Beneficial arthropod behavior mediated by airborne semiochemicals. IX. Differential response of Trichogramma pretiosum, an egg parasitoid of Heliothis zea, to various olfactory cues

The behavior of Trichogramma pretiosum Nixon wasps when exposed to different olfactory cues was studied in a wind tunnel. Compared to clean air, the sex pheromone of its host Heliothis zea (Boddie) increased wasp residence times, walking times, and path lengths on a platform and decreased walking velocity. If wasps were released on top of a glass rod above a platform, the odor caused the wasps to land shortly after takeoff. In addition, a clear dose effect with regard to total residence and walking times was found. These responses were not elicited by three dosages of the sex pheromone of Spodoptera frugiperda (J.E. Smith) or by a blend of saturated acetates. These results correspond with the observation that H. zea is a common field host of T. pretiosum, whereas eggs of S. frugiperda are rarely attacked by this parasitoid.