Sensibilidade de Podisus nigrispinus (Hemiptera: Pentatomidae) a inseticidas utilizados em algodoeiro

Abstract

Among many tactics applied in Integrated Pest Management (IPM) programs, biological and chemical stands out. However, integration of these techniques is compromised by broadspectrum, non-selective pesticides. Therefore, the aim of this study was to evaluate the physiological selectivity of four pesticides commonly used in cotton crops in Brazil (cyantraniliprole, chlorantraniliprole, pymetrozine and etofenprox) to the predator Podisus nigrispinus (Dallas, 1851) (Hemiptera: Pentatomidae) in laboratory conditions. P. nigrispinus eggs, nymphs and adults were obtained from a rearing established in laboratory, and sprayed with pesticides in a Potter Precision Tower, calibrated according to recommendations of the “Internacional Organization for Biological Control of Noxious Animals and Plants” (IOBC). The highest concentration of the pesticides, recommended by their manufacturers, was applied in the experiments. Insects were maintained in laboratory conditions (25±2ºC, 70±10% relative umidity and 12-hour photophasefotofase de 12horas. As food source, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) larvae were offered. In each bioassay, pesticides were categorized in toxicity classes (according IOBC). Etofenprox was slightly harmful to P. nigrispinus eggs (class 2) and harmful to second instar nymphs and adults (class 4). Pymetrozine was hamless (class 1) to eggs and adults of the predator, and slightly harmful to nymphs (class 2). Cyantraniliprole and chlorantraniliprole were both considered harmless to eggs and sligthtly harmful to nymphs and adults. Pymetrozine caused no lethal effect to any P. nigispinus development stage, however it caused sublethal effects when applied in nymphs (reduction in egg viability of the first generation) and adults (reduction in pre-oviposition period). Due to the lower toxicity caused by pymetrozine, this compound should be preferred in cotton IPM programs, aiming the preservation of the predator P. nigispinus. Etofenprox was the most toxic pesticide evaluated in lab; therefore, it should be evaluated in greenhouse and field conditions to confirm its toxicity.