Category Archives: EntoNotes

Data I’m never going to publish – factors affecting sycamore flowering and fruiting patterns

As a teenager I used to have a favourite thinking place, underneath a large beech tree half-way down the school drive.  I used to watch the activities of my school mates, while contemplatively chewing beech nuts (my school friends found this mildly disgusting).

Some years beech nuts were much easier to find than others; although I didn’t realise it at the time, this was my introduction to the phenomenon of masting.  At this point I had better fill you in on the basics of tree reproduction. Like most plants, trees reproduce by producing flowers that are pollinated, depending on the species, by vertebrates, insects or the wind. The fertilised flowers then produce seeds that are housed in what we term fruit or cones, and which in many cases aid their dispersal. Reproduction is energetically a costly process, reserves channelled to reproduction cannot be use for growth and defence.  Trees have evolved three different approaches to this problem. Some trees produce a moderate number of seeds in most years, others have an Irregular fruiting pattern and some, such as beech and oak, have strongly periodic fruiting patterns, “mast” years.  Interestingly (my wife hates me starting sentences off like this), trees that mast are wind pollinated.

Beech (Fagus sylvatica) mast production over a sixteen year period in England. Data from Hilton & Packham (1997

You might wonder why, if reproduction is costly, that some trees are ‘willing’ to expend so much energy in one go.  There are two schools of thought regarding this. One, which I find fairly convincing, is the “predator satiation” hypothesis (Janzen, 1971).  This basically says that the trees, by having on and off years, starve their specialist seed predators in the off years, thus reducing predator pressure by killing lots of them off. In the mast years, there are enough seeds to feed the surviving predators and produce another crop of trees.  A more recent, and less exciting suggestion (to me anyway), is that if the trees have a mass synchronised flowering effort, i.e. a mast year, then the chances of being pollinated are greatly increased (Moreira et al., 2014).

People tend to associate masting with trees that produce heavy fruit, acorns, hazel nuts and beech nuts for example, and I was no exception, so it wasn’t until a couple of years (1995) after I started my mega-sycamore study at Silwood Park that I had a bit of a revelation. I realised that not all of the trees flowered and that there seemed to be a lot fewer seeds that year than I remembered there being the year before. Sycamore seeds come equipped with two little wings (they are wing dispersed) and occur in little bunches (infructescences) so are quite noticeable.

Winged sycamore seed and ‘bunch’ of sycamore fruit

My sycamore study was one of my many side projects set up to satisfy my’ satiable curiosity’ and I had, at the time thought that I had made sure I was measuring everything that could possibly interact with the aphids feeding on the trees. I had, however, somehow overlooked sycamore flower production 🙂 I had taken into account that in some years the sycamore aphid can be present in huge numbers and and I was well aware from the work of my PhD supervisor

Sycamore aphids emerging in spring – some years you can see even more on the newly flushing buds

Tony Dixon, that the aphids can cause substantial losses to tree growth (Dixon, 1971), so had included tree girth and height measurements into my massive data collection list. Strangely, however, despite knowing from my work with

The effect of the sycamore aphid, Drepanosiphum platanoidis, on leaf area of two sycamore, Acer pseudoplatanus, trees over an eight year period (Dixon 1971).

the bird cherry-oat aphid Rhopalosiphum padi, that even quite low numbers of aphids could have substantial negative effects on cherry production (Leather, 1988), I had totally overlooked sycamore flowering and seed production. I am just thankful, that I only missed three years of flowering data 🙂

The effects of bird cherry aphid infestation on reproductive success of the bird cherry, Prunus padus (Leather, 1988)

