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“Ecological Armageddon”, we’ve known for years that insects are in decline so why so much fuss now?

Unless you have lived in a news vacuum for the last two weeks or so, you will be aware of the impending “Ecological Armageddon” that is about to be unleashed upon us.  A paper in the journal PLoS ONE  in which it was reported that there had been a 75% decline in the biomass of flying insects in protected areas in Germany since 1989 was the starting pistol that began the media frenzy.  The newspapers, both broadsheet and tabloids were quick to react as were the radio and TV stations and the coverage was global as this selection of links shows.

https://www.nytimes.com/2017/10/29/opinion/insect-armageddon-ecosystem-.html

https://www.theguardian.com/environment/2017/oct/18/warning-of-ecological-armageddon-after-dramatic-plunge-in-insect-numbers

http://www.independent.co.uk/news/science/flying-insects-numbers-drop-ecological-armageddon-75-per-cent-plummet-a8008406.html

http://www.express.co.uk/news/science/868283/Armageddon-end-of-the-world-Germany-insects-Sussex-University-UK-Government

https://www.hs.fi/ulkomaat/art-2000005414880.html

https://risingsunoverport.co.za/53144/enviro-monday-flying-insect-populations-declining-drastically-germany/

https://www.washingtonpost.com/world/europe/buzz-off-german-study-finds-dramatic-insect-decline/2017/10/19/6a087d40-b4c8-11e7-9b93-b97043e57a22_story.html?utm_term=.00836ee55dca

Entomologists were in great demand for a few days, all being asked to comment gravely on the paper and its implications.   I was also persuaded to air my thoughts on air, Talk Radio having caught me at an unguarded moment.  I should never have answered the ‘phone 😊

As the media frenzy subsided, the more considered responses began to appear.  Manu Saunders very sensibly attempted to put the study in perspective and point out its limitations. Two entomologists from the Game & Wildlife Conservancy Trust which hold an even longer data set, put forward their interpretation and an ecological consultancy also took the opportunity to comment.  The authors of the paper and the blog commentators were careful not to point the finger directly at pesticides as the main cause of this decline, although they did rule out climate change.  Agricultural intensification and the practices associated with it, were however, suggested as likely to be involved in some way, something that has been known for more than a century as the naturalist and novelist Gene Stratton-Porter  pointed out in 1909  in her novel A Girl of the Limberlost,

 Men all around were clearing available land.  The trees fell wherever corn would grow. The swamp was broken by several gravel roads…Wherever the trees fell the moisture dried, the creeks ceased to flow, the river ran low, and at times the bed was dry.  From coming in with two or three dozen rare moths a day, in three years time Elnora had grown to be delighted with finding two or three. Big pursy caterpillars could not be picked from their favourite bushes, where there were no bushes. Dragonflies could not hover over dry places and butterflies became scare in proportion to the flowers”.

What puzzles me about the media response is why now and why this particular study?  We have known for a long time that some insect groups have been in decline for many years.  The parlous state of UK butterflies and moths has been highlighted on more than one occasion over the last couple of decades (e.g. Conrad et al., 2004; Thomas et al., 2004; Fox et al., 2013), and declines in the abundance of bibionid flies (D’Arcy-Burt & Blackshaw, 1987), dragonflies (Clausnitzer et al., 2009) and carabid beetles (Brooks et al., 2012) have also been noticed and written about.  In addition, the results of a 42-year study on insects associated with cereal fields in SE England was published recently (Ewald et al., 2015), with little or no fanfare associated with it.  I commented on the decline of some insect species (and entomologists) in a blog post in 2013 and in December of last year, wrote about the general decline of insect numbers and lack of long term studies, incidentally citing the German study when it was originally published in a little known German publication back in 2013 and with far fewer authors 😊

The media response to this not new news puts me in mind of the Ash Die Back scare of 2012 when the press and politicians having

Pests and diseases recorded as entering the UK 1960-2015.  The two arrows indicate the replacement of local forest offices with central district offices and reduction in entomology and pathology staff.

been warned and made aware of the increasing incidence of non-native pests and pathogens entering the country for many years beforehand, suddenly, and in response to an intractable problem, went overboard in reporting doom and destruction

https://www.theguardian.com/environment/2012/nov/09/ash-dieback-disease-impossible-eradicate

https://www.theguardian.com/environment/2012/oct/24/ash-dieback-disease-east-anglia

http://www.telegraph.co.uk/news/earth/earthnews/9566224/Deadly-fungus-in-Ash-trees-could-be-next-Dutch-elm-disease-warns-Woodland-Trust.html

http://www.abc.net.au/am/content/2012/s3620359.htm

My hypothesis, for what it is worth, is that it is like when a tap washer starts to wear out, and your tap starts to drip. At first you just ignore it or turn the tap ever more tightly every time you use it.  Eventually something gives, either the tap breaks off (this happened to me very recently) or the drip becomes a flood.  Either way, something needs to be done, i.e. call the plumber.  In the case of the Ash Die Back episode, the UK government responded positively, albeit too late to prevent it, but by setting up the Tree Health and Plant Biosecurity Expert Taskforce of which I was privileged to be a member, recommendations were made that resulted in increased forest research funding and additional legislation being put in force to hopefully reduce the chances of further invasions.  I suspect that the current “Ecological Armageddon” scenario will not result in a similar response, although it may encourage research councils worldwide to think more seriously about funding more research into sustainable agriculture and for governments to encourage farmers to adopt farming strategies that encourage more wildlife and use fewer inputs.  At the same time, given the increasing number of studies that implicate urbanisation as a major factor in the decline of insect numbers (e.g. Jones & Leather, 2012; Dennis et al., 2017) it would behove local planning authorities to increase their efforts to provide much-needed green spaces in our towns and cities and to ban the use of decking in gardens and the replacement of front gardens with concrete and tarmac car parking areas.

What it does highlight as Manu Saunders said in her blog, is that we need funding for more long-term studies.  We also need to find instances where the data already exist but have not yet been analysed, amateur records and citizen science projects may be of use here.  Alternatively, as was very recently done in France (Alignier, 2018), it is possible, using the identical protocol, to resample a site after a gap of decades, to see what changes have occurred.

