How to Enforce Monogamy

Female Anopheles gambiae mosquitoes are the primary vectors for transmission of malaria-causing parasites. Unlike most other insects that mate multiple times, An. gambiae females undergo a postmating switch in which they become refractory to further mating and rely on sperm from a single male to fertilize eggs throughout their lifespan. In addition, the postmating switch induces morphological changes in the female reproductive tract and the ability to lay mature eggs. Male mosquitoes transmit the steroid hormone 20-hydroxyecdysone (20E) to females during mating. Gabrieli et al. profiled transcriptional changes in the female reproductive tract and identified changes in the expression of several 20E-responsive genes. Experimentally reducing the amount of 20E in males used for forced mating inhibited egg laying in females and the ability of mating to reduce the female’s receptiveness to a second partner. Injection of 20E into the thorax of virgin females caused them to be refractory to subsequent mating and insemination and induced egg laying. Moreover, mating or injection of 20E induced overlapping changes in gene expression consistent with the remodeling of the reproductive tract and implicated new enzymes involved in polyamine synthesis in egg laying. Thus, male-derived 20E leads to gene expression changes in the female reproductive tract that influence subsequent morphology and behavior. Targeting this signaling pathway may be an effective alternative to pesticides currently used to control malarial mosquitoes. P. Gabrieli, E. G. Kakani, S. N. Mitchell, E. Mameli, E. J. Want, A. Mariezcurrena Anton, A. Serrao, F. Baldini, F. Catteruccia, Sexual transfer of the steroid hormone 20E induces the postmating switch in Anopheles gambiae . Proc. Natl. Acad. Sci. U.S.A. 111 , 16353–16358 (2014). [Abstract][Full Text]