids, or the superfamily Cynipoidea. IV, Psyche, 10, 210-216.

Awmack, C.S. & Leather, S.R. (2002) Host plant quality and fecundity in herbivorous insects. Annual Review of Entomology, 47, 817-844.

Blair, K.G. (1945) Notes on the economy of the rose‐galls formed by Rhodites (Hymenoptera, Cynipidae). Proceedings of the Royal Entomological Society, Series A, 20, 26-31.

Bronner, R. (1985) Anatomy of the ovipositor and oviposition behavior of the gall wasp Diplolepis rosae (Hymenoptera: Cynipidae). Canadian Entomologist, 117, 849-858.

Bugbee, R. E. (1951). New and described parasites of the genus Eurytoma illiger from rose galls caused by species of the cynipid genus Diplolepis Geoffrey Hymenoptera: Eurytomidae). Annals of the Entomological Society of America, 44, 213–261

Callan, E.Mc. (1940) On the occurrence of males of Rhodites rosae (l.) (Hymenoptera, Cynipidae). Proceedings of the Royal Entomological Society of London, Series A., 15, 21-26.

Da Silva Tavares, J. (1930) Quelques Cécidies du Centre de la France, Publications de la Société Linnéenne de Lyon75, 145-167.

Gordh, G & Headrick, D.H. (2001) A Dictionary of Entomology, CABI, Wallingford

Jones, L.P., Turvey, S.T.,  Massimino, D. & Papworth, S. K.(2020) Investigating the implications of shifting baseline syndrome on conservation. People & Nature,

Laszló, Z. (2001) The parasitic complex of Diplolepis rosae (LinnaeuS, 1758) (Hymenoptera, Cynipidae): influencing factors and interspecific relationships. Entomologica Romanica, 6, 133–140.

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

Osten Sacken, R. (1870) Contributions to the natural hstory of the Cynipidæ of the United State and their galls.  Transactions of the American Entomological Society, 3, 54-64.

Packer, L., Monckton, S.K., Onuferko, T.M. & Ferrari, R.R. (2018) Validating taxonomic identifications in entomological research. Insect Conservation & Diversity, 11, 1-12.

Randolph, S. (2005) The Natural History of the Rose Bedeguar Gall and its Insect Community, The British Plant Gall Society.

Rennie, J. (1857) Insect Architecture. John Murray, London.

Rohwer, S. A. & Fagan, M. M. (1917) The type-species of the genera of the Cynipidea, or the gall wasps and parasitic cynipoids. Proceedings of the U.S. National Museum, 53, 357-380.

Shorthouse, J.D. (1973) The insect community associated with rose galls of Diplolepis polita (Cynipidae, Hymenoptera). Quaestiones Entomologicae, 9, 55-98.

Stille, B. (1984) The effect of hosptlant and parasitoids on the reproductive success of the parthenogenetic gall wasp Diplolepis rosae (Hymenoptera, Cynipidae). Oecologia, 63, 364-369.

Stille, B. & Dävring, L. (1980) Meiosis and reproductive strategy in the parthenogenetic gall wasp Diplolepis rosae (L.) (Hymenoptera, Cynipidae), Heriditas, 92, 353-362.

Urban, J. (2018). Diplolepis rosae (L.) Hymenoptera: Cynipidae): development, ecology and galls in the Brno region. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 66, 905-925.

Wakefield, P. (1816) An Introduction to the Natural History and Classification of Insects in a series of Familiar Letters with Illustrative Engravings. Darton, Harvey & Darton, London.

Walker, P., Leather, S.R. & Crawley, M.J. (2002) Differential rates of invasion in three related alien oak gall wasps (Cynipidae: Hymenoptera). Diversity & Distributions, 8, 335-349.

Weld, L. H. (1926) Field notes on gall-inhabiting cynipid wasps with descriptions of new species. Proceedings of the United States National Museum, 68, 1-131.

https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-3032.1940.tb00573.x

https://www.britishplantgallsociety.org/bedeguar-keys.pdf

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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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An unintended consequence – Maris Huntsman: A great choice for entomological careers but not so good for farmers

I could have used Sod’s Law or Murphy’s Law as the lead in for this article, but as you will see (if you keep on reading), this story isn’t all doom and gloom 😊. During the 1960s, cereal growers in the UK and on mainland Europe, were subjected to onslaughts on two fronts, yellow rust* ((Puccinia striiformis) (Doling & Doodson, 1968) and cereal aphids (Fletcher & Bardner, 1969; Kolbe, 1969).  Although cereal aphids had been a sporadic problem in Europe for several decades previously (Kolbe, 1969,1973; Rautapää, 1976) and even earlier than that (e.g. Marsham, 1798), 1968 was an exceptional year for them (Fletcher & Bardner, 1969; Kolbe, 1969).  Presaging  Richard Root’s seminal work on crop apparency and pest occurrence, the Dutch agronomist Willem Feekes predicted that changes in agricultural practice, in particular cereal production, would lead to increased pest and disease problems (Feekes, 1967). This was further emphasised by Wilhelm Kolbe of Bayer, who suggested that the big increase in cereal production in Europe between 1950 and 1970 and the switch from oats to wheat was the cause of the cereal aphid problem (Kolbe, 1973).   Similarly, in the UK, where oats were 51% of the cereal crop in 1930, they had fallen to 11% by 1965 (Marks & Britton, 1989).

