Steward~(TM) dispersion and cotton leaf interactions: impact on cotton insect pests and safety to beneficial arthropods

摘要

Steward~(TM) 15SC is a new cotton oxadiazine insecticide from DuPont. It is a potent sodium channel blocker with a novel mode of action. Steward~(TM) controls all major worms, tarnished plant bug, and fleahoppers at 0.09-0.11 lbs ai/a, mainly through ingestion and direct spray contact. Steward~(TM) is neither soluble nor systemic. However, due to its lipophilicity and seed oil-based formulation, Steward~(TM) disperses well over leaf surfaces and penetrates into the leaf's waxy cuticle optimizing control of certain sucking insects and providing rainfastness and good residual activity. The behavior of Steward~(TM) alone and in tank-mixes in the application process and their interactions with the cotton leaf are being investigated; particularly as they apply to droplet flight, evaporation, droplet impact, leaf spreading, retention, leaf penetration, and residual. In addition to causing neural toxic effects, Steward~(TM) is an effective antifeedant, providing quick crop protection despite the delay in insect mortality. The major mode of indoxacarb entry into the insect pest is through ingestion, followed by direct spray contact with exposure to a dried residual being the least effective. These differences in toxicity, based on the various modes of entry, allow Steward~(TM) to exhibit differential selectivity against herbivorous vs insectivorous (predators/parasites) arthropods. This selective activity of Steward~(TM) allows the conservation of beneficials in a commercial cotton ecosystem. In addition, Steward's safety to workers and the environment, consistent and reliable efficacy, low use rate, and unique mode of action make Steward~(TM) an excellent fit in cotton IPM programs and a prudent choice to alternate, replace, or complement existing insecticide chemistries.