A good year for mind-controlling ladybird-munchers

Dinocampus_coccinellae

Dinocampus coccinellae: a fearsome foe of ladybirds. Photo: Wikimedia Commons

For my Masters Research Project (MRP) I am taking a look at righting and death-feigning among beetles, including a couple of ladybird species. I made the decision that I would try and work with natural populations wherever possible – the only problem with that, of course, is that nature can be the cruellest cohabiter.

Upon setting up a colony of seven-spot ladybird (Coccinella septempunctata), it quickly became apparent that I had a bit of an issue; namely finding quite a few specimens protectively guarding yellow cocoons. Doing such a good job of it, in fact, that it was almost impossible to remove them from both cocoon and plant. Dinocampus coccinellae had joined my project uninvited.

I was aware of possible parasitism of beetle juvenile stages, including those of ladybirds, but not the wasps with a penchant for taking on adults. Little did I know that this is the Braconid wasp D. Coccinellae’s stock-in-trade – and one that it’s building up such a reputation for its it’s started to become a minor mainstream news story. Indeed, once I was aware of it, I started to see ladybirds in their natural habitat sitting on cocoons seemingly everywhere, like some strangely beautiful horror movie in the undergrowth.

Coccinella septempunctata in aggressive cocoon-cuddling mode. Photo: Brad Foster (Twitter @bradwaspfoster)

The parasitoid was first given a full biological description in 1926 after it was first noted in Europe, and since then, boy has it settled in.

One facet of the appeal of insects is a feeling that the aliens are among us already – and indeed parasitoids really did inspire that scene in the film Alien. With D. coccinellae, it is isn’t just about depositing an egg inside the ladybird and leaving its young to, all being well (from the wasp’s perspective of course), burst out of its host’s body an adult. It goes in for full-on control and manipulation, creating ‘zombies’ from ladybird hosts that guard a wasp cocoon spun between its legs by larvae after they’ve had their feeding fun. In its sensory-controlled state, the ladybird twitches to deter predators as the larvae pupates and hangs in there for adulthood. They do a fine ‘bodyguard’ job too, with studies showing only 15% survival against predators with host protection, and 65% with.

This may well be a problem of particular concern to the seven-spot ladybird, as research has shown that while it’s wily wasp enemy can decimate its populations, successful parasitism and emergence rates of the wasp are significantly lower when it makes an ovipositional attack on the invasive Harlequin ladybird, Harmonia axyridis, while the two-spot ladybird, Adalia bipunctata, is an unsuitable host altogether. To make matters much worse for C. septempunctata, it has been demonstrated that its toxic defence chemicals actually act as a considerable attractant to D. coccinellae. Bloody hell, nature.

It seems that a perfect storm is gathering, where a wasp, a highly-successful invasive competitor, a fairly narrow (and early in the year) breeding period and other environmental stressors are combining to make life extremely difficult for one of the UK’s classic ladybird species. Will it withstand the onslaught? Too early to tell – but there are certainly reasons for concern.

As for my experiment, maintenance of colony health since the first sightings has proved a game of watching intently for signs of parasitism, removing rapidly, rinsing and repeating. But stare into D. coccinellae’s intensely beautiful shiny green eyes under a microscope and you can’t help feeling this is an animal you’re never going to quite have the measure of. Allow me this excessive sweep of anthropomorphism: its gaze really does follow you around.

While my run-in with this small wasp has provided much by way of irritation, once you’ve taken a step back from your emotional response, it’s hard not to simply admire a highly-specialised species succeeding in its niche. That is, however, likely to be extremely cold comfort for those looking to conserve the UK’s native ladybirds.

Advertisements

The ageless joy of the bug hunt

Pterostichus

Black clock beetle, Pterostichus madidus

There are, sadly, probably more misguided perceptions about insects than there are accurate ‘takes’. But there are plenty of preconceived ideas about those who take an interest in them, too.

High among them is the sense that insect interest is just for kids; something that should be ‘grown out of’. Such views are supported by the high availability of products bearing insect iconography among children’s’ toys and clothing, with such imagery generally tapering off (but not entirely) with age.

Personally, I have recently come to a realisation that it’s not just my decidedly mediocre mathematics that put me off the idea of pursuing zoological interests in favour of journalistic ones, before returning now, in my thirties, to a world of pitfall traps and invertebrate amazement once again. I have been labouring for way too long under feelings that a keen intense interest in insects, and indeed nature more broadly, for its own sake is somehow juvenile – something to cringe about rather than indulge or even celebrate.

I still sometimes feel pangs of embarrassment when spotted out collecting ladybirds for my Master’s Research Project – but certainly feel more shame about the embarrassment than the insect love itself now, which is at least progress of sorts. It may never truly go away, but the act of marvelling at the bustle in the undergrowth is now, thankfully, winning.

This tussle with perceptions both real and imagined leads me to suspect that there are thousands of adults out there suppressing a love of everything insect in the name of misguided concepts of maturity. Indeed, it’s been notable, since starting this course, how many of my friends with kids have remarked to me how their child is really into one insect or another. Yeah, but which do YOU love?

