Monthly Archives: March 2019

Pick and Mix 29 – More stuff that caught my eye

What happens when you microwave two grapes and why

What happens if all the insects disappear?

Artists illustrating the digital collection at  The Natural History Museum London

Erica McAlister writes about the wonderful Dark-Edged Bee Fly

More from Erica on the wonders of flies

Growing carrots in bottles

Spanish salt pans, conservation and bird migrations

Interactions between fire and butterflies – how prescribed burning helps rare species

Successful eradication of an invasive species

This might upset a few people – is the term rewilding just a trendy buzzword for restoration?

 

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Green islands – safe and healthy in a sea of death

Those of you whom work in forests, will, I am sure, be familiar with the term “green island”.  To a forester or forest entomologist, a green island is a clump of trees that have, for some reason or other, survived the ravages of an insect outbreak.  The earliest reference I can find to this phenomenon is in a 1927 paper by the German myrmecologist Hermann Eidmann (1897-1949), who described them as green oases, or, as the paper was written in German, more correctly, “grüne Oasen” (Eidmann, 1927).

Red wood ants helping maintain a “grüne Oasen”   green oasis” in a German pine forest (Eidman, 1927).

As well as “farming aphids” to obtain sugar from their honeydew, ants also have a similar mutualistic relationship with plants that give them a sugary reward to protect them from herbivorous insects, except those that also provide the ants with sugar (Janzen 1966; Bentley, 1977).  The mutualisms can be very sophisticated. In Michigan, the North American black cherry, Prunus serotina, times nectar production from its extra-floral nectaries to attract the ant Formica obscuripes  when the larvae of its major herbivore, the eastern tent caterpillar, Malacosoma americanum are at their most vulnerable (Tilman, 1978).  Trees that are protected have greatly reduced levels of herbivory. When more than one ant colony is involved, rather than single trees being protected, a group of trees can be saved from defoliation, and form a green island.  The areas covered by these green islands can be quite extensive, for example two ant colonies of the ant  Formica polyctena were enough to protect pine trees from the nun moth Lymantria monacha in Sweden within a 45 m diameter around the colonies (0.16 ha) (Wellenstein, 1980) and green islands of up to 3 ha have been reported (Eidmann, 1927).

Left – canopy of trees near ant nests, on the right, trees not close to ant nests Wellenstein (1980)

 

In Finland, one colony of the ant F. aquilonia is enough to create subarctic mountain birch (Betula pubescens), green islands of up to 0.12 ha in area (Laine & Niemelä, 1980).

Green islands attributed to the activity of the ant Formica aquilonia in subarctic Finland (Laine & Niemela, 1980).

It would seem that the case for the ants protecting the trees against defoliating herbivores and being the cause for the green islands is very convincing.  Tom White, never one to avoid a controversy, disagreed. He suggested that it was the nest building activities of the ants that were the cause for the green islands, the refuse dumps provide higher concentrations of nutrients that the roots of surrounding trees can access and additionally soil moisture conditions are improved, both these factors encouraging more vigorous growth in those trees close to ant nests, making them less palatable to herbivores (White, 1985).   The Finnish team responded to this with some additional data and arguments defending their hypothesis (Niemelä & Laine, 1986) and there the matter rested, for a while at least. Not satisfied with their post hoc response, the Finns came up with, to me at any rate, a very convincing field experiment where they showed that soil nitrogen did not vary significantly with distance from ant nests and that birch leaf nitrogen content and moth larval growth rates and survival were also not affected by distance from ant nests (Karhu, 1998; Karhu & Neuvonen, 1998), indicating that the green islands were indeed, due to predation by the ants and not improved tree nutrition.

Soil nitorgen in realtion to distance from ant colonies (Karhu & Neuvonen, 1998).

You might think that this would be the last word, but you would be wrong 🙂  The Karhu and Neuvonen paper, is, in the journal, followed by a “comment” paper by no less a person than Tom White (White 1998) in which he disputes in no uncertain terms, their interpretation of their new data.  Matthias Schaefer, the then Editor of Oecologia, felt that some sort of explanation was needed and added a final note to the saga, which in itself makes very interesting reading.  I get the feeling that there were some strong emotions involved 🙂

Pouring oil on troubled water – wise words from Editor-in-Chief Mathias Schaefer

 

References

Bentley, B.L. (1977) Extrafloral nectaries and protection by pugnacious bodyguards. Annual Review of Ecology & Systematics, 8, 407-427.

Eidmann, H. (1927) Weitre Beobachtungen über den Nutzen de roten Waldameise.  Anzeiger für Schädlingskunde, 3, 49-51.

Janzen D.H. (1966) Coevolution of mutualism between ants and Acacias in Central America. Evolution, 20, 249-275.