Cereal production UK

The shift in cereal crops may indeed have been a contributory factor, but I think, certainly in the UK, that we can add another factor to the equation. Over at Maris Lane**, where the Plant Breeding Institute was based at Trumpington, Cambridge, a new variety of wheat, Maris Huntsman, with good resistance to both powdery mildew and yellow rust (Ruckenbauer, 1975) had been developed and introduced as a recommended variety to farmers in 1972 (Hughes & Bodden, 1978).  By 1977 it accounted for almost 40% of the wheat sold in the UK (Hughes & Bodden, 1978), although a mere two years later, it had fallen to just over 20% (Johnson, 1992).  Based at Trumpington, entomologist Henry Lowe, had, since the late1960s been investigating the resistance of crop plants to aphids, first beans (e.g. Lowe, 1968) was at the time, investigating the resistance of varieties of wheat to aphids (Lowe, 1978, 1980). He found, as one might expect that not all cereal species and varieties were equally susceptible to aphids, and if given a free choice, the grain aphid Sitobion avenae, showed a preference for Maris Huntsman.

So what does this have to do with launching the careers of a couple of dozen entomologists? Well, back in the late 1960s Tony Dixon, then based in Glasgow, got interested in the bird cherry-oat aphid, Rhopalosiphum padi  (Dixon, 1971; Dixon & Glen, 1971), a minor pest of cereals in the UK, mainly because of its great ability to transmit Barley Yellow Dwarf Virus (Watson & Mulligan, 1960. In those countries, such as Finland and Sweden, where spring sown cereals are the norm, it is a pest in its own right, able to cause yield reduction without the help of a virus (Leather et al., 1989). Tony moved to the University of East Anglia as Professor of Ecology in 1975 and started his new career there by appointing six new PhD students. Three of these were looking at aspects of cereal aphid ecology, Allan Watt researching the biology of S. avenae and Metoplophium dirhodum, Ian McLean looking at the predators and Nick Carter modelling their populations in order to develop a forecasting system.  Research groups at Imperial College and at the University of Southampton also began to work on the problem.  Fortuitously although cereal aphid numbers had fallen since the  

Numbers of Sitobion avenae caught in the Brooms Barn suction trap (data from Watson & Carter, 1983)

populations picked up in 1974 and then rose to outbreak levels again in 1976, just as the new PhD students started their field work. I joined the group in 1977 to work on R. padi, followed in subsequent years by Keith Walters (now a colleague at Harper Adams University), John Chroston, Sarah Gardner, Nigel Thornback, Ali Fraser, Shirley Watson, Trevor Acreman, Dave Dent, and after I left for pastures new, Alvin Helden (now Head of School at Anglia Ruskin University). Similar numbers of students were appointed at Southampton, including Nick Sotherton, now Director of Research at the Game and Wildlife Conservation Trust.  There were also groups started at Imperial College and the University of Reading. There was a certain element of rivalry between the groups, Steve Wratten for example, was an ex-student of Tony’s and there was a certain degree of animosity between Roy Taylor (of Taylor’s Power Law fame) at Rothamsted and Tony Dixon, we had mini-conferences to exchange findings and generally got on well.  Allan Watt for example went to work for Steve Wratten as a post-doc before moving up to Scotland to work on the pine beauty moth alongside me.  It was a great time to be working on aphids and I think we all benefitted from the experience and I for one, am very grateful to the plant breeders for developing a  variety of wheat, that although resistant to rust and powdery mildew, is very attractive to the grain aphid 🙂

Having fun in a Norfolk cereal field; me, Allan Watt and Ian McLean (Nick Carter had the good sense to stand behind the camera).

You may be wondering why I penned this reminiscence. Well, last year, my colleague Tom Pope and I were discussing cereal aphids at coffee time (as you do), and I mentioned how Maris Huntsman had launched my career.  It just so happened that Tom had access to old, ancient and modern varieties of cereals to hand and a final year project student keen on aphids so it doesn’t take a genius to guess what happened next 🙂

Host preferences of Sitobion avenae (Dan Hawes & Tom Pope). Can you guess which is Maris Huntsman?

So, Maris Huntsman, a great choice for attracting aphids and producing entomologists 🙂 and of course a great big vote of thanks to the PBI

 

References

Dean, G.J.W. & Luuring, B.B. (1970) Distribution of aphids on cereal crops. Annals of Applied Biology, 66, 485-496.

Dixon, A.F.G. (1971) The life cycle and host preferences of the bird cherry-oat aphid, Rhopalosiphum padi (L) and its bearing on the theory of host alternation in aphids. Annals of Applied Biology, 68, 135-147.

Dixon, A.F.G. & Glen, D.M. (1971) Morph determination in the bird cherry-oat aphid, Rhopalosiphum padi (L). Annals of Applied Biology, 68, 11-21.

Doling, D.A. & Doodson, J.K. (1968) The effect of yellow rust on the yield of spring and winter wheat. Transactions of the British Mycological Society, 51, 427-434.

Feekes, W. (1967) Phytopathological consequences of changing agricultural methods. II Cereals. Netherlands Journal of Plant Pathology, 73 Supplement 1, 97-115.

Fletcher, K.E. & Bardner, R. (1969) Cereal aphids on wheat. Report of the Rothamsted Experimental Station 1968, 200-201.

Hughes, W. G., & Bodden, J. J. (1978). An assessment of the production and performance of F1 hybrid wheats based on Triticum timopheevi cytoplasm. Theoretical and Applied Genetics, 53, 219–228.

Janson, H.W. (1959) Aphids on cereals and grasses in 1957. Plant Pathology, 8, 29.

Johnson R. (1992) Past, present and future opportunities in breeding for disease resistance, with examples from wheat. [In] Johnson R., Jellis G.J. (eds) Breeding for Disease Resistance. Developments in Plant Pathology, vol 1. Springer, Dordrecht

Kolbe, W. (1969) Studies on the occurrence of different aphid species as the cause of cereal yield and quality. Pflanzenschutz Nachrichten Bayer, 22, 171-204.

Kolbe, W. (1973) Studies on the occurrence of cereal aphids and the effect of feedingdamage on yields in relation. Pflanzenschutz Nachrichten Bayer, 26, 396-410.

