Can we predict biocontrol services on cereal aphid populations in winter wheat (Triticum aestivum) based on landscape diversity?

Understanding the relationship of landscape diversity with pest and natural enemy populations will enhance aphid management strategies in wheat, while demonstrating biocontrol effectiveness in a changing environment. Given the increase in biofuel production and corresponding incentives, wheat growers may be experiencing shifts toward simplification of landscapes with increased insecticide use. To alleviate dependence on preventative insecticide use, the decision-making process may be refined to include economic thresholds that quantify landscape complexity. As shown in other cropping systems, we predict that bioservices will increase as plant diversity increases within a field and adjacent areas. Therefore, landscape complexity could be used to estimate bioservice effectiveness for cereal aphids. Growers would benefit from this prediction through identifying risk and prioritizing sampling efforts among fields. We tested our hypothesis during the Kansas wheat growing season in 2012, where winter wheat fields within simple versus complex landscapes were assessed for presence of predators, parasitoids, and changes in biocontrol service indices. These indices were measured as the change of three cereal aphid populations in open versus caged plants over four weeks in 11 fields. Two caging treatments, small and large mesh, were used to separate effects of predators and parasitoids from parasitoids alone. The effects of the bioservices on cereal aphid populations in simple and complex landscapes during the 2012 study will be discussed along with the potential to enhance IPM programs for cereal aphid management.