Padronização da produção on farm do bioinseticida à base de Bacillus thuringiensis subsp. kurstaki

Abstract

Brazil represents a great role in the global agricultural sector, considered the fifth-largest cereals’ producer and leader in soybean production. Among the biggest problems that affects the productivity are pests, with an estimated 12 billion dollars in annual losses in Brazil. Given the high cost of chemical pesticides, the development of pest resistance to chemical agents, toxicity, and environmental damage, the use of biological control has become increasingly prominent. Initially, the present study presents a field research to analyze the use of bioinputs in farms. It was possible to verify the widespread use of bioinputs by farmers in Mato Grosso (Brazil). However, 45% of users of biological inputs do not execute quality control. They also report significant aspects to be improved, such as qualified labor and accessibility to information. After field research, Bacillus thuringiensis subsp. kurstaki (HD-1 (S1450)) was evaluated regarding its growth compared to commercial media and new formulations. The proposed new formulations included modifications in the sources of carbon, nitrogen, inorganic nutrients, and quantity of constituents. The evaluated parameters were measured using CFU/mL count, cell density, and percentage of sporulated cells. Formulation scaling tests were also executed for 5 and 100 liters, and storage at different temperatures was subsequently evaluated. The results reveled that the increase in carbon and nitrogen sources is essential for the rapid availability of the nutrient to the microorganism, reducing the growth time necessary to reach ideal cell density. The final product keeps 93.52% sporulation after 30 days of storage, with a concentration of Cry1Ab/Ac proteins much higher than the commercial product. Tests on Spodoptera frugiperda caterpillars confirmed the results found in the quantification of proteins where the final product with 180 days of fermentation killed 100% of the individuals in 2 days. Furthermore, the cost of raw materials for its production was only R$1.53 per liter. Therefore, the final product represents an excellent proposal for an on-farm application.