Can robust pollinator communities compensate for reduced pollen flow? Testing the interactive effects of pollenizers and insecticides on fruit production

In recent years, wild pollinator populations have faced intensifying environmental and chemical pressures that endanger the health and diversity of their communities. Their presence is paramount in providing ecosystem services to growers of specialty crops worldwide, especially those that rely heavily on pollination to produce marketable fruit. One such crop, seedless watermelon (Citrullus lanatus), produces triploid fruits that require pollen transfer from a diploid pollenizer plant to a tetraploid recipient. Current recommendations advise growers to plant one pollenizer for every two to three tetraploid plants, but since C. lanatus pollenizers do not produce viable fruit, this method consumes ample resources and arable land. It is known that wild pollinators are highly productive in this cropping system, especially when relieved of the chemical pressures they encounter in conventionally managed fields. However, it is unclear if this efficiency may allow growers to significantly reduce the ratio of pollenizers to tetraploid plants, thus increasing marketable yield and salvaging resources. To investigate this, during the 2025 growing season, two sites across Indiana were planted with C. lanatus pollenizers in combination with the ‘Fascination’ tetraploid in decreasing ratios of 1:2, 1:4, and 1:8. One field received a conventional insecticide regimen while the other was managed with an integrated, threshold-focused approach. We measured pollinator effectiveness in both fields by examining differences in yield, fruit weight, and incidence of Hollow Heart, a disease caused by inadequate pollen transfer. Pollinator visitation rates were also examined, and present species were noted to visualize community composition.