Comparative efficacy of nanoscale inert dusts against pulse beetle, Callosobruchus maculatus at different ambient humidity levels

Nanoscale silica, alumina and clay were evaluated for their toxicity to the pulse beetle, Callosobruchus maculatus under low (32%), mid (52%) and high (75%) ambient humidity levels. Nanosilica at 250 ppm showed complete mortality of pulse beetle and was found to be superior to the standard check, diatomaceous earth at 1000 ppm. The efficacy of nanoalumina @ 250 ppm was at par with that of the check and nanoclay was ineffective in providing a complete mortality even at 15 DAT at all the doses tried. The influence of ambient humidity on the efficacy of nanoparticles was found to be very significant and an increase in the RH levels caused a marked reduction in the efficacy of treatments. The result showed that nanosilica could be used as a promising alternative to the diatomaceous earth as a grain protectant in pest management programs of C. maculatus.