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The desert locust, Schistocerca gregaria (Orthoptera: Acrididae), is one of the most important crop pests in the world. It usually lives in relative solitude but under certain conditions it starts to swarm, causing significant loss of vegetation and crops.

Locust nymph eating lettuce

The swarming response results in a number of changes in the locust: alteration of the normal camouflage to more striking colouration and the change in behaviour that causes them to gather together into a swarm (called a band if they are nymphs).

Scientists knew about the physical stimuli which causes swarming but were uncertain about the underlying biochemical changes. The physical stimulus was experimentally demonstrated using a small paintbrush to ‘tickle’ the locusts and found that the hind femora was the most effective site for inducing swarming (Simpson et al, 2001).

The hind femora caused the highest percentage, 76% to 100% (shown in red), of S. gregaria to exhibit swarming behaviour (adapted from Simpson et al, 2001). © Malin Nikunlassi

Recently scientists discovered the major component of the signalling pathway which results in swarming: the neurochemical serotonin (Anstey et al, 2009), a neurotransmitter found in many organisms, from insects to humans.

Serotonin - based on the amino acid tryptophan with an additional hydroxyl group (OH) marked in red. © Malin Nikunlassi

Knowledge about the role that serotonin plays may provide new novel ways of controlling the locusts without resorting to mass spraying of pesticides.

For additional reading on locusts and grasshoppers as pest species, visit the International Society for Pest Information which has a number of freely available full text resources.

References:

Simpson S.J., Despland E., Hägele B.F. and Dodgson T. (2001) Gregarious behavior in desert locusts is evoked by touching their back legs. PNAS 98: 3895-3897

Anstey M.L., Rogers S.M., Ott S.R., Burrows M. and Simpson S.J. (2009) Serotonin Mediates Gregarization Underlying Swarm Formation in Desert Locusts. Science 323: 627-630

I find stick insects and examples of convergent evolution fascinating, so in my opinion a combination of the two makes for good reading. It so happens that such a paper was published last year and was brought to my attention by David Robinson during a recent Phasmid Study Group meeting.

Buckley et al, 2008 did a phylogenic study that involved the endangered Lord Howe Island stick insect, Dryococelus australis (Phasmatodea: Phasmatidae), a species that was previously thought extinct. Dryococelus australis is placed in the subfamily Eurycanthinae, along with the genera Eurycantha,  which has a mostly Australasian distribution around New Guinea and surrounding islands.

The study used two sections of DNA from both nuclear and mitochondrial DNA to compare the relationships between  various subfamilies and genera that were thought to be closely related to D. australis. They found that whilst the genera Eurycantha is morphologically (its body structure) similar to D. australis, they are only distantly related. One of the reasons that Dryococelus and Eurycantha were previously thought to be closely related was that both genera looked very similar and had unusually large spines on their hind legs. Now it seems that these leg spines evolved independently of each other; an example of convergent evolution.

You can read the whole article online with images of the leg spines and a phylogenetic tree.

Reference:

Buckley, T.R., Attanayake, D. and Bradler, S. (2008) Extreme convergence in stick insect evolution: phylogenetic placement of the Lord Howe Island tree lobster. Proceedings of the Royal Society B, 16th December [Online] Available at: http://journals.royalsociety.org/content/g622w01455v03763/ [Accessed 25th Hanuary 2009]

Today my supervisor showed me some photographs of male leafhoppers (Hemiptera: Cicadellidae) feeding on river mud, a behaviour not previously recorded.

It got us thinking and we talked about unusual feeding amongst the Hemiptera in general, including some observations I made last year and a those featured in a summary paper about the Heteroptera.

Consumption of faeces (coprophily) and carrion (necrophily) has previously been observed in 35 Heteropteran species in eight families, the majority of which were seen in the Coreidae, six species, and Alydidae, four species (Jérôme, 2007). This behaviour has been mostly (95% of the time) recorded in male insects.

During July and August 2008 I saw Pentatoma rufipes (Hemiptera: Pentatomidae) & Coreus marginatus (Hemiptera: Coreidae) feeding on fresh (wet) bird droppings. At the time I presumed this was well-recorded behaviour, made a note of it, and carried on with my field work. Whilst I wont presume observations of those two species have never been published, the summary paper by Jérôme doesn’t mention those two species.