Latteur, G. (1971) Evolution des populations aphidiennes sur froments d’hiver.  Mededelingen van de Faculteit Landbouwwetenschappen, Rijksuniversiteit Gent, 36, 928-939.

Leather, S.R., Walters, K.F.A., & Dixon, A.F.G. (1989) Factors determining the pest status of the bird cherry-oat aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae), in Europe: a study and review. Bulletin of Entomological Research, 79, 345-360.

Leather, S.R., Carter, N., Walters, K.F.A., Chroston, J.R., Thornback, N., Gardner, S.M., & Watson, S.J. (1984) Epidemiology of cereal aphids on winter wheat in Norfolk, 1979-1981. Journal of Applied Ecology, 21, 103-114.

Lowe, HJ.J.B. (1967) Interspecific differences in the biology of aphids (Homoptera: Aphididae) on leaves of Vicia faba I. Feeding behaviour. Entomologia experimentalis et applicata, 10, 347-357.

Lowe, H.J.B. (1974) Effects of Metopolophium dirhodum on Spring wheat in the glasshouse.  Plant Pathology, 23, 136-140.

Lowe, H.J.B. (1978) Detection of resistance to aphids in cereals.  Annals of Applied Biology, 88, 401-406.

Lowe, H.J.B. (1980) Resistance to aphids in immature wheat and barley. Annals of Applied Biology, 95, 129-135.

Macer, R.C.F. (1972) The resistance of cereals to yellow rust and its exploitation by plant breeding.  Proceedings of the Royal Society London B., 181, 281-301.

Marks, H.F. & Britton, D.K. (1989)  A Hundred  Years of British Food and Farming: A Statistical Survey. Taylor & Francis.

Marsham, T. (1798) Further observations on the wheat insect, in a letter to the Rev. Samuel Goodenough, L.L.D. F.R.S. Tr.L.S. Transactions of the Linnaean Society London, 4, 224-229.

Rautapää, J. (1976) Population dynamics of cereal aphids and method of predicting population trends. Annales Agriculturae Fenniae, 15, 272-293.

Rogerson, J.P. (1947) The oat-bird cherry aphis Rhopalosiphum padi (L.) and comparison with R. crataegellum Theo. Bulletin of Entomological Research, 38, 157-176.

Ruckenbauer, P.  (19 75) Photosynthetic and translocation pattern in contrasting winter wheat varieties. Annals of Applied Biology, 79, 351-359.

Watosn, M.A. & Mulligan, T. (1960) The manner of transmission of some Barley Yellow‐Dwarf Viruses by different aphid species. Annals of Applied Biology, 48, 711-720.

Watson, S.J. & Carter, N. (1983) Weather and modelling cereal aphid populations in Norfolk (UK). EPPO Bulletin, 13, 223-227.

Zayed, Y. & Loft, P. (2019) Agriculture: Historical Statistics. House of Commons Briefing paper 3339

 

*Yellow rust is still a  still a major problem for cereal growers worldwide

**an address that is immortalised in the names of several cultivars of crops developed by the PBI

 

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The Devil’s Darning Needle – Dragonfly names at home and abroad

Guess what?  I’m procrastinating yet again. 🙂 I’m supposed to be finishing off the aquatic insects chapter of my book, but despite being confined to the house because of Covid-19, I’m finding it difficult to settle down to a protracted session of book writing; but a blog post, no problems 🙂

Crimson pepper pod / add two pairs of wings, and look / darting dragonfly  Matsuo Bashō (1644-1694)

As I have already written about the weird and wonderful names of caddisflies, it seemed appropriate to do a similar exercise for another group of insect associated with the aquatic environment, the Odonata, in particular, the dragonflies. Although individual species of dragonflies have accrued a host of descriptive names in the English language, hawkers, chasers, darters, clubtails, skimmers, to name but a few, globally, names for the group as a whole, show much less imagination.  On the other hand, some of them have very weird translations back into English 🙂   Countries where the language has Germanic roots tend to name them with variations on Dragonfly.  There are, of course, some exceptions; the Danes call them goldsmiths, or possibly jewellers. Countries with a language with Latin roots go for versions based on the Latin for balance or level, libella which in turn is descended from the word libra, which as well as being a scale was a unit of measure. This might seem a bit odd, but in some cultures, the Devil was thought to use dragonflies to weigh or measure people’s souls so this could be how this came about. Perhaps of interest, the Libellulidae (Common Skimmers) are the largest family of Odonata, and was named thus by the French entomologist Jules Rambur (1801-1870), a very obviously Latinised version of the French Libelluele.

Returning to the common names of species, the Danes seem to mainly call their Odonates water nymphs, and like the English, precede that with a colourful description.  For example, Lestes sponsa is the Plain Copper Water Nymph, the Hawkers, on the other hand, are mosaikgoldsmeds which literally translates to mosaic jewellers, but which Google Translate, very helpfully renders as hawker.  I was very disappointed with the French; I expected some wonderfully descriptive and lyrical names.  Agrion blanchâtre, whitish Agrion was a bit of an anti-climax 🙂

Despite their beauty, dragonflies somehow seem to have got a bit of a bad press along the way, and become associated with the Devil, as mentioned earlier about measuring and weighing souls.  They were also reputed to sew up the mouths of naughty children, hence the Devil’s darning needles, and make people blind and deaf; eye-pokers and ear cutters. The claspers being the needles and pokers. One of the common names in Romania is St George’s Horse, which so legend has it, the devil transformed into a giant dragonfly (Mitchell & Lasswell, 2005).  This may also explain the horse references in Croatian and Lithuanian.  For a long and very informative read about the folklore of dragonflies and their names, this is an excellent, if long read. Make sure you check out the Turkish for dragonfly, yusufçuk; it seems to be one of a kind.  I am sure that there must be an explanation somewhere 🙂

 

Bulgarian           vodno konche  vodno = water but konche means of course!

