Sublethal Effects of Indoxacarb and Beta-Cypermethrin on Rhopalosiphum padi (Hemiptera: Aphididae) under Laboratory Conditions

Abstract

Rhopalosiphum padi (L.) (Hemiptera: Aphididae) is a devastating pest of wheat worldwide. Beta-cypermethrin is widely used to control piercingsucking pest insects, including R. padi. Field-applied insecticides gradually descend to sublethal concentrations with the passage of time. Sublethal concentrations of insecticide may affect physiology and behavior of pests, potentially leading to pest resurgence. This study investigated potential sublethal effects of beta-cypermethrin and indoxacarb on an experimental population of R. padi. Indoxacarb is a relatively new pesticide with a mechanism of action that is different from that of beta-cypermethrin. The leaf dip method was used to test the acute toxicity of these insecticides to adult aphids, and life tables were constructed to analyze the effects of 2 sublethal concentrations of beta-cypermethrin (B-LC10, B-LC30) and indoxacarb (I-LC10, I-LC30) on the development and reproduction of the F0 and F1 generations of R. padi. Results of these analyses showed that sublethal concentrations of the 2 insecticides can significantly reduce the fecundity and longevity of the F0 generation. Also, sublethal concentrations of both insecticides prolonged the development of nymphs in the subsequent generation. Life table parameters demonstrated that the evaluated insecticides at sublethal concentrations did not stimulate aphid reproductive potential. This information could be important to enable a more effective use of these insecticides in management programs for R. padi.