Egg and Larval Parasitism of the Grape Berry Moth (Lepidoptera: Tortricidae) in Three Grape Habitats in New York

Abstract

To describe parasitoids of grape berry moth, Endopiza viteana Clemens, infested grapes were collected during two seasons in three grape habitats: wild grapes (the native host), organically managed commercial vineyards, and conventionally managed commercial vineyards. Three species of egg and larval parasitoids were prominent among the (eight) species collected. Trichogramma pretiosum Riley, an egg parasitoid, was collected only during the second season when E. viteana populations were high and was responsible for a large proportion of parasitoid-induced mortality that season. The larval parasitoids Glypta mutica Cushman and Apanteles polychrosidis Viereck caused low levels of mortality during both seasons. All of the major parasitoid species were collected in each habitat type. Neither levels of parasitism nor the number of parasitoid species collected were consistently higher in the more diverse wild grape habitat compared with the two grape monocultures, although on average, levels of parasitism were slightly higher in the wild grape habitat. G. mutica was responsible for a higher proportion of the overall parasitism in the wild than in the cultivated habitats, whereas A. polychrosidis was responsible for a higher proportion of the parasitism in the cultivated habitats. The proportion of overall parasitism contributed by T. pretiosum was equivalent across habitats. Gated E. viteana cohorts were used to estimate generational mortality in the egg and larval stages. Parasitoids were responsible for 12–42% mortality in three cohorts. Total mortality for the egg and larval stages was between 63 and 72%. The parasitoid complex and resulting level of parasitism at individual sites are influenced by factors independent of those we used to define the habitat types. No generalizations can be made about the expected species composition or level of parasitism in any of the habitats examined.