Pick & Mix 41 – some links to entertain and inform

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

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

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

Did bird vaginas evolve to fight invading penises?

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

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

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

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

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

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

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The Natural World in Haiku Form – Volume 3

In what is now a tradition, this is my third collection after all, I have gathered together all the haikus I have written and tweeted over the last  year and present them here for light relief.

 

Plants and seasons

 

Waterside willows,

weeping greenly in the sun.

 Spring is with us now

Harper Adams 20 March 2019

 

Old school entomology

 

Fragrantly flowered

Prunus laurocerasus;

Insect killing jars

Harper Adams 10th April 2019

 

Hedgerow bounty

 

Green and berry red,

Autumn bounty in the hedge

Feeds winter wildlife

Harper Adams September 10th 2019

 

Recycling

 

Autumnal fungi

Springing forth through soft and hard.

From death, new life fruits

Harper Adams September 25th 2019

 

Sorbus green, Sorbus red

 

Sorbus on the turn

Autumn colours on the way

summon falling leaves

Harper Adams October 14th 2019

 

 

Languedoc autumn

 

Oaks with leaves unshed,

Acorns crunching underfoot.

Autumn in Languedoc

Vinca 3rd November 2019

 

Winter icumen in

 

Stark against the sky

Field maples stripped of their leaves

Herald winter’s chill

Sutton 29 November 2019

 

Brown Flutterby

 

Brown leaf flutters by

Heading downward from the sky.

Landing, with a sigh.

January 11th 2019 Vinca

 

Entomology

 

Honeydew

 

As sweet as honey,

Aphid poo; feeds bees, wasps, ants,

Also flies and plants

Harper Adams 2th April 2019

 

Protected

 

Black attendant ants

protect these aphids on broom;

paid in honeydew

Vinca 3rd June 2019

 

Agapanthia villosoviridescens

 

Leisurely flying

and easily grasped by hand.

Now, safely set free 🙂

Harper Adams University

27 June 2019

 

Weather

 

Rain

 

Rain and yet more rain.

Puddling in yards, splashed by cars.

Will it ever stop?

June 12th 2019 Harper Adams University

 

Scented rain

 

A drop of light rain

is just enough, to bring forth

the scent of hawthorn

 

or alternatively

 

A drop of light rain;

and then the scent of hawthorn

floats fragrantly by

Harper Adams 24th April 2019

 

Vertebrates

 

A plurality of sheep

 

Sheep, sheep, sheep, sheep, sheep

Done chomping, now digesting

Sleepy sheep, sheep sleep.

7th May 2019

Harper Adams University

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

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

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

The figure as shown in Victor Moran’s paper.

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

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

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

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

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

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

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

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

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

 

 

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

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

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

References

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

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

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

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

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

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

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

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

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

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

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

 

 

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The Roundabout Review 2019 – navel gazing again

Welcome to my, now very, very definitely, traditional review of the past year.

A new roundabout – Jennett’s Park, Bracknell – I have no idea what it is meant to signify

 

Impact and reach

I have continued to post at about ten-day intervals; this is my 273rd  post.  As I wrote last year, there never seems to any difficulty in coming up with ideas to write about; the problem is more in deciding which one to use and when.  As happened last year, some of my blogs have, albeit in slightly modified forms, made it into print (Cardoso & Leather, 2019).

Many of you remain lukewarm about the idea that social media has a place in science. I would, however, ask you to think again and if you need any more convincing, read this paper that very clearly demonstrates the benefits arising from such interactions (Côté & Darling, 2018); evidence that science communication via social media is a very worthwhile use of our time. Highlights of the year included a joint blog with Stephen Heard, about paper titles. Semi-related to my Blogging and Tweeting are my other forms of science communication, giving talks and helping at outreach events, such as the Big Bang Fair, which continue unabated.  I also had three Skype a Scientist dates this year, two with schools in the USA and one with a school in Switzerland.  I really enjoyed the experience and hope that the pupils were as pleased as I was. If you have not come across this scheme, check them out here.

