Insecticidal efficacy of green synthesized silver nanoparticles, Bacillus thuringiensis and Triazophos against Pectinophora gossypiella

Pink bollworm (Pectinophora gossypiella) poses a significant threat to cotton crops worldwide, resulting in economic losses surpassing sustainable levels for farmers since 2011. This study examines different approaches to controlling pink bollworm infestations, specifically silver nanoparticles (AgNPs), bio-formulations of Bacillus thuringiensis (Bt), and a commercial insecticide (Triazophos), in both laboratory and field environments. AgNPs were synthesized using neem plant leaf extract (Azadirachta indica). The formation of AgNPs was confirmed through UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and a zeta sizer analyzer. In the laboratory, the effectiveness of individual and combined applications of AgNPs, Bt, and Triazophos was tested against 2nd and 4th instar pink bollworm larvae. Mortality rates were measured at 1, 2, and 5 days after application. The results showed that the treatment combining AgNPs and Triazophos (40ppm + 50ppm) achieved a larval mortality rate of over 90%, surpassing the other treatments. In field conditions, the combination of Triazophos and AgNPs at 40ppm (100ml + 50ml) proved most effective in managing P. gossypiella populations. These findings underscore the potential of nanoparticles as efficient larvicidal agents for controlling P. gossypiella. Furthermore, they emphasize the importance of reevaluating past management strategies for cotton crops given emerging alternatives to traditional insecticides. Future research directions may involve further optimizing nanoparticle formulations and investigating their broader ecological impacts on cotton ecosystems.