Integration of BT technologies and insecticides against caterpillars

The convenience brought by Bt technology meant that its massive use, in disagreement with technical recommendations, combined with the characteristics of an agroecosystem favorable to the multiplication of pests, resulted in control escapes, management difficulties and resistance pressure, mainly from caterpillars. Combining biotechnology with the rational use of insecticides and other integrated strategies is the safest way to face this problem

According to data from the Biotechnology Information Council (CIB) in the 17/18 harvest, Brazil presented more than 65 approved events, both for weed control and insect control, in different crops. One of the major milestones was the release of caterpillar-resistant cotton in 2005, and later corn in 2007. In 2009, Bt soybean (Intacta RR2 Pro) was released, with the expression of the Cry1Ac protein.

The contribution of transgenics in corn and cotton was of great value for integrated pest management. It helped to reduce insecticide applications in these crops by around 20%, and particularly in the caterpillar complex there was an 80% reduction in the first years of adoption. In soybean cultivation, the data also shows benefits, but in certain regions with lower gains compared to other crops.
Since the release of genetically modified plants with resistance to pests, major changes have occurred, whether due to changes in insect behavior, adaptation in the production system, the presence of alternative hosts or changes in the main pests of each crop.
One of the factors to be analyzed in the Brazilian Cerrado is that the agroecosystem used in the Central-West region is a favorable environment for the multiplication of pests, as soy prevails as the main crop to be established in the vast majority of areas, which can be rotated or not, After harvest, a cover crop is established or the area remains “fallow”. In this farming system, pests have been adapting for several years, even before the entry of Bts. Factors such as favorable climatic conditions, high temperatures and mild winters make them ideal for the multiplication of insects. 
Both soybeans and other crops are subject to attack by various insects from germination to harvest. In Integrated Pest Management (IPM), it is essential to recognize pests and their natural enemies. Monitoring is the operation that gathers information to make control decisions, including damage and the intensity of the occurrence. However, in IPM programs, control decision-making is a factor that changes depending on several factors such as efficiencies in management strategies, machine yard, control costs, among others, which vary over the years. 
IPM is characterized by altering the agroecosystem as little as possible, and based on this assumption, pest control in soybean crops is no longer carried out through exclusive dependence on chemical insecticides, but rather systems that emphasize the management of the arthropod population in the agroecosystem.
Among pests, caterpillars can cause great damage to soybean crops. Until the 2014/2015 harvest, they were considered by many researchers to be the main pest. One of the caterpillars, Helicoverpa armigera, in the Chapadões region, had an estimated control cost of around 50 dollars per hectare, in the 2013/2014 and 2014/2015 harvests. 
In general, in the Central-West region, the intensity of the attack by different species of caterpillars has forced producers to carry out one to seven sprays on the crop to control it, in a Bt and non-Bt environment in soybeans.
Among the various caterpillars in the production system, those from the Spodoptera complex (Spodoptera frugiperda and S. eridania) and Helicoverpa armigera stand out, which in Cerrado conditions present a high frequency, destroying leaves, pods and grains, compromising production. 
In Brazil (as it presents conditions of several cycles, overlapping generations of these pests), an increase has been observed mainly in the number of individuals of the Spodoptera complex.

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