Parasitoid wasps turn caterpillar hosts into bodyguards

June 4th, 2008 - 5:59 pm ICT by ANI  

Washington, June 4 (ANI): Scientists have unearthed strong evidence that parasites induce such changes in the behaviour of their hosts as are beneficial to their survival.

Research from the University of Amsterdam, the Netherlands, and the Federal University of Vicosa, Brazil, studied a moth, whose caterpillars feed on leaves of the native guava tree and on an exotic eucalyptus.

During the study, the researchers observed that small caterpillars were attacked by an insect parasitoid wasp, which then quickly inserted up to 80 eggs into it.

The eggs of the parasitoid hatched inside the caterpillar host, and the larvae fed on the body fluids of the host.

The researchers said that the caterpillar continued feeding, moving and growing like its unparasitized brothers and sisters.

Upon growing fully, the parasitoid larvae emerged together through the host’s skin, and started pupating nearby.

According to the researchers, unlike other host-parasitoid combinations, the host in their study remained alive.

The host, however, displayed spectacular changes in its behaviour like stopping feeding, and remaining close to the parasitoid pupae.

It even defended the parasitoid pupae against approaching predators with violent head-swings.

The caterpillar died when the adult parasitoids emerged from their pupae.

Published in PLoS ONE, the study did not find any behaviour changes in unparasitized caterpillars, who continued feeding and developing into adults.

Given that parasitoid pupae guarded by caterpillars suffered half as much predation as those without bodyguards, the researchers concluded that the behavioural changes of the host resulted in increased survival of the parasitoids.

The researchers admitted that it was yet to be discerned how the parasitoid changed the behaviour of its host.

They, however, guess that perhaps the one or two parasitoid larvae, which remained behind the host, affected its behaviour, and sacrificed themselves for the good of their brothers and sisters. (ANI)

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