Author
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Charlet, Laurence |
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Submitted to: Biological Control
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/15/2000 Publication Date: N/A Citation: N/A Interpretive Summary: A number of insect herbivores that coevolved with native sunflower species have successfully exploited cultivated sunflower. Among the species attacking the sunflower head, the banded sunflower moth has caused economic loss to producers. Integrated pest management, including the use of biological control, is needed to reduce insect infestations below economic levels without the reliance on pesticides. The purpose of this study was to examine both cultivated and native sunflowers in the major production region of North and South Dakota and Minnesota to determine the species of parasites attacking the banded sunflower moth, investigate the seasonal occurrence, development, and overwintering of the major parasites recovered, evaluate their impact on banded sunflower moth larvae, and determine the effect of altered planting dates on parasitism. A number of species of banded sunflower moth parasites have moved from native sunflowers and attack the moth in commercial sunflower fields. Two different parasite species attacking banded sunflower moth larvae in cultivated sunflower appear to have adapted well, overwintering in the host in the soil and searching successfully for larvae even at low pest densities. Parasites effectively attacked the banded sunflower moth in sunflower planted at three different dates. Conservation of these parasites in the sunflower agroecosystem is therefore needed, because they play an important role in the control of the banded sunflower moth. The ability of these natural enemies to fit into management strategies, like the altering of planting date, emphasizes that successful integration of IPM practices to include biological control is feasible. Technical Abstract: Parasitoids of the banded sunflower moth, Cochylis hospes Walsingham, 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 Glypta prognatha Dasch and Trathala sp. (Ichneumonidae), Chelonus phaloniae Mason 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. Mortality, parasitization, and overwintering development through pupation of C. hospes larvae and two of its endoparasitoids, G. prognatha and C. phaloniae were followed over a two-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. Results from 1994 and 1995 showed that parasitization rates for the total season by the two most abundant parasitoids was 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. |
