Insects on Bt-cotton: desperate reactions 

The article reporting1 recent evidence of caterpillars feeding on Bt-cotton, this provides evidence for survival and successful reproduction of a pestiferous species on Bt-cotton. The results of this study were not unexpected; they were anticipated even before the commercial operation of the technology.

An article in BioSpectrum2 has claimed that resistance has not been determined in the study conducted1. This is an improper allegation because determining the extent of resistance is not a requisite for determining survival. It is important to understand that the level of resistance is determined among surviving populations for working out future pest management strategies and not to ascertain survival. The same article speculates that survival may be the result of below-lethal concentrations of toxin produced by some of the Bt plants2.

If this is true, then it is to be noted that the commercial Bt plant population comprises of certain individuals producing sub-lethal levels of Bt toxin that foster survival of target insects. If this is confirmed, it would prove significant because such plants may increase the probability of producing resistant insect populations. Whatever be the reason, it is ultimately necessary that the farmer is ensured of crop protection against targeted insects. The article1 suggests that the insurance of Bt plants against caterpillar pests needs to be revisited throughout the country

Source : Current Science