I hope for the sake of our descendants that the reports of an “Ecological Armageddon” have been exaggerated.  This should however, be a wake-up call to all those with the power to do something to mitigate the decline in biodiversity worldwide.  Governments need to respond quickly and to think long-term and responsibly.  The current attitude of politicians to adopt a short-term ‘how safe is my job’ political viewpoint is no longer a viable one for the planet. It is precisely that attitude that got us into the situation that we find ourselves in now.

References

Alignier, A. (2018) Two decades of change in a field margin vegetation metacommunity as a result of field margin structure and management practice changes. Agriculture, Ecosystems & Environment, 251, 1-10.

Brooks, D.R., Bater, J.E., Clark, S.J., Montoth, D.J., Andrews, C., Corbett, S.J., Beaumont, D.A., & Chapman, J.W. (2012) Large carabid beetle declines in a United Kingdom monitoring network increases evidence for a widespread loss of insect biodiversity. Journal of Applied Ecology, 49, 1009-1019.

Clausnitzer, V., Kalkman, V.J., Ram, M., Collen, B., Baillie, J.E.M., Bedjanic, M., Darwall, W.R.T., Dijkstra, K.D.B., Dow, R., Hawking, J., Karube, H., Malikova, E., Paulson, D., Schutte, K., Suhling, F., Villaneuva, R.J., von Ellenrieder, N. & Wilson, K. (2009)  Odonata enter the biodiversity crisis debate: the first global assessment of an insect group.  Biological Conservation, 142, 1864-1869.

Conrad, K.F., Woiwod, I.P., Parsons, M., Fox, R. & Warren, M.S. (2004) Long-term population trends in widespread British moths.  Journal of Insect Conservation, 8, 119-136.

Darcy-Burt, S. & Blackshaw, R.P. (1987) Effects of trap design on catches of grassland Bibionidae (Diptera: Nematocera).  Bulletin of Entomological Research, 77, 309-315.

Dennis, E.B., Morgan, B.J.T., Roy, D.B. & Brereton, T.M. (2017) Urban indicators for UK butterflies. Ecological Indicators, 76, 184-193.

Ewald, J., Wheatley, C.J., Aebsicher, N.J., Moreby, S.J., Duffield, S.J., Crick, H.Q.P., & Morecroft, M.B. (2015) Influences of extreme weather, climate and pesticide use on invertebrates in cereal fields over 42 years. Global Change Biology, 21, 3931-3950.

Fox, R. (2013) The decline of moths in Great Britain: a review of possible causes. Insect Conservation & Diversity, 6, 5-19.

Hallmann, C.A., Sorg, M., Jongejans, E., Siepel, H., Hofland, N., Schwan, H., Stenmans, W., Müller, A., Sumser, H., Hörren, T., Goulson, D. & de Kroon, H. (2017) More than 75% decline over 27 years in total flying insect biomass in protected areas. PLoS ONE. 12 (10):eo185809.

Jones, E.L. & Leather, S.R. (2012) Invertebrates in urban areas: a reviewEuropean Journal of Entomology, 109, 463-478.

Knowler, J.T., Flint, P.W.H., & Flint, S. (2016) Trichoptera (Caddisflies) caught by the Rothamsted Light Trap at Rowardennan, Loch Lomondside throughout 2009. The Glasgow Naturalist26, 35-42.

Thomas, J.A., Telfer, M.G., Roy, D.B., Preston, C.D., Greenwood, J.J.D., Asher, J., Fox, R., Clarke, R.T. & Lawton, J.H. (2004) Comparative losses of British butterflies, birds, and plants and the global extinction crisis.  Science, 303, 1879-1883.

 

 

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Prunella – mistress of plasticity

Now that I have your attention, this is not an article about soft porn or fetishes, but rather a paean for that humble ‘weed’ Prunella vulgaris – Self-heal, Heal all, Woundwort, Heart of the Earth and many other names, depending on where in the World you come from.   Prunella vulgaris is in the family Lamiaceae, so related to mints and dead-nettles.  It is an edible weed, the young leaves can be used in salads and it can also be used in soups, stews, or used whole and boiled as a pot herb.

The instantly (to me at any rate) recognisable flower of Prunella vulgaris

Prunella as I will now familiarly call her, has a very wide geographical native range and has also been introduced into South America where she does very well indeed (Godoy et al., 2011).

Distribution of Prunella vulgaris, blue native, brown introduced. http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:455176-1

 The name Prunella is derived from ‘Brunella’, a word which is itself a derivative, coming from the German name for quinsy, (a type of throat inflammation), die Braüne, which it was historically used to cure.  That is the other aspect of this glorious plant, it has many medicinal properties, hence the many common names refer to its healing powers, almost as many as Athelas of Lord of the Rings fame 😊  It was traditionally used in European herbal medicine for sore throats, fever reduction and like Athelas, for accelerating the healing of wounds (Matthiolus, 1626).  More recently it has become of interest as a possible cure for conditions associated with the herpes simplex virus (Psotováa et al., 2003) and inhibiting anaphylactic shock and other immediate type allergic reactions (Shin et al., 2001).  So truly a wonder drug, and again proving that “Old Wives Tales” are in many cases based on more than just superstition.

My interest in Prunella vulgaris, is however, based on its wondrous plasticity, as the three photographs below show nicely.  Depending on grazing (or mowing) pressure, Prunella can grow to reproductive maturity at heights  ranging from just over 2 cm to just under 30 cm. Truly remarkable.

I am of course, not the first person to be fascinated by this plasticity and the taxonomic and evolutionary ins and outs of this lovely plant (Nelson, 1965; Warwick & Briggs, 1979) but I still find it fascinating, and who knows, perhaps one day I might do some work on it myself 😊

The other thing that I like about Prunella is that she is also provides a living for aphids.  She has her own rare and specific one, Aphis brunellae, but is also kind enough to let a few other species make a living on her, Aphis gossypii, Aphis nasturtiiAulacorthum solani,  Macrosiphum euphorbiae, the ubiquitous Myzus persicae, M. ornatus and Ovatomyzus chamaedrys (Blackman & Eastop, 2006).

