Bt Sweet Corn and Selective Insecticides: Impacts on Pests and Predators

Abstract

Sweet corn, Zea mays L., is attacked by a variety of insect pests that can cause severe losses to the producer. Current control practices are largely limited to the application of broad-spectrum insecticides that can have a substantial and deleterious impact on the natural enemy complex. Predators have been shown to provide partial control of sweet corn pests when not killed by broad-spectrum insecticides. New products that specifically target the pest species, while being relatively benign to other insects, could provide more integrated control. In field trials we found that transgenic Bt sweet corn, and the foliar insecticides indoxacarb and spinosad are all less toxic to the most abundant predators in sweet corn (Coleomegilla maculate [DeGeer], Harmonia axyridis [Pallas], and Orius insidiosus [Sav]) than the pyrethroid lambda cyhalothrin. Indoxacarb, however, was moderately toxic to coccinellids and spinosad and indoxacarb were somewhat toxic to O. insidiosus nymphs at field rates. Bt sweet corn and spinosad were able to provide control of the lepidopteran pests better than or equal to lambda cyhalothrin. The choice of insecticide material made a significant impact on survival of the pests and predators, while the frequency of application mainly affected the pests and the rate applied had little effect on either pests or predators. These results demonstrate that some of the new products available in sweet corn allow a truly integrated biological and chemical pest control program in sweet corn, making future advances in conservation, augmentation and classical biological control more feasible.

Post-market environmental monitoring of Bt maize in Spain: Non-target effects of varieties derived from the event MON810 on predatory fauna

“…When a commercially available rove beetle predator, Atheta coriaria Kraatz, was tested in the laboratory for its susceptibility to Cry1Ab toxin, the one tested in this study, no negative influence on the main biological parameters of the predator was found when the toxin was provided via the food web (García et al, 2010) Abundance of plant-dwelling generalist predators, such as Orius spp. and spiders, has been reported to increase occasionally in Bt maize (Jasinski et al, 2003;Musser & Shelton, 2003;de la Poza et al, 2005). Higher densities of Orius spp.…”

Biological control and sustainable food production

“…This reduction in parasitism is not surprising given that host populations were significantly decreased by the Bt crop. Predation rates on sentinel lepidopteran eggs or larvae did not differ between Bt and untreated non-Bt fields (Musser & Shelton 2003;Sisterson et al 2004;Naranjo 2005b), but were significantly reduced by the application of broad-spectrum insecticides (Musser & Shelton 2003). Studies in commercially managed cotton fields revealed much higher predation rates in Bt cotton compared to non-Bt fields, where more insecticides were applied (Head et al 2005).…”

Temporal Changes in Chlorantraniliprole and Indoxacarb in Four Midwestern Soils and Bioefficacy Against the Eastern Subterranean Termite (Isoptera: Rhinotermitidae)

“…While indoxacarb may have low acute toxicity to many predators at the suggested rates, and even reduced rates, it may reduce Harmonia axyridis population growth by affecting survival, development, and reproduction (Galvan et al, 2005b). At suggested rates, indoxacarb has been found to be toxic to the predacious mirid Hyaliodes vitripennis (Bostanian et al, 2004), moderately toxic to coccinellids and somewhat toxic to Orius insidiosus nymphs (Musser and Shelton, 2003). When using indoxacarb as a part of an integrated pest management plan it will be important to identify the beneficial insects in the field and to determine if they are adversely affected by indoxacarb.…”