Sexually deceptive orchids and a duped wasp

PhD candidate Amy Martin and Dr Anne Gaskett of the University of Auckland, and Dr James O’Hanlon of the University of New England, set up field trials over six sites to study the Australasian tongue orchid (Cryptostylis subulata) and its sole pollinator, the parasitoid wasp Lissopimpla excels, otherwise known as the ‘orchid dupe wasp’.

The tongue orchid achieves pollination by mimicking the appearance and pheromones of the female wasp thereby fooling the male wasp into mating with their flowers and so achieving pollination. Previous research has shown that once a male is attracted by an orchid, it will ejaculate on the flower about 70 percent of the time.

Despite previously held beliefs that deceptive flowers do not harm or elicit great costs from their pollinators, the study found orchids not only affected individual pollinator behaviour but may have an influence on population dynamics more generally.

“Sperm economics is an important part of the sexual behaviour of a wide range of species because it can change how they reproduce and survive,” Ms Martin says.

“Most orchid pollinators have the ability to reproduce whether eggs are fertilised by sperm or not and that raises a fascinating question about whether some species have evolved to adapt to sexually exploitative plants which is one of the questions we are trying to answer with research of this kind.”