Aphis brunellae, rare in the UK – with thanks to the two Bobs for permission to use the photograph. http://influentialpoints.com/Images/Aphis_brunellae_colony_on_Prunella_vulgaris_c2015-08-21_15-37-27ew.jpg

 

Finally, you will have noticed that the Prunella aphid is A. brunellae, which is derived from the original name of Prunella (I guess Prunella Scales is happy, she could have been Brunella Scales).  Interestingly, her alter-ego was not removed until fairly recently, her tombstone is shown below.

References

Blackman, R.L. & Eastop, V.F. (2006) Aphids on the World’s Herbaceous Plants and Shrubs Volume 1 Host Lists and Keys.  Wiley, Oxford.

Godoy, O., Saldaña, A., Fuentes, N., Valladares, F. & Gianoli, E. (2011)  Forests are not immune to plant invasions: phenotypic plasticity and local adaptation allow Prunella vulgaris to colonize a temperate evergreen rainforest. Biological Invasions, 13, 1615-1625.

Matthiolus, P.A. (1626) Kräuterbuch.  Noringberg.

Nelson, A.P. (1965) Taxonomic and evolutionary implications of lawn races in Prunella vulgaris (Labiatae). Brittonia, 17, 160-174.

Psotová, J., Kolá, M., Sousek, J., Ívagera, Z., Vicar, J. &Ulrichová, J. (2003) Biological activities of Prunella vulgaris extract. Phytotherapy Research, 17, 1082-1087.

Shin, T.Y., Kim, Y.K. & Kim, H.M. (2001) inhibition of immediate-type allergic reactions by Prunella vulgaris in a murine model.  Immunopharmacology & Immunotoxicology, 23, 423–435.

Warwick, S.I. & Briggs, D. (1979) The genecology of lawn weeds III. Cultivation experiments with Achillea millefolium L., Bellis perennis L., Plantago lanceolata L., Plantago major L. and Prunella vulgaris L. collected from lawns and contrasting grassland habitats.  New Phytologist, 83, 509-536.

 

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The Natural World in Haiku form

Traditionally in the world of journalism, August is regarded as lacking any news of note, and is, in the UK at any rate, dubbed the “Silly Season”.  In homage to that view-point, and instead of doing one of of my usual blog posts, I searched for all the haikus I have tweeted over the last three years and present them here for light relief.

 

Thirsty snails

Short of water, snails

Circle and swirl on the rocks,

Waiting for a storm.

All the stones of any consequence were encrusted with snails.  Then the rain came and they were gone.

Italy 25 July 2014

 

Evening lift-off

Italian evening;

Bats swoop as stag beetles lift

Into lurching flight

Note the hole in the left elytrum, the resident kitten at our Italian holiday villa really enjoyed herslf snatching the poor lumbering beasties (in this case a Rhinoceros beetle) out of the air ☹

Italy 27 July 2014

 

Breakfast?

Italian morning;

Lizards scurry on the stairs

as cicadas sing

Admittedly not on the stairs, but close enough 😊

28 July 2014

 

Seasons

 

Spring has sprung

 White, pink fluttering,

the gentle breeze scattering;

cherry blossom falls

Outside my office – 24 May 2016

 

Summer?

Blue sky, sun shining

Ducklings following mother

Winged aphids – summer?

4 May 2016

 

Summer?

Dull, damp, cold drizzle.

Clouds glowering down on me.

Flaming June my foot 😦

29 June 2017

 

St Martin

September sunshine;

Eating lunch sitting outside.

What could be better?

10 September 2014

 

On the way

 September morning,

Sunlit, moist mist-laden trees;

Autumn is coming

8 September 2014

Autumn

Crickle, crackle; leaves,

underneath my slipping feet.

Autumn is with us.

20 October 2015

 

I used to camp here as a lad!

Sodden tent, wet feet.

Rolling hills and drystone walls.

English Lake District

8 October 2014

 

Damp

How I hate mizzle;

as wet as real rain, but no

comforting refrain

26 November 2015

 

Satisfaction

Shuffling through brown leaves

On a sunny autumn day;

So satisfying.

2 November 2016

 

Wet Pavements in Lille

Desert boots are great

except when soles are holey.

Then rain means wet feet

10 December 2014

 

Transience

Icing sugar snow,

Gently being washed away;

Grey drizzle falling

29 January 2015

Miscellanea

 

Job downside

Academics hate

marking student assignments

on a sunny day

7 December 2016

 

Sunday lunch

 Butterflied mint lamb

roast potatoes and carrots;

apple and pear tart.

11 December 2016

 

Dedicated to @IMcMillan who spends a lot of time at stations

Cardboard coffee cups

tentatively raised to lips;

Morning commuters

7 July 2016

 

Definition

Searching for the why

and how things are like they are;

Entomology

20 December 2015

 

Blood Moon

Lustrous, silver orb

Bloody, awe-inspiring moon

Night-time amazement

28 September 2015

 

Evening entertainment

Bats, swiftly looping

Snatching insects from the sky

Feeding on the wing

26 July 2017

 

Regular readers, rest assured, normal service will be returned in the next post 🙂

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CROPSS – Inspiring biology students to consider careers in crop protection

A couple of years ago, the BBSRC decided to scrap one of their most successful and inclusive PhD training awards, the iCASE.    In their own words, BBSRC will no longer operate an annual competition for industrial CASE (iCASE) studentships, instead allocating the majority of these studentships to the BBSRC Doctoral Training Partnerships (DTP) for awarding alongside their standard studentships.    At one fell stroke the BBSRC reduced the diversity of their PhD portfolio by a significant amount and also dealt a huge blow to those of us working in crop protection, at a time when food security and the need to feed the world is of paramount importance.  Later that year the BBSRC, possibly in response to those of us who kicked up a public fuss about the loss of the iCASE scheme came up with a very inadequately funded scheme called STARS aimed at getting undergraduates interested in some of the vulnerable skill sets that the BBSRC by their actions had made even more vulnerable.  Despite the paltry amount of money available I felt that I had to apply, if only because having complained about lack of funding it would show lack of commitment to the cause 🙂  I duly applied putting forward an application to run a one week crop protection summer school for fifteen students a year for three years.  I was successful and last week we ran our first CROPSS Summer School here at Harper Adams University.  We particularly targeted first and second year undergraduates doing biology and ecology courses at other universities with little or no agricultural content in their degrees.  Our participants came from the universities of Bath, Birmingham, Bristol, Cambridge, Liverpool and Swansea, and apart from one student who came from a farming family, they had no previous experience of agriculture, let alone crop protection.

