07 Oct Bed bug traumatic insemination strategies

Whenever I get the opportunity to collect large samples of bed bugs for my experiments I always take advantage. 11 days ago I had a golden opportunity and I collected about 50 bugs off the bottom of a box spring. To facilitate the collection of the most number of bugs possible with the least amount of injury to the bugs I find a large harbourage and scrape the entire conglomeration of bugs and bug shells into the bottle in one swipe – the faster this is done the more bugs you can collect before the bugs start running which makes collection more difficult.

I then leave the entire sealed jar in a corner for a week or so to make the bugs hungry. The bugs tend to remain in their harbourages if they are well fed so a little starvation facilitates their movement in the experiment arena. I then dump a number of bugs into the arena from the jar and with the bugs comes a bit of the harbourage material from the box spring. The bugs will then treat that pile of material as their harbourage in the arena.

Yesterday as I was observing the experiment I noticed one bug mount (I assume it was for sexual purposes) another bug and the bug at the bottom ran full speed (while carrying the other bug) around the arena. The bottom bug after a frantic dash ran straight into the pile of harbourage material covering itself with the material and stayed there.

To make sense of this behaviour it is important to note that the sexual reproduction of the bed bug occurs through what is known as traumatic insemination. That means the male pierces the exoskeleton of the female with its genitalia to deposit sperm. If this happens too often, and the males are more than willing to facilitate repeated sexual interactions, the female dies from infection. The females therefore attempt to avoid the males after being fertilized. But given that the bugs I collected all came from 3 or four large harbourages on the box spring and the females seemed to be living in peace with the males, why were the males and females living in communal peace on the box spring harbourage?

In yesterdays experiment I noted that the first instinct of the bed bug, when attacked for sexual purposes, was to run to the harbourage. I theorize that, given the cramped nature of bed bug harbourages, that there is no room for the male to mount the female in these locations so the female is safe. That is why females and males can live together in the same harbourage without the females dying of repeated traumatic insemination induced infection.