My blog had visitors from 179 countries (181 last year, 165 in 2017, 174 in 2016 and 150 in 2015), so only another 16 to go to achieve total global domination 😊  My blog received 63 710 views (54 300 last year,  40 682 in 2017,  34 036 in 2016; 29 385 in 2015). As with last year, most views came from the USA, with views from India holding on to 4th place and Nigeria entering the top ten for the first time.

Top ten countries for views

Top reads

My top post (excluding my home page) in 2019 was the same as last year, one of my aphid posts,  A Winter’s Tale – Aphid Overwintering, (with almost 200 more reads this year than last, 4108 to be precise) although there may have been some disappointment felt by those who were hoping to find a reference to Shakespeare’s play or the song by Queen. It is now my all-time winner with just over 13 000 views, with Not All Aphids are Vegans with over 11 000 views still maintaining an honourable second place.  My top ten posts continue to be either about aphids or entomological techniques/equipment, which I guess means that I am filling an entomological niche. Aptly, my two posts about the loss of insects made it into the top ten this year.

A Winter’s Tale – aphid overwintering 4,108
Not all aphids are vegans 2,458
“Insectageddon” – bigger headlines, more hype, but where’s the funding? 1,829
Aphid life cycles – bizaare, complex or what? 1,762
Meat eating moths 1,226
Entomological Classics – The Pooter or Insect Aspirator 1,217
Not Jiminy Cricket but Gregory Grasshopper – someone ought to tell Walt 1,158
Ten papers that shook my world – watching empty islands fill up – Simberloff & Wilson (1969) 1,089
Entomological classics – the sweep net 1,052
Global Insect Extinction – a never ending story 1,045

 

My Pick & Mix link fests stalwartly foot the table, although disappointingly, my second collection of natural history haikus is also in the bottom ten 😦

Trends

Although in general, there still seems to be no signs of the number of people viewing my site reaching an asymptote or for that matter, the figures for December were the lowest of the year, by a considerable margin.  Is this the beginning of the end?

Linear still the best fit but is it levelling off?

Tweeting for entomology

I still find my interactions on Twitter very rewarding, although this past year I have become somewhat more political; Brexit and Trump, need I say more?  Most of my tweets are, however, still entomological and ecological and the increase in political comment has not stopped my followers from growing.  I finished 2018 with 6884 followers and begin 2020 with just over 8000, 8088 to be precise.   Many thanks to all my readers and especially to those who take the time to comment as well as pressing the like button.  My top commenters, as indeed they were last year, were fellow bloggers, Emma Maund, Emily Scott, Jeff Ollerton, Amelia from A French Garden and Philip Strange.  I look forward to interacting with you all in 2020.

In theory I am semi-retired from my daytime job, academia but I hasten to add, not from entomology.  I do, however, seem to be spending considerably more than 60% of my time doing stuff that I thought I would no longer have to do 😦

This time last year, I reported that I had submitted a proposal to OUP for a semi-popular entomology book.  I am happy to report that it was accepted, and I am now behind schedule in writing Insects – A Very Short Introduction 🙂

On a less happy note; to me, this has been, in some ways, a horrendous year.  Due largely to the selfish, bigoted and xenophobic behaviour of a large proportion of my very privileged generation, we are set to leave the great European project that has kept Europe largely peaceful for more than forty years. I would remind you, that not all of us voted to deprive our children and grandchildren of the rights and privileges that we have enjoyed since 1975.  It is also appropriate to remember that my father and his generation fought to enable us to enjoy that peace.

My late father (a fervent pro-European) and I (equally pro-EU), both aged 21; he in 1945 after having served in the Royal Marines since he was 17, endured the D-Day landings and fought in the Pacific, me in 1976, in my penultimate year at Leeds University. My teeth would have been the same but I had braces as a child 🙂

On the other hand, a lot of good things have happened; new friends, old friends and family all make life worth living, so in the words of the song “pick yourself up, dust yourself off and start all over again”.

A Happy and Prosperous New Year to you all.

References

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

Côté, I.M. & Darling, E.S. (2018) Scientists on Twitter: preaching to the choir or singing from the rooftops?  Facets, 3, 682-694.

*The number of views for my annual reviews are as follows: 2014 (86), 2015 (110), 2016 (179), 2017 (115, of which 112 were in January).

