Green synthesis of silver nanoparticles by entomopathogenic fungus Beauveria bassiana and their bioefficacy against mustard aphid (Lipaphis erysimi Kalt.)

Brassica campestris is the most commonly grown brassica oil seed crop that occupy significant place in the edible oil production with its seeds containing 42% oil. However, the mustard aphid (Lipaphis erysimi Kalt.) reduces its yield and oil content to the extent of 9-96% and 5-6%, respectively. In this study, we investigated synthesis of silver nanoparticles from the entomopathogenic fungus Beauveria bassiana and its impact against mustard aphid. Bioefficacy of 25 isolates of B. bassiana was evaluated against mustard aphid. Based on the percent mortality of the mustard aphid, the isolates were categorized into two groups: Group I (0-50%; 20 isolates) and Group II (51-100%; 5 isolates). Maximum percent mortality was observed in B4 and B13 isolates with 90 and 64%, respectively. All these isolates were screened for production of silver nanoparticles (AgNPs) by a simple eco-friendly method, using cell filtrate. In the UV-VIS spectra, the highest Plasmon band was observed at 420 nm at every 24 h which reached the maximum intensity at 120 h (0.745). Maximum silver nanoparticles production was observed in B4 and B13 isolates. Even though there was significant mortality of mustard aphid L. erysimi by the synthesized nanosilver particles of all the 25 isolates, the isolates B4 and B13 showed the maximum mortality (60.088%). AgNPs from B4 and B13 isolates were further characterized using Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD). Nanoparticles of 3-25 run size were found in both the isolates. This study, possibly the first report, on the synthesis of silver nanoparticles using entomopathogenic fungus B. bassiana and its efficacy against mustard aphid (L. erysimi) suggests the potential use of silver nanoparticles for insect management in agriculture.