Sperm competition in the Acari

First copulation increases longevity and fecundity of Histiostoma feroniarum (Acari: Astigmata: Acaridida) females

“…Similar morphology of the female reproductive system in all astigmatid species strongly suggests a uniform sperm utilization pattern favouring the last mating male (Radwan and Witalin´ski 1991;Witalin´ski and Walzl 1995;Witalin´ski 1999). This is also in full accord with post-insemination mate association observed in S. berlesei and R. robini and considered as a form of post-copulatory mate guarding (Radwan and Siva-Jothy 1996).…”

“…In contrast to the species described above, many feather and itch mites (Astigmata: Psoroptidia) display pre-copulatory mate guarding behaviour and morphological adaptation (Witalin´ski et al 1992;Alberti and Coons 1999;Witalin´ski 1999). This type of guarding which also occurs in the free living Histiostoma feroniarum, evidently opposes last-sperm priority.…”

Fine structure of the spermatophore and spermatozoa in inseminated females ofPergamasus mites (Acari: Gamasida: Pergamasidae)

“…According to Yasui (1997), frequent (day by day) inseminations are necessary to obtain optimal fecundity in Parasitus fimetorum, since the stock of spermatozoa from a single insemination is quickly exhausted. Thus, the numerous matings may represent "trials"-more or less successful-undertaken by subsequent males (Witaliñ ski, 1999). Furthermore, we showed previously that the endogynium of Pergamasus mites is provided with spines that keep the spermatophore in position and likely might prevent removal.…”

“…Further on, the females may have evolved a sperm access system as an "answer" to this new insemination route, thereby regaining control of the process. Alberti (1988) first published an observation of sperm cells in the hemocoel of a pergamasid female, which gave this hypothesis some support (see also Witaliñ ski, 1999). Recently, Moraza and Lindquist (1998) discussed the present state of gamasid systematics and considered in detail the above results and hypothesis.…”

“…The alternative explanation for cheliceralprobing, as a behavior of males that try to replace the rival spermatophore with their own sperm, is unlikely in light of Yasui's (1997) observations (see above and Witaliñ ski, 1999).…”