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Merry Christmas Everyone

Hope you all have a great Christmas and a Happy New Year.  Many thanks to all my readers and especially to those of you who share my posts on Twitter and other social media platforms.  It is much appreciated.

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Pick & Mix 40 – An early Christmas present

A history of the use of holly

Kissing under the mistletoe – why do we do it?

Advent botany – plants used to celebrate Christmas around the world

More advent botany – this time from Jeanne Osnas

At this time of year you are quite likely to find butterflies in the house – this is what you should do with them

Fascinating video about the evolution of humans with a haunting soundtrack

Turns out we can’t blame Jimi Hendrix or Katherine Hepburn for the UK’s parakeets 🙂  If you want to read the scientific version it it is here

Turning science into fiction – check it out

Why don’t modern day scientists write like Darwin?

Long live the apostrophe – we need them desperately

 

 

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Leaf blowers – disturbing the peace and fatal to insects?

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

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

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

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

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

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

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

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

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

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

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

I like this one as it is a Scarab 😊

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

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

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

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

 

References

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

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

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

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

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

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

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

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

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

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

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

 

 

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Pick & Mix 39 – conservation, trophy hunting, palm oil, Charles Darwin, kale and much more

An example of the double-think of creationists  – evolution doesn’t exist but natural selection does!

On the practice of naming new species after awful people

To boycot palm oil or not – this conservation biologist makes a good case for not

The lengths some people go to complete their collections

Wonderful story about Art Shapiro’s long-tem data set, 47 years and counting

Kale, I can’t stand the stuff, but clever marketing has convinced a lot of people that it is great 🙂

Did you know that Charles Drawin drew more than one tree of life before deciding on the one we all know?

Fascinating spider facts and photographs from Ray Cannon

Interesting read about what happened when some conservation scientists suggested that banning trophy hunting might be bad for conservation efforts

Are you concerned about an insect apocalypse? For starters, kill your lawn.

 

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

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

Wings, beautiful wings (very much not to scale)

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

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

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

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

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

Exopterygota

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

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

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

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

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

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

Grasshopper wings

Dictyoptera        Cockroaches, termites and allies, net wings

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

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

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

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

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

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

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

Feathery thrips wing – Photo courtesy of Tom Pope @Ipm_Tom

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

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

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

Siphonaptera     Fleas – tube without wings, referring to their mouthparts

 

Endopterygota

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

The pointy end of a female snakefly

Megaloptera      Alderflies, Dobsonflies – large wings

Neuroptera        Lacewings – veined wings

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

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

The Royal Entomological Society Strepsipteran

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

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

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

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

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

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

Moth wing with displaced scales

 

Hymenoptera    Wasps, bees, ants – membrane wings

Wing of a wood wasp, Sirex noctilio

 

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

 

*

 

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Weevily clever – on being behaviourally resistant

I am currently sharing my office with a Tupperware container of weevils, Hylobius abietis, the Large pine weevil to be exact.  The reason, just in case you were wondering, is that I have had an undergraduate doing her final year research project with me on ways in which this highly pestiferous weevil might be prevented from feeding on newly planted conifers.  The weevils in my office are those that were left over from her project and being the old softie that I am, and having worked on Hylobius since 1987 I couldn’t bear to throw them away :.)

My office pets – easy to maintain and quite cute

Adult and larvae of Hylobius abietis

You might think that having worked on an insect with the sole aim of trying to reduce its pestiferousness, that I might have succeeded by now.  Say that to the many scientists who have addressed this problem for more than a century and you will be rewarded with the sound of hollow laughter.  The laughter is even hollower if you point them to the statement made by the first UK Forestry Commission entomologist,  J W Munro, who a mere ten years after the formation of the Forestry Commission wrote “The pine weevil (Hylobius abietis) problem still occupies the attention of the Forestry Commissioners” Munro (1929).  Ninety years on I can make exactly the same statement and judging by the global number of papers written about Hylobius, I think I can confidently state that the same can be said for the forest industry as a whole.

Not a problem that is going away! Papers published on Hylobius abietis since 1910.  Data from Google Scholar and Web of Science.

