Predatory arthropods in two soybean cropping systems

Predatory arthropods help control a variety of pests in soybean. In southeast Virginia, common predators include Orius insidiosus, Geocoris spp., several species of Carabidae, and Lycosidae, Salticidae and Linyphiidae spiders. Few studies have examined how the predator community differs in soybean that is planted early in the growing season, as full-season crops, compared to later in the season, as double-crop soybeans. Information on predator abundance, succession and diversity can be useful when designing IPM strategies for soybean. To explore differences in soybean predatory arthropod communities in relation to planting date, soybean plots (each 0.12 ha) were surveyed from early vegetative growth stage through full maturity. Each plot was sampled biweekly using pitfall traps and sweep nets. All arthropods were identified to the lowest taxonomic position possible. Predatory species abundance and diversity throughout the growing season in full-season and double-crop systems were analyzed using ANOVAs.  Results show that different insect and spider species are dominant depending on planting date and diversity is usually higher in full-season soybean. At least 60 spider species were identified throughout the growing season.