The Summer School started on Sunday afternoon, with an introduction from me about why crop protection was important and how Integrated Pest Management is all about ecology, NOT spraying and eradication, something I have been banging on about for many years 🙂  This needs to be reiterated again and again and as loudly as possible. We then had an excellent dinner and I took them all to the bar where I cruelly subjected them to a Pub Quiz, all picture rounds.  The first round was all about charismatic megafauna (almost all answered correctly), then dog breeds (about 75% correct), then common British wild flowers (about 60% correct), common British trees (40% correct), common British insects (30% correct), I think you can see where I am going with this  🙂

The week was divided up between agronomy, entomology, nematology, plant pathology, weed science and spray technology, with a mixture of lectures, field work and laboratory work.  In the evening we had guest speakers from the different crop protection sectors, from the agrichemical industry through to government, our last speaker being the Chief Plant Health Officer, Nicola Spence.  The external speakers had been asked to explain how they had ended up in their current positions and to talk about careers in those areas.  I was very impressed with the willingness of the students to engage with the speakers and the questions they asked were extremely discerning.

We were very lucky to be blessed with excellent weather and the harper Adams University Catering Department came in for very high praise indeed J  apparently our catering is much better than at the universities represented by our delegates.

As the old adage goes, a picture is worth a thousand words…..

Catching insects in the Natural England plots

Sorting pitfall traps catches

Plant pathology in the brand new labs

Heading off with John Reade to sample weeds

Enjoying the sun and spotting weeds

Simon Woods from the Engineering Department explaining the fine points of knap sack sprayers

Andy Cherrill extolling the joys of motorised suction sampling

Enjoying the bar with one of the guest speakers, Neal Ward

All in all, we all had a good time, and if you don’t believe me here are some of the responses from the student feedback

The students were great, enthusiastic, engaged and we really enjoyed the course and are very much looking forward to seeing a new CROPSS cohort next year.

Finally, for those of you interested, here is the timetable of the week:

 

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Pick and mix 7 – more eclectic links from the past week

Links to stuff I have read with interest; quite a lot about bees this week 😊

Interesting reflections on a life in science by Rich Lenski when he gave an address to newly graduated PhD students

A nice summary of what conservation biocontrol is all about, incidentally by a former PhD student of mine 🙂

An interesting opinion piece on how conservation efforts should move away from a species focus and use functional traits instead

Green walls – are they good for wildlife? – coincidentally written by another former student of mine 🙂

I totally agree – ecologists need to get outside more often

A blistering tale – what makes Blister beetles cause blisters

Saving the honeybee from the Varroa mite using a fungal biological control agent?

If you like bees and/or are a beekeeper, this interesting article by Norman Carreck, Science Director of the International Bee Research Association is a must read

Worrying evidence that it is not just insecticides that are killing bees – fungicides may also be a major culprit

On being a sustainable entomologist and helping to save the planet

 

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Data I am never going to publish – A tale of sixty trees

In 1981 I spent a lot of time trudging through snow, cross-country skiing and snow-shoeing my way across the snowy wastes of Finland to snip twigs off bird cherry trees.  This was part of my post-doc which was to develop a forecasting system for the bird cherry-oat aphid, Rhopalosiphum padi.  On returning to the lab I then spent many a happy hour counting how many aphid eggs were nestled in between the buds and the stem on each twig.  It was while doing this that I noticed that some of the twigs were infested with the overwintering larval shields of the bird cherry ermine moth, Yponomeuta evonymellus.  Of course I then started counting them as well 🙂  I noticed that trees with lots of aphid eggs didn’t have very many larval shields and I wondered why. Some later observations from marked trees in Scotland appeared to provide evidence that the aphids and the moths tended to either prefer different trees or perhaps excluded each other.

Negative correlation between moths and aphids – more moths equals fewer aphids and vice versa

Based on these data I hypothesised that the two insects were indirectly competing for resources by altering plant chemistry and/or architecture thus making the trees less or more suitable for egg laying in the autumn (Leather, 1988).  I tested this experimentally when I was working for the Forestry Commission in Scotland using potted bird cherry trees that I defoliated to a lesser or greater extent to see if I could induce changes in foliar quality and tree growth rates that might influence subsequent colonisation by the aphids and moths. As predicted, those trees that had been defoliated, albeit by me and not by moth larvae, were less attractive to aphids in the autumn (Leather, 1993).  These effects were still apparent five years after the beginning of the experiment (Leather, 1995) when I had to desert my trees as I moved to a new position at Imperial College’s Silwood Park campus.

Given that apart from the location, the SE of England, this was my idea of a dream job for life (colleagues at the time included John Lawton, Mike Hassell, Bob May, Stuart McNeill, Mike Way, Brad Hawkins, Shahid Naeem, Mike Hochberg, Chris Thomas to name but a few), I decided to start up two long-term projects to see me through the next 30 years, one observational (my 52 sycamore tree project), the other experimental, a follow up to my bird cherry defoliation experiment.

I went for a simplified design of my earlier experiments, just two defoliation regimes, one to mimic aphid infestation (50%), the other to mimic bird cherry ermine moth defoliation (100%) and of course a non-defoliated control.  I also planted the trees in the ground to better simulate reality.  Using potted plants is always a little suspect and I figured that I would need to do rather a lot of re-potting over the next 30 years 🙂

The grand plan!

I sourced my trees from a Forestry Commission nursery thinking that as the national organisation responsible for tree planting in the UK I could trust the provenance of the trees.  Things didn’t go well from the start.  Having planted my trees in autumn 1992 and established the treatments in the spring of 1993 I discovered that my bird cherry, rather than being from a native provenance (seed origin) were originally from Serbia! Hmm 🙂  It was too late to start again, so I decided to carry on.  After all, bird cherry although widely planted in the SE, has a native distribution somewhat further north and west, which meant I was already operating close to the edge of ‘real life’, so what did an extra 1600 kilometres matter?