Kaiser, W., Huguet, E., Casas, J., Commin, C. & Giron, D. (2010)  Plant green-island phenotype induced by leaf-miners is mediated by bacterial symbionts. Proceedings of the Royal Society B, 277, 2311-2319.

Karhu, K.J. (1998) Effects of ant exclusion during outbreaks of a defoliator and a sap-sucker on birch. Ecological Entomology, 23, 185-194Kah.

Karhu, K.J. & Neuvonen, S. (1998) Wood ants and a geometrid defoliator of birch: predation outweighs beneficial effects through the host plant. Oecologia, 113, 509-516.

Laine, K.J. & Niemela, P. (1980) The influence of ants on the survival of mountain birches during an Oporinia autumnata (Lep., Geometridae) outbreak. Oecologia, 47, 39-42.

Niemela, P. & Laine, K.J. (1986) Green islands – predation not nutrition. Oecologia, 68, 476-478.

Tilman, D. (1978) Cherries, ants and tent caterpillars: timing of nectar production in relation in relation to susceptibility of caterpillars to ant predation. Ecology, 59, 686-692.

Wellenstein, G. (1980) Auswirkung hügelbauender Waldameisen der Formica rufa‐Gruppe auf forstschädliche Raupen und das Wachstum der Waldbäume. Zeitschrift für Angewandte Entomologie, 89, 145-157.

White, T.C.R. (1985) Green islands – nutrition not predation – an alternative hypothesis. Oecologia, 67, 455-456.

White, T.C.R. (1998) Green islands – still not explained.  Oecologia, 113, 517-518.

 

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The Verrall Supper 2019 – entomological convivality

For many entomologists The Rembrandt Hotel in South Kensington and the first Wednesday of March means only one thing – the Verrall Supper. I report on the activities of the Verrall Association annually and if you click on this link you will be able to work your way back through previous reports to my very first attempt.  This will, once again, be largely a photographic record.  This year the first Wednesday of March was the 6th but despite the date of the Supper always being the first Wednesday in March it still seemed to have caught a few Verrallers by surprise.  Consequently numbers were slightly down compared with last year’s, although the number of non-attending Verrallers paying to retain their membership was at an all-time high.  One notable absence, due to a slipped disc, was Richard Lane, the newly elected Treasurer of the Entomological Club, under whose auspices, the Verrall Association is privileged to run.

More positively we were slightly up on female entomologist this year, 36 % compared with last year’s 32%.  There is still much progress to be made, but we have seen a year on year increase now for the last four years so, perhaps one day we will hit that magic 50:50 mark.

I performed a humanist blessing, which seemed to meet with satisfaction from all sides, and unbeknownst to me was caught on video by one of the Verrallers  I reproduce it here if anyone feels like using it at a similar occasion.

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

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

Clive Farrell doing his usual stint on the Registration Desk.  Something seems to be puzzling him?

Max Barclay presenting Professor Helmut van Emden with a copy of the latest Royal Entomological Society Handbook, Beetle Larvae.  Van’s father was a Coleopterist who started this book more than fifty years ago, hence the presentation.

Pre-Supper drinks – and some evidence that not all Verrallers are gray, male and balding, although many are 🙂

The Wyebugs Team – Mike Copland and Sue Stickels – Ray Cannon in the background talking with Keith Walters and Roger Booth

And here they are revealed!

People with drinks including the President of the Royal Entomological Society Chris Thomas, doing some arm-waving, and the rather too-long queue for the bar.  There was supposed to be another bar but there was an electrical fault.

The next set of photographs are what I describe as ‘Ento Bling’. When it comes to “smart casual”, which is the dress code for the Verrall Supper, I feel that in most cases, it is easier for female entomologists to show their dedication to insects than the male of the species, alternatively, perhaps males are just less imaginative and go for the easy tie option 🙂

The food, as usual, was excellent and most tables seemed to have a healthy mix of entomologists of different age classes and sex.

You try your best but bald heads keep appearing 🙂

 

And finally, I wonder who this was?  🙂  I’ll give you a clue – she is a Dipterist!

 Many thanks to all who attended and I hope to see you all again next year plus many new faces.

 

 

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Pick and Mix 28 – some video treats

A very interesting, if somewhat gruesome video, of a botfly larva being removed from a human

Continuing with the fly stuff, here are some maggots having an evening meal 🙂 Seriously though, the article is all about using insects as food

And continuing with flies and food – don’t forget that bees are not the only pollinators

Now some hungry mosquitoes, which are of course. also flies

More flies – this time on how to stop them eating your wheat crop

Cockroach farming for food and medicine

Beetles like light too

Magnificent Monarchs in flight – a moving experience

A musical introduction to insect orders

A moving video from a teenage girl about insect extinction

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