Selectivity of insecticide use in soybean crop to the predator Podisus nigrispinus (Hemiptera: Pentatomidae)

Abstract

The selectivity of different insecticides to nymphs and adults of Podisus nigrispinus was evaluated in this study. Tests were carried out in the laboratory according to IOBC standard protocol. We evaluated different active ingredients that were applied using a Potter tower. Insect survival was assessed at 24-hour intervals for up to five days after exposure to treatments. Adult survivors of each treatment were assigned to breeding-pairs to evaluate possible effects on fertility. The pyrethroids bifenthrin, zeta-cypermethrin, beta-cyfluthrin, lambda-cyhalothrin and deltamethrin alone or in mixtures with neonicotinoids and diamides, such as beta-cyfluthrin + imidacloprid, lambda-cyhalothrin + thiamethoxan and chlorantraniliprole + lambda-cyhalothrin, as well as the organophosphate, chlorpyrifos, were the most harmful (class 4 classification) insecticides for the preservation of P. nigrispinus for both nymph and adult predators. Conversely, the insecticide growth regulators (IGRs) lufenuron, teflubenzuron, triflumuron, tebufenozide and novaluron were classified as harmful (class 4) only for P. nigrispinus nymphs. These products were classified as harmless (class 1) and slightly harmful (class 2) for adult predators. Among the evaluated products, the most selective for P. nigrispinus were those belonging to the spinosyns (spinosad and spinetoram) and the diamides group (flubendiamide and chlorantraniliprole), which were classified as harmless (class 1) and slightly harmful (class 2) for both P. nigrispinus nymphs and adults. Next, the most selective product was methoxyfenozide, which ranged between slightly harmful (class 2) and moderately harmful (class 3) to nymphs and harmless (class 1) to adults of the natural enemy.