Coreus marginatus on bramble

Whilst there are some theories about why these bugs engage in this unusual behaviour, I intend to do some information hunting and find out more. I’ve been told that butterflies feed on faeces or mud, so that seems a good place to start looking.

Jérôme, C. (2007) Note on coprophily and necrophily in the Hemiptera Heteroptera. Entomologie, 77: 107-112.

Dolycoris baccarum (Hemiptera: Pentatomidae) belongs to one of my favourite insect families, the shield bugs. I have fond memories of seeing shield bugs as a child and they make me think of summer. I hope to see all of the British Pentatomidae and have been planning my some of my summer trips to fill the gaps.

Dolycoris baccarum (adult)

I find D. baccarum particularly attractive because of the pattern on its antennae and connexivum (the part with black markings either side of the abdomen). Another notable feature of D. baccarum is that it’s covered in fine hairs. If you look hard in the photo above you can see them.

The adults overwinter and become active in late Spring, laying their eggs around June. It often feeds on Prunus spinosa (blackthorn/sloe) from which it gets one of its vernacular names, the sloe bug, but will feed on other plants.

For more information, photographs and an illustrated stages chart, go to the British Bugs page. I got some information from the photographic shieldbug guide by Martin Evans and Roger Edmondson which I recommend and is referenced below.

Reference:

Evans, M. & Edmondson, R. (2005) A Photographic Guide to the Shieldbugs and Squashbugs of the British Isles. WGUK.

I’ve been reading some blogs and came across two interesting posts and two new blogs:

A Cybertaxonomy Discussion: Vince Smith has posted a blog response to concerns a fellow taxonomy blogger (Roderic Page) has with Scratchpads, the online taxonomy database used by Vince & the NHM, and the potential for redundant data and time wasting when trying to gather information from multiple Scrathpads. Instead, Page sugguests using Semantic MediaWikis which would be able to deal with human-language queries on bulk taxonomic/entomological information, such as “Which Hemiptera might I find in Essex during July?” or “How many beetles are there excluding weevils?”.

Whilst I don’t want to reiterate the posts, I am inclined to agree with Vince’s view from my experience with taxonomists/entomologists at museums and people who are happier working with paper rather than computers. With so much taxonomic information not readily accessible in any form I think Scratchpads & similar more traditionally organised databases will become more commonly used before the more (conceptually) advanced Semantic MediaWikis.

Scanning Moths: There are some excellent scanned images of moths over at cicindela,  which have even managed to capture individual scales at a reasonable resolution!

I’d recommend visiting cicindela as the author as plenty of other good photographs.

Cincindela and iPhylo have been added to the blogroll.

One of the species I took back from the Phasmid Study Group meeting was Mnesilochus sp., originally from Mount Apo in the Philippines. I was looking for species which at privet as I no longer have access to as many food plants as I did last and was informed that Mnesilochus will eat practically anything.

Like most phasmids you can easily see sexual dimorphism: the female is much larger than the male.

Mnesilochus sp. male (left) & female (right)

The female seems especially cryptic as she has a nobbly bit on her abdomen and usually angles her thorax when resting.

Mnesilochus abdominal extrusion

They have already started laying eggs which I shall photograph when I have better light.

Entomology News: Today BBC News had a top story titled ” Liberia worms swarm ‘emergency’ “. For a moment I was really curious, thinking they were talking about annelids before realising they meant army worms, the vernacular for particularly voracious caterpillars! The swarm of caterpillars is the worst Liberia has seen in over 30 years and they are currently undertaking aerial spraying in an attempt to control the insects.

I came across a more positive story from Monash University on some research undertaken by Dr Adrian Dyer on the responses of bees to human faces. They found that the bees could ‘average’ different views of the human face (0° and 60°) to recognise a previously unseen facial angle (30°). The research team think the study may help with the construction of AI facial recognition.

Update: You can read the full research article on bee vision at the PloS ONE website.