Burmese             နဂါးငွေ့တန် it looks very pretty but when you do retranslate, it gives you Milky Way!

Croatian             vilin konjic – fairy horse

Czech                  vážka

Danish                guldsmed goldsmith?

Dutch                 libel and drakenvlieg

Finnish                sudenkorento    suden can mean wolf

French                libellule

Gaelic                 tairbh nathrach taken separately = bulls snake

German              Libelle and Drachenfliege and der Wasserjungfer (water maid of honour)

Greek                  λιβελούλα  liveloúla

Icelandic            Drekafluga

Irish                    dragan

Italian                 libellula

Latvian               spāre

Lithuanian          laumžirgis depending on where you break the word up you can get laumž meaning fairies or žirgis meaning horse!

Maltese              mazzarell or ibellula

Norwegian         Drage flue but also Øyenstikker eye-poker

Polish                 ważka

Portuguese        libélula but also Cavalo judeu, Jewish horse

Romanian          libelulă

Russia                 strekoza

Slovak                 vážka

Spanish               libélula

Swedish              trollslända  note that  troll is troll or perhaps hobgoblin

Turkish               yusufçuk if you break this up into two words you get Joseph’s dick!

Welsh                 gwas y neidr Adder’s servant

 

Finally, to end with a bit of biology, Odonates use their wings in a unique manner. Other four-winged insects beat them synchronously, but dragonflies can beat the fore and hind pairs independently. This allows three different modes of flight in which the wing pairs beat (1) synchronously, as those of other insects, (2) alternately between the two sets, or (3) synchronously but out of phase with each other. This allows dragonflies and damselflies to display a variety of aerial aerobatics, including hovering, backward flight, and the ability to turn on a midair pivot. No wonder they are such good predators.

 

Reference

Mitchell, F.L. & Lasswell, J.L. (2005) A Dazzle of Dragonflies. Texas A & M University Press.

 

Postscript

I also discovered that Clematis virginiana is, in some parts of the World, called the Devil’s darning needle 🙂

 

 

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The Verrall Supper 2020 – even Covid-19 couldn’t stop these entomologists having a good time

For many entomologists The Rembrandt Hotel in South Kensington and the first Wednesday of March means only one thing – the Verrall Supper. I report on the activities of the Verrall Association annually and if you click on this link you will be able to work your way back through previous reports to my very first attempt.  This will, once again, be largely a photographic record.  This year the first Wednesday of March was the 4th but despite the date of the Supper always being the first Wednesday in March it still seemed to have caught a few Verrallers by surprise.  In addition the dreaded Covid-19 (Coronavirus), understandably, made some of our older members wasr of travelling to the capital. Consequently, numbers were slightly down compared with last year’s, although the number of non-attending Verrallers paying to retain their membership was at an all-time high.  One notable absence, due to the concerns of his wife, was our former Treasurer, Verrall Supper Secretary and oldest member of the Entomological Club, was Van (Professor Helmut van Emden).  His presence was sorely missed.  As far as I know he has only missed the Verrall Super twice.

We seem to have stalled a bit on my mission to increase the proportion of female entomologists; is year, we were 36 % the same as last year. There is still much progress to be made, but we have seen a year on year increase now for the last four years so, perhaps one day we will hit that magic 50:50 mark.

Like last year, I performed a humanist blessing, which seemed to meet with satisfaction from all sides, I reproduce it here if anyone feels like using it at a similar occasion.

As we come together at this special time, let us pause a moment to appreciate the opportunity for good company and to thank all those past and present whose efforts have made this event possible. As we go through life, the most important thing that we can collect is good memories.  Thank you for all being here today to share this meal as a treasured part of this collection.

This was then followed by a religious grace by Chris Lyal.  Never let it be said that the Verrall Association is not inclusive 🙂

And now as the old cliché goes, let the pictures tell the story.

Welcome to the Verrall Supper – Simon Leather and Clive Farrell ready and waiting for the first guests to sign in.  Note the precariously placed pint which a few minutes later tipped over and flooded the sign-in sheets 🙂

Three stalwarts of the Entomological Club, Paul Brakefield, Chris Lyal and Clive Farrell.

Two superheroes, Erica ‘Fly Girl’ McAlister and Richard ‘Bug Man’ Jones discussing books, Pete Smithers, Tom Miller (all the way from the USA) and Jim Hardie, enjoying a chat, and finally, Gordon Port discussing weighty matters with the oldest Verraller present, Marion Gratwick.

Some of the former Harper Adams entomologists, with former and current teaching staff, Ben Clunie, Scott Dwyer, Christina Conroy, Sue Stickells, Mike Copland, Ruth Carter and Simon Leather.

The younger end of the Verrall Supper, many of whom I have taught including one form the first Harper Adams cohort, Ashleigh Whiffin, now a Curator at the Scottish National Museum and Katy Dainton form cohort two, now a research entomologist at the Forestry Commission Northern Research Station at Roslin.

A diverse range of ages and career stages with plenty of wine to moisten teh vocal chords 🙂

Varying degrees of sartorial elegance were very much in evidence, including some ‘gentlemen’ without ties.  A good job Van wasn’t there 🙂

Can you spot the Knight of the Realm on the far left and on the far right on another table, the father of one of our more notorious politicians?

Did you know that Orlando Bloom’s mother is a Verraller? (in case you were wondering she is the foreground on the left with beret talking to Claudia Watts). One the right we have Mike Hassell, Austin Burt and Richard Lane, probably talking about malaria 🙂

 

 

Richard Hopkins in charge of the NRI table. NRI definitely helped with the sex ratio and good to see that there are so many female entomologists keen to enter the profession.

