Efficacy of organically approved insecticides against brown marmorated stink bug, Halyomorpha halys and other stink bugs

Abstract

The brown marmorated stink bug, Halyomorpha halys (Stal), is a serious invasive pest in the USA. Organic growers have limited options to effectively manage this pest. Several organically approved insecticides including pyrethrins, azadirachtin, spinosad, potassium salts of fatty acids, sabadilla, extract from Burkholderia sp., and two combination products were evaluated for toxicity to H. halys nymphs and adults using laboratory bioassays and evaluated in field experiments on tomatoes and peppers using weekly applications of the highest labeled rates of the products. In submersion bioassays, high mortality (>70%) of H. halys nymphs was achieved with pyrethrins, azadirachtin, azadirachtin + pyrethrins, potassium salts + spinosad, and sabadilla alkaloids. Using the same bioassay for adult H. halys, only pyrethrins, azadirachtin + pyrethrins, and potassium salts resulted in high mortality. In bean dip bioassays, only pyrethrins resulted in moderate mortality of nymphs and high mortality of adults. In field experiments, which included weekly insecticide applications, none of the insecticides that were tested significantly reduced stink bug feeding injury (from all species) to tomatoes or peppers with the exception of one harvest date of peppers in 2014, where pyrethrins + azadirachtin had less injury than the control. Our results confirm that several organically approved insecticides may demonstrate a high level of activity on H. halys in laboratory bioassays, but when applied in the field, none of the products that we tested appear to be consistently effective at reducing stink bug injury to peppers or tomatoes.