Parasite gives its host the munchies

Melissa Bernardo

Parasite gives its host the munchies

PORTLAND, OREGON—Parasites can do everything from making their hosts sick to forcing them to kill themselves. Now, scientists have found one that gives its owner the munchies. The tiny parasitoid wasp (Cotesia nr. phobetri) deposits its eggs in immature tiger moths, and as the wasps develop, they eat the Grammia incorrupta caterpillar from the inside out. Infected caterpillars still go about the business of bulking up for their next stage of life, but the wasp larvae give them a very bad case of carbohydrate cravings, ecologists report here today at the annual meeting of the Society for Integrative and Comparative Biology. Normally the caterpillars eat equal amounts of protein and carbs, but when infected, they up their carb intake by about 30%. This diet dumps more calories into the moths’ fat bodies, which the parasites gobble up, emerging (pictured) much bigger as a result. Moreover, going for the starches instead of proteins seems to delay the moth’s ability to mount an effective immune response against this unwanted guest, the scientists report. This behavior is one of the few clear-cut examples of diet manipulation by parasites and may have implications to human health in that there may be a similar, albeit still undiscovered, manipulative power in human gut parasites, they note.