The mainly ‘natural’ distribution of bird cherry (left, Leather, 1996) and the current distribution including ‘introduced’ trees https://www.brc.ac.uk/plantatlas/index.php?q=plant/prunus-padus

Next, I discovered that my fence was neither rabbit nor deer proof.  I almost gave up at this point, but having invested a lot of time and energy in setting up the plot I once again decided to carry on. On the plus side, the trees most heavily defoliated and bitten back were mainly from the 100% defoliation treatment, but did give me some negative growth rates in that year.

My original plan was to record height (annually), bird cherry egg numbers (every December), bird cherry ermine moth larval shields (annually), bud burst and leaf expansion once a week, leaf-fall (annually), and once a month, defoliation rates in two ways, number of damaged leaves and an overall estimation of percentage defoliation.  This was a personal project, so no grant funding and no funding for field assistants.  It soon became clear, especially when my teaching load grew, as Imperial started replacing whole organism biologists with theoretical and molecular biologists, and I was drafted in to take on more and more of the whole organism lecturing, that I would not be able to keep both of my long term projects going with the same intensity.  Given the ‘problems’, associated with the bird cherry project, I decided  that I would ditch some of my sampling, bud burst was scored on 21st March every year and defoliation only measured once, in late summer and egg sampling and height recording came to a halt once the trees grew above me (2005)!  This allowed me to carry on the sycamore project as originally intended*.

I kept an eye on the trees until I left Silwood Park in 2012, but by 2006 I was only monitoring bud burst and leaf fall feeling that this might be useful for showing changes in phenology in our ever-warming world.  One regret as I wandered between the then sizeable trees in the autumn of 2012 was that I had not taken a before and after photograph of the plots.  All I have are two poor quality photos, one from 2006, the other from 2012.

The Sixty Tree site April 2006.

The Sixty Tree site April 2010 with a very obvious browse line

 

So, after all the investment in time, and I guess to a certain extent money (the trees and the failed fencing, which both came out of my meagre start-up funding**), did anything worthwhile come out of the study?

The mean number of Rhopalosiphum padi eggs per 100 buds in relation to defoliation treatment

As a long-time fan of aphid overwintering it was pleasing to see that there was a significant difference not only between years (F= 8.9, d.f. = 9/29, P <0.001), but also between treatments with the trees in the control treatment having significantly more eggs laid on them than the 100% defoliation treatment (F= 9.9, d.f. = 2/ 29, P <0.001 with overall means of 1.62, 1.22 and 0.65 eggs/100 buds).  This also fitted in with the hypothesis that trees that are defoliated by chewing herbivores become less suitable for aphids (Leather, 1988).  I must admit that this was a huge surprise to me as I had thought that as all the trees were attacked by deer the year after the experimental treatments they would all respond similarly, which is why I almost gave up the experiment back in 1994.

Bud burst stage of Prunus padus at Silwood Park on March 21st 1996-2012; by treatment and combined

When it came to budburst there was no treatment effect, but there was a significant trend to earlier budburst as the trees became older which was strongly correlated with warmer springs, although as far as spring temperatures were concerned there was no significant increase with year.

Mean spring temperature (Silwood Park) 1993-2012 and relationship between mean spring temperature and bud bust stage on 21st March.

Mean date of final leaf fall of Prunus padus at Silwood Park 1995-2012; by treatment and combined

At the other end of the year, there was a significant difference between date of final leaf fall between years but no significant difference between treatments.  In retrospect I should have adopted another criterion.  My date for final leaf fall was when the last leaf fell from the tree.  Those of you who have watched leaves falling from trees will know that there are always a few who are reluctant to make that drop to the ground to become part of the recycling process.  Even though they are very obviously dead, they hang there until finally dislodged by the wind.   I should really have used a measure such as last leaf with any pigment remaining.  I am sure that if I could be bothered to hunt down the wind speed data I would find that some sort of correlation.

Mean height (cm) of Prunus padus trees at Silwood Park 1993-2005 and Diameter at Breast Height (DBH) (cm) at the end of 2012

Except for the year after the deer attack, the trees, as expected, grew taller year by year.  There was however, no significant difference between heights reached by 2005 or in DBH at the end of 2012 despite what looked like a widening gap between treatments.

Defoliation scores of Prunus padus at Silwood Park 1993-2004; % leaves damaged and overall defoliation estimates

My original hypothesis that trees that were heavily defoliated at the start of their life would be more susceptible to chewing insects in later life, was not supported.  There was no significant difference between treatments, although, not surprisingly, there was a significant difference between years.  Average defoliation as has been reported for other locations was about 10% (Kozlov et al., 2015; Lim et al., 2015).

Number of Prunus padus trees with severe deer damage

That said, when I looked at the severity of deer attack, there was no effect of year but there was a significant effect of treatment, those trees that had been 100% defoliated in 1993 being most attractive to deer.   In addition, 20% of those trees were dead by 2012 whereas no tree deaths occurred for the control and less severely defoliated treatments.

I confess to being somewhat surprised to find as many significant results as I did from this simple analysis and was momentarily tempted to do a more formal analysis and submit it to a journal.  Given, however, the number of confounding factors, I am pretty certain that I would be looking at an amateur natural history journal with very limited visibility.  Publishing it on my blog will almost certainly get it seen by many more people, and who knows may inspire someone to do something similar but better.

The other reason that I can’t be bothered to do a more formal analysis is that my earlier work on which this experiment was based has not really hit the big time, the four papers in question only accruing 30 cites between them.  Hardly earth shattering despite me thinking that it was a pretty cool idea;  insects from different feeding guilds competing by changing the architecture and or chemsitry of their host plant.  Oh well.  Did anything come out of my confounded experiment or was it a total waste of time?  The only thing published from the Sixty Trees was a result of a totally fortuitous encounter with Marco Archetti and his fascination with autumn colours (Archetti & Leather, 2005), the story of which I have related in a previous post, and which has, in marked contrast to the other papers, had much greater success in the citation stakes 🙂

And finally, if anyone does want to play with the data, I am very happy to give you access to the files.

