| Popis: |
The direct impact of broad-spectrum insecticides on primary parasitoids is considered a major contributing factor to the high pest status of diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), in many parts of the world. As a result, selective insecticides are often put forward as a solution to the problem of integrating chemical and biological control methods. However, there is paucity of studies that have directly contrasted effects of selective and broad-spectrum insecticides on parasitism rates and parasitoid species richness in the field. We compared effects of weekly and bi-weekly application regimes of a selective insecticide (Dipel®) and a broad-spectrum insecticide (dichlorvos) on parasitism rates of P. xylostella and species richness of its primary parasitoids against unsprayed control for two cropping seasons. Parasitoids were reared from immature P. xylostella in all treatments, and parasitism rates were not significantly different among the treatments. During October–Decemb... |