Unlike the rest of my sycamore data set, the flowering data collection was actually set up to test a hypothesis; i.e. that aphid numbers affected flowering and seed set. Sycamore is in some ways similar to the well-known masting species such as oak and beech in that it is (jargon coming up) heterodichogamous. All flowers are functionally unisexual and appear sequentially on a single inflorescence. The inflorescences can however be either protandrous, i.e. male anthesis takes place before the stigmas become receptive, or protogynous where the reverse sequence takes place. Where it differs from the typical masting species is that is produces wind dispersed seeds and is wind and insect pollinated; oak, beech and hazel are entirely wind pollinated.  Pierre Binggelli, then based at the Unibersity of Ulster, hypothesised that protandrous trees may suffer less herbivore damage than protogynous trees (Binggeli, 1992). He suggested that protogynous trees, having less energy available to invest in defensive chemistry, are more attractive to insect herbivores, particularly chewers. On the other hand, sycamore trees that have been subject to previous insect infestation have fewer resources available to produce female flowers, become protandrous and avoid infestation by herbivores the following year. Presumably the next year, having escaped insect attack by being protandrous they should become protogynous again. So, if I wanted to test this hypothesis, I needed to learn how to sex sycamore flowers. Despite a handy guide that I came across (Binggeli, 1990), ) I found it almost impossible, to do, so

A. Protogynous inflorescence (female II flowers of Mode G are male II in Mode B). B. Protogynous infructescence, Mode B. C. Protogynous infructescence, Mode G. D. Protandrous inflorescence.
E. Protandrous infructescence. F. Vegetative shoot, G. Flowering shoot (Mode E).
H. Fruiting shoot (Flowering Modes B,C,D & G). (From Binggeli, 1990)

contacted Pierre, who very kindly agreed to check some of my ‘guesses’ for me.  Despite this help, I still found it very difficult so opted (very unwisely as it turned out) to collect fruit samples from each tree, put them in paper bags, and bring them back to the lab for sexing at a later date.  As you have probably guessed, I ended up with lots of paper bags which I then, not very cleverly, stored in plastic bin bags.  This went on for several years as I kept putting off the day when I would have to sit down and sex several thousand bunches of sycamore fruit. Then came the happy disastrous day when I came back from holiday to find out that the cleaners had disposed of my bin bags. To tell the truth I was not that upset as it gave me an excuse to stop collecting the fruit samples and reduced my feelings of guilt about having huge piles of unsexed sycamore fruit bunches cluttering up the lab 🙂 I did, of course, carry on counting the number of flowers on the trees, which was much easier data to collect and analyse.

I reluctantly ended my study in 2012 when I left Silwood Park for pastures new, but despite this I still haven’t analysed all my sycamore data, although I was very happy a couple of years ago when a PhD student from the University of Sheffield (Vicki Senior) volunteered to analyse some of my sycamore aphid data which was published last year (Senior et al., 2020). The winter moth data and orange ladybird data are also being analysed by a couple of my former students and hopefully will also be published by next year.

So what does the sycamore fruiting data show? Well, first, despite sycamore being reproductively somewhat atypical of other masting trees species, I would contend that my 17-year data set of sycamore fruit production looks remarkably similar to the Hilton and Packham beech masting data set. I am thus confident in stating that sycamore is a masting species.

Mean sycamore fruit production at Silwood Park, averaged from 52 trees 1996-2012,

Am I able to link sycamore seed production with aphid abundance, is the fruiting pattern a result of herbivory?  I can’t test Pierre Binggeli’s hypothesis about sex changing trees, because I lost the data, but I can try and see if aphid infestation affects fruit production. The two most common aphid species on the Silwood Park sycamore trees are the sycamore aphid Drepanosphum platanoidis and the maple aphid, Periphyllus acericola.  

Mean sycamore aphid and mean maple aphid loads (average annual counts per 40 leaves from all trees) 1996-2012.

They can both occur in high numbers, but in general, the average numbers of P. acericola are much higher than D. platanoidis. The reason why P. acericola has much higher numbers is a result of its over-summering strategy.

Over-summering morphs of the sycamore and maple aphid. Images from https://influentialpoints.com/Gallery/Drepanosiphum_platanoidis_common_sycamore_aphids.htmhttps://influentialpoints.com/Gallery/Periphyllus_acericola_Sycamore_Periphyllus_Aphid.htm#other

While the sycamore aphid spends the summer aestivating (basically a summer version of hibernation in that metabolism is reduced and reproduction ceases), the maple aphid produces a huge number of nymphs, known as dimorphs, which over-summer in dense, immobile aestivating colonies.  The sycamore aphid can escape predators by flying off the leaves if disturbed, the maple aphid dimorphs on the other hand, rely on their huge numbers to ensure survival of some of them over the summer to resume development and reproduce as autumn approaches, a form of predator satiation. They thus suffer a huge reduction in numbers compared with the sycamore aphid. (I must publish that one day). This makes drawing conclusions about the of herbivory (aphid feeding) on the trees a bit difficult.