References

Archetti, M. & Leather, S.R. (2005) A test of the coevolution theory of autumn colours: colour preference of Rhopalosiphum padi on Prunus padus. Oikos, 110, 339-343. 50 cites

Kozlov, M.V., Lanta, V., Zverev, V., & Zvereva, E.L. (2015) Global patterns in background losses of woody plant foliage to insects. Global Ecology & Biogeography, 24, 1126-1135.

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.  14 cites

Leather, S.R. (1988) Consumers and plant fitness: coevolution or competition ? Oikos, 53, 285-288. 10 cites

Leather, S.R. (1993) Early season defoliation of bird cherry influences autumn colonization by the bird cherry aphid, Rhopalosiphum padi. Oikos, 66, 43-47. 11 cites

Leather, S.R. (1995) Medium term effects of early season defoliation on the colonisation of bird cherry (Prunus padus L.). European Journal of Entomology, 92, 623-631. 4 cites

Leather, S.R. (1996) Biological flora of the British Isles Prunus padus L. Journal of Ecology, 84, 125-132.  14 cites

Lim, J.Y., Fine, P.V.A., & Mittelbach, G.G. (2015) Assessing the latitudinal gradient in herbivory. Global Ecology & Biogeography, 24, 1106-1112.

 

 

*which you will be pleased to know, is being analysed as part of Vicki Senior’s PhD project, based at the University of Sheffield.

**£10 000 which even in 1992 was not overly-generous.

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Sloth Moths – moving faster than their hosts

One of the minor downsides of our Biology and Taxonomy of Insects module on the MSc course is, that we do have to review a lot of families within some of the groups, Lepidoptera being a prime example.  Current estimates range from 250 000 to 500 000 species in 124 families (Kristensen et al., 2007). Going through the basic biology of each family can be pretty dry stuff, even if I have a personal anecdote or two to help lighten information overload.  I am, for example, able to wax lyrical for several minutes about small ermine moths and their incredible silk-production activities, but even after more than 40 years of playing around with insects I don’t have a personal story for every family of Lepidoptera 🙂 so I am always on the lookout for an extra interesting or mind-blowing fact to help leaven the student’s knowledge diet.

Imagine my delight then when I came across a clip* from a BBC One Wildlife programme, Ingenious Animals, describing an obligate association between sloths and moths and not just because of the rhyming opportunity** 🙂

Sloth with moths – BBC One Ingenious Animals

The earliest record of a moth associated with a sloth that I have been able to find is in 1877 (Westwood, 1877) which merely records that the unidentified moth was “parasitic on the three-toed sloth”. In 1908 a Mr August Busck on a visit to Panama saw a two-toed sloth, Choloepus hoffmanni fall from a tree and noticed several moths flying out of the sloth’s fur.  He caught these and on his return to the United States presented them to Dr Harrison Dyar (Dyar, 1908a).  If the name seems familiar to you that is because Harrison Dyar is better known in connection with Dyar’s Law, the observation that larval growth in arthropods is predictable and follows a geometric progression (Dyar, 1890). The moths were identified by Dyar as a new species which he named Cryptoses choloepi.  Dyar hypothesised that the moths and their larvae lived in the fur of the sloth and it was this that caused the sloth’s matted hair.

Cryptoses choloepi (Lepidoptera, Chrysauginae)

http://nmnh.typepad.com/department_of_entomology/2014/03/sloths-moths-and-algae-whos-eating-whom.html

Shortly after publishing the first note Dyar came across two more moth specimens, this time collected from a sloth in Costa Rica.  He felt that these were another species, possibly Bradipodicola hahneli (Dyar, 1908b).  The next mention of a sloth moth that I could fine is in a marvellously titled paper (Tate, 1931) who refers to a moth shot in western Ecuador whose fur was “literally alive with a small species of moth, whose larvae possibly fed on the greenish algae which grew in the hair”.  The idea that sloth moths fed on the fur of living sloths was further reinforced by Brues (1936) although this was not based on any personal observations.  It was only in 1976 that it was discovered that the larvae of the sloth moth Cryptoses choloepi were actually coprophagous (Waage & Montgomery, 1976), the female moths waiting for the three-toes sloth B. infuscatus to descend from the trees to relive their bowels, which they do about once a week.  As an aside, I have known Jeff Waage for many years in his role as a biological control expert but until I discovered this paper about a month ago, had no idea that he had ever spent time inspecting sloth faeces 🙂  Jeff and his co-author Gene Montgomery, described the association between the moths and the sloths as phoretic, rather than parasitic, as they saw no harm being caused to the sloths, but a number of benefits accruing to the moths, namely oviposition-site location being simplified, the fur of the sloth acting as refuge from avian predators and diet enhancement from sloth secretions (Waage, 1980).  It turns out however, that some species of sloth moth do spend their whole life cycle on the sloth, B. hahneli lose their wings once a sloth host is found and their eggs are laid in the fur of the sloth (Greenfield, 1981).  The algae that these moths presumably feed on is considered to be in a symbiotic association with the sloths, providing camouflage and possibly nutrition in the form of trace elements (Gilmore et al., 2001).  Hereby lies a tale.  The two-toed sloths have a much wider diet and home range than three-toed sloths and also defecate from the trees, unlike the three-toed sloths which have a very narrow diet (entirely leaves) and narrow home ranges, yet descend from the relative safety of the forest canopy to defecate, albeit only once a week, but still a risky undertaking (Pauli et al., 2017).  Rather than a phoretic relationship Pauli and colleagues see the relationship between sloths, algae and moths as a three-way mutualism, beautifully summarised in their Figure 3.

Postulated linked mutualisms (þ) among sloths, moths and algae: (a) sloths descend their tree to defecate, and deliver gravid female sloth moths (þ) to oviposition sites in their dung; (b) larval moths are copraphagous and as adults seek sloths in the canopy; (c) moths represent portals for nutrients, and via decomposition and mineralization by detritivores increase inorganic nitrogen levels in sloth fur, which fuels algal (þ) growth, and (d ) sloths (þ) then consume these algae-gardens, presumably to augment their limited diet. This figure brazenly ‘borrowed’ from Pauli et al. 2014).

The sloths take the risk of increased predation by descending to ground level, because by helping the moths they improve their own nutrition and hence their fitness.  Yet another great example of the wonders of the natural world.

