Survival of Geocoris punctipes Say (Hemiptera: Lygaeidae) Following Exposure to Selected Reduced-Risk Insecticides

Abstract

Survival of Geocoris punctipes Say adults following exposure to azadirachtin, spinosad, thiamethoxam, diazinon, and imidacloprid was assessed in laboratory assays and greenhouse tests. In the laboratory assays, adults were continuously exposed for 48 h to filter papers treated with the individual insecticides. Survival was greatest following exposure to the untreated control (100 ± 0.0%), azadirachtin (95.0 ± 2.2%), and imidacloprid (81.7 ± 7.9%). Mean (± SEM) survival following exposure to spinosad (55.0 ± 11.2%) and thiamethoxam (46.6 ± 3.3%) was significantly lower, whereas diazinon killed all adults within 12 h of exposure. In the greenhouse tests, adults were continuously exposed to bush beans, Phaseolus vulgaris L., foliage treated with the individual insecticides. Mean (± SEM) survival following 144 h of continuous exposure to treated foliage was 97.5 ± 2.5% for the untreated control, 92.5 ± 5.3% for azadirachtin, 92.5 ± 3.7% for diazinon, 72.5 ± 8.4% for imidacloprid, 70.0 ± 8.4% for spinosad, and 57.5 ± 8.8% for thiamethoxam. Statistically significant differences were observed with thiamethoxam versus diazinon, azadirachtin and the control. The results for the filter paper assay and the greenhouse tests are encouraging in terms of potential natural enemy conservation in IPM programs employing these insecticides.