Virulência de Cordyceps javanica a lagartas de Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) sob condições de laboratório

Abstract

Spodoptera frugiperda is considered one of the main pests in several crops of economic interest such as corn, soybeans, cotton and rice. Such characteristics of polyphagia and easy distribution make it an increasing concern for this pest in several cultures around the world. Several strategies are already used for its control, such as chemical, varietal and biological control. However, due to the inappropriate use of chemicals and the use of transgenic varieties without refuge areas, there was an increase in the selection pressure evolved in the selection of resistant ones. To obtain an efficient way in its integrated management, one must seek more action button for its control: in this study, we evaluated if the isolate CG1228 of the entomopathogenic fungus Cordyceps javanica presents potential for its control being sprayed directly on the caterpillars. We used the following treatments: control (distilled water + 0.04% Tween 80), C. javanica at concentrations of 1 x 106, 1 x 107 e 5 x 107 blastospores/mL, these being treatments 2, 3 and 4, respectively. We maintained caterpillars on a natural diet in B.O.D at a constant temperature of 25.5°C and 12h photophase, using “Pérola” cultivar bean leaves as diet and estimated mortality on the 2nd, 5th, 6th, 7th and 8th days after pulverization, for the analysis of the results, Tukey's test at 5% significance level, Oneillmathews at 5% significance level, analysis of variance (ANOVA) and Shapiro-Wilk test were used. The second day after application was the day with the highest number of deaths; the highest concentration showed the best result compared to the control.