We used Malaise traps to sample arthropod community composition at biweekly intervals across an agroecosystem landscape in southern Ontario, Canada, to evaluate the relative impact of site spacing, seasonal timing, weather conditions, local plant community attributes, and agricultural extent across the local landscape on spatial and temporal variation in arthropod community composition. The 15 field sites sampled spanned a wide gradient of agricultural extent that in isolation had a strong impact on spatial variation in arthropod community composition. DNA barcoding of the samples identified >10,000 different arthropod BINs (Biodiversity Index Numbers). Local variation in plant community composition and canopy copver best explained variation in arthropod community dissimilarity. Weather variables followed closely in explanatory power, driven primariy by seasonal variation in temperature. Significant effects of time remained after accounting for environmental variables, with little independent effect of spatial distance. The proportion of agricultural land at the landscape scale had little detectable effect after controlling for the influence of the other environmental variables. Our results suggest that plant community composition, cover, weather conditions, and seasonality structured the arthropod community to considerable degree.

Arthropod biodiversity was sampled biweekly during May-October 2019 from 29 Malaise traps located across 12 farms and 3 conservation areas in southern Ontario. The samples were stored in ethanol and the resulting liquid was used to used to identify biodiversity index numbers (BINs) using DNA metabarcoding via lab analyses conducted at the University of Guelph Centre for Biodiversity Genomics. Plant biodiversity (to genus at minimum and to species as appropriate) and relative abundance were sampled from 10 quadrats measuring 1 x 1 m positioned around the arthropod Malaise traps at monthly intervals from May-September.