Peacock_butterfly_(Aglais_io)_2

Peacock butterfly, Aglais io

I’m currently trying to indoctrinate my nieces in the ways of the insect world, in a not entirely dissimilar but somewhat gentler manner to that with which Harper Adams’ entomology course leader Simon Leather attempts to indoctrinate all students with a solid appreciation of the aphid. It’s going pretty well, but the bigger challenge might well be to ensure they don’t shun interest upon reaching a certain age.

Not everyone’s going to be so interested they pursue insects to an academic level of course, but it’s hard not to imagine that ecological prospects might be a fair bit more solid if every child bug enthusiast let themselves be an adult bug enthusiast without casting shade on themselves.

It’s not just suppression of interest for erroneous ideas about growing up that can make one lose sight of the simple pleasure of observing the fascinating and often downright bizarre machinations of the insect realm, though. On embarking upon entomological study, there’s a secondary risk of getting so heavily into the mighty detail of it all, whether that’s at a molecular or genetic level or simply studying the minutiae of an insect behavioural trait, that the simple pleasure of exploring what’s out there, or even marvelling at insects per se is lost. Every entomologist should aim to remind themselves every day what a joy getting the chance to work with such remarkable creatures is.

Whatever happens from here, I’ve got my bug love back – and this time I’m not going to let it lapse. Anyway, I need to wrap this up as I’ve got pitfall traps to set.

An Update (Part 1)

It has been a hot minute since we posted the last article which introduced us, so a little update about what us budding entomologists have been getting up to on the course so far and my thoughts on it seemed rather apt. I present to you part one of the overview/highlights of what we’ve done so far:

Module 1: Biology & Taxonomy of Insects

Following the introductory Research & Information Skills module, this was the first entomology module with two weeks of entomological goodness for the cohort to get stuck into, and boy, we weren’t left disappointed. The module started with a session on Orthoptera and a general run through of insect anatomy led by Dr. Andy Cherrill. This was followed by practical session which involved a delightful dissection of the desert locust (Schistocerca gregaria).

 

The next day we covered the order Thysanoptera (thrips) with Dr Tom Pope (@ipm_tom), followed by a zoom through the superorder Dictyoptera (comprising of the orders Mantodea (mantids) and Blattodea (cockroaches and termites)) with Dr. Rob Graham. With everyone on the course being from varied backgrounds and holding different levels of experience within different things, the session on insect pinning and curation was extremely useful for everyone. The cohort spent the afternoon pinning, micropinning and carding insects in a thrilling practical session led by PhD student Francisca Sconce (@FranciscaSconce).

received_10212882523289166[1]

Pinned 3rd instar desert locust nymph and carabid (specimens pinned and photographed by Linzi (@Apis_linzi)).

After a whizz through a lecture on sampling methods by Prof. Simon Leather (@EntoProf) we covered a range of methods, ranging from beating to sweep netting and from pitfall traps to malaise traps. The afternoon was spent in the great outdoors sweep netting and getting to use the Vortistm, a vacuum used to suck up and sample insects (and relatives).

20171004_145807[1]

Fellow entomologist Brinna (@BrinnaBarlow) trying her hand at sampling some insects using the Vortis suction sampler.

The first week of this module ended with a bang, with the first guest speaker from the Natural History Museum: hymenopterist Dr. Andy Polaszek (@AndyPolaszek)! In a blitz through the hyper diverse Hymenoptera, we covered several groups, focusing on their identification as well as some tidbits on their biology. We put what we learnt during the morning lecture to test in an intense identification practical.

 

 

 

Week two of the module started with an aphid-packed day on Hemiptera. The next day was Lepidoptera-filled. We had a practical session which involved taking morphometric measurments in waxmoths (Galleria mellonella) and dissecting out the females ovarioles to count the number of eggs.

20171010_150657[1]

A female wax moth (Galleria mellonella) dissected with ovarioles spread out, as part of the Lepidoptera class practical.

Speaker number two from NHM was THE fly girl herself, Dr. Erica McAllister (@flygirlNHM)! She vividly captured our interest and introduced us to the weird and wonderful world of flies. Leading on nicely from the zoom through Diptera, we had a session on Forensic Entomology, full of murder (not literally of course…that’d be bad) and maggots with one of the UK’s leading forensic entomologist’s Dr. Amoret Whitaker. The module ended with shimmer and shine a.k.a beetles, with coleopterist Dr. Max Barclay (@Coleopterist)!

 

This module was certainly a personal favourite of mine (so far), we covered SOOO MUCH in a relatively short space of time. With informative lectures from the university lecturers, plenty of hands on practicals, combined with several external speakers who are experts within their respective fields; I feel as though we thoroughly covered the major insect orders in a very engaging manner! A truly fantastic start to the course!

Make sure to check out the next post “An Update (Part 2)” on Saturday!

 

By Aqib Ali  (Twitter:@EntoAqib , Email: Aqib1996@hotmail.co.uk , Linkedin: Aqib Ali)

MSc Entomology Twitter: @EntoMasters