Mean combined aphid load, showing how the number of dimorphs of the maple aphid skew the perceived aphid load.

Given that Tony Dixon showed that sycamore aphids cause a significant reduction in tree growth (Dixon, 1971), I

Relationship between mean combined aphid load (sycamore and maple aphid) and mean sycamore fruit production.

expected to see a negative relationship between aphid numbers and fruit production. What I did find was that there was a significant positive relationship between sycamore aphid numbers and fruit production, i.e. the more sycamore aphids, the more fruit produced, whereas with the maple aphid it was the other way round, more maple aphids, fewer fruit. If I combined the aphid loads, then the relationship becomes significantly positive, the more aphids you get the

R.

Relationship between mean combined aphid load and the number of sycamore fruit produced the following year.

significantly negative relationship between aphid numbers and sycamore fruit production, but as I pointed out earlier this is driven by the preponderance of maple aphid dimorphs in the summer. You might also argue, that rather than looking at aphid numbers and sycamore fruit production in the same year, I should be comparing aphid numbers with fruit production the following year, i.e. a lag effect. I did indeed think of this, and found that there was, for both aphid species, no significant relationship between aphid numbers the previous year and fruit produced the following year. In fact, if I was an undergraduate student I would point out that there was a positive trend between aphid numbers and fruit production 🙂  If I do the same analysis using the combined aphid load, then the relationship becomes significantly positive, the more aphids you get the more sycamore fruit you get the following year which although counter-intuitive fits with the idea that stressed trees tend to produce more offspring (seeds) (Burt & Bell, 1991) and given that we know from Tony Dixon that the sycamore aphid causes a significant reduction in growth (Dixon, 1971) which is an indication of plant stress (Grime, 1979) makes perfect sense. 

Relationship between mean combined aphid load and the number of sycamore fruit produced the following year.

Instead of mean aphid load, perhaps we ought to be thinking about aphid occurrence at crucial times of the year for the tree, for example budburst. If you go back to the top of the page and look at the photograph of the infested buds you can see that there can be a huge number of aphids present at this time of year just when the trees are starting to wake up and put on new growth. Any interference to the uptake of nutrients at this phase of their life cycle could be detrimental to fruit production.  One way to measure this is by looking at the date the first aphids appear on the buds in the expectation that the earlier the aphids start to feed, the bigger their impact on the trees. Sure enough, the earlier the aphids start feeding, the lower the number of fruit produced.

Significant negative relationship between date of first appearance of aphids on the buds and number of fruit produced in spring.

Although all the relationships I have discussed and shown are significant, the amount of variation is explained is pretty low (over 20% but less than 30%). The relationship that explains most of the variation in any one year is the size of the tree, the bigger the tree the more fruit it produces.

Relationship between size of sycamore tree and number of fruit produced (2009).

As a rule of thumb, the bigger a tree the older it is and older trees have more resources and can afford to produce more offspring than younger smaller trees.

In conclusion, what I can say with confidence is that there is significant variability in sycamore fruit production between years and this is, in my opinion, evidence of masting events, and may be linked to the size and timing of aphid load but is moderated by the size and age of the trees. If you have any other suggestions please feel free to add them in the comments.

If anyone is interested in delving into the data in more depth I will be very happy to share the raw data and also the local weather data for the site.

References

Binggeli P. (1990) Detection of protandry and protogyny in sycamore (Acer pseudoplatanus L.) from infructescences. Watsonia,18, 17-20.

Binggeli P. (1992) Patterns of invasion of sycamore (Acer pseudoplatanus L.) in relation to species and ecosystem attributes. D.Phil. Thesis, The University of Ulster.

