Hymenopteran parasitoid communities in agricultural drainage ditches: Community composition and comparison between crop and non-crop vegetation

Environmental concerns and host resistance have led to the development of several methods of biological control as alternatives to heavy pesticide use, with parasitoidic Hymenoptera playing a prominent role as biological control agents due to their high host specificity making them ideal for importation against invasives. Agricultural drainage ditches used to prevent flooding in areas with high water tables can serve as an existing source of non-crop vegetation on farms, which can be beneficial to both native and non-native parasitoid wasps due to presence of alternate hosts and floral food sources. To better understand the role these agricultural ditches play in parasitoid community composition, we used sticky traps on five farms to sample aerial hymenopteran populations within drainage ditches and nearby cropland throughout the three summer months of 2021-2023. In total, 36,654 total specimens from 25 different families were collected from three separate locations in each transect. 15,975 specimens were collected in agricultural ditches, while 10,623 and 10,056 specimens were collected from samples taken 1.5m and 9.1m into the adjacent cropland, respectively. We analyzed the composition of parasitoid communities within agricultural drainage ditches and compared it to that of adjacent cropland across spatiotemporal and other factors. This will allow us to better understand the role these diverse habitats play in shaping agroecosystems throughout the growing season.