Boll Weevil - Control

Control

Following World War II the development of new pesticides such as DDT enabled U.S. farmers again to grow cotton as an economic crop. DDT was initially extremely effective, but US weevil populations developed resistance by the mid 1950s. Methyl parathion, malathion, and pyrethroids were subsequently used, but environmental and resistance concerns arose as they had with DDT and control strategies changed. In 1978 a test was conducted in North Carolina to determine feasibility of eradicating the weevil from the growing areas. Based on the success of this, area-wide programs were begun in the 1980s to eradicate the insect from whole regions. These are based on cooperative effort by all growers together with the assistance of the Animal and Plant Health Inspection Service (APHIS) of the United States Department of Agriculture (USDA). The program has been successful in eradicating weevils from Virginia and the Carolinas, Georgia, Florida, south Alabama, California, Arizona, and Louisiana. Efforts are ongoing to eradicate the weevil from the rest of the United States. Continued success is also based on prohibition of unauthorized cotton growing, outside of the program, and constant monitoring for any recurring outbreaks.

In the 1980s, entomologists at Texas A&M have pointed to the spread of another invasive pest, fire ants, as a factor in the weevils' population decline.

Other avenues of control that have been explored include weevil-resistant strains of cotton, the parasitic wasp Catolaccus grandis, the fungus Beauveria bassiana, and the Chilo iridescent virus. Genetically engineered Bt cotton is not protected from the boll weevil.