Male-killing bacteria and STIs in Ladybugs?

Bugs get STIs too? For creatures who are so different from humans, how would something like that even be possible? In 2015, British researchers Patek et. al sought to analyze the epidemiology of sexually transmitted mites in populations where there are more female than male ladybugs due to a male-killing bacteria, Spiroplasma.

Researchers observed this phenomenon by creating two experimental groups which consisted of infected males who mated with virgin, uninfected females in a ‘standard’-mating opportunity group and a ‘frequent’-mating opportunity group. The standard opportunity group was used to emulate the ‘standard’ one female: one male population while the ‘frequent’ opportunity group emulated a four female: one male mating population ratio. What they found was that ‘frequented’ males copulated for shorter periods of time and were less likely to produce a mature mite infection on their female mates than the ‘standard’ males. Moreover, the males that mated more frequently did not prevent females from remating.

This experiment suggests that male mating rates are plastic and adjust to the environment that they are in regardless of whether or not the sex ratios are 1:1 or 4:1 and would imply that mating more frequently under shorter periods of time limits copulation time, and thus the likelihood that and STI would be transmitted. This information is important because in humans, it may shed light into how copulation times could affect the likelihood of transmitting an STI.

Pastok, D., Atkinson, D., & Hurst, G. D. (2015). Assessing the impact of male-killing bacteria on the spread of a sexually transmitted infection. Animal Behaviour, 107, 41-48. http://dx.doi.org/10.1016/j.anbehav.2015.06.002