Killer wasps drive flies to medicate their kids with booze

Aurich Lawson

Our interaction with medication involves many conscious decisions. We recognize a threat (either existing or pending), diagnose the nature of the threat, and then choose a remedy to match it. But does medicating really require that level of decision-making? A study in today's issue of Science suggests fruit flies are capable of medicating not only themselves but their offspring as well. And their medication of choice? Alcohol.

The threat for these flies is any of a number of small, parasitic wasps. These wasps lay eggs on the larva or pupa of the flies, and their offspring feed on the animal internally, often killing them in the process. (Flies have larval stages, during which we call them maggots, and pupate just as butterflies do before emerging in their adult form.) Once infected, there isn't much one of the larva can do to get rid of the parasite.

Its one option: booze. Fruit flies, as their name implies, like to dine on fruit, especially during the larval stages. In many cases, that involves ingesting the alcohol that's produced by natural fermentation of rotting fruit (this can approach 20 percent alcohol content). Some species of flies have developed the ability to tolerate this alcohol as they chew through the fruit as maggots. But for most of the wasp species, even moderate levels of alcohol are toxic.