IPM in Midwestern Agriculture: Implications to Pests, Pollinators, and Yield

There is an existing conflict thrust upon U.S. food production systems; optimize crop yield to provide sustenance to a growing population while minimizing ecological impacts of high-intensity agriculture. This balancing act is experienced by Indiana’s watermelon growers who must maintain marketability of a crop that is reliant on insect pollinators. The dependence on pollinators to produce yield means that growers have to consider the negative impacts pesticide applications may have on both the desired pest and non-target pollinators. Navigating these trade-offs must be considered not just in the watermelon fields, but the surrounding agricultural landscape that has become increasingly reliant on prophylactic insecticides to control pests. This dissertation work results from an intensive set of experiments replicating grower practices in experimental fields throughout Indiana to assess the relationships of pests, pollinators, and crop yield.

Beginning with a priming year in 2017, watermelon plots were planted within larger corn fields to replicate the agriculture landscape and provide a “snapshot” of typical environment. These plots were paired at multiple locations and provided a contrast between a conventional management system that replicates grower insecticide programs with an IPM approach that removes insecticide applications outside of those based on scouting recommendations. I found that, while pest abundance and damage was higher in IPM fields, the increased pollinator visits in IPM fields led to higher yields in watermelons while corn yield was unaffected by an absence of insecticide use. Managed pollinator hives were placed in these fields and IPM resulted in the colonies exhibiting greater weight gain, lower mortality, increased reproductive growth, and higher insecticide residue accumulation. Insecticide residues were found more frequently at higher levels in the leaf tissue, crop pollen, field soil, and honey bee-collected pollen taken from CM fields. Despite these findings, there was a variable effect of the surrounding land use on the quality of collected pollen or the insecticides gathered by pollinators. These experiments demonstrate that IPM is a viable set of practices for specialty crop growers in the Midwest; successfully monitoring insect pests and conserving pollination services from both managed and wild pollinators. These findings provide a comprehensive look at the effect of IPM practices not just on the a specialty crop, but to the surrounding agricultural landscape as well. An IPM approach can be implemented by growers to decrease non-target effects from insecticides while maintaining or even improving productivity and profitability.