Find the aphid: Molted carapaces act as protective decoys for aphids

Dec 19, 2008
An aphid being parasitized by an aphidiinae wasp. Credit: Muratori et al., BMC Evolutionary Biology 2008

By leaving the remains of their old exoskeletons, called 'exuviae', in and around their colonies, aphids gain some measure of protection from parasites. Research published in the open access journal BMC Evolutionary Biology has shown that parasitoid wasps are likely to attack the empty shells, resulting in a lower attack rate on their previous occupants – much like in the popular 'shell game' confidence trick.

Frédéric Muratori and his collaborators from the Université catholique de Louvain, Belgium, and McGill University, Canada, studied the insects in an effort to explain the aphids' tendency to leave exuviae around their colonies, behaviour the authors describe as 'bad housekeeping'. He said, "By leaving exuviae around the colony, aphids make detection easier for the parasite wasps. As such, this behaviour has been thought counter-selective. Here we show that the exuviae act as a decoy, and the time the wasps spend investigating the old shells limits the damage done to the aphid population".

Aphidiinae wasps use an ovipositor at the rear of their abdomen to lay their eggs inside aphids. Eventually, the development of the parasitoid larva is fatal for the aphid concerned. The authors predicted that the areas littered with exuviae decoys would be seen as poor hunting grounds by the wasps who would move on to other patches. In fact, Muratori describes how, "We found that parasitoid females spent more time in patches that contained exuviae than in patches that contained only aphids, suggesting that these females either did not recognize exuviae as low quality hosts or needed time to correctly identify them".

The potential gain for the individual aphids comes from the increased time available to escape from the colony while the wasps are investigating the decoys. According to the authors, "Aphids release an alarm pheromone when they are under parasitoid attack, giving other aphids time to escape. In nature this is achieved by dropping off the plant".

Paper: Bad housekeeping: why do aphids leave their exuviae inside the colony? Frederic B Muratori, David D Damiens, Thierry Hance and Guy Boivin, BMC Evolutionary Biology (in press)
www.biomedcentral.com/bmcevolbiol/

Source: BioMed Central

Explore further: Researchers discover new mechanism of DNA repair

Related Stories

The very hungry sea anemone

9 minutes ago

The surprising culinary preferences of an abyssal sea anemone have been unveiled by a team of scientists from the National Oceanography Centre (NOC).

Extreme lab at European X-ray laser XFEL is a go

22 minutes ago

The Helmholtz Senate has given the green light for the Association's involvement in the Helmholtz International Beamline (HIB), a new kind of experimentation station at the X-ray laser European XFEL in Hamburg, ...

Recommended for you

Researchers discover new mechanism of DNA repair

11 hours ago

The DNA molecule is chemically unstable giving rise to DNA lesions of different nature. That is why DNA damage detection, signaling and repair, collectively known as the DNA damage response, are needed.

The math of shark skin

18 hours ago

"Sharks are almost perfectly evolved animals. We can learn a lot from studying them," says Emory mathematician Alessandro Veneziani.

Cuban, US scientists bond over big sharks

23 hours ago

Somewhere in the North Atlantic right now, a longfin mako shark—a cousin of the storied great white—is cruising around, oblivious to the yellow satellite tag on its dorsal fin.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.