Maximização da produção in vivo de Spodoptera frugiperda multiple nucleopolyhedrovirus (Lefavirales: Baculoviridae)

Abstract

The biological control of pests is a management tactic applied in production systems, and studies that enable its production are necessary to meet the growing demand for biological products. In Brazil, we can highlight the availability on the market of formulations with entomopathogens, as in the case of the Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) (Lefavirales: Baculoviridae) used to control Spodoptera frugiperda (Lepidoptera: Noctuidae). However, the production of this bioinsecticide requires an in vivo system and involves costs with the multiplication and maintenance of the host in an artificial diet, as well as in the viral inoculation stage. Thus, advances in the production system of bioinsecticides based on entomopathogenic viruses are extremely necessary to meet the agricultural market. Therefore, aiming to maximize the in vivo production of SfMNPV in S. frugiperda was proposed: 1) to determine the number and duration of larval stages of S. frugiperda; (2) to determine the influence of temperature and food availability on the cannibal behaviour of S. frugiperda; (3) determine and evaluate artificial diets used in the viral inoculation step of SfMNPV. Thus, based on the results there was a range of five to seven stages and a larval duration between 11 to 17 days. Regarding cannibalism, it was found that 15g of diet is adequate to avoid this behaviour in 3rd and 4th instar larvaes in 72h, regardless of temperature, and that for the 5th instar this amount is equivalent to 10g. Furthermore, it has been proven that it is possible to inoculate the virus without loss of viral polyhedra production in a diet based on textured soy protein, and with a diet of simplified composition to complete the viral infection stage. When evaluating a cold texture diet for viral inoculation at temperatures of 25 and 31°C at 4, 6 and 8 days of larval development, the temperature of 31°C at the age of 6 days stood out, complementing the feeding with a wheat germ-based diet, with no losses in the production of viral polyhedra.