Sperm as a Water Source

Some males are able to do anything for sex. And bugs can bring it to extremes.

Praying mantis male really loses its head, as the female starts eating him during the copulation. Spider males won't lose their skin as this is the only thing left of them (the rest has already entered into the female's stomach). Dragonfly males won't get a moment of pleasure if they do not offer the female a meal; so do many spider males.

A new curious sexual behavior adds to the long gallery of sexual oddities in the bug world, in which females always take advantage of males. If you thought only men buy women a drink to win her favors, that's wrong.

There are beetle females that will mate just for quenching their thirst. It's the case of the bean weevil Callosobruchus maculatus, which feeds on stored pulses, which usually contain no more than 10 % water.

With such a dry diet, the male's ejaculate is a precious water source for females.
To check this hypothesis, Martin Edvardsson at Uppsala University, Sweden, put females of bean weevil on dry beans with or without access to water. Those kept on beans alone mated with more males, presumably to get the water in the seminal fluid.

"The energy used to produce the ejaculate, which makes up a whopping 10 % of a male's weight, is well spent. Once impregnated, females lose interest in sex - probably to avoid further injury from the male's spiny penis. They are more likely to mate again if they are thirsty. This is a massive investment for the male. It buys them time before the females remate and their sperm have to compete with that of other males." said Edvardsson.

Females with access to water had a lifespan on average with a day and half longer than those kept without water. In the case of this species, the adults live just about nine days, and this apparently little difference is in fact a huge difference on the total number of eggs they deposit.