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The Violent Sex Lives of Tahitian Bugs

Hidden among the bushes of this lush landscape, a battle between the sexes rages on
Hidden among the bushes of this lush landscape, a battle between the sexes rages on

National Geographic grantee  Nik Tatarnic is taking a closer look at the traumatic sex lives of Tahiti’s tiny bugs. Follow Nik’s expedition on Explorers Journal as he investigates the bizarre sexuality of the genus known as Coridromius.

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In a few weeks we will be heading to French Polynesia for the first of two trips to study the sex lives of traumatically inseminating bugs (genus Coridromius) endemic to Tahiti. Along with my colleagues Luke Holman and Jean-Yves Meyer, we will be exploring how interspecies interactions  are driving the evolution of two species that live and forage together on the same plants.

For those of you who don’t know, traumatic insemination (TI) is an unusual mating system found in various invertebrates. Essentially, males use hypodermic genitalia to puncture females through the side of the body, injecting sperm into the female’s body cavity. The sperm then travel through the blood to the ovaries. Not surprisingly this form of mating can be costly to females, and has led to the evolution of cost-mitigating female “paragenitalia”, specialized reproductive organs, at the site of insemination in many species.

In Coridromius and other TI bugs, males occasionally make mistakes and attempt to mate with juveniles, other males, or even other species! In the case of these Tahitian bugs,we suspect that both sexes of one of the species in question mimic males of the other species as a way to “fly under the radar” and survive in a mixed species population.

For some background on the bugs in question check out my recent paper (with my colleague Prof Gerry Cassis) in American Naturalist, available free online. You can also check out our review of traumatic insemination in terrestrial Arthropods in Annual Review of Entomology (Contact me if you don’t have access).