Refuge delays the emergence of insects resistant to Bt technology

The Brazilian Agricultural Research Corporation (Embrapa) is placing several cultivars on the market with Intacta RR2 PRO™ technology, which can be better preserved with the adoption of refuge areas. This technology brings together characteristics such as resistance to the herbicide glyphosate for weed management and also has the Bacillus thuringiensis (Bt) toxin that helps control the main species of caterpillars. However, the concern of Embrapa researchers is to extend the useful life of this technology for soybean cultivation. In the case of Bt corn, for example, which has been on the market for the longest time, there are already reports of cases of resistant insects. This topic will be addressed by Embrapa in five mini-lectures held during the 2016 Rural Show.

Refuge

To slow down the problem in soybean cultivation, Embrapa advocates the adoption of sustainable management practices. Among the measures, it is recommended to cultivate refuge areas, which is the maintenance of a percentage of at least 20% of the area (in the same plot) with the same non-Bt crop, both sown at the same time. "Furthermore, for the refuge to be effective, no Bt plant must be more than 800 meters away from a non-Bt plant", explains researcher Samuel Roggia, from Embrapa Soja.

Therefore, according to Roggia, it is not considered a refuge when the producer sows, for example, 500 hectares of Bt soybeans alongside another 500 hectares with non-Bt soybeans. A distance of 800 meters between different plants must be observed to favor mating between insects susceptible to the Bt toxin and potentially resistant individuals - coming from areas with Bt plants. "This measure could delay the selection of insects resistant to technology", he highlights.

Roggia also warns that in areas with Bt soy and refuge areas it is necessary to monitor pests and use Integrated Pest Management practices, that is, the application of insecticides only when the control level is reached.