 

Post script

Although not as exotic as the sloth moth, we in the UK can also lay claim to a coprophagous moth, Aglossa pinguinalis, the Large Tabby which feeds on, among other things, sheep dung.  In Spain it is recorded as a cave dweller feeding almost entirely on animal dung, apparently not being too fussy as to the source.

 

References

Bradley, J.D. (1982) Two new species of moths (Lepidoptera, Pyralidae, Chrysauginae) associated with the three-toed sloth (Bradypus spp.) in South America.  Acta Amazonica, 12, 649-656.

Brues, C.T. (1936) Aberrant feeding behaviour among insects and its bearing on the development of specialized food habits.  Quarterly Review of Biology, 11, 305-319.

Dyar, H.G. (1890) The number of molts of lepidopterous larvae. Psyche, 5, 420–422.

Dyar, H.G. (1908a) A pyralid inhabiting the fur of the living sloth.  Proceedings of the Entomological Society of Washington, 9, 169-170.

Dyar, H.H. (1908b) A further note on the sloth moth. Proceedings of the Entomological Society of Washington, 10, 81-82.

Dyar, H.G. (1912) More about the sloth moth. Proceedings of the Entomological Society of Washington, 14, 142-144.

Gilmore, D.PP., Da Costa, C.P. & Duarte, D.P.F. (2001) Sloth biology: an update on their physiological ecology, behaviour and role as vectors of arthropods and arboviruses.  Brazilian Journal of Medical and Biological Research, 34, 9-25.

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

Kristensen, N., Scoble, M.J. & Karsholt, O. (2007)  Lepidoptera phylogeny and systematics: the state of inventorying moth and butterfly diversity.  Zootaxa, 1668, 699-747.

Pauli, J.N., Mendoza, J.E., Steffan, S.A., Carey, C.C., Weimer, P.J. & Peery, M.Z. (2014) A syndrome of mutualism reinfocrs the lifestyle of a sloth.  Proceedings of the Royal Society B, 281, 20133006. http://dx.doi.org/10.1098/rspb.2013.3006.

Pinero, F.S. & Lopez, F.J.P. (1998) Coprophagy in Lepidoptera: observational and experimental evidence in the pyralid moth Aglossa pinguinalisJournal of Zoology London, 244, 357-362.

Tate, G.H.H. (1931) Random observations on habits of South American mammals.  Journal of Mammalogy, 12, 248-256.

Waage, J.K. (1980) Sloth moths and other zoophilous Lepidoptera.  Proceedings of the British Entomological and Natural History Society, 13, 73-74.

Waage, J.K. & Montgomery, G.G. (1976) Crytopses choloepi: a coprophagous moth that lives on a sloth.  Science, 193, 157-158.

Westwood, J.O. (1877) XXVIII. Entomological Notes.  Transactions of the Entomological Society, 25, 431-439.

 

*For the clip about the sloth moth see here http://www.bbc.co.uk/programmes/p04840xn

**Now, when I see a sloth,

My first thought is for the moth,

That has to make that desperate jump

When the sloth decides to take a dump!

 

 

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Ladybird, ladybug or Alder warbler

Insects with common names are usually those that are notable in some way, be that because they are causing us harm or are beautiful, brightly coloured and give us joy.  Vernacular names for agricultural pest insects usually refer to the crop they are harming, such as the grain aphid, the apple moth, the large pine weevil.  For non-pests however, names appear more arbitrary.  One of the most well-known and loved insect, is the ladybird, or if you are from North America, the ladybug.  These are not, however, the only names that these useful animals have acquired since they first attracted human attention.  They have, over the centuries, acquired a wonderful variety of names around the world.o start with, you may well ask why they have the prefix lady.  In England they were originally called “Our Lady’s bird”.  Leaving aside the mystery of why they were called birds, the first part of the name referred to the fact that the most commonly noticed ladybirds are red (albeit with white or black spots), and in the Middle ages images of the Virgin Mary usually showed her in a red dress.  Another linkage to the Virgin Mary is that the most commonly seen ladybird is the seven spot ladybird (Coccinella septempunctata), and this was associated with the Seven Joys and the Seven Sorrows of Mary.

 

The association with Mary is also seen in Spanish, mariquita, meaning little Mary and in German Marienkäfer, Mary’s beetle.  The reference to the colour red is reflected in the fact that ladybirds belong to the family Coccinellidae which comes from the Latin for scarlet, coccineus, see also cochineal.

Other languages also make reference to the Virgin Mary, in Bosnian, as in German, they are called Mary’s beetle, bubamara.  The Basuques, as far as I can make out with the help of Google Translate, refer to them as Mary’s yolk, marigorringoa. The religious association is also seen in Dutch, lieveheersbeestje which means  the Lord’s sweet little creature.  The Russians call ladybirds Божья коровка [bozhya korovka] which translates to God’s little cow. Lithuanians have two names for ladybirds, Dievo karvytė  God’s cow  but also call them boružė .  The Welsh have lost the religious reference and instead refer to ladybirds as red cows, buwch goch gota. The Greeks make a religious link with a reference to Easter, pashalitsa (Easter is Pasha), but also refer to it as “kind of beetle with fine plumage (feathers)”, είδος κάνθαρου με ωραία πτερά.  The Portuguese have opted for joaninha (ninha means baby), whereas the Slovenians and Slovaks have homed in on the spots, ladybird being pikapolonica (pika is dot) and slunéčko sedmitečné  (sedmit is seven) respectively. The Bulgarians call them калинка (kalinka) but the Finns take the prize for the most obscure name, with Leppäkerttu, which literally translated means alder warbler 🙂

It seems apposite, that as in Finnish they apparently sing,  I should include these two rhymes; one that most of us have come across in some form or other

 

and one from Sweden that will probably be less familiar to English speakers, but which similarly exhorts the ladybird to fly away and at the same time introduces yet another feathered name for the ladybird.

Guld-höna, guld-ko!
Flyg öster, flyg vester,
Dit du flyger der bor din älskade!

Gold-hen, gold-cow!
Fly east, fly west,
You’ll fly to where your sweetheart lives.