 

As so far, I have only received positive emails about the evening, I think I am justified in assuming that most, if not all, had a good time.  It was great to have seen you all and I hope to see even more of you next year, when we meet again on March 3rd 2021.

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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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Striders, Skaters, Tailors, Water Spiders and Measurers too – Gerrid Names Around the World

Dedicated followers of my blog will know that I have a bit of a thing about the names people call commonly seen insects around the World. Who can forget the Wheat Dolphin, the Alder Warbler, the Hairy Winged Water Butterflies and the great Thrips debate?  You may also recall that I am writing a book, the deadline for which is fast approaching.  I am also a first-class procrastinator and being just about to start the chapter on aquatic insects which is proving to be a bit more challenging than I thought it would be, found myself heading straight into procrastinator mode 🙂

I have always found Gerrids* fascinating, their ability to skim across the surface of ponds and streams, and to dodge my childhood attempts to catch them bare handed along with the painful discovery, that, like any insect with a piercing mouthpart, they can ‘sting’ 🙂 Although not as exciting as aphids 🙂 Gerrids have some interesting facets to their biology and ecology. They have short- and long-winged forms (Fairbairn, 1988), use ‘ripple communication’ to attract mates (Hayashi, 1985) and some species show territorial behaviour and mate guarding (Arnqvist, 1988).  Even more fascinating, and something I didn’t’ discover until I was in my early forties and swimming off the coast of Mauritius (work, not holiday), that although 90% of Gerrids are freshwater dwellers, there are forty species within the genus Halobates, the Sea and Ocean Skaters, five of which are truly marine.  The naturalist Johann von Eschscholtz first discovered them during his voyage on the Russian expeditionary ship Rurik between 1815 and 1818.  I hope that when I get round to finishing my book you will be able to read more about them.  In the meantime, more details can be found in the key references listed at the end of this article.

My previous excursions into global insect names have involved my own limited language skills, Google Translate and direct emails to friends from around the World.  This time I thought I would give the Twitter community a chance to display their collective wisdom.  I was not disappointed. Within 48 hours of posting my request for help, had an excellent collection of names, including dialectal variations, which I would never have come across otherwise.  The majority of the names, as you might expect, refer to the ability that Gerrids have of walking or skating on water, so much so that in parts of North America they are known as Jesus Bugs. More surprising, are the references to tailors and shoemakers and measuring.  This could have its roots in the way in which before the invention of tape measures, cloth merchants and tailors measured lengths of fabric using yardsticks or by extending their arms and holding the cloth from hand to shoulder, which could be seen to resemble the way in which Pond Skaters moved their legs. That said, in the UK, the name, water measurer is reserved for members of the Hydrometridae. Some confusion or overlap also occurred with Water Boatmen, in the USA, the Corixids, in the UK, the backswimmers, Notonecta. Corixids have paddle shaped legs and swim, while backswimmers, also with paddles, swim upside down.  True Pond Skaters, the Gerrids, move across the water surface, they really do walk on water.

Finally, here, mainly from Europe, are the results.  If anyone has more languages to add please do so in the comments.

Afrikaans             Waterloper – water walker

Arabic                   بركة متزلج   barakat mutazalij – no idea but looks pretty 🙂

Bulgarian            водомерка Vodomеrka (voda = water, mеrka = measure)

Canadian             Water skeeters, Jesus Bugs

Czech                    Vodoměrka (voda = water, měř = measure)

Danish                  Skøjteløbere – which word by word translates to skater-runners but simply means skaters

Dutch                    Schaatsenrijders – skaters.

Finnish                  Vesimittari =water measurer; mittari is also the Finnish name for Geometridae moths, such as winter moth = hallamittari = frost measurer

Flemish                Schrijvertje, little writer.

French                  Araignée d’eau, also Patineur,  which is also the name used for an ice skater! Derived from « Patin » which is an ice skate. In the local language of South-Eastern France, le provençal. It is called Lou courdounié, that means “the shoe maker” (cordonnier in French). Apparently, the movement of their legs is reminiscent of the way in which shoemakers work

Galician                Zapateiro, shoe maker, but also costureira, dress maker, pita cega, blind hen, and cabra cega, blind goat

German               Wasserläufer, water runners. In some parts of Germany, the colloquial term is Schneider or Wasserschneider, water tailor

Hungarian           Molnárpoloskák, where molnár = miller and poloskák = Heteroptera

Italian                    Ragni d’acqua, directly translates as water spiders

Latin                      Tippula – water walker, very light – see this extract from Ian Beavis’ book

Polish                    Nartnik wodny. Nartnik is a derivation of narciarz meaning skier; wodny means associated with water.

Portuguese        Alfaiate, tailor

Russian                 Vodomerki (водомерки),  = water measurers

Spanish                The “official” name in Spanish seems to be “guérridos” (from its Latin name, Gerris lacustrae), but more commonly called zapateros,      shoe makers. Patinador de estanque skater of ponds, also chinche de agua, watert bug, cucaracha de agua, water flea, saltacharcos (?),  limpia aguas Tapaculos, clean water Tapaculos in southern Spain’s Spanish. Any clues on the etymology of the last two gratefully received.

Swedish               Skräddare , tailor, because their leg-motions look like scissors cutting.  Also known as vattenlöpare, water-runners.

Tamil                  நீர்தாண்டி (neerthaandi); neer means water and thandi is akin to crossing/crosser, so water crosser would be the closest direct translation.  It may be an overactive imagination, but to me the first character looks like someone skating 🙂

Welsh                   Rhiain y dwr, Lords of the water but also hirheglyn y dŵr, water long-legs

 

Many thanks to all those who responded to my Twitter request, it was very much appreciated.

