Comparative effects of a selective insecticide, Bacillus thuringiensis var. kurstaki and the broad-spectrum insecticide cypermethrin on diamondback moth and its parasitoid Cotesia vestalis (Hymenoptera; Braconidae)

作者：Stemele M A^*

来源：Crop Protection, 2017, 101: 35-42.

DOI：10.1016/j.cropro.2017.07.015

• Abatement
• Bacillus thuringiensis
• Cypermethrin
• Effective yield
• Parasitism
• Potential yield

Cotesia vestalis (Haliday) (Hymenoptera: Braconidae) (= plutellae) is an important parasitoid of Plutella xylostella L. (Lepidoptera: Plutellidae) consistently accounting for high field mortality. However, indiscriminate use of broad-spectrum insecticides is reported to undermine this parasitoid's impact. To investigate the implications of selective and broad-spectrum insecticides on C. vestalis, trials were conducted in Eastern Cape Province, South Africa. Plutella xylostella infestation, C vestalis parasitism, and yield variables were measured over three growing seasons on unsprayed cabbage, and cabbage treated with selective Biobit (R) (B. thuringiensis var. kurstaki, 32000 lUimg) or broad-spectrum Cypermethrin (cypermethrin, 200 g/l). Plutella xylostella infestation was higher in control compared to treated cabbage during winter and spring but not summer. However, parasitism was consistently higher in the control (>= 55%) compared to the Biobit (<= 45%) and Cypermethrin (<= 25%) treatments throughout the study period. Consistent with higher parasitism, the C vestalis yield loss abatement function was highest in the control followed by Biobit and least in Cypermethrin during winter (42 > 24 > 10%), spring (36 > 35 > 22%) and summer (41 > 36 > 23%). These results demonstrate that Biobit reduces P. xylostella field density and crop damage with minimal impact on the C vestalis yield loss abatement function.

• 出版日期2017-11