Efficacy of Organic Insecticides and Repellents against Brown Marmorated Stink Bug in Vegetables
The brown marmorated stink bug (BMSB), Halyomorpha halys (Stål), is a major pest of vegetable crops, fruit crops, and even ornamental plants in the Mid-Atlantic States. Organic growers have limited chemical options to manage this pest, and are in need of better management options. Several organically-approved insecticides including pyrethrins (Pyganic), azadirachtin (Aza-Direct), azadirachtin + pyrethrins (Azera), spinosad (Entrust), potassium salts of fatty acids (M-Pede), sabadilla alkaloids (Veratran D), extract from Burkholderia sp. (Venerate), and one experimental product, potassium salts + spinosad (Neudorff 1138), were evaluated for toxicity to BMSB nymphs and adults using lab bioassays and field trials on tomatoes and peppers. Another potential control option is to use natural chemicals to deter BMSB feeding in vegetables. Kaolinite [Al4Si4O10 (OH)8] (Surround WP); a white, plate-shaped, aluminosilicate mineral that is sprayed on plants to alter the appearance, feel, and smell of a plant to an insect. Essential oils (Ecotec) are chemicals produced by plants which are repellent and even toxic to certain insects, and by mimicking octopomine these chemicals disrupt the insect's neurotransmitters. Treatments were evaluated in choice test bioassays and field experiments on peppers using weekly applications of the highest labeled rates of the products. The results showed that, although some organically-approved insecticides demonstrate a high level of activity on BMSB in lab bioassays, none of these products appear to be effective at reducing stink bug damage to fruiting vegetables in the field. However, kaolinite provided significant control of BMSB nymphs (p=0.03) and adults (p=0.01) in both choice test bioassays and in field trials. Essential oils did not provide any significant control of BMSB in choice test bioassays or in field trials. Further research is needed to determine if the efficacy of kaolinite holds up under heavy pest pressure.