 

A gold cow with wings – Kamadhenu  a wish-fulfilling Hindu goddess

In Hindi, ladybirds are called sonapankhi, or golden wings and are associated with passing or failing exams, depending on whether it stays on your hand long enough for you to count the spots or not.

And finally, to prove that not all verse about ladybirds is doggerel, this poem by the poet Clive Sansom captures both the beauty and fragility of nature.

The Ladybird

Tiniest of turtles!
Your shining back
Is a shell of orange
With spots of black.

How trustingly you walk
Across this land
Of hairgrass and hollows
That is my hand.

Your small wire legs,
So frail, so thin,
Their touch is swansdown
Upon my skin.

There! break out
Your wings and fly:
No tenderer creature
Beneath the sky.

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Have you read The Origin of the Species?

As biologists we all acknowledge the influence that Charles Darwin has had on our professional lives but how many of us have actually read On the Origin of Species by Means of Natural Selection in its entirety?  The importance of The Origin has long been recognised by universities, even we agricultural zoology students at Leeds University back in 1973 had The Origin on our first year recommended reading list.  How many of my classmates bought it, let alone actually read it, is anyone’s guess.  I suspect not many.  I was somewhat odd, in that I had already read it, as far as I can remember when I was about 16 and just starting in the Lower 6th  (Year 12 in today’s parlance).  I was helped by the fact that both my parents were biologists and my Dad’s copy of The Origin was readily available. I was, and still am, a prodigious reader, although I must confess that I now find it much more difficult to read ‘hard’ books than I did then.

Finally, here is my question.  If as a professional biologist, of whatever ilk, does not having read The Origin make you any less of a biologist?  Should you be outed and castigated as an incomplete biologist?  Probably not.  What do you think?  I asked how many people had read  The Origin using a Twitter survey last week as a simple yes/no question.  The survey generated 53 responses, of  which 57% said yes.  The survey below is slightly more nuanced, taking into account the one respondent who tweeted “partially?”  🙂 Just realised that I managed to miss out the less than 18 category, my apologies.  If you are such a prodigy please feel free to tick the 18-25 box but add a note in the comments section so that I can adjust later.

 

Many thanks for your participation and rest assured, if you have not read The Origin I am not judging you in any way  🙂

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An inordinate fondness for biodiversity – a visit behind the scenes at the Natural History Museum

Last week  (13th February) I traveled with the MSc Entomology students to the Natural History Museum, London.  As part of their course they are taken behind the scenes and meet some of the curators and their favourite beasts.  This one of my favourite course trips and although I have made the pilgrimage for many years I always find something new to marvel at as well as reacquainting myself with some of my old favourites.  After an early start (0645) we arrived exactly on time (for a change), 10.30, at the Museum site in South Kensington.  I always have mixed feelings about South Kensington, having spent twenty years of my life commuting to Imperial College, just up the road from the museum.  I loved teaching on the Applied Ecology course I ran, but over the years the working atmosphere in the Department became really toxic* and I was extremely glad to move to my present location, Harper Adams University.  After signing in, which with twenty students took some time, Erica McAlister (@flygirl) led us through the thronged galleries (it was half term) to the staff

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Nostalgia time, my first biological memory, aged 3.

areas, where the research, identification and curating takes place.  Our first port of call was the Diptera where Erica regaled us with lurid tales of flies, big and small, beneficial and pestiferous.

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Erica McAlister extolling the virtues of bot flies

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Any one fancy cake for tea?  Kungu cake, made from African gnats

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Early advisory poster

As we left to move on to the Hymenopteran, hosted by David Notton, I noticed this classic poster warning against mosquitoes.  David chose bees as the main focus of his part of the tour, which as four of the students will be doing bee-based research projects was very apt.

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Admiring the bees

Whilst the students were engrossed with the bees I did a bit of fossicking and was amused to find that tobacco boxes were obviously a preferred choice by Scandinavian Hymenopterists in which to send their specimens to the museum.

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Finnish and Swedish tobacco boxes being put to good use

Next was that most eminent of Coleopterists, Max @Coleopterist Barclay who as usual enthralled the students and me, with stories of

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Max Barclay demonstrating a Lindgren funnel and talking about ‘fossilised’ dung balls

beetles large and small, anecdotes of Darwin and Wallace and the amusing story of how ancient clay-encased dung balls were for many years thought by anthropologists and archaeologists to be remnants of early humankind’s bolas hunting equipment.  It was only when someone accidentally broke one and found a long-dead dung beetle inside that the truth was revealed 🙂

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Often overlooked, the Natural History Museum is an exhibit in itself

 As we were leaving to move on to the Lepidoptera section, I felt obliged to point out to the students that not only is the outside of the museum stunningly beautiful but that the interior is also a work of art in itself, something that a lot of visitors tend to overlook. Once in the Lepidoptera section  Geoff Martin proudly displayed his magnificent collection of Lepidoptera, gaudy and otherwise, including the type specimen of the Queen Alexandra’s Birdwing which was captured with the aid of a shotgun!

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Lepidopterist, Geoff Martin, vying with his subjects in colourful appearance 🙂

Lunch and a chance to enjoy the galleries was next on the agenda.  Unfortunately, as it was half term this was easier said than done, although I did find a sunny spot to eat my packed lunch, as a Yorkshireman I always find the prices charged for refreshments by museums somewhat a painful.  In an almost deserted gallery I came across this rather nice picture.

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A lovely piece of historical entomological art.

Then it was on to the Spirit Collection.  Erica had laid on a special treat, Oliver Crimmen, fish man extraordinaire.  I may be an entomologist but I can sympathise with this branch of vertebrate zoology.  Fish, like insects are undeservedly ranked below the furries, despite being the most speciose vertebrate group.  I have been in the Spirit Room many times but have never seen inside the giant metal tanks.  Some of these, as Ollie demonstrated with a refreshing disregard for health and safety, are filled with giant fish floating in 70% alcohol.

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Fish man, Oliver Crimmen, literally getting to grips with his subjects.

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A fantastic end to the day culminated with a group photo with a spectacular set of choppers 🙂

Many thanks to Erica McAlister for hosting and organising our visit and to the NHM staff who passionately attempted to convert the students to their respective ‘pets’.

*one day I will write about it.

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