Compatibility of behavioral disruptors in attract-and-kill formulations for sustainable control of Drosophila suzukii (Diptera: Drosophilidae).

Drosophila suzukii (Diptera: Drosophilidae) is a major pest of soft-skinned fruits, inflicting economic losses through pre-harvest infestation. Among reduced-risk strategies, Attract-and-Kill (A&K) presents an alternative to full-cover insecticide sprays by concentrating exposure to insecticide-laced lures. However, compatibility of insecticides and attractants, as well as application volume, requires optimization to improve efficacy. We evaluated A&K formulations that combined organic Entrust SC (spinosad), Pyganic (pyrethrin), and conventional Gowan Malathion-8 Flowable (malathion), Mustang Maxx (zeta-cypermethrin) insecticides with 2 attractants, Combi-Protec (4:1, plant extract: sugar) and Decoy (citric acid), under laboratory conditions using blueberries. Each attractant-insecticide tank mix was applied at 5 droplet levels (0, 2, 6, 10, and 14). Compared to the 0 droplet, spinosad reduced fruit damage with Decoy, while malathion reduced fruit damage with Combi-Protec and Decoy, demonstrating strong synergism. Spinosad, malathion, and zeta-cypermethrin induced adult mortality depending on the attractant used. A&K achieved a rapid mortality rate within 5 h, at 85.4%, when applied as droplets in Munger cells, significantly faster than simulated full-cover sprays (33.9%) applied across glass plates, thereby limiting the window for oviposition and resistance development. A dose-response trend was observed, where 6 or more droplets consistently resulted in higher mortality and reduced egg-laying, although not always statistically significant. These findings highlight the potential of A&K systems, particularly those incorporating malathion or spinosad with Decoy, to achieve rapid and effective control of D. suzukii. Optimized A&K formulations can enhance integrated pest management (IPM) by minimizing environmental exposure, reducing reliance on full-cover applications, and slowing resistance evolution.