 

References

Arnqvist, G. (1988)  Mate guarding and sperm displacement in the water strider Gerris lateralis Schumm. (Heteroptera: Gerridae).  Freshwater Biology, 19,269-274.

Cheng, L. (1985) Biology of Halobates (Heteroptera: Gerridae). Annual Review of Entomology, 30, 111-135.

Fairbairn, D.J. (1988) Adaptive significance of wing dimorphism in the absence of dispersal: a comparative study of wing morphs in the waterstrider Gerris remigis. Ecological Entomology, 13, 273-281.

Hayashi, K. (1985) Alternative mating strategies in the water strider Gerris elongntus (Heteroptera, Gerridae). Behavioral Ecology & Sociobiology, 16, 301-306.

Spence, J.R. & Anderson, N.M. (1994) Biology of water striders: interactions between systematics and ecology.  Annual Review of Entomology, 39, 101-128.

*Gerrids are true bugs, Hemiptera, which are characterised by the possession of piercing and sucking mouthparts.

Many thanks to all those who responded to my Twitter request, it was very much appreciated.

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Collect by all means, but….

Some of Wallace’s beetles

 

Leaving aside grant writing and committee meetings, which are, in theory, voluntary, the part of academic life I hate the most is marking assignments and exams.  At this time of year, however, I find myself actually enjoying marking student assignments. You may well ask why, what is it that makes these assignments different?  The reason is simple enough; many years ago, when thinking about ways in which to satisfy learning outcomes and to give our MSc students worthwhile skills in a different and enjoyable way, I had a flash of inspiration. I came up with two assignments that I felt our aspiring entomologists would appreciate and that I, and my colleagues would enjoy marking.  One is a written piece of work based on the Royal Entomological Society student essay competition. This not only gives the students the chance to write about something they like in a totally different format than their usual essays and lab reports, but as they are encouraged to submit their essays to the prize committee, they get the chance to gain a monetary reward, and many do so*.

The second assignment which I ‘borrowed’ from my own days as an entomology student, is to collect and curate a small insect collection, with the added twist of preparing a factsheet/booklet, suitable for use at outreach events, describing the collection with notes on the biology and ecology of the specimens, capped off with a fun fact for each insect. The students do a fantastic job with both the collections and the accompanying leaflets, booklets and posters (they are allowed a very free rein as to how they present the fact sheets).  They are so good in fact, that I borrow some of them to use at outreach activities**.

Some examples of the student collections.  Apologies for the lousy photographs 😊

Now on to the meat of my post. Although initially aimed at the use of live animals (by which they meant vertebrates, the three Rs of biomedical research, reduction, refinement replacement (Russell & Burch, 1959) now widely permeate society and have meant that many of the zoology practical classes that I did as an undergraduate, e.g. examining the effect of adrenaline on exposed frog hearts, or infecting scores of day-old chicks with Eimeria tenella, ready for killing (by the students) and subsequent dissection of the gut, are, and rightly so, no longer part of the student curriculum.  Although as entomologists we deplore the common perception that insects are not, for the most part, recognised as animals by funding bodies, or the general public, we are glad that this allows us to escape the dreaded ethics forms and licences to allow us to work on living material. As entomologists however, whether we work on pests or on insects of conservation interest, we are deeply in love with our study animals and although some of us (not me, I have always been an observer rather than a pinner) may own or manage large collections of insects, we do this from necessity not from a love of killing.  This is, and always has been, something of a conflict for us entomologists since the first one emerged from the undergrowth clutching a treasured specimen (Newman, 1841).

Newman (1841) on why entomologists are more humane than non-entomologists

 

Joseph Greene – another early ethical entomologist

Living insects are not always amenable to transport and display; the standard fare at outreach events are stick insects, leaf insects, flower beetles and Madagascan hissing cockroaches, fulfilling the hardiness, cuteness and “yuk” factors respectively and in all cases, being large enough to see easily.  I have taken living specimens of the “World’s biggest aphid” along on many occasions, only to be greeted with responses that can only be described as of complete underwhelming disdain 😊We want and need to show the fantastic diversity of insects and the easiest way to do this is with the standard display boxes.

Our basic outreach display box of common British insects

Boxes such as the above do not usually cause much controversy although some visitors do ask why we need to kill and pin the insects.  It is the boxes of what look like identical specimens lined out in serried rows that cause the most questioning.

Serried rows – the infinite variety withing species – thanks to Erica McAlister from the NHM for the photograph.

My response is to ask my interlocutor to imagine that they are a 10 metre tall explorer from a distant Galaxy that has landed on Earth and collected a couple of humans, which you carefully preserve and take back to your home planet and donate them to a museum as typical Earth specimens. Now, imagine another intrepid collector arrives on Earth with the description of your specimens which unbeknownst to either of you happen to be two males from an Amazonian tribe. Alien Explorer 2 has landed in Iceland at a ladies day at a hot spring.  What is han to make of the specimens han trapped? This is usually enough to make my point and of course I also explain about the huge importance of type specimens and the advantage of being able to look and compare whole specimens from every angle, which despite the huge advances in photography and 3-D imagery is not always possible with virtual images.

Unfortunately, not everyone has had the need for collecting and the importance of reference collections explained to them by an entomologist,  and some individuals can get very worked up about what they perceive as needless cruelty or desecration of Nature, sometimes with very unfortunate outcomes. The late Philip Corbet, one of the most eminent Odonatologist of modern times, then in his early 70s, was once badly beaten up by a member of the public at a Nature Reserve to which he (Philip) had been invited to collect a rare type specimen.  Adam Hart and Sierian Sumner received a deluge of personal abuse for asking people to kill and collect wasps as part of a citizen science project and at the risk of reopening a can of worms, annelid expert Emma Sherlock from the Natural History Museum London, was hounded on-line and in the main stream media for investigating the largest ever Lumbricus terrestris, to see if it was a species new to science or a genetic aberration.

