A significant outbreak of Helicoverpa caterpillars in the Brazilian states of Mato Grosso, Mato Grosso do Sul in the south-west of the country and Maranhão in the north are reportedly affecting transgenic Intacta soybean crops. The GM technology, which was developed by Monsanto (now owned by Bayer), is designed to confer resistance to the pest through the expression of a Cry1Ac gene, however, the dry weather has enabled pest populations to flourish.