Efeito de fotoprotetores ultravioleta na eficácia de Spodoptera frugiperda multiple nucleopolyhedrovirus (Lefavirales: Baculoviridae)

Abstract

The Caterpillar Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) is considered, for corn culture, the most important pest insect. The use of chemical insecticides is still the most used management tactic; however, due to the negative impacts, other methods have been considered, such as the use of entomopathogenic viruses. Thus, the use of baculoviruses to control pest insects has been performed in numerous crops of economic interest, as for example in corn culture, where the Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) (Baculoviridae) is widely used to control the caterpillar. However, several factors can affect baculovirus efficiency in the field, ultraviolet radiation is the main one, since it inactivates the virus, affecting its persistence in the environment. Thus, there is a need to study the association of entomopathogenic vírus formulations with chemical compounds that protect the inclusion protein bodies and allow greater persistence in the field. The objective of this research was to search for alternatives that improve the baculovirus efficiency in the field through studies with (1) protection effectiveness tests of two chemical compounds (Optical Brightener (BrOpt) and Titanium Dioxide (TiO2)) and their isolated toxicity to S. frugiperda in laboratory, (2) evaluate the addition of inerts (kaolinite and clay) and chemical compounds (BrOpt) and (TiO2) in SfMNPV formulations and their efficiency on the mortality of S. frugiperda caterpillars in Field and semi-field, (3) test the ultraviolet radiation protection ability of chemical compounds (BrOpt) and (TiO2) and baculovirus formulations with different inerts over time. From the results obtained, it was found that: (1) protective effect iveness and higher mortality at concentrations of 3 and 5% TiO2 and 3% BrOpt; (2) in semi-field, the formulates and these plus the chemical compounds (TiO2 and BrOpt) were more efficient than the pure viral solution, in the field, formulations plus the chemical compounds were more efficient than the formulations alone and than the pure viral solution; (3) the Clay formulation was the one that presented more efficiency over time and, when added to the chemical compound BrOpt, it obtained similar efficiency in all intervals evaluated.