The worm in question

In Emmas’s own words, “To identify earthworms generally there are less than half I can identify accurately alive, the rest you always have to preserve to identify. For the people saying you shouldn’t preserve animals how are you ever to conserve them? You need to add a name to the animal to be able to learn more about it and to conserve it if it needs help. Like the little polychaete worm that halted the big road development a few years back. If a specimen hadn’t been taken and given a name then it is just a worm, and there are lots of worms and therefore worms are not in need of protection”.

This is also the case for many insect species, which can for example, only be identified by close examination of their genitalia, in many cases, by dissection, so certainly not possible to do with living specimens.  Another point of concern that could be raised is the phenomenon of moth trapping.  Until I went on Twitter, I hadn’t thought deeply about moth trapping.  I was involved with running one of the Rothamsted Insect Survey moth traps when I was doing my PhD at the University of East Anglia, but hadn’t realised that it was a bit of a phenomenon with even hard-core ornithologists running traps in their gardens. Given the reports of insect declines over the last couple of decades (Leather, 2018) is this something we should deplore and restrict? Very sensibly, moth trappers (moth’ers) have not ignored the problem and the consensus seems to be that moth trapping per se, pales into insignificance when compared with the other pressures on insect populations.

I suspect that like most entomologists, I have what might seem to non-entomologists a contradictory relationship with insects.  My research spans the world of conservation and crop protection.  As an ecologist, my group and I are trying to come up with ways in which to enhance and protect insect diversity and abundance.  The other members of the group are looking at better ways to protect our crops so that we can feed the world, and this inevitably involves killing pest insects to reduce their populations.  In my own garden, insects are allowed to flourish and I cringe when I see or hear people telling me how they run their fingers and thumbs along rose buds to squash the aphids.  I feel guilty if I accidentally wash a spider down the drain when I am having a shower, but have no compunction at all in squashing a mosquito or swatting a stable fly when she attempts to suck my blood!

It is precisely this conflict of interests that has made entomologists think harder about the ethics of their profession than many ‘civilians’ do when swatting mosquitoes or spraying their vegetable gardens (e.g. Fischer & Larson, 2019; Didham et al., 2019).  In the end I turned to verse 🙂

Because we love them

We need to think carefully

When we collect them

 

References

Didham, R.K., Leather, S.R. & Basset, Y. (2019) Ethics in entomology. Antenna, 43, 124-125.

Fischer, B. & Larson, B.M.H. (2019) Collecting insects to conserve them: a call for ethical caution.  Insect Conservation & Diversity, 12, 173-182.

Greene, J. (1880) The Insect Hunter’s Companion 3rd Edition, W. Swan Sonnenhein & Allen, London.

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

Newman, E. (1841) A Familiar Introduction to the History of Insects. John van Voorst, London.

Russell, W.M.S & Burch, R.L. (1959) The Principles of Humane Experimental Technique. Methuen & Co, London.

 

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If you scroll down the RES page link you will see that our students have done remarkably well over the years.

 

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an example followed by some of our former students 😊

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Leaf blowers – disturbing the peace and fatal to insects?

There is a petition doing the rounds at the moment hosted by the 38 Degrees organisation calling for a ban on leaf blowers, citing their detrimental effect on insects as the raison d’etre.  I’ve signed it, mainly because of the noise and the air pollution effects, especially as “Leaf Blower Man” goes past my office frequently at this time of year😊

The Leaf Blower Man in action outside my office and the aftermath – I wonder what happens to the leaves next?

You may, (or perhaps not), be wondering what has brought about this most recent media outburst against leaf blowers.  Taking this as a great opportunity to procrastinate still further, I tracked down the first media mention about the dangers of leaf blowers to a newspaper article published in the German newspaper Augsburger Allgemeine on November 14th in which it reported a press release, dated the 16th October, from The German Ministry for the Environment and Nature Conservation, strongly advising people not to use leaf blowers because of the danger they  cause to the environment, not just from pollution but because of the harm they do to insects and other small animals.

Der Bund für Umwelt und Naturschutz (BUND) fordert nun nicht nur Privatleute, sondern auch die Kommunen zum Verzicht auf den Einsatz auf: „Laubbläser sind nicht nur ohrenbetäubend laut und verschmutzen die Luft durch ihre Verbrennungsmotoren, sie schaden auch der Bodenbiologie gravierend“, sagt die Artenschutzexpertin des BUND, Silvia Bender. „Denn neben Blättern werden auch Insekten und Spinnen aufgesaugt und gehäckselt sowie Pflanzensamen zerstört.“ Ohnehin seien die Geräte überflüssig: „Wir empfehlen daher Grundstücksbesitzern und auch Kommunen dringend, auf Laubbläser und Laubsauger zu verzichten und stattdessen wieder zu Rechen und Harke zu greifen.“”

“The Federal Government for the Environment and Nature Conservation (BUND) now demands not only private individuals, but also the communities to abandon the use: “Leaf blowers are not only deafening loud and pollute the air through their internal combustion engines, they also harm the soil biology seriously,” says the species protection expert of the BUND, Silvia Bender. “In addition to leaves and insects and spiders are sucked up and chopped and plant seeds destroyed.” Anyway, the devices are superfluous: “We therefore recommend landowners and communities urgently to dispense with leaf blower and leaf vacuum and instead to rake and rake again.”

