In-vitro Study to Determine the Dose of Beauveria bassiana for Management of Spodoptera frugiperda

Pest insects known as fall army worm (Spodoptera frugiperda) can feed on over 80 different types of crops. It has the potential to significantly reduce the yields of major cereal crops including oats (Avena sativa L.). The oat crop is one of the preferred hosts of this pest. This fodder crop is directly used as animal feed so, chemical control of pests is not preferable. One of the alternatives for the management of fall army worm on fodder oats is the use of microbials which have some advantages over the use of chemical insecticides, as they are highly host specific with low environmental contamination. Beauveria bassiana is a fungus and can be used to control this pest. So, the present study was undertaken to standardize the dose of Beauveria bassiana for management of fall army worm. The virulence test was conducted against third instar larvae of S. frugiperda. The larvae were treated with three doses of B. bassiana of 1×1012spore/ml concentration i.e.,1, 2, and 3ml/L, by dipping them for 30 seconds in 10 ml of suspension. In case of control, larvae were treated with distilled water containing a drop of Tween- 80 (0.02%). At 24 hours after treatment, the differences in the mean larval mortality among different doses of B. bassiana were non-significant. However, at 48 and 72 hours after treatment, the differences in the mean larval mortality among different doses of B. bassiana were significant. Highest larval mortality was recorded at 48 and 72 hours after treatment in 3 ml/L (29.39 and 86.67%, respectively).