Chapter 12 - Microbial Control of Insect and Mite Pests of Cotton

Abstract

The widespread adoption of Bt cotton (cotton that has been genetically modified to produce insecticidal proteins from Bacillus thuringiensis) has had a major influence on cotton insect pest management and the potential roles that entomopathogens may play as microbial control agents (MCAs) in cotton insect pest management and insecticide resistance management. Prior to Bt cotton, sprayable Bt and baculoviruses were gaining traction as insecticide resistance in Lepidoptera created control gaps. Today, many lepidopteran pests are adequately controlled by Bt cotton, and this presents other opportunities for entomopathogens to contribute to insect management. One opportunity for MCAs is to use their alternative modes of action to manage resistance to chemical insecticides and plant-based Bt toxins. This management may occur within the crop as a supplement to Bt toxins or on alternate hosts. A second opportunity for MCAs is to manage increasingly prevalent sucking insect pests that are not managed by Bt cotton. To date, microbial biocontrol options for sap sucking pests are limited to entomopathogenic fungi and may include inundative applications or management to promote natural epizootics. There is also increasing interest in tritrophic interactions among the insect pathogen, insect, and plant. These studies are revealing potential for significantly reducing application rates of the MCAs if activity can occur through colonization of the plant and potentially provide other benefits to the plant such as protection from plant pathogens.