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.

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MRP: Optimising rearing conditions for black solider flies – Julian Beniers

Julian Beniers is a man with a mission. Before he even applied for the MSc course, he had formulated his Master’s Research Project (MRP), methods and all. During his BSc at HAS University of Applied Sciences, he started a project on black solider flies (Hermetia illucens) and became interested in their biology and behaviour. He then furthered this interest when doing an internship with the same species before coming to Harper Adams University (twitter: @HarperAdamsUni). By the time he arrived in Shropshire, his MRP was complete in all but execution.

Julian will be investigating the effect of protein and carbohydrate levels in black solider fly larvae foods and its relation to larval mass over the course of larval development, and potentially macronutrient levels within the larvae too (time permitting). He wants to answer the question “When do black soldier fly larvae begin producing large fat reserves, and specifically, at what weight does this normally occur?”. Black solider fly larvae rapidly become larger during their first instars and protein is likely to the most important macronutrient of their diet, whereas later in larval development, carbohydrates and fats may become more important. To answer his research question, Julian will attempt to map protein and fat content of larvae at precise intervals throughout their development by killing, drying and subjecting the dried tissue to Soxhlet and leco fat and protein analysis, respectively. He’ll also be using a variety of different foods with varying levels of protein and carbohydrate to see if these can be used to determine an optimal diet and growth rate. He suspects the larval mass at which a change in macronutrient storage occurs in between 140-160 mg.

This research is potentially quite commercially important because of the widespread use of black soldier fly larvae in the pet trade (food for exotic pets) and in human entomophagy (food for us). Interestingly, Julian gently suggests that this research may actually have been done before internally within pet food companies, however, as the Robin Hood of trade secrets, Julian attempts to get this research published, which could make things easier for other companies and independent rearers.

More generally, Julian is an avid keeper of entomofauna and is curious about the upcoming entomophagy industry in the West (an age-old industry in other parts of the world); he is planning to attend the Royal Entomological Society’s entomophagy day on April 4th.

Please don’t hesitate to contact me (details below) or Julian with advice or questions (twitter: @Julianosaurus; email: julianbeniers@hotmail.com; LinkedIn).

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Featured photo: Black solider fly larvae – photographed by Julian Beniers, of course!

Blog written by Max Tercel (email: max.tercel@hotmail.com; twitter: @MaximumInsect).

 

 

 

 

 

Master’s Research Project: methods of sampling ant-associated beetles – Jack Weatherington

The ecological dominance of ants (Hymenoptera: Formicidae) is striking across a very wide spatial scale, reaching its pinnacle in the rainforests and savannahs of the tropics (Hölldobler and Wilson, 1990). The jurisdiction of this Queendom reaches Britain too. Red wood ants (Formica rufa), where found, can constitute a vital part of the local ecology of forests, feeding on aphid honeydew and pretty much any invertebrates they can overpower, like the little myrmidons they are. Jack Weatherington, a fellow MSc student boasting an impressive knowledge of insect taxonomy, has chosen the red wood ant as the focus for his Master’s Research Project (MRP). However, he faced a dilemma! Continue reading

Master’s Research Projects: gut analysis of coprophagous dipteran larvae – Alex Dye

The first in a series of posts detailing some of the Master’s Research Projects (MRPs) being undertaken here at Harper Adams University features the dipterist, head our MSc twitter page, and all-round good guy, Alex Dye! Continue reading