Alcohol Consumption as Self-Medication against Blood-Borne Parasites in the Fruit Fly

Department of Biology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA.
Current biology: CB (Impact Factor: 9.57). 02/2012; 22(6):488-93. DOI: 10.1016/j.cub.2012.01.045
Source: PubMed


Plants and fungi often produce toxic secondary metabolites that limit their consumption, but herbivores and fungivores that evolve resistance gain access to these resources and can also gain protection against nonresistant predators and parasites. Given that Drosophila melanogaster fruit fly larvae consume yeasts growing on rotting fruit and have evolved resistance to fermentation products, we decided to test whether alcohol protects flies from one of their common natural parasites, endoparasitoid wasps. Here, we show that exposure to ethanol reduces wasp oviposition into fruit fly larvae. Furthermore, if infected, ethanol consumption by fruit fly larvae causes increased death of wasp larvae growing in the hemocoel and increased fly survival without need of the stereotypical antiwasp immune response. This multifaceted protection afforded to fly larvae by ethanol is significantly more effective against a generalist wasp than a wasp that specializes on D. melanogaster. Finally, fly larvae seek out ethanol-containing food when infected, indicating that they use alcohol as an antiwasp medicine. Although the high resistance of D. melanogaster may make it uniquely suited to exploit curative properties of alcohol, it is possible that alcohol consumption may have similar protective effects in other organisms.

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    • "In addition to physiological defenses, some Drosophila species (D. melanogaster, D. simulans, D. hydei, D. virilis) can modify their oviposition behaviors in response to parasitoid presence (Kacsoh et al. 2013). Specifically, when in the presence of female L. boulardi wasps (and other larval endoparasitoid species in the case of D. melanogaster), female flies increase their preference for substrates high in ethanol content, which in turn medicates developing larvae against development endoparasitoids (Milan et al. 2012). Given the habit for SWD to oviposit in ripening or ripe fruit, when compared to the decomposing (and thus higher in ethanol content) substrates used by nearly all other Drosophila, it may be that self-medication is a less viable defensive option for SWD when compared to other species. "
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