Deposition, distribution, persistence and fate of bacillus thuringiensis variety kurstaki (BTK) in pecan orchards following aerial and ground appucations to control pecan nut casebearer larvae

Nontarget impacts of insecticide-based population control of eastern spruce budworm (Lepidoptera: Tortricidae) on nontarget caterpillar communities and parasitism

“…Therefore, in view of the limited half-lives of the insecticides used, their application early in the season may have limited their impact on species that feed later in the season. Another explanation for the absence of late-season effect in the year of treatment may be that insecticides that are applied by aircraft are more concentrated in the canopy than in the understorey (Armstrong and Yule 1978;Sundaram et al 1997). Because of this, treatments may affect caterpillars feeding in the canopy more than those feeding in the understorey.…”

Scientific support, literature review and data collection and analysis for risk assessment on microbial organisms used as active substance in plant protection products –Lot 1 Environmental Risk characterisation

“…Ultraviolet radiation in sunlight causes rapid degradation of Bt spores, with a half-life of c. 30 minutes (Krieg, 1975, reviewed by Joung & Cote, 2000, while insecticidal activity of δ endotoxin persists for longer, with a half-life of 1 -3 days although longer persistence has been reported in some cases (Joung & Cote, 2000). A half-life of <24h was reported on pecan (Sundaram et al, 1997), while on potato activity was reported to be greatest over the first 24 h after application and then decreased steadily over 10 days . In soil, Bt δ endotoxin declines according to first order kinetics, with a period of rapid degradation followed by a slower rate of decline.…”