Bt Cotton

These genes are responsible for the generation of insecticidal proteins, and as a result, plants that have been genetically modified produce one or more toxins as they grow. The genes that have been put into cotton create poisons that are nearly solely active against caterpillar pests, which are a type of caterpillar (Lepidoptera). The bacteria Bacillus thuringiensis, on the other hand, has genes that encode for toxins that have insecticidal activity on some beetles (Coleoptera) and flies, according to other strains of the bacteria (Diptera). In addition to maize, several of these genes are being utilised to control pests in other crops, including cotton.

What kinds of Insects does it manage to keep under control?

Bollgard cotton (a trademark of Monsanto) was the first Bt cotton to be commercially available in the United States, having been introduced in 1996. Cotton from the original Bollgard variety contains a toxin known as Cry 1Ac, which has excellent efficacy against the tobacco budworm and the pink bollworm, among other insects. Despite the fact that these two insects are particularly important caterpillar pests of cotton, standard insecticides are difficult and expensive to treat with conventional methods. Because of this, Bt cotton was widely embraced by growers throughout the Cotton Belt, largely for the control of pink bollworm, as well as the Mid-South and Southeast, mostly for the control of tobacco budworm. Aside from bollworm, boltgard toxin also has modest efficacy against loopers, autumn armyworm, and sugar beet armyworm, though to a lower level.

Bollgard II cotton, which was released in 2003 and represents the next generation of Bt cottons, was the first of its kind. Among the genes in Bollgard II is a second gene derived from the Bt bacterium, which codes for the production of Cry 2Ab. WideStrike (a trademark of Dow AgroSciences) was first registered for usage in the fall of 2004 and has since become widely used. WideStrike cotton, like Bollgard II cotton, expresses two Bt toxins (Cry1Ac and Cry1F). When compared to the original Bollgard technology, both Bollgard II and WideStrike exhibit superior activity against a broader range of caterpillar pests. The original Bollgard technology, as well as WideStrike, are no longer available for purchase in the United States. Several caterpillar pests are improved in control by the most recent Bt cotton varieties, such as Bollgard III, WideStrike 3, and TwinLink Plus, which express another Bt toxin, Vip3A, which is found in the most recent Bt cotton varieties.

What is the Impact of Bt cotton on Insect Pest Management?

Current Bt cotton methods significantly reduce the need for caterpillar pesticide application. Indeed, in Tennessee, insecticide applications for caterpillar pests are only rarely required in cotton types such as Bollgard III, WideStrike 3, and TwinLink Plus, which are resistant to caterpillars. According to research and practical experience in the Mid-South and Southeast, some pests are more problematic in Bt cotton as a result of a reduction in the use of broad-spectrum insecticides for control of tobacco budworm and bollworm in Bt cotton fields. Infestations of tarnished plant insects, clouded plant bugs, and stink bugs are more common in Bt cotton than in conventional cotton. The reduction in insecticide use that has resulted from the eradication of the boll weevil is likely to be the most significant contributor to this problem.

Resistance and the Handling of Resistance

It appears likely that some cotton pests may evolve resistance to Bt crops if the technology is widely employed, and this has already been shown for some species of cotton bug. In the case of the bollworm, it has developed some resistance to the Bt toxins Cry1Ac, Cry1F, and Cry2A, among others. For example, having a refuge, whether it is non-Bt cotton or other non-Bt crops or wild hosts, that serves as a supply of vulnerable insects that might potentially breed with any resistant insects developed in Bt cotton fields is a fundamental resistance control method. Children born as a result of this union would be susceptible to the poisons produced by Bt crops (assuming the genetic trait for resistance is at least partially recessive). The introduction of Bt crops that produce two or more toxins that are reasonably distinct to one another is a second resistance management strategy. It is presumed that it is less likely that any one insect will be resistant to more than one toxin at the same time. Cotton types that are resistant to Bt toxins currently exist in two or three variants.

Is Genetically Modified Cotton Safe?

The poisons produced by Bt are extremely specific. The toxins produced by genetically modified cotton and corn are poisonous to a small number of arthropod species, according to the USDA. Because cotton is predominantly a fibre crop, the possibility of food being contaminated with cotton-derived toxins is quite remote. However, comprehensive testing has revealed that the usage of Bt crops, including intake of food products derived from them, poses a very low risk to public health.

Conclusion 

Therefore it can be concluded, the usage of Bt crops has the potential to have negative consequences for arthropods that are not intended for consumption. A number of people have expressed concern that pollen from corn, which contains Bt toxins, could wind up on plants that act as hosts for monarch butterflies, swallowtail butterflies, and other butterflies. In the case of cotton, this is only a minor concern because, unlike maize, it is not pollinated by the wind. Also worth considering is that Bt crops typically result in a reduction in the use of wide spectrum insecticides, which in turn results in a reduction in the impact of these applications on the environment and nontarget creatures.