Formulações de Aspergillus nomius para controle de Chrysodeixis includens e Spodoptera frugiperda

Abstract

Leafhopper lizards Chrysodeixis includens (Kurtzman, 1987) and Spodoptera frugiperda (JE Smith, 1797) (Lepidoptera, Noctuidae), also known as carpiaceous caterpillars are the main pests in soybean and corn crops. The insecticides are long and of great practicality, but they bring the direct and indirect emissions that cause the impact on the environment. The use of microorganisms for the control of pests represents an ecological advance for the exercise of tasks caused by the indiscriminate work of insecticides. The Aspergillus nomius fungus can be an alternative for the integrated management of difficult to control caterpillars. Formulating an entomopathogenic microorganism arises when it is desired to use it under field conditions as a biological insecticide. Unlike the chemical insecticides, the pathogens can be applied pure, but in this condition does not allow protection, distribution and homogenous coverage of the pathogen. This can be achieved with the aid of the adjuvants added in the formulation. The objective of the work was to develop an insecticide to the control database of C. includens and S. frugiperda with desirable physical-chemical characteristics for field applicability. The bioassays were conducted with the recent formulations of the LabMIP-UFSM and the fungus of A. nomius developed at the Laboratory of Microbiology and Soil Biology of UFSM. The treatments consisted of 10% of A. nomius conidia + 45% of a base formulation and 45% of: M1-Nimbus; M2-Nimbus 25%(v/v) + sunflower oil 75%(v/v); M3-100 sunflower oil; M4-Nimbus 25%(v/v) + Corn oil 75%(v/v); M5-Corn oil. For the homogenization of the formulations, ultrasonic and mechanical equipment were used. To evaluate the physicochemical characteristics, equipment was used to evaluate pH, density and surface tension. The stability of the formulations was evaluated visually. The stability characteristics, the foam formation of the application syrup, the effect of the formulations on temperature (50 ° C) and the effectiveness of the formulations with contact contamination and ingestion of C. includens and S. frugiperda were evaluated. The basic formulations of A. nomius showed good physicochemical characteristics of stability and formation of foams, in the formulation and in the application syrup. The high temperature prevented the germination of conidia in most of the formulations, except for the treatment with 100% Nimbus. Regarding the control efficiency, the formulations with the A. nomius fungus control the 3rd instar caterpillars of C. includens and S. frugiperda with control efficacy around 50%.