Parasite-induced risk of mortality elevates reproductive effort in male Drosophila.

A trade-off between sex and somatic maintenance is fundamental to life-history theory. Tests of this trade-off usually emphasize deleterious consequences of increased reproduction on life span. Here we show the reverse effect, that reductions in the expected life span elevate sexual activity. Experimentally parasitized male Drosophila nigrospiracula lived shorter lives, but before dying, they courted females significantly more than unparasitized controls. This greater courtship resulted in increased mating speed, and potentially greater reproductive success than parasitized males would have achieved otherwise. The results show that an environmental reduction in life span increases reproductive effort, and support the hypothesis of a trade-off between these key life-history traits.