Burt, A. & Bell, G. (1991) Seed production is associated with a transient escape from parasite damage in American beech.  Oikos, 61,145–148.

Dixon, A.F.G. (1971) The role of aphids in wood formation. 1. The effect of the sycamore aphid, Drepanosiphum platanoides (Schr.) (Aphididae) on the growth of sycamore. Journal of Applied Ecology, 8, 165-179.

Hilton, G.M. & Packham, J.R. (1997) A sixteen-year record of regional and temporal variation in the fruiting of beech (Fagus sylvatica L.) in England (1980-1995). Forestry, 70, 7-16.

Hilton, G.M. & Packam, J.R. (2003) Variation in the masting of common beech (Fagus sylvatica L.) in northern Europe over two centuries (1800-2001). Forestry, 76, 319-328.

Janzen, D. H. (1971) Seed predation by animals. Annual Review of Ecology and Systematics, 2,465–492.

Leather, S.R. (1988) Consumers and plant fitness: coevolution or competition? Oikos, 53, 285-288.

Leather, S.R. (2000) Herbivory, phenology, morphology and the expression of sex in trees: who is in the driver’s seat? Oikos, 90, 194-196.

Moreira, X., L. Abdala-Roberts, Y. B. Linhart, and K. A. Mooney. (2014_. Masting promotes individual- and population-level reproduction by increasing pollination efficiency.Ecology, 95, 801–807.

Grime ., J.P. (1979) Primary strategies in plants, Transactions of the Botanical Society of Edinburgh, 43,2, 151-160.

Senior, V.L., Evans, L.C., Leather, S.R., Oliver, T.H. & Evans, K.L. (2020) Phenological responses in a sycamore-aphid-parasitoid system and consequences for aphid population dynamics; A 20 year case study. Global Change Biology, 26, 2814-2828.

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Let your dandelions and other flowering ‘weeds’ be

This last couple of weeks parts of my daily walks have been accompanied by, the to me, unwelcome din of motor lawnmowers as lots of my fellow villagers strive to turn their lawns into ecological deserts. One of my neighbours has, to my knowledge, cut his lawn five times since the beginning of March, me I’ve done my spring cut and that’s it until autumn.

An ecological desert 😦

This mania for close-cropped lawns, sometimes ‘artistically’ striped, is, I think, the fault of my grandparent’s generation, which took a municipal park attitude to gardens, especially the bit that the neighbours could see; close-cropped, weed-free grass with regimented flower beds, also equally weed-frees. Out of sight, back gardens could be less manicured, and depending on the space available, might include a vegetable garden (also scrupulously weed-free), and a patch of lawn to be used by children for ball games and other activities. Unfortunately they drummed this philosophy into their children, who in their turn, with only a few exceptions (me for one), passed this fetish on to my generation. Sadly, my father, a keen gardener, also espoused this view as did the parents of all my friends. I spent many a grumpy hour removing dandelions and thistles from our front lawn and flower beds at my father’s behest!

So what are these weeds that so many people seem to hate? To those growing crops of economic value, be they agricultural, horticultural or silvicultural, then I guess the following definitions are very reasonable and relatable.

Plants that threaten human welfare either by competing with other plants that have food, timber of amenity value, or by spoiling and thus diminishing the value of a product

Weeds arise out of the mismatch between the habitats we create and the plants we choose to grow in them

Begon, Harper & Townsend (1996)

A plant that originated under a natural environment and, in response to imposed and natural environments, evolved and continues to do so as an interfering associate with our desired plants and activities” Aldrich & Kremer (1997)

There are more tolerant descriptions of weeds available, which are much more in accord with my views:

What is a weed? A plant whose virtues have not yet been discovered” (Emerson, 1878)

, “A weed is but an unloved flower!” (Wilcox, 1911)

A plant condemned without a fair trial” (de Wet & Harlan, 1975)

