Spatial scale of non-target effects of cotton insecticides

Isadora Bordini; Steven E Naranjo; Alfred Fournier; Peter C Ellsworth

doi:10.1371/journal.pone.0272831

Spatial scale of non-target effects of cotton insecticides

PLoS One. 2023 May 10;18(5):e0272831. doi: 10.1371/journal.pone.0272831. eCollection 2023.

Authors

Isadora Bordini¹, Steven E Naranjo², Alfred Fournier¹, Peter C Ellsworth¹

Affiliations

¹ Department of Entomology, Maricopa Agricultural Center, University of Arizona, Maricopa, AZ, United States of America.
² USDA-ARS, Arid-Land Agricultural Research Center, Maricopa, AZ, United States of America.

Abstract

Plot size is of practical importance in any integrated pest management (IPM) study that has a field component. Such studies need to be conducted at a scale relevant to species dynamics because their abundance and distribution in plots might vary according to plot size. An adequate plot size is especially important for researchers, technology providers and regulatory agencies in understanding effects of various insect control technologies on non-target arthropods. Plots that are too small might fail to detect potential harmful effects of these technologies due to arthropod movement and redistribution among plots, or from untreated areas and outside sources. The Arizona cotton system is heavily dependent on technologies for arthropod control, thus we conducted a 2-year replicated field experiment to estimate the optimal plot size for non-target arthropod studies in our system. Experimental treatments consisted of three square plot sizes and three insecticides in a full factorial. We established three plot sizes that measured 144 m2, 324 m2 and 576 m2. For insecticide treatments, we established an untreated check, a positive control insecticide with known negative effects on the arthropod community and a selective insecticide. We investigated how plot size impacts the estimation of treatment effects relative to community structure (27 taxa), community diversity, individual abundance, effect sizes, biological control function of arthropod taxa with a wide range of mobility, including Collops spp., Orius tristicolor, Geocoris spp., Misumenops celer, Drapetis nr. divergens and Chrysoperla carnea s.l.. Square 144 m2 plots supported similar results for all parameters compared with larger plots, and are thus sufficiently large to measure insecticidal effects on non-target arthropods in cotton. Our results are applicable to cotton systems with related pests, predators or other fauna with similar dispersal characteristics. Moreover, these results also might be generalizable to other crop systems with similar fauna.

Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't

MeSH terms

Animals
Arthropods*
Coleoptera*
Gossypium
Heteroptera*
Insect Control / methods
Insecticides* / toxicity

Substances

Insecticides

Grants and funding

This work was supported by Western Integrated Pest Management Center (IB, PE, SN, AF), Western Sustainable Agriculture Research and Extension (IB, PE, SN, AF), Arizona Cotton Growers Association (PE), United States Department of Agriculture – National Institute of Food and Agriculture (Extension Implementation Program, award number 2017-70006-27145) (PE, AF), Cotton Incorporated (PE) and United States Department of Agriculture, Agricultural Research Service- Arid Land Agricultural Research Center (SN). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.