“One of the reasons they are interesting is that parasites are often able to get in there and selectively manipulate behaviour,” she told New Scientist. “It’s a very novel study, because there are very, very few papers on how behaviour actually changes,” says Shelley Adamo at Dalhousie University in Halifax, Canada, an expert in insect behavioural physiology who is familiar with Biron’s work. To view a video of the parasite and grasshopper in action, which includes a brief interview, in French, with lead researcher Frederic Thomas, visit the Canal IRD website.

Now Biron and his colleagues have shown that the worm brainwashes the grasshopper by producing proteins which directly and indirectly affect the grasshopper’s central nervous system. David Biron, one of the study team at IRD in Montpellier, France, notes that other parasites can also manipulate their hosts’ behaviour: “‘Enslaver’ fungi make their insect hosts die perched in a position that favours the dispersal of spores by the wind, for example.”īut the “mechanisms underlying this intriguing parasitic strategy remain poorly understood, generally”, he says. Once in the water the mature hairworms – which are three to four times longer that their hosts when extended – emerge and swim away to find a mate, leaving their host dead or dying in the water. Somehow mature hairworms brainwash their hosts into behaving in way they never usually would – causing them to seek out and plunge into water. 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.

The parasitic hairworm persuades its grasshopper host to leave its forest home and plunge into water, so the worm can emerge and find a mateĪ 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 insects’ proteins reveal.

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