Does IPPM bear fruit? Evaluating reduced-risk insecticide programmes on pests, pollinators and marketable yield.
Integrated pest and pollinator management (IPPM) has been touted as a novel approach to control pests while mitigating negative effects of insecticides on pollinators. In addition to non-chemical approaches, IPPM programmes focus on insecticide treatments with low bee toxicity, threshold-based applications and restricted timings to avoid sprays during pollinator foraging. However, the singular and combined effect of this approach on pollination services and pest management is understudied and generally lacks field validation. In two field studies, we evaluated the effect of IPPM insecticide programmes on striped cucumber beetle (Acalymma vittatum) management, pollination and watermelon yield. The first trial (2020) featured insecticide treatments representing a factorial combination of (1) products varying in bee toxicity (bifenthrin, cyclaniliprole and acetamiprid), (2) application frequencies (weekly vs. threshold-based) and (3) application timings (AM vs. PM), as well as an untreated control. These data were then used to inform a second trial (2021) that applied two insecticide treatments (IPPM based or grower standard) to commercial-scale (20-30 acres) fields in collaboration with regional watermelon farms. Weekly beetle densities, pollinator visitation and yield data were collected to determine programme efficacy. Overall, beetle infestations were successfully managed with all insecticide treatments, none of which compromised marketable yield. In 2020, threshold-based insecticide programmes offered statistically similar levels of pest control but required 20%-80% fewer applications compared to a weekly programme. Furthermore, pollinator visitation was increased in threshold-based programmes by ~42% across all products. The on-farm validation trial in 2021 upheld these findings; IPPM fields had effective beetle control but with 1-7 fewer insecticide applications compared to grower standard fields. IPPM fields also had 62% greater pollinator visitation and 49% more melons during harvest compared to grower standard fields.