I have, as I have mentioned several times already, been doing a lot of walking during the covid pandemic, or should it now be referred to as the Covid Pandemic? At this time of year, Spring, the early flowers of the hedgerows and roadside verges are alreday out; cherry plum (Prunus cerasifera), blackthorn or sloe (Prunus spimosa) and closer to the ground, but as equally pretty, daisies (Bellis perennis), dandelions (Taraxacum officinale), Lesser Celandines ( Ficaria verna (although some of you may know it as Ranunculus ficaria), and Wood Anemones (Anemonoides nemorosa). The latter two species, although relatively common, are unlikely to be found in the average garden, as they have fairly specific habitat requirements.  Daisies and dandelions on the other hand, are pretty much ubiquitous, although the former do not attract as much opprobrium from the traditional gardener as dandelions do. This is a great shame, as ecologically speaking dandelions are an extremely important resource for pollen and nectar feeding insects.

Given the concerns about the decline of insects in general over the last forty years, we should be celebrating the dandelion, not trying to eradicate it from our lawns. Just feast your eyes on some of the beauties that I have seen over the last few days.

Pollen beetles March 20th 2021

Male tawny mining bee Andrena fulva – Sutton March 25th 2021

Bumble bee, Sutton March 30th 2021

Seven spot lady bird, too early for aphids, Oulton Road March 30th 2021


Peacock butterfly in a very striking pose, Guild Lane, Sutton, April 3rd 2021.

I’m not alone in my love of dandelions 🙂

We shouldn’t forget the humble daisy either. It provides nectar to many butterfly species, including among others, the Green Hairstreak, the Grizzled Skipper, the Small Copper and the Small White. They are also important resources for honey bees (Raquier et al., 2015), bumblebees and hoverflies (Blackmore & Goulson, 2014).

A nice patch of daisies.

Domestic gardens, if managed correctly, have tremendous potential as reservoirs of insects and other invertebrates of ecological importance (Davies et al, 2009). The easiest thing that you can do to help the insects is to reduce the frequency at which you mow your lawn and grass verges. To sum it up in a nutshell, the less you move, the more flowers you get and the more flowers you get the more nectar and pollen feeding insects you make happy, some of which can be rare and endangered (Wastian et al., 2016).  

The less frequently you mow, the more flowers you get. The more flowers you get, the more bumblebees you get (George, 2008).

It is not just flower feeding insects that benefit from reducing your lawn mowing activities; grass feeding insects also benefit from longer grass ( Helden & Leather, 2005) and if, for some strange reason, you are not a great fan of bugs, just remember that the more bugs you have the more birds you will attract (Heden et al.,  2012). So do your bit to save the planet, be like me, only mow your lawn twice a year.

References

Aldrich, R.J. & Kremer, R.J. (1997) Principles in Weed Management. Panima Publishing Corporation.

Begon, M., Harper, J,L. & Townsend, C.R. ( 1996) Ecology, 3rd Edition, Blackwell Science, oxford.

Blackmore, L.M. & Goulson, D. (2014) Evaluating the effectiveness of wildflower seed mixes for boosting floral diversity and bumblebee and hoverfly abundance in urban areas. Insect Conservation & Diversity, 7, 480-484.

Davies, Z.G., Fuller, R.A., Loram, A., Irvine, K.N., Sims, V. & Gaston, K.J. (2009) A national scale inventory of resource provision for biodiversity within domestic gardens. Biological Conservation, 142, 761-771.

De Wet, J.M.J., Harlan, J.R.  (1975) Weeds and domesticates: Evolution in the man-made habitat. Economic Botany, 29, 99–108.

Emerson, R.W.(1878) The Fortunes of the Republic. The Riverside Press, Boston, USA.

Garbuzov, M., Fensome, K.A. & Ratnieks, F.L.W.  (2015)   Public approval plus more wildlife: twin benefits of reduced mowing of amenity grass in a suburban public park in Saltdean, UK. Insect Conservation & Diversity, 8, 107-119.

George, W. (2008) The Birds and the Bees: Factors Affecting Birds, Bumblebees and Butterflies in Urban Green Spaces, MSc Thesis, Imperial College, London.

