We will evaluate the impact of insect pest populations on soybean yields while assessing the return-on-investment of common pest control tactics used by Illinois soybean farmers (insecticide seed treatments and foliar insecticides applied at growth stages R3 or R5).

Our aim is to determine 1) how often the insecticides that Illinois farmers use can be expected to provide a positive return on investment and (2) the population density various insect pests must reach before control with an insecticide is economically justified. While published studies have examined the yield impacts of these tactics, our approach differs from published research in that (1) we will assess both seed treatments and foliar sprays (most studies have examined one or the other) and (2) we will thoroughly document insect population densities. This will allow us to identify the pest complexes most likely to negatively impact soybean production and therefore require control with an insecticide. We will work on both university research farms and in commercial farm fields, allowing us to compare tightly controlled experiments with multiple treatments to farmer-selected practices in a real-world setting and at a larger scale.

The results will provide an assessment of the return on investment for the most common insect control tactics used in Illinois soybean production.

Our thorough assessment of pest populations will allow us to determine the relationship between insect pest populations and soybean yield in a field setting.

This project will form the basis for a graduate student thesis or dissertation, providing training for the agricultural research sector in Illinois.

This series of experiments will allow us to develop more accurate economic thresholds for insect management.