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The nuptial gift that leaves a bitter taste

发布时间:2019-03-08 06:20:12来源:未知点击:

By Nell Boyce AS A wedding present, the male rattlebox moth gives his mate toxic chemicals that stop spiders eating her. Thomas Eisner and his colleagues at Cornell University in Ithaca, New York, say their discovery is the first known example of a sexually transmitted chemical defence. The researchers already knew that male rattlebox moths, Utetheisa ornatrix, add plant-derived toxins called pyrrolizidine alkaloids to their sperm “package”, and that this protects their mates’ fertilised eggs against predators such as ladybirds. To find out if these chemicals also protect the mother herself, the researchers fed female moths on a diet of pinto beans, which contain no pyrrolizidine alkaloids, and mated them with males that had eaten seeds containing the toxins. The females were then thrown onto webs of wolf and orb-weaving spiders. Amazingly, the females were set free by the spiders ( Proceedings of the National Academy of Sciences, vol 96, p 5570). But the spiders happily gobbled the mates of males fed with pyrrolizidine-free pinto beans. Eisner says he was surprised that female moths could become unpalatable so quickly. The protective alkaloids appear to disperse throughout a female’s body during mating, which continues for several hours. She seems to be safe from spiders as soon as copulation ends. In the wild, female moths can munch on toxic plants, so they are not completely reliant on males for protection. But they may sometimes experience shortages. “Getting a supplement in a time of shortage may be the most important part,” says Eisner. “I think it’s a very elegant piece of work,” comments Carol Boggs of Stanford University in California,