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

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

Lerman, S.B., Contostac, A.R., Milamb, J. & Bang, C. (2018) To mow or to mow less: Lawn mowing frequency affects bee abundance and diversity in suburban yards. Biological Conservation, 221, 160-174.

Requier, F., Odoux, J., Tamic, T.,Moreau, N., Henry, M., Decourtye, A. & Bretagnolle, V. (2015)  Honey bee diet in intensive farmland habitats reveals an unexpectedly high flower richness and a major role of weedsEcological Applications, 25, 881–890.  

Wastian, L., Unterweger, P.A.& Betz, O. (2016) Influence of the reduction of urban lawn mowing on wild bee diversity (Hymenoptera, Apoidea). Journal of Hymenoptera Research, 49, 51–63.

Wilcox, E.W. (1911) Poems of Progress and New Thought Pastels. London: Gay & Hancock, 1911.

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Bee’s knees, a gnat’s whisker, knee-high to a grasshopper, a flea in your ear and other insect idioms

Idiom a group of words established by usage as having a meaning not deducible from those of the individual word

I’m fond of saying that I have been an entomologist since I was knee-high to a grasshopper, which I automatically expect my audience to understand means since I was very young.

Knee-high to a grasshopper?

What I didn’t know was that this well known phrase only dates from about 1850 and replaced the earlier knee-high to a mosquito or bumblebee or splinter. I can find no explanation as to why this change occurred; perhaps it was because someone felt sorry that the Orthoptera didn’t have any idioms associated with them as opposed to the Hymenoptera which dominate the insect idiom world.  “Rightly so” I can hear the Hymenopterists exclaiming, “after all there are more of them than any other Order” (Forbes et al., 2018).

Hymenoptera

When I go into the Entomology Lab I expect it to be a “hive of activity” where everyone is as “busy as a bee” and there is a “real buzz”.

Strangely enough, despite the hymenopteran references I would hope that my students are all working on aphids, but then some people would say that I have “a bee in my bonnet” about them and I will definitely be making “a beeline” to the aphid cultures shortly after I arrive as I think that aphids are the “bee’s knees” when it comes to insects 🙂 I can get quite

waspish” when I hear people making disparaging remarks about aphids although I would never describe myself as getting as “mad as a hornet” over the matter. In fact I love aphids so much that if someone asks me why I do, I will never say “none of your beeswax” and you might think that I “have ants in my pants”  as I wait for an opportune moment to explain about the “birds and the bees” when applied to aphid reproduction.

Diptera

Erica McAlister author of The Secret Life of Flies will tell you that flies are where it’s at and it is certainly worth being “a fly on the wall” when Erica starts talking about flies in general.

Unless you have “the attention span of a gnat” you will be enthralled by her anecdotes. The only “fly in the ointment” is that some of her flies have absolutely disgusting habits.  Erica herself, “wouldn’t hurt a fly”, no matter how unsavoury its lifestyle. I have heard it said, that sometimes, the less strong-stomached members of her audience, can be seen “dropping like flies”.  I confess that I am a bit worried that if Erica reads this I will come within a “gnat’s whisker” of being slapped in the face 🙂 Speaking of gnats, I just found this expression in a detective novel published in 1932 (Wilkinson, 1932) “antiquated gnat of a custom”, but have not been able to find out exactly what it means and its origin – any suggestions welcomed.

Lepidoptera

No one could describe me as being as “gaudy as a butterfly” as my usual attire is a pair of blue jeans, a shirt with rolled up sleeves and a pair of desert boots, although I do have some butterfly-themed clothing.

Gaudy as a butterfly – nope

The previous sentence reminds me that I have written about dress codes in an earlier post,  and the role this might have in curing the feeling of “having butterflies in one’s stomach” before giving a talk. Speaking of nervousness coupled with shyness, something many of us feel in social situations, which can cause some of us to imbibe liquids containing alcohol, I find that even after a few drinks I am not much of a “social butterfly”, a garrulous drunk is probably the best description 🙂

Everything got a little bit hazy

Coleoptera

Now you might think that the Coleoptera, having, at the moment, the most species described would have provided us with a plethora of beetle inspired idiomatic expressions. Sadly as I “beetle along” in my “beetle crushers” I very soon come to the end of their influence on idiomatic English.  Just to make any coloepterist who might be reading this feel a bit better, the narrator in Rudyard Kipling’s Stalky & Co (a humorous novel about late Victorian schoolboys) is nicknamed Beetle, possibly because Kipling, like me, could be described as “beetle-browed”.

