Suceptibility of Spodoptera frugiperda (Lepidoptera: Noctuidae) to modified Cry toxins from Bacillus thuringiensis

Abstract

The fall armyworm, Spodoptera frugiperda (J. E. Smith, 1797) is the major corn pest in Brazil and several countries worldwide. One of the alternatives used for the management of this pest is using transgenic plants that express insecticidal toxins produced by the bacterium Bacillus thuringiensis (Bt). However, issues caused by the resistance evolution of this species have challenged the technology sustainability. In Brazil, reports of resistance have already been in different Bt maize technologies. An alternative for insect resistance management in Bt crops is the use of modified toxins with higher toxicity to the target pest. Furthermore, are capable of killing resistant insects. The collaborating group of this project (Alejandra Bravo - UNAM) has used this technique already successfully. Those collaborators have already produced two modified toxins: Cry1AbMod for control of Manduca sexta and Cry1AcMod for control of Pectinophora gossypiella and Plutella xylostella. The aim of this project are: (1) to evaluate the susceptibility of S. frugiperda resistant populations to Cry toxins to Cry1Ab and Cry1Fa modified toxins; (2) to evaluate the sublethal effects of these toxins in the offspring and (3) to evaluate the intergenerational transfer capacity of the Cry1Ab and Cry1Fa toxins to the eggs. This work aims to provide an important strategy for the insect-resistant management since these modified proteins may have the ability to control insects, that are already resistant to current Bt proteins, as well as the Bt technologies that are still being used and there is risk of field resistance evolution.