Impact of potential prey availability on within field movement of spiders in agroecosystems

Agricultural monocultures such as soybeans are reliant upon arthropods predators because insect pests are adapting quickly to pesticides. Practical biological control agents must be rapid colonizers, maintain a presence as pests decline, and be opportunistic feeders. Not only do generalist predators such as spiders fulfill these requirements, they do well in complex landscapes and can rapidly adjust to environmental changes or prey availability. The ability of spiders to disperse great distances makes them excellent biological control in areas of high disturbance such as crop fields.

This study focuses on the interaction of potential prey item and spider movements within soybean fields of Kentucky. Prey items, some of which are pests of soybeans, and spiders were collected from ten Kentucky full season soybean fields using pitfall traps, sweep net samples, and standardized hand sampling. All sampling was along a grid in each field, with the GPS coordinates of each sample recorded. Soybean pests were identified down to the species level. Spiders were identified down to family level as were all remaining potential prey items. Combing the abundance data of potential prey items and spiders with the location found within the field, maps of spatial analyses by distance indices (SADIE) were created. These maps indicate aggregation patterns of spiders as compared to potential prey/soybean pests. This information can then be combined with information about potential edge effects and other variables on how to augment spider populations in soybean fields for biological control.