Toxicity, Feeding Preference, and Repellency Associated with Selected Organic Insecticides Against Acrosternum hilare, and Euschistus servus, (Hemiptera: Pentatomidae)

Experiments were conducted to evaluate the toxicity, feeding preference, repellency, and field efficacy associated with the organic insecticides azadirachtin, pyrethrins, and spinosad against two stink bug species, Acrosternum hilare, (Say) and Euschistus servus, (Say) (Hemiptera: Pentatomidae). Laboratory toxicity bioassays were conducted using treated green bean pods. The conventional pyrethroid λ-cyhalothrin was included for comparison. A. hilare, adults and nymphs were most susceptible to λ-cyhalothrin and to tank mixes of pyrethrins + spinosad. E. servus, adults were susceptible to λ-cyhalothrin, spinosad, and all tank mixes, whereas E. servus, nymphs were susceptible to λ-cyhalothrin only. Feeding preference tests were conducted using insecticide-treated tomatoes and counting the number of feeding stylet sheaths on fruit after 24 h. All tomatoes treated with either azadirachtin, pyrethrins, or tank mixes resulted in fewer numbers of stylet sheaths than the untreated control, whereas treatment with spinosad alone did not. In filter paper repellency tests, both E. servus, and A. hilare, were repelled by pyrethrins and exhibited no response to azadirachtin. E. servus, was attracted to spinosad in comparison with a water-treated control; however, A. hilare, displayed no response. In field efficacy trials, each of the organic insecticides reduced the number of stink bugs in soybean, Glycine max, (L.) Merr., for up to 2 d after treatment; however, none of the insecticides reduced stink bug damage to fruit in tomatoes even after multiple applications. Implications for organic growers and integrated pest management programs are discussed.