Baseline responses of bollworm, Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (F.), to indoxacarb and pyridalyl

Document Type

Article

Publication Date

4-1-2005

Abstract

Bollworm, Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), are annual pests of cotton in the Southern United States. Tobacco budworm, especially, has developed resistance to several classes of insecticides. Indoxacarb and pyridalyl are novel insecticides that have demonstrated significant efficacy against these pests. The objectives of these studies were to evaluate bioassay methods for indoxacarb and pyridalyl and to generate baseline dose-mortality data. Using the adult vial test (AVT), LC50 and LC90 values of pyridalyl for bollworm and tobacco budworm exceeded 100 μg/vial. For indoxacarb, LC 50 and LC90 values ranged from 15.7 to > 100 μg/vial. Dose-mortality values of indoxacarb and pyridalyl were greater than those for spinosad and cypermethrin and also were greater than the discriminating concentrations of cypermethrin, methomyl, profenofos, and endosulfan used in the AVT for monitoring tobacco budworm and bollworm susceptibility. The AVT did not prove to be an efficient method for monitoring susceptibility to indoxacarb and pyridalyl. Indoxacarb and pyridalyl also were evaluated with diet overlay bioassays using first instar larvae of each species. The LC50 values of indoxacarb and pyridalyl for these insect species ranged from 1.05 to 1.33 ppm and 1.54 to 1.55 ppm, respectively. The indoxacarb LC90 for tobacco budworm was 4.54 ppm. For pyridalyl, the LC 90 values ranged from 3.13 to 7.91 ppm for both species. These results demonstrate that the diet overlay bioassay is more efficient than the AVT for monitoring changes in susceptibility to indoxacarb and pyridalyl. These data form baseline values and allow scientists to monitor for future changes in the susceptibility of bollworm and tobacco budworm.

Publication Source (Journal or Book title)

Journal of Agricultural and Urban Entomology

First Page

99

Last Page

109

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