Bt cotton and the predator Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) in the management of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) resistance to lambda-cyhalothrin

This study sought to provide relevant information for developing effective programs to manage Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) resistance to insecticides by quantifying and describing the interactions between cotton Bt and Podisus nigrispinus (Dallas) (Heteroptera; Pentatomidae) in the management of lambda-cyhalothrin resistance in S. frugiperda fed Bt cotton leaves expressing Cry1Ac (Bollgard, Monsanto, St Louis, MO, USA). These effects were assayed by studying functional responses. Third instar S. frugiperda larvae were used for the following treatments: strains resistant (1) or susceptible (2) to lambda-cyhalothrin fed Bollgard cotton leaves and strains resistant (3) or susceptible (4) to lambda-cyhalothrin fed non-Bt cotton leaves. The predatory behavior of P. nigrispinus females was best represented by a sigmoid curve. The type of P. nigrisinus functional response was not affected by the cotton cultivar or S. frugiperda strain used in the trials. P. nigrispinus females invested a greater amount of handling time (Th) in S. frugiperda larvae that were suseptible to insecticides and fed non-Bt cotton (Th = 1.72 h) compared to those from the insecticide-resistant strain fed with Bt cotton (Th = 1.23 h) or even compared to those that were lambda-cyhalothrin resistant and fed Bt (Th = 1.17 h) or non-Bt cotton (Th = 1.17 h). The results in the present study can be applied in the development of management programs targeting S. frugiperda resistance to pyrethroid lambda-cyhalothrin. The integration of Bt cotton concurrent with biological control by the Asopinae P. nigrispinus is important for successfully managing S. frugiperda resistance to lambda-cyhalothrin.