Bioassay on Toxicity of Plant Extracts against Aphis craccivora Koch (Hemiptera: Aphididae) in French Bean (Phaseolus vulgaris L.)

The present experimental study was conducted under laboratory conditions in the department of Entomology, School of Agricultural Sciences and Rural Development, Nagaland University, Medziphema Campus during 2017 to 2018. For bioassay on the toxicity of plant extract on Aphids (Aphis craccivora Koch) in French beans, five botanicals were used namely, Neem (Azadirachta indica), Datura (Datura stramonium), Lantana (Lantana camara), Nigeria Eucalyptus (Eucalyptus globules) and Citronella (Cymbopogon winterianus) with one chemical i.e. Dimethoate 30 EC and control. The laboratory bioassay was done using dipping method and the LC 50 values were calculated using Probit analysis. The results from the Probit analysis at 24, 48 and 72 hours showed that the standard check Dimethoate 30 EC was the most toxic @ 0.01%. For botanicals, L. camara and A. indica extract @ 3% concentration, reported the highest mortality followed by D. stramonium extract @ 4%. In comparision E. globules and C. winterianus @ 5% reported the lowest mortality. Based on the study the order of toxicity of plant products based on Probit analysis are A. indica > L. camera > D. stramonium > C. winterianus > E. globules.