Evaluation of the performance of Spodoptera frugiperda caterpillars after contamination by bacteria and yeast

Abstract

The increase in the use of pesticides in the field has been bringing serious implications for the human health and the environment. In order for pesticides to be lethal only to target pests, the idea of biological control, which proposes eliminating pests from specific pathogens, avoiding causing harm to human beings and their environment, emerged. Baculoviruses, a virus that cause pathogenicity for specific insects, has been used as biological control. However, its laboratory production faces difficulties, one of which is the contamination of the caterpillars used (S. frugiperda - the main pest of soybean and maize) by undesirable microorganisms. The objective of this work was to evaluate the behavior of caterpillars used for the production of Baculovirus after contamination by previously identified microorganisms. For this, was identified the microorganisms present in the caterpillars: Staphylococcus aureus (22.5%), Staphylococcus sp. (42.5%), Klebsiella oxytoca (2%), Pseudomonas aeruginosa (8%), A. flavus and Penicillium sp. (52%) and yeasts (72%). Subsequently, these microorganisms were inoculated individually in healthy caterpillars, which were observed for a period of 12 days, in an ideal environment (temperature 25 º C and Humidity 70%). It was concluded that the bacteria Pseudomonas aeruginosa and Klebsiella oxytoca proved very harmful to the caterpillar, causing weight loss and early death. The caterpillars contaminated by fungi had similar behaviors. The caterpillars contaminated by the bacteria Staphylococcus aureus and Staphylococcus sp. until the 9th day showed no difference in the weight gain rate when compared to the control group. Among the caterpillars of the control group there was no death.