Mating strategies and spermiogenesis in ixodid ticks

Mate-seeking and sperm-transfer in the ixodid hard ticks, which include important vectors of zoonotic pathogens, generally reflect their peculiarly prolonged pattern of feeding. The metastriate ticks, including Dermacentor, Amblyomma, and Rhipicephalus, invariably attain sexual maturity and mate solely on their hosts. The more primitive prostriate Ixodes ticks, however, may copulate both in the absence of hosts and while the female engorges. These expanded opportunities for insemination complicate the mating systems of the Ixodes ricinus complex of species. In these ticks, autogenous spermatogenesis must precede host contact, whereas anautogenous oogenesis requires that the females store sperm. All hard tick males undergo a courting ritual before they can deposit their spermatophores within the female's genital tract. These diverse and prolonged patterns of sexual interaction provide opportunities for interactions between populations and individuals that may be relevant to the role of ticks as vectors of zoonotic pathogens.