Pheromone Mating Disruption of Rhyacionia zozana (Lepidoptera: Tortricidae): Influence on the Associated Parasite Complex

Abstract

Larval and pupal parasites were collected before and after a mating disruption test of Rhyacionia zozana (Kearfott) to determine if the pheromone treatment affected either the species distribution or abundance of the parasite complex. Total percentage of parasitism was not changed because of the disruption treatment. In treated areas, however, abundance of the most numerous moth parasite, Glypta zozanae Walley and Barron, was reduced significantly below check plantation levels. In contrast, abundance of the pupal parasite Mastrus aciculatus (Provancher) was higher in pheromone-disrupted areas. No changes in the sex ratios of these species were attributable to the pheromone treatment. Parasite community structures were compared using a similarity index. The degree of likeness between treated and check plantations decreased after disruption, probably because of the changes in the incidence of parasitism by G. zozanae and M. aciculatus . Accounting for parasitism and reduced mating, surviving host populations in check plantations were over four times greater than in pheromone-disrupted areas. The importance of the host's sex pheromone as a potential kairomone and effects of changes in the host density caused by the mating disruption treatment on the associated parasite complex are discussed.