If you want to read the original source it is here; it also extols the virtues of the exercise you gain from raking up your leaves 😊

Although it had taken almost a month for the German press to latch on to the story, presumably they were waiting for autumn to properly kick-in; BBC World ran with the story on 15th November and the first British Newspapers by  18th November and a feature piece by Kate Bradbury in the Daily Telegraph appeared on November 26th which finally prompted me to put fingers to keyboard 😊

Kate mentioned in her article that there was no scientific evidence that leaf blowers directly harmed insects and after spending some time with Google Scholar and Web of Science, I can confirm this. Perhaps someone might like to do a project on it?  I’m sure it might appeal to a keen undergraduate or MSc student.  Kate correctly points out that leaves form leaf litter and as she aptly puts it “are natures’ winter blanket” providing shelter for countless animals. Including vertebrates. Those insects that overwinter on the ground, or in the upper layers of the soil, despite their fantastic anti-freeze chemistry (Leather et al., 1983) are also very grateful for a nice thick layer of leaves to help buffer the effects of a cold winter and keep them hidden from natural enemies (Thomas et al., 1992). Additionally, leaf litter also provides a valuable food source for the very important, and often overlooked ecological recyclers such as the soil dwelling flies (Frouz, 1999) and of course, the invaluable and underappreciated earthworms (Cothrel et al., 1997).  An example of how important leaf litter is for insect survival, is the way in which the horse chestnut leaf miner can be controlled in gardens and parks by the removal of the leaves from under infested trees as soon as leaf fall has ended (Kehrli & Bacher, 2003).  Leaf blowers may not be harming insects and other invertebrates physically, (although I imagine that being blasted by what must seem like a hurricane, can’t be a totally benign experience), but they certainly have the potential to reduce their populations, which given the current worries about Insectageddon (Leather, 2018), Is not something we should be happy to encourage.

So, if they are not physically damaging our invertebrate friends, and there is, as yet, no scientific evidence that they do so, how are leaf blowers harming insects and their allies.  Leaf litter is an invaluable resource, it not only provides nutrients for plants and helps sequester carbon (Berg & McLaugherty, 2008), and as I mentioned earlier, it provides livelihoods for fungi, bacteria, insects and other invertebrates, and the litter grazers in turn, provide tasty meals for other invertebrates further up the food chain* (Scheu, 2001; Miyashita et al., 2003).  By removing fallen leaves to satisfy health and safety directives and/or some folks preferences for tidy pavements and lawns, we are at the same time as we pollute our atmosphere with nasty hydrocarbons, depriving these useful organisms of much-needed resources ☹ Whilst I sympathise with local councils and their desire to keep their citizens safe from potentially slips and falls, I really don’t see the need for leaf-free lawns and parks.

Shiny, leaf-free (almost), and safe for humans versus beautiful, leaf strewn and good for earthworms and their ilk and aesthetically pleasing (to me at any rate).

And if you must keep your pavements leaf-free then why not use a quieter and less polluting alternative such as a human with a stiff broom or if a mechanical alternative is the only option, then an electrically powered mechanical road-sweeper is an acceptable substitute.

I like this one as it is a Scarab 😊

Leaf blowers have been used to harm insects, albeit on a larger scale than that wielded by the local council worker or gardener, and in conjunction with a vacuum device.  Inspired by the use of tractor driven vacuum machines developed to control Lygus bugs in strawberry fields (Pickel et al., 1994), Phyllis Weintraub and colleagues (Weintraub et al., 1996) developed a tractor-propelled blower-vacuum combi to manage insect pests in celery and potato crops. The insects are first dislodged by a blower and then vacuumed up for later disposal ☹  More recently, a similar technique has been used to control Colorado Potato Beetles.

There may be no scientific evidence to show that leaf blowers used as intended are bad for insects but on the other hand there is no evidence that shows the opposite, and given the noise and atmospheric pollution they produce and the undoubted harm they cause by litter, my sympathies lie with those wanting to ban the things.

I think that most entomologists would say that the only good leaf blower is one that has been reverse engineered to be a G-Vac and used for insect sampling.  I suspect that insects would have a different opinion as most of those insects we catch usually end up dead, even if it is for the good of science 😊

My colleague Andy Cherrill demonstrating his patent G-vac or ‘Chortis’ as we call it 😊

 

References

Berg, B. & McClaugherty, C. (2008) Plant Litter – Decomposition, Humus Formation, Carbon Sequestration. Springer, Berlin 338 pp.

Cothrel, S.R., Vimmerstedt, J.P. & Kost, D.A. (1997) In situ recycling of urban deciduous litter. Soil Biology &Biochemistry, 29, 295-298.

Frouz, J. (1999) Use of soil dwelling Diptera (Insecta, Diptera) as bioindicators: a review of ecological requirements and response to disturbance. Agriculture, Ecosystems & Environment, 74, 167-186.

Kehrli, P. & Bacher, S. (2003) Date of leaf litter removal to prevent emergence of Cameraria ohridella in the following spring.  Entomologia experimentalis et applicata, 107, 159-162.

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., Bale, J.S. & Walters, K.F.A. (1993) The Ecology of Insect Overwintering. Cambridge University Press, Cambridge.

Miyashita, T., Takada, M. & Shimazaki, A. (2003) Experimental evidence that above ground predators are sustained by underground detritivores. Oikos, 103, 31-36.

Pickel, C., Zalom, F.G., Walsh, D.B. & Welch, N.C. (1994) Efficacy of vacuum machines for Lygus Hesperus (Hemiptera: Miridae) control in coastal California strawberries. Journal of Economic Entomology, 87, 1636-1640.

Scheu, S. (2001) Plant and generalist predators as links between the below-ground and above-ground system. Basic & Applied Ecology, 2, 3-13.

Thomas, M.B., Sotherton, N.W., Coombes, D.S. & Wratten, S.D. (1992) Habitat factors influencing the distribution of polyphagous predatory insects between field boundariesAnnals of Applied Biology, 120, 197-202.

Weintraub, P.G., Arazi, Y. & Horowitz, A.R. (1996) Management of insect pests in celery and potato crops by pneumatic removal.  Crop Protection, 8, 763-769.

 

 

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