THYNNINE WASPS DISCRIMINATE AMONG HEIGHTS WHEN SEEKING MATES - TESTS WITH A SEXUALLY DECEPTIVE ORCHID

The flower of a sexually deceptive orchid, Chiloglottis reflexa, mimic s both the sex pheromone and the appearance of a female thynnine wasp (Neozeloboria nr. proxima). The flower is pollinated when visited by m ale wasps, who attempt mating with the flower. We have used these mime tic flowers to investigate mating behavior of the male wasps. In field choice experiments, males strongly prefer to visit flowers that are v ery low in the habitat, 15 cm, vs. flowers that are placed at 55 or 10 5 cm. These studies suggest that male precopulatory response is strong ly dependent on the microlocation of the female (or female mimic). Oth er 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 mimet ic flowers, particularly stature, that act to efficiently attract pote ntial pollinators.