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Strangely enough, traumatic insemination is not just limited to female-male couplings. In the African bat bug Afrocimex constrictus , both sexes are subject to traumatic intromission from males. In this species, both males and females have ectospermaleges, but only females have mesospermaleges. Although the ectospermaleges of each sex differs, male bat bugs have shown symptoms of suffering from traumatic inseminations. Not only were there characteristic mating scars on the males, but there were also foreign sperm found throughout the bodies of the homosexually mated males. There is debate as to whether these same sex traumatic inseminations are a result of sexual competition or just carelessness.
Furthermore, some females in A. constrictus have developed these male spermalege structures. Males, as well as females that had the male genitalia form, experienced fewer traumatic inseminations than the typical female that had the female genitalia form. Scientists believe that females mimic the male condition in order to reduce the frequency of the costly traumatic inseminations. (Reinhardt et al. 2007).
In male bed bugs, the intromittent organ is highly specialized for traumatic insemination (see [link] ). The organ is not only sclerotized , but also curved and needle-like, perfect for puncturing the exoskeleton (Usinger 1966 as cited by Reinhardt&Siva-Jothy 2007).
However, males do not just intromit their parameres anywhere on their partners (Reinhardt et al. 2003). In C. lectularius, females have a unique organ called the spermalege, which is thought to have evolved as a counter adaptation to the antagonistic traits of the male (see [link] ). The spermalege consists of both the ectospermalege and the mesospermalege . During traumatic insemination, a male bed bug inserts his intromittent organ into the ectospermalege, a groove in the right-hand posterior margin of the fifth sclerite, and pierces the pleural membrane (Stutt&Siva-Jothy 2001). The sperm is then injected into the mesospermalege, which contains hemocytes. Once the wound at the injection site heals, a melanized scar forms (Usinger 1966 as cited by Reinhardt&Siva-Jothy 2007).
An interesting point to note is that bed bugs copulate exclusively by traumatic insemination. This may seem odd because female cimicids possess a fully functional female reproductive tract. In the past few decades, not once has a male bed bug ever been observed copulating by placing his paramere into a female’s vagina (Carayon 1966 as cited by Reinhardt&Siva-Jothy 2007, Reinhardt et al. 2003) In fact, females only use the genital tract for oviposition (Carayon 1966 as cited by Reinhard&Siva-Jothy 2007).
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