Thynnine wasps discriminate among heights when seeking mates: tests with a sexually deceptive orchid.

The flower of a sexually deceptive orchid, Chiloglottis reflexa, mimics both the sex pheromone and the appearance of a female thynnine wasp (Neozeloboria nr. proxima). The flower is pollinated when visited by male wasps, who attempt mating with the flower. We have used these mimetic flowers to investigate mating behavior of the male wasps. In field choice experiments, males strongly prefer to visit flowers that are very low in the habitat, 15 cm, vs. flowers that are placed at 55 or 105 cm. These studies suggest that male precopulatory response is strongly dependent on the microlocation of the female (or female mimic). Other insect-mimicking orchids, which together attract several groups of Hymenoptera, may be useful in analogous experiments on mating behavior. Additionally, these experiments help elucidate features of the mimetic flowers, particularly stature, that act to efficiently attract potential pollinators.