Evolution of sexual traits influencing vectorial capacity in anopheline mosquitoes

Abstract

Mating plugs promote malaria parasites Males of some of the malaria-transmitting mosquitoes “plug” females after copulation to stop interloping males from mating. The mating plug also delivers a steroid hormone into the female uterus. This hormone pulse promotes egg production and stimulates egg laying. It also curbs the mosquitoes' immune responses, which allows parasites such as malaria to develop unhindered. Mitchell et al. discovered that plugs are a recent evolutionary acquisition (see the Perspective by Alonzo). South American anopheline mosquitoes lack these plugs altogether, whereas African and Indian species have complex plugs replete with hormones. It is unlikely to be a coincidence that the most elaborate mosquito plugs are also found in regions where malaria transmission rates are highest. Science , this issue p. 985 ; see also p. 948