So why is the large pine weevil, or Hylobius as those of us who work on it or attempt to control it, call it so hard to manage? The simple answer is that we have helped it become a pest in the first place and in the second place it has a couple of attributes that give it a bit of an edge. You might even go so far as to say that it is a clever little beast.

First a little bit of history is in order. Up until the beginning of the 20th century references to Hylobius are few and far between, especially in the UK, although there are some German references from the latter half of the 19th Century, a reflection of the fact that the German forest industry was well in advance of that in the UK. Prior to the establishment of conifer plantations, populations of Hylobius would have been small and scattered as the larvae need conifer stumps or large pieces of fallen branch in which to develop.  The adults, which can live for up to four years (Leather et al., 1999), would normally feed on the cambium of thin barked twigs in the upper canopy of conifer trees, and the larvae, depending on how shaded the host stump was, could take from a year to two years to reach adulthood.  The adults are extremely responsive to host volatiles (Nordenhem & Eidmann, 1991) and can locate host plants and egg-laying sites remarkably quickly*.  Plantation forestry with its cycles of clear-fell and subsequent restocking with two year old conifer saplings has been akin to setting up a deliberate breeding programme for Hylobius.  In some cases 100% of all new planting can be destroyed by the adults ring-barking the saplings and on average 30% would be lost if plants were not pre-treated with insecticide.

How to turn an innocuous forest insect into a major pest. Plantation forestry and how it created a forest pest. (Figure adapted from Leather et al, 1999).

Over the years there have been a number of attempts at controlling Hylobius without using insecticides, including cultural methods, physical barriers and biological control using entomopathogenic nematodes (Williams et al., 2013), none of which have been as effective as insecticidal treatment. The latter, although reasonably effective at preventing sapling damage, may not, however, be reducing Hylobius numbers.  This is because Hylobius is, as well as being good at detecting host volatiles, also great at detecting and avoiding insecticides.  A former PhD student of mine, Dan Rose, showed this is in a series of elegant experiments where he manipulated insecticide presence and absence at different scales (Rose et al., 2005).  First he tested if adult Hylobius could detect the presence of an insecticide at a whole plant level, by giving them a choice in semi-field conditions between treated and untreated saplings.  They could, they avoided feeding on treated plants.  Then he gave them a choice of plants where he had sprayed half the canopy with an insecticide, and, yes, you guessed it, they only fed on the untreated parts.

 Given a choice, adult Hylobius abietis will not feed on insecticide treated plants or on those parts of a tree that have been treated with an insecticide

Dan wondered just how good their discriminatory powers were, so using our standard choice boxes,

Standard Hylobius abietis host choice test box

he presented his weevils with pieces of pine twig that had had insecticide painted on to them alternating with equal width untreated stripes, and yes, you guessed, they only ate the untreated parts of the twig.

  Adult Hylobius abietis only fed on the untreated stripes.

Next he sprayed twigs all over, but some with large droplets and some with fine droplets and then gave them the choice between a coarse sprayed twig and a fine sprayed one and as you may have guessed,  they were able tell the difference, and fed on the twigs with the bigger spaces between the droplets of insecticide.

Given a choice between twigs treated with a large droplet spray and a fine droplet spray, adult Hylobius abietis will feed on the twigs with the large droplet size spray application.

 

So this is an indication that adult Hylobius are behaviourally resistant to insecticides, well at least the ones he tested them against. Hylobius are not alone in possessing this trait, other weevils (Haddi et al., 2015) and at least one aphid species (Fray et al., 2014) are also able to detect and avoid insecticide treated substrates.

Hylobius adults are also quite resistant to insecticide poisoning when you force them to eat treated plant material. Some individuals take almost three weeks to die and then if they are removed from the insecticide treated food they soon return to normal.

Figure borrowed from Rose et al.,( 2005)

Remarkable rate of recovery (Figure borrowed from Rose et al., (2006)

 

Hylobius abietis adults are able to recover from pesticides if given the chance, even after a week of exposure.

Given that they are able to recognise and avoid eating treated plant material and if they do, show remarkable powers of recovery, it is very likely that in the field, the reason that the insecticidal treatment works is more to do with repellence than toxicity, so it is unlikely that weevil popualtions are reduced.

