Controlling Fall armyworm (Lepidoptera:Noctuidae) Infestations in Whorl Stage Corn with Genetically Modified Bacillus thuringiensis formulations

Abstract

Development of more potent strains of Bacillus thuringiensis (Berliner) (Bt) using recombinant DNA technology may lead to improved insecticidal products for controlling pests like the fall armyworm, Spodoptera frugiperda (J. E. Smith), which have been difficult to manage with conventional Bt-based products. EG1999, a variant Bt strain developed by recombinant DNA technology from EG2348 (the active ingredient of the bioinsecticide Condor®), showed improved control of FAW infestations in whorl stage field corn in 1994 (oil flowable and granular formulations) and sweetcorn in 1995 [wettable granule (ECX9526) (WG)] and granular [ECX9526 (G) formulations] as compared with Javelin® (WG), an insecticide derived from a naturally occurring Bt strain, and methomyl (Lannate® LV). In 1994, leaf samples taken 1 h, 1, 2, 3, 5, and 7 d after spraying and assayed in the laboratory with fall armyworm showed that the Bt products (recombinant and natural) had less than 48 h residual toxicity to 1st instar larvae. In 1994 freshly hatched FAW were placed on plants in A-frame cages to evaluate this as a method to establish artificial field infestations for use when natural FAW populations are low. The plant damage and insecticide control in the cages were similar to the heavy natural infestations outside the cages.