EFICIÊNCIA DE Spodoptera frugiperda Multiple Nucleopolyhedrovirus (SfMNPV) COMO BIOINSETICIDA NO CONTROLE DE Spodoptera frugiperda SOB CONDIÇÕES DESAFIANTES DE TEMPERATURA E RADIAÇÃO SOLAR

Abstract

The fall armyworm, Spodoptera frugiperda, is one of the most destructive agricultural pests in Brazil, causing substantial damage to major crops such as maize, soybean, and cotton. Although chemical control remains widely used, it has led to the selection of resistant pest populations and negative environmental impacts. In this context, bioinsecticides based on baculoviruses, particularly Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV), have emerged as sustainable alternatives for pest management. This study aimed to evaluate the impact of extreme environmental conditions on the viability and efficacy of SfMNPV. Mortality bioassays were conducted following the exposure of the product to a constant temperature of 50 °C, with or without direct solar radiation, across four time intervals (0h, 16h, 27h, and 82h). Degel curves were also performed to simulate thermal storage failures, exposing the virus to 40 °C after prior refrigeration at -5 °C and -18 °C. Results demonstrated that both exposure time and solar radiation significantly reduced virus efficacy, with larval mortality dropping from 78.9% to 22.0% after 82 hours under solar exposure. Two-way ANOVA revealed no significant interaction between the two factors, indicating independent effects. No significant differences were found between the two storage temperatures. These findings highlight the need for proper thermal management and strategic application during periods of low solar intensity to preserve viral viability under field conditions.