To reduce populations rather than divert them elsewhere and given the pressure to remove pesticides from the forest environment, a biological control approach is the logical best option. Entompathogenic nematodes are probably the best option and have received  a lot of attention over the last thirty years or so (Williams et al., 2013), but again Hylobius has a tactic or two up its elytra to make it more difficult to control than other insect pests.  First, like its North American cousin, Hylobius pales (Cornell & Wilson, 1984; Moore, 2001), it can play dead, a phenomenon known as thanatosis or death feigning. In human terms, when they see/feel a nematode approaching, they hold their breath and collapse in a heap. In insect terms, they close their spiracles, the point of entry for the nematodes, and hope that the nematodes give up and go away before they have to breathe again.  If they do have to breathe when the nematodes are still in contact with them then clever old Hylobius is able to brush them away (Ennis et al., 2010). Biological control of adult Hylobius is thus unlikely to be successful, and the larvae and their stump habitats are now the main target of biological control methods (Williams et al., 2013).

Clever, cute and long-lived, what more can you ask for in a pet or should that be pest? 🙂

 

References

Cornell, J.A. & Wilson, L.F.  (1984) Dispersion and seasonal activity of the pales weevil, Hylobius pales (Coleoptera: Curculionidae), in Michigan Christmas tree plantations. Canadian Entomologist, 116, 711-717.

Ennis, D.E., Dillon, A.B. & Griffin, C.T. (2010) Pine weevils modulate defensive behaviour in response to parasites of differing virulence. Animal Behaviour, 80, 283-288.

Fray, L.M., Leather, S.R., Powell, G., Slater, R., McIndoe, E. & Lind, R.J. (2014) Behavioural avoidance and enhanced dispersal in neonicotinoid-resistance Myzus persicae (Sulzer). Pest Management Science, 70, 88-96.

Haddi, K., Mendonça, L.P., Dos Santos, M.F., Guedes, R.N.C & Oliveira, E.E. (2015) Metabolic and behavioral mechanisms of Indoxacarb resistance in Sitophilus zeamais (Coleoptera: Curculionidae). Journal of Economic Entomology, 108, 362-369.

Leather, S.R., Day, K.R. & Salisbury, A.N. (1999) The biology and ecology of the large pine weevil, Hylobius abietis (Coleoptera: Curculionidae): a problem of dispersal? Bulletin of Entomological Research, 89, 3-16.

Moore, R. (2001) Emergence trap developed to capture adult large pine weevil Hylobius abietis (Coleoptera: Curculionidae) and its parasite Bracon hylobii (Hymenoptera: Braconidae). Bulletin of Entomological Research, 91, 109-115.

Munro, J.W. (1929) The biology and control of Hylobius abietis L. Part 2. Forestry, 3, 61-65.

Nordenhem, H. & Eidmann, H.H. (1991) Response of the pine weevil Hylobius abietis L. (Col. Curculionidae) to host volatiles in different phases of its adult life cycle. Journal of Applied Entomology, 112, 353-358.

Nördlander, G., Hellqvist, C., Johansson, K. & Nordenhem, H. (2011) Regeneration of European boreal forests: effectiveness of measures against sedling mortality caused by the pine weevil Hylobius abietis. Forest Ecology and Management, 262, 2354-2363.

Rose, D., Leather, S.R. & Matthews, G.A. (2005) Recognition and avoidance of insecticide-treated Scots pine (Pinus sylvestris) by Hylobius abietis (Coleoptera: Curculionidae): implications for pest management strategies. Agricultural and Forest Entomology, 7, 187-191.

Rose, D.R., Matthews, G.A. & Leather, S.R. (2006) Sub-lethal responses of the large pine weevil, Hylobius abietis, to the pyrethroid insecticide lambda-cyhalothrin. Physiological Entomology, 31, 316-327.

Williams, C.D., Dillon, A.B., Harvey, C.D., Hennessy, R., McNamara, L. & Griffin, C.T. (2013) Control of a major pest of forestry, Hylobius abietis, with enomopathogenic nematodes and fungi using eradicant and prophylactic strategies. Forest Ecology & Management, 305, 212-222.

 

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