Synergistic Effect of Bacillus thuringiensis subsp. aizawai with Synthetic Pyrethroids against Insecticide Resistant Helicoverpa armigera (Hubner)

Studies were carried out to find the effects of joint action between Bacillus thuringiensis subsp. aizawai (Bta) (Agree ) and synthetic pyrethroids against third instar larvae of H. armigera on different hosts. The joint action of Bta+pyrethroids at LC25+LC25 revealed supplemental synergism as the combined application on different hosts showed 4.75-21.72 and 18.36-38.26% more than the expected mortality at LC50 of Bta alone and LC50 of pyrethroids alone, respectively.