University of Exeter biologists say that some female beetles often mate simply to quench their thirst and overcome dehydration. The sexual imperative is provided by male beetles who produce unusually large ejaculates (up to 10 percent of their body weight), tempting dehydrated females to accept sexual invitations simply to get hold of the water in the seminal fluid.
Published in Animal Behaviour, the study examined the behaviour of the beetleCallosobruchus maculates, a serious pest in warm climates. Some females were given unlimited access to water while others were not and all the females were free to mate. The researchers found that thirsty females mated 40 percent more frequently than those with free access to water.
The University of Exeter’s Dr Martin Edvardsson explained that the female beetles can absorb the water in the seminal fluid through their reproductive tracts and need to mate less frequently the more water they take from each mating. This is to a male’s advantage, says Edvardsson, because the longer the female goes without mating with another male, the greater his chance of successful fertilization. By transferring a large amount of water with the sperm, a male can help ensure his sperm has more time to fertilize the eggs without having to compete with the sperm from future matings.
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