Effect of Distance from Wetland Borders on Hymenopteran Wasps and Spider Abundance in Maize-soybean Cropping System

Abstract

The non-crop habitats within agroecosystems are important resources for ecological and biological insect pest management. Diversified cropping systems are known to influence pests populations, however, how neighboring habitats to the agricultural fields affect insect pest natural enemies population dynamics is not clear. This study focused on understanding the influence of wetland borders on Hymenoptera wasps and predatory spider prevalence in a maize-soybean intercrop system. The Hymenoptera wasps and spiders population estimates were carried out in twelve farmers’ fields stratified within 0-300 and 500-1100 meters from the wetland borders. Data were collected once a week starting one week from the emergence of maize and soybean plants until post-flower growth of the two crops. Results showed crop fields within 0-300 meters from the wetland borders had significantly higher numbers of wasps and spiders, while crop fields set up at 500-1100 meters from the wetland borders, the population of Hymenoptera wasps and spiders was significantly reduced. The findings of this study indicate that stable habitats such as wetland borders harbour higher numbers of natural enemies of crop pests and crop fields at close proximity benefit from quick migration of natural enemies from the pool in stable habitats. These findings can be used to design field architectures such as field margins or borders that can support insect pest natural enemies survival and migration into crop fields.