A parasitic worm that makes the grasshopper it invades jump into water and commit suicide does so by chemically influencing its brain, a study of the insectsâ€™ proteins reveal.
The parasitic Nematomorph hairworm (Spinochordodes tellinii) develops inside land-dwelling grasshoppers and crickets until the time comes for the worm to transform into an aquatic adult. Somehow mature hairworms brainwash their hosts into behaving in a way they never usually would â€“ causing them to seek out and plunge into water.
Once in the water the mature hairworms â€“ which are three to four times longer than their hosts when extended â€“ emerge and swim away to find a mate, leaving their host dead or dying in the water. David Biron, one of the study team at IRD in Montpellier, France, notes that other parasites can also manipulate their hostsâ€™ behaviour: â€œâ€™Enslaverâ€™ fungi make their insect hosts die perched in a position that favours the dispersal of spores by the wind, for example.â€