Biology and seasonal abundance of parasitoids of the banded sunflower moth (Lepidoptera: Tortricidae) in sunflower.

摘要

Mortality, parasitization, and overwintering development through pupation of the banded sunflower moth, Cochylis hospes Walsingham, larvae and two of its endoparasitoids, Glypta prognatha Dasch and Chelonus phaloniae Mason, were followed over a 2-year period (1987 to 1989). Development of parasitoids in the field was determined for each species by examination of moth eggs and larvae during the 1989 season. Parasitoids of C. hospes, recovered from cultivated sunflower, Helianthus annuus L., from North and South Dakota and Minnesota in 1994 and 1995, parasitized 24 and 17% of larvae, respectively. Species of Hymenoptera collected included G. prognatha and Trathala sp. (Ichneumonidae), C. phaloniae and Macrocentrus ancylivorus Rohwer (Braconidae), and Perilampus robertsoni Crawford (Pteromalidae). The most abundant parasitoid was G. prognatha. In 1994 and 1995, C. phaloniae, an egg-larval parasitoid, emerged earlier but was less abundant than the later occurring larval parasitoid G. prognatha. Species of parasitoids collected from cultivated sunflower and five species of native sunflowers were similar. An additional parasitoid, Mastrus sp. (Ichneumonidae), was recovered only from the native sunflowers H. annuus and H. tuberosus L. Results from 1994 and 1995 showed that parasitization rates for the total season by the two most abundant parasitoids were similar in fields using three planting dates. These results suggest that altering planting date could be successfully used as a pest management strategy without disrupting the biological control of the banded sunflower moth. Conservation of these parasitoids in the sunflower agroecosystem is needed since they play an important role in the management of C. hospes.