Different transmission strategies of a parasite in male and female hosts.

We investigated whether a parasite with two routes of transmission responds to the different transmission opportunities offered by male and female hosts by using different transmission strategies in the two sexes. The parasite Ascogregarina culicis, which infects the mosquito Aedes aegypti, can be transmitted as its host's pupa transforms into an adult or when a female lays its eggs. As the latter transmission route is missing in males, we expected, and found, that the parasite releases a greater proportion of its infectious forms during emergence when it is within a male than when it infects a female. The transmission route, which influences the parasite's dispersal and the evolution of its virulence, was also affected by the dose of infection and the parasite's previous transmission route. Our results emphasize the complexity underlying the development of parasites and show their ability to tune their strategy to their environment.