Determining selectivity of isocycloseram and afidopyropen and their compatibility with conservation biological control in Arizona cotton

Authors: BORDINI, ISADORA - University Of Arizona; NARANJO, STEVEN E. - Retired ARS Employee; FOURNIER, AL - University Of Arizona; ELLSWORTH, PETER C. - University Of Arizona

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2024
Publication Date: 10/8/2024
Citation: Bordini, Isadora, Naranjo, Steven E., Fournier, Al, Ellsworth, Peter C. 2024. Determining selectivity of isocycloseram and afidopyropen and their compatibility with conservation biological control in Arizona cotton. Pest Management Science. 81:639-653. https://doi.org/10.1002/ps.8460.
DOI: https://doi.org/10.1002/ps.8460

Interpretive Summary: Integrated Pest Management (IPM) for Arizona cotton has continually evolved for >30 years with a foundation of integrated avoidance tactics, thresholds, sampling, and use of selective technologies fostering conservation biological control. To continue providing growers with the most up do date information on pest control options it is essential to comprehensively assess the efficacy of novel insecticides against our primary pests, Bemisia argentifolii and Lygus hesperus, as well as their impacts on non-target arthropods, to maintain the stability and advancement the Arizona cotton IPM plan. Cotton field trials were conducted to evaluate the effects of novel insecticides, isocycloseram and afidopyropen, on non-target arthropods, including key predators in our system. Assessments were made on over 27 arthropod taxa through community analyses, individual predator abundance, and biological control function via predator to whitefly ratios and a sentinel prey method to measure sources of in-field mortality. Comparisons were made with an untreated check, a proven fully selective insecticide, and acephate-treated positive controls. This latter material is known to have broad negative effects on the arthropod community and serves to ensure that our experimental design was able to detect known effects. Overall, afidopyropen showed no significant differences from the untreated check across all metrics examined, and was classified as a fully selective insecticide for the Arizona cotton system. In contrast, isocycloseram exhibited some negative impacts on certain metrics relative to the untreated check, yet it proved to be less detrimental to non-target arthropods compared to the positive control, acephate, hence it was classified as a partially selective insecticide in Arizona cotton. These findings will provide growers and their pest control advisors the latest information on control options that allow them to preserve biological control in their fields.

Technical Abstract: BACKGROUND: Selective tools, including selective insecticides and transgenic cotton, have been crucial in reducing insecticide usage within the integrated pest management (IPM) plan for Arizona cotton. To guide growers effectively, cotton field trials evaluated the effects of the novel insecticides, isocycloseram and afidopyropen against our primary pests, Bemisia argentifolii and Lygus hesperus, and their impacts on nontarget arthropods, including key predators: Collops spp., Orius tristicolor, Geocoris spp., Misumenops celer, Drapetis nr. divergens and Chrysoperla carnea s.l. Assessments involved over 27 arthropod taxa through community analyses, individual predator abundance, and biological control function via predator to prey ratios and a sentinel prey method. Comparisons were made with an untreated check, a proven fully selective insecticide (flonicamid) and acephatetreated positive controls. RESULTS: Overall, relative to the untreated check, afidopyropen showed no significant differences, whereas isocycloseram exhibited some negative impacts, primarily reducing M. celer and Geocoris spp. nymphs, yet it was less detrimental compared with the positive control, acephate, and it did not affect four of the six key predators and most nontarget arthropods. CONCLUSION: Afidopyropen was classified as a fully selective insecticide and isocycloseram as a partially selective insecticide. Their fit for conservation biological control in Arizona cotton IPM and similar systems is discussed.© 2024 Society of Chemical Industry.