Traumatic Insemination - Homosexual Traumatic Insemination

Homosexual Traumatic Insemination

Traumatic insemination is not limited to male–female couplings. Male homosexual traumatic inseminations have been observed in Xylocoris maculipennis and the Afrocimex genus.

In the genus Afrocimex, both species have well developed ectospermalege (but only females have a mesospermalege). The male ectospermalege is slightly different from that found in females, and amazingly enough, Carayon (1966) found that male Afrocimex bugs suffer actual homosexual traumatic inseminations. He found the male ectospermalege often showed characteristic mating scars, and histological studies showed "foreign" sperm were widely dispersed in the bodies of these homosexually mated males. Sperm cells of other males were, however, never found in or near the male reproductive tract. It therefore seems unlikely that sperm from other males could be inseminated when a male that has himself suffered traumatic insemination mates with a females. The costs and benefits, if any, of homosexual traumatic insemination in Afrocimex remain unknown.

Klaus Reinhardt of the University of Sheffield and colleagues observed two morphologically different kinds of spermalege in Afrocimex constrictus, a species in which both male and females are traumatically inseminated. They found females use sexual mimicry as a way to avoid traumatic insemination. In particular, they observed males, and females who had male spermalege structures, were inseminated less often than females with female spermalege structures.

In Xylocoris maculipennis, a flower bug, after a male traumatically inseminates another male, the injected sperm migrate to the testes. (The seminal fluid and most of the sperm are digested, giving the inseminated male a nutrient-rich meal.) It has been suggested, although there is no evidence, that when the inseminated male ejaculates into a female, the female receives both males' sperm.