The bee-fly, Bombylius major (Diptera: Bombyliidae), is one of my favourite British insects. Its appearance is quite distinctive as it’s reasonably sized (the body excluding the proboscis is ~1cm), quite hairy and has distinctive dark wing patterns. It’s a good flier and can often be found hovering, teasing you to take a photograph, before darting away when you get too close.

Bombylius major at rest, © Tristan Bantock

It emerges fairly early in the year (early March onwards) and will hopefully be one of the first insects I take photos of in 2009. So far I’ve been unable to take a good photo yet as the individuals I’ve encountered were too skittish to get close enough to. Fortunately a fellow flickr entomologist, tristanba (Tristan Bantock), has allowed me to use some of his photographs to illustrate this post.

Bombylius major in flight, © Tristan Bantock

Whilst the long proboscis looks a little intimidating, the fly is harmless as it uses it for feeding on the nectar of flowers. If you happened to be a sapient solitary bee you wouldn’t be pleased to see B. major flying around your burrow as its larvae parasitise the bee larvae.

An article on ants (Hymenoptera: Formicidae) joins two other (Chrysiridia rhipheus and cochineal/Dactylopius coccus) insect related featured articles on Wikipedia.

The Biology section of the featured articles is dominated by dinosaurs and things with feathers or fur and needs more insect content!

The beetle family Scarabaeidae contains some well known British insects like the chafers and scarabs, of which the most notable species is probably Melolontha melolontha (cock chafer/may-bug).  Of the 20,000+ species in the family, none were known to be primarily carnivorous, with most members eating plant matter or dung.

Melolontha melolontha, a British member of the Scarabaeidae family

In the Scarabaeidae subfamily Scarabaeinae the principal food stuff is dung, although some species eat carrion, rotting fruit or fungus. In a recently published paper one Peruvian species in the Scarabaeinae subfamily, Deltochilum valgum, has been found to be a predator of millipedes (Larsen et al, 2009).

In comparison to other dung beetles, D. valgum has a modified head, hind legs (the tibiae) and abdomen (pygidium), which makes it suited for attacking and feeding on millipedes. The beetle uses part of its head, the clypeus, as a lever to prise apart segments of a millipede’s body, often resulting in decapitation.

To test food preference the experimenters used a variety of bait traps containing dung, carrion, fungus, fruit and millipedes. They found that D. valgum was only attracted to millipedes and that it preferred millipedes which were injured but still alive.

Thanks to Linda for showing me a BBC News article on this. Irritatingly the BBC had inadequately referenced the study, so it took me a little while to find the actual article.

References:

Larsen, T.H., Lopera, A., Forsyth, A. and Génier, F. (2009) From coprophagy to predation: a dung beetle that kills millipedes. Biology Letters, 20th January [Online] Available at:

http://journals.royalsociety.org/content/g17124g4q8733365/

[Accessed 21st January 2009]

On Saturday 17th January the Phasmid Study Group had their winter meeting. Unfortunately I missed the AGM part but I managed to attend the two talks and got some new species to rear: Pseudophasma velutinum, P. rufipes ova and Meuseilochus sp. from Mount Apo. I will upload some photos of them soon.

The first talk was given by Mark Bushell and was a continuation of his Philippines phasmid hunting expedition. He’s a good story teller, so I enjoyed listening to his adventures and seeing the many photographs of foreign fauna. Whilst in the Philippines Mark discovered a new species of phasmid!

The second was given by David Robinson and gave a summary of the typical activities and the purpose of the International Congress of Entomology before covering some research on the phylogenetics of Dryococelus australis, the Lord Howe Island stick insect.

Dryococelus australis has quite an interesting story and I think it’s the only phasmid that has such an extensive breeding program. It used to be found on Lord Howe Island, an island east of mainland Australia. When black rats were introduced to the island, the stick insect was made locally extinct. As this was the only location that D. australis was know to occur, it was thought to be extinct. Sometime in 2001 a small colony was discovered on Ball’s Pyramid, a tiny outcrop of rock over 20km away from Lord Howe Island.

The phylogenetics paper has an example of convergent evolution and deserves its own post, so I’ll try and write a summary later this week.

There was a wonderful photograph of the castes of the ant Camponotus discolor on Myrmecos Blog.