Operation bug drop: In-field drone releases of natural enemies to control lettuce aphid (Nasonovia ribisnigri) and western flower thrips (Frankliniella occidentallis) in California lettuce

Augmentative releases of lab-reared naturally enemies are an effective biological control strategy for managing insect pest populations but the practice is underutilized by California lettuce growers. The use of unmanned aerial vehicles (drones) to conduct inundative releases of natural enemies has reduced the labor and time cost enough that some growers have incorporated the approach into their pest management programs. However, scientific validation of current drone release programs is lacking, as are established best-use practices for the technology. In the summer of 2022 and 2023, we completed two trials in organic romaine lettuce fields in Salinas valley of California to evaluate current industry practices for drone-releases of two beneficial predatory arthropod species, green lacewing (Chrysoperla rufilabris) and predatory mites (Amblyseius cucumeris), to suppress field populations of lettuce-currant aphid (Nasonovia ribisnigri) (Hemiptera:Aphididae) (Mosley 1841) and western flower thrips (Frankliniella occidentalis>) (Pergrande 1895), pests of major economic significance for lettuce producers in California’s central coast region. Results from this study will provide insight into the effectiveness of current drone release methods for aphid and thrips management in lettuce and inform overall best-use-practices for the technology.