Putting IPPM to the test: Integrating multiple tactics to enhance watermelon pollination by wild bees

Conventional watermelon production relies on a number of agricultural inputs to achieve commercial yields, including the use of grass cover crops (e.g., cereal rye) to protect seedlings against sand-blasting damage, intense spray programs to control pests and stocking managed bees to secure pollination. However, this production system is far from sustainable and insecticides can have detrimental effects on beneficial arthropods (i.e., natural enemies and pollinators). Flowering cover crops, such as hairy vetch, can provide extra resources (e.g., alternative non-crop prey, nectar and pollen) to support beneficial arthropods, which can control pests minimizing insecticide applications and pollinate the crop without bee stocking. We hypothesize that sustainable production can underpin similar or greater yields than conventional production while minimizing inputs.

The study was conducted at three locations across Indiana in 2023-2024. In 2023, we tested different cover crops including mustard, buckwheat, crimson clover and vetch compared to rye, each with five replicates per location. In 2024, we established two plots per location. One plot received conventional watermelon management, i.e., rye as a cover crop, regular insecticide applications and stocking commercial bumblebees, while the second plot received sustainable watermelon management, i.e., vetch as a cover crop, threshold-based recommendations and no stocking managed bees. In both years, weekly surveys were conducted from May to September recording density and diversity of beneficial arthropods and pests. Quantity (fruit set) and quality (weight) were recorded at harvest to measure pollination services. Results from these trials with a focus on wild bees will be presented.