WHILE few can resist the allure of a beautiful orchid, some wasps outdo the most ardent flower lover. Male orchid dupe wasps become so enamoured with Australian tongue orchids, which give off the scent of female wasps, that they ejaculate. But what price does the wasp pay for this misdirected mating?
Many insects are sexually deceived into liaisons with flowers, but few go as far as Lissopimpla excelsa, says Anne Gaskett of Macquarie University in Sydney, Australia, who led the study (The American Naturalist, ) testing the wasp鈥檚 behaviour towards Cryptostylis.
Gaskett noticed that some wasps in the bush outside Sydney left a visible blob on tongue orchid flowers following their visits. 鈥淲e decided to check if they were wasting their sperm on the flowers,鈥� she says, which closer examination confirmed.
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Field experiments also showed nearly three-quarters of the male wasps ejaculated on the flowers first time round, but wised up after repeated visits. The team then looked for an explanation in the results of studies on 222 insects which were fooled by various orchid species.
鈥淭he orchids that caused the most extreme behaviour 鈥� pollination with ejaculation 鈥� have the highest pollination rate of any known sexually deceptive orchid,鈥� says Gaskett. This may be good for the orchid but not for the wasp. Gaskett thinks its special reproductive system might explain why males haven鈥檛 evolved to avoid the orchids: female wasps reproduce asexually to spawn males, while sexual reproduction produces females.
鈥淚f you鈥檙e the female and you miss out on mating because your male is out with an orchid, you can still reproduce,鈥� she says.
鈥淚t鈥檚 a very interesting hypothesis,鈥� says Florian Schiestl at the University of Zurich, Switzerland. A simple test would be to see if the orchid dupe wasps have more males than a related species that doesn鈥檛 fancy flowers, he says.
