model of production. Under most definitions, organic products do not use transgenic Bt cotton which contains a bacterial gene that codes for a plant-produced protein that is toxic to a number of pests especially the bollworms. For most producers, Bt cotton has allowed a substantial reduction in the use of synthetic insecticides, although in the long term resistance may become problematic. Global pest problems Significant global pests of cotton include various species of bollworm, such as Pectinophora gossypiella. Sucking pests include cotton stainers, the chili thrips, Scirtothrips dorsalis; the cotton seed bug, Oxycarenus hyalinipennis. Defoliators include the fall armyworm, Spodoptera frugiperda. Cotton yield is threatened by the evolution of new biotypes of insects and of new pathogens. Maintaining good yield requires strategies to slow these adversaries' evolution. North American insect pests Historically, in North America, one of the most economically destructive pests in cotton production has been the boll weevil. Boll weevils are beetles who ate cotton in the 1950s, that slowed the production of the cotton industry drastically. “This bone pile of short budgets, loss of market share, failing prices, abandoned farms, and the new immunity of boll weevils generated a feeling of helplessness” Boll Weevils first appeared in Beeville, Texas wiping out field after field of cotton in south Texas. This swarm of Boll Weevils swept through east Texas and spread to the eastern seaboard, leaving ruin and devastation in its path, causing many cotton farmers to go out of business. Due to the US Department of Agriculture's highly successful Boll Weevil Eradication Program (BWEP), this pest has been eliminated from cotton in most of the United States. This program, along with the introduction of genetically engineered Bt cotton, has improved the management of a number of pests such as cotton bollworm and pink bollworm). Sucking pests include the cotton stainer, Dysdercus suturellus and the tarnish plant bug, Lygus lineolaris. A significant cotton disease is caused by Xanthomonas citri subsp. malvacearum. Harvesting Most cotton in the United States, Europe and Australia is harvested mechanically, either by a cotton picker, a machine that removes the cotton from the boll without damaging the cotton plant, or by a cotton stripper, which strips the entire boll off the plant. Cotton strippers are used in regions where it is too windy to grow picker varieties of cotton, and usually after application of a chemical defoliant or the natural defoliation that occurs after