Beetle-browed, although my wife has been known to describe them as looking like furry caterpillars

Siphonoptera (Mecoptera)

Leaving the beetles behind us we come across the Siphonoptera, the fleas. Some people might say I have “a mind like a flea” but did you know that fleas have been recently re-classified as parasitic scorpionflies (Tihelka et al., 2020), which might make those people who say they “wouldn’t hurt a flea” think twice about using that phrase or the term “fleabag”.

Insects in general

As someone whose favourite insects are Hemipteran, I would love to say that the greatest number of insect idioms are provided by the true bugs, but that would be untrue. In general, when non-entomologists use the word bug, they mean insects in general, a particular “bugbear” of mine. I would go as far as to say that it really “bugs me”. In fact, I’d love to put “a bug in someone’s ear” about it and if I came across a journalist using bugs correctly I’d certainly go “bug-eyed”. I’m writing this in my warm centrally-heated house, feeling as

Not only snug as a bug but an example of one of my bugbears!

snug as a bug in a rug” although once this pandemic is over I’m pretty sure that the “travel bug” will bite me, and I’ll be heading off to France to enjoy great food, good wine and plenty of sunshine.

References

Forbes, A.A., Bagley, R.K., Beer, M.A. et al. (2018) Quantifying the unquantifiable: why Hymenoptera, not Coleoptera, is the most speciose animal order. BMC Ecology, 18, 21.

Tihelka , E., Giacomelli, M.,Huang, D., Pisani, D., Donoghue, P.C.J. &  Cai, C. (202o) Fleas are parasitic scorpionflies. Palaeoentomology,3, 641–653.

Wilkinson, E. (1932) The Division Bell Mystery, George Harrap & Co Ltd, London. Reprint available via the British Library Crime Classics series

Glossary

Hymenoptera

a bee’s dick – a very small amount https://stronglang.wordpress.com/2017/08/21/a-new-cooking-measurement/

a hive of activity – a place/situation where everyone is busy

ants in your pants/antsy – agitated or restless due to nervousness or excitement

as busy as a bee – very busy

as mad as a hornet – very angry

bee’s knees – an excellent person or thing, of the highest quality

birds and the bees – a euphemism for the basic facts about reproduction as told to a child

none of your beeswax – none of your business

to have a bee in one’s bonnet – to be preoccupied/obsessed with something

to make a beeline – to move swiftly and directly towards something or someone

Diptera

dropping like flies – dying or collapsing in large numbers, giving up on or pulling out of an endeavour

fly in the ointment – a small problem which nonetheless spoils the whole plan

fly on the wall – an unnoticed witness

wouldn’t hurt a fly – used to emphasize how inoffensive and harmless a person or animal is

Lepidoptera

as gaudy as a butterfly – very colourful

social butterfly – a person who is socially dynamic, successful at networking, charismatic, and personally gregarious

to have butterflies in one’s stomach – to feel nervous/anxious/excited in your stomach

Coleoptera

Beetle along – hurry, scuttle

Beetle-browed – having shaggy and projecting eyebrows

Beetle crushers – large shoes/boots

Siphonoptera (Mecoptera)

a flea in (someone’s) ear – an unwelcome idea or answer

mind like a flea – jumping from one idea to another

fleabag – a dirty or shabby person or animal, typically one infested with fleas or a seedy and dilapidated hotel

wouldn’t hurt a flea – gentle and kind

Insects in general

as snug as a bug (in a rug) – very comfortable/cosy

bug-eyed – with bulging eyes, astonished, amazed

to bug someone – to annoy someone

to put a bug in someone’s ear about something – to give someone a hint about something

travel bug – a strong desire to travel; an obsessive enthusiasm for or addiction to travellin;

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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.

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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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