Searching times and residence times of Trichogramma sibericum Sorokina were measured in the laboratory on individual cranberry leaves that had been treated with the sex pheromone of blackheaded fireworm [Rhopobota naevana (Hübner)] and on leaves that were left untreated. Mean searching time was higher on leaves treated by passive diffusion with either 50 or 100 μg of the main component of fireworm pheromone, (Z)-11-tetradecen-1-ol acetate (Z11-14: Ac), than on control leaves. Mean residence times were also higher on leaves treated by passive diffusion with 50 μg of Z11-14: Ac than on leaves untreated with pheromone. Pretrial oviposition experience in either the presence or the absence of host pheromone did not influence variation in searching time or residence time. This indicates that neither associative learning of the odor of host pheromone nor a more generalized increase in response to chemical stimuli after oviposition (priming) affects retention responses of T. sibericum to pheromone. Results are discussed in the context of current theories on the evolution of learning in insect parasitoids and as they relate to the concurrent use of pheromone-based mating disruption and releases of T. sibericum for pest management of the blackheaded fireworm.
