RESUMO
Spodoptera frugiperda is an important pest of several crops. Use of chemical insecticides in insect control has not been successful. In the present study, bio-nano formulation of bimetallic nanoparticles were synthesized using fungal metabolites from Metarhizium anisopliae and tested for insecticidal activity. Metarhizium anisopliae metabolites was synthesized along with bimetallic nanoparticles at different volumes for bioassay studies. Bimetallic nanoparticles showed colour change from light greenish to white. Synthesis of bimetallic NPs was confirmed by UV-vis spectrophotometer, with absorption peak at 387 nm. Functional groups in the synthesized BMNPs were analyzed by FTIR, which showed the presence of functional amines, carboxylic acids, alkenes, alkyl halides, phosphine oxides, anhydrides, phosphines, sulfonates, acid chlorides and alkynes. XRD analysis confirms the crystalline nature of nanoparticles. SEM analysis exhibits, the nanoparticles to be spherical in shape with size ranging 9.50 nm. EDaX analysis confirmed the elemental composition of synthesized NPs, while DLS for size distribution ranging at 80 to 137 nm. The larvicidal activity of monometallic and mycogenic bimetallic nanoparticles were tested on third instar S. frugiperda larvae. The highest mortality was observed in BMNPs at a concentration of 100 µg/ml after 48 h exposure. Pupicidal and antifeedant activity was also observed in the tested BMNPs. Detoxification enzymes studies of BMNPs showed considerable lowering these enzyme which may result in toxic manifestation in the insect. These results strongly suggest that, bimetallic nanoparticles synthesized using M. anisopilae can be used for protecting the crops against S. furgiperda.