In vivo and in vitro toxicities of pithraj and neem against rice green leafhopper (Nephotettix cincticeps Uhler)

Seed extracts of Aphanamixis polystachya Wall et Parker (pithraj) and Azadirachta indica A. Juss (neem) were evaluated for their in vivo and in vitro toxicity to Nephotettix cincticeps Uhler (rice green leafhopper). Crude extracts from both plants showed toxicity to leafhopper. Among them, the methanol extract of pithraj (MCX) was most toxic and showed 95% mortality effects at 72 h after treatment (HAT), followed by neem (74%). When LD50's were compared, it was found that the neem extract possessed the highest toxicity (LD50 16.59 μg/insect) at 72 HAT. Both the pithraj (MCX) and neem extracts showed their enzyme inhibition effectiveness against rice green leafhopper. The highest inhibition rate (IR) was caused by neem (60%) at the concentration of 2.0 mg/ml, followed by MCX (47%). The lowest IR50 value (0.97 mg/ml) was observed in neem at 30 min.