Department of Entomology, Maricopa Agricultural Center, University of Arizona, Maricopa, AZ, United States of America.
USDA-ARS, Arid-Land Agricultural Research Center, Maricopa, AZ, United States of America.
PLoS One. 2023 May 10;18(5):e0272831. doi: 10.1371/journal.pone.0272831. eCollection 2023.
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.
在任何具有田间部分的综合虫害管理（IPM）研究中，小区大小都具有实际意义。由于物种动态在小区中可能会根据小区大小而变化，因此此类研究需要在与物种动态相关的规模上进行。对于研究人员、技术提供商和监管机构来说，适当的小区大小对于了解各种昆虫控制技术对非靶标节肢动物的影响尤为重要。由于节肢动物在小区之间的移动和重新分布，或者来自未处理区域和外部来源，小区太小可能无法检测到这些技术的潜在有害影响。亚利桑那州的棉花系统严重依赖于节肢动物控制技术，因此我们进行了为期两年的重复田间实验，以估计我们系统中非靶标节肢动物研究的最佳小区大小。实验处理包括三种正方形小区大小和三种杀虫剂的完全因子。我们建立了三种小区大小，分别为 144m2、324m2 和 576m2。对于杀虫剂处理，我们建立了一个未处理的对照、一种已知对节肢动物群落有负面影响的阳性对照杀虫剂和一种选择性杀虫剂。我们研究了小区大小如何影响相对于群落结构（27 个分类群）、群落多样性、个体丰度、效应大小、具有广泛移动性的节肢动物分类群的生物控制功能的处理效应的估计，包括 Collops spp.、Orius tristicolor、Geocoris spp.、Misumenops celer、Drapetis nr. divergens 和 Chrysoperla carnea s.l.。与较大的小区相比，144m2 的正方形小区对所有参数的支持结果相似，因此足以测量杀虫剂对棉花中非靶标节肢动物的影响。我们的结果适用于具有相关害虫、捕食者或其他具有类似扩散特征的动物区系的棉花系统。此外，这些结果也可能适用于具有类似动物区系的其他作物系统。
