Aggressive sex spurs female bedbugs to become more flexible

Cheryl Power/Science Photo Library/Corbis

Aggressive sex spurs female bedbugs to become more flexible

Sex comes at a high cost for female bedbugs. A male pokes a hole into her abdomen to fertilize her, and, as a result, the puncture wound spills fluids and hemolymph (bug blood). Biological models of this sort of “sexual conflict” predict that the female will evolve resistance in the form of a thicker abdomen or vigorous self-defense strategies to prevent damage from the male sex organ. The male would then counterevolve a sharper or stiffer penis, leading to an evolutionary arms race. However, researchers report online today in the Journal of the Royal Society Interface that females appear to be opting for tolerance instead of resistance. Using a suite of microscopes, scientists discovered that female bedbugs have begun to incorporate elastic proteins called resilins into a specific region of their abdomens most likely to be punctured. The stretchier region, known as spermalege, is easier for males to puncture, causing less tissue damage and fluid loss. Unlike many traditional resistance methods employed by females, the easier penetration didn’t appear to reduce the male’s health or life span. Even better, a strategy of tolerance as opposed to resistance frees both sexes from the evolutionary arms race of escalating sexual conflict.

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