How do beetles mate

The method of mating, though brutal, does up the odds for successful beetle fertilization. The team found that evolutionary changes happened not in just one population of beetles, but across several. Seed beetles are not alone in traumatic mating. Hood points out that bed bug males use a hypodermic needle penises to simply pierce the female abdomen. And there are plenty of examples of sexual cannibalism including spiders and preying mantises.

Even ducks have pretty violent sex. While the traumatic mating in seed beetles at least makes some sense, Dougherty tells Hood that overall, it's not yet clear how sexual conflict drives evolution in the rest of the animal kingdom.

Jason Daley is a Madison, Wisconsin-based writer specializing in natural history, science, travel, and the environment. Davey, K. Reproduction in the insects. Freeman, San Francisco. Smith, R. Academic Press, New York. Thornhill, R. The Evolution of Insect Mating Systems.

Harvard University Press, Cambridge, Massachusetts. Waldbauer, Gilbert. Insects Through the Seasons. BugInfo Mating in Insects. Locating and recognizing mates. Courtship ritual. Post-mating behavior. Selected References: Beebe, W. But why have male beetles evolved such hellish genitals?

What benefits do they gain by physically harming their partners? In this theory, the spines are important for winning these competitions, and the wounds they inflict are simply a nasty side-effect. Size, it seems, really does matter. The genitals of these different populations are very varied and to study them under a microscope, Hotzy and Arnqvist first had to fluff their subjects.

Under a microscope, they measured the length of the longest spines and the size of the entire spine-bearing area. They studied female beetles too, and all from a single population. Each one was allowed to mate once with a single male. A week later, Hotzy and Arnqvist dissected their sexual tracts to see how much scarring they had, using the distinctive black pigments on the scars to spot them.

Two days later, the females were then paired with a second male, taken from one of the 13 worldwide populations. One week later, they counted all the eggs she laid. Every one of these must have been fathered by the second male, so their number represents his ability to successfully oust the sterile sperm of the first partner. Either way, they have clearly evolved to allow the male seed beetle to out-ejaculate his rivals. This fierce competition for fertilisation rights is fairly common among insects and has led to the evolution of some truly horrific sexual strategies.

Some species, like the dung fly , also have armoured genitals. Others, like the familiar fly Drosophila melanogaster , have toxic semen laden with chemicals that actually slash the lifespans of females, who can literally mate their way to death.