Traumatic insemination

The bed bug is a well-known creature as it is often featured in a children’s bedtime rhyme. We know they can bite and leave a nasty sore but what is uncommon about them is the way they reproduce. 
The bed bug (Cimex lectularius) reproduce by a method known as traumatic insemination which means the male pierces through the female’s abdominal area with his genitalia and inseminates into her body. What is even worse for this species is it is not only the female that suffers this treatment. It is known that the male will mount another male if he displays the right body size (Stutt and Siva-Jothy, 2001). The males cannot tell between sexes, rather a large body size is what indicates a potential mate so if a male has the right body size than he too is seen as a potential breeder.

 Copulation occurs through extragenital insemination, this is where insemination occurs without the use of the female’s genitalia. The male inserts his specialised intromittent organ into a grove on her abdomen called the ectospermalege. This is where the male always inseminates as it directly overlies the mesospermalege, where the sperm will be ejaculated. Once he has managed to pierce through the female’s external wall, his intromittent organ will reach the mesospermalege. Once ejaculation has occurred into the mesospermalege the sperm then migrates to the ovaries where fertilization will take place. Although the females do have a genital track it is not used for copulation and only functions for egg laying (Stutt and Siva-Jothy, 2001).

 Traumatic insemination is costly for the females and is believed to have evolved more by the male than the female. By traumatic insemination the male is able to copulate multiple times with no resistance by the females. This allows the male to control mating frequencies and therefore is able to pass on his genes at a higher rate. The female has also evolved to respond to the high costs of traumatic insemination by the use of the mesospermalege which assists in reducing the effects of wounding and likelihood of infection caused by traumatic insemination (Stutt and Siva-Jothy, 2001).

 References:
 Stutt, A. D. and Siva-Jothy, M. T. 2001,‘Traumatic insemination and sexual conflict in the bed bug Cimex lectularius’, Proceedings of the national academy of sciences, Vol. 98, no. 10, pp. 5683-5687.