Ecotone edge effects on arthropod biodiversity and aphid management in Texas sorghum

High biodiversity levels signal a healthy environment and bring valuable benefits to agroecosystems, providing diverse functions like pollination, decomposition, and pest management. Agricultural crop production modifies and creates sharp edges with semi-natural habitats (i.e. ecotone edge), which may affect arthropod biodiversity. To assess these differences in Texas sorghum fields, we conducted an arthropod biodiversity survey over a two-year period from 2023-2024. Arthropod sampling in South Texas sorghum fields consisted of using a sweep net and net blower to measure biodiversity while leaf sampling was used to monitor a pest aphid species, Melanaphis sorghi (Sorghum aphid). The sampling was performed across several distances into the sorghum fields from field edges that shared a border with either sorghum (control), cotton, or semi-natural land (primarily grasses). Specimens were identified to the family-level taxon for biodiversity measures with selected species identifications such as M. sorghi. Statistical analyses were conducted to measure differences in biodiversity and population density. Our findings reveal that sorghum field edges exhibited no difference in arthropod biodiversity when bordering cotton or semi-natural fields. However, some arthropod population densities of sorghum pests' natural enemies are significantly and positively correlated to sorghum field edges with more diverse neighboring vegetation. This correlation between ecotone edge was relevant to M. sorghi suppression as judged by aphid densities set as economic thresholds for pest management considerations. Understanding the impact of ecotone influence on biodiversity and pest management in field crops, like sorghum, is relevant to ecosystem health and the pest management service a healthy agroecosystem provides.