Effective concentration of entomopathogens Beauveria bassiana (Bals) Vuil as biological control agents for Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae)

Abstract

Fall armyworm (Spodoptera frugiperda JE Smith) is an invasive pest that attacks corn plants. This pest control can be done using several techniques. Biological control for S. frugiperda is using the entomopathogenic fungus Beauveria bassiana. The study to obtain an effective concentration of the entomopathogenic fungus B. bassiana for controlling S. frugiperda. The study was conducted at the Insect Bioecology Lab and Biological Control Laboratory, Faculty of Agriculture, Universitas Andalas. The study was designed in a Completely Randomized Design (CRD) with five treatments and was repeated five times. The treatments consist of a suspension of the fungi B. bassiana with different densities, namely 106, 107, 108, 109 conidia/ml and control (aquadest + tween 80). Parameters observed were larval mortality, percentage of Pupae formed, percentage of adults offsprings, and the number of normal and defective adults as well as male and female adults. Data were analyzed by Analysis of Variance (ANOVA), further tested with LSD at a 5% level, and analysis probit to known LC100. The results showed that the higher the concentration, the higher the mortality of the larvae. The effective suspension of B. bassiana as control of S. frugiperda was a concentration of 109, caused larvae mortality percentage of 84%, Pupae formation of 4%, adults offspring 2%, and sex ratio male: female (1:0), normal and abnormal adults 0:1. To get larvae mortality up to 100%, the LC100 is 1018 conidia/ml.