ABSTRACT
Arthropod pest and beneficial populations were compared in unreplicated 3 hectare plots of unsprayed, spinosad-treated and conventional insecticide-managed cotton in a season-long trial programme on the Darling Downs, Queensland, Australia. Pest activity was assessed twice-weekly by visual methods and beneficial populations estimated by weekly suction samples of 5 x 20 metre lengths of row in each treatment. Most insecticide applications were made using a ground rig sprayer. Helicoverpa spp. were well managed in the spinosad-treated plot, but spinosad had no effect on green mirids (Creontiades dilutus (Stål)) and cotton aphids (Aphis gossypii Glover). The data clearly showed the non-disruptive nature of spinosad (Tracer) on three key predator groups - beetles, true bugs and spiders. There were no differences in predator populations between the unsprayed and spinosad-treated plots for the duration of the season. Cotton aphid populations were controlled by beneficials under the spinosad program. Predator populations in the conventional treatment were substantially reduced. There was an indication that relative to the unsprayed, hymenoptera densities were reduced in both the spinosad-treated and conventionally-treated plots. The non-disruptive effect of spinosad on predator populations suggests this product has an important place in integrated pest management programs.
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