Studies on different aspects of efficacy of some commercial microbial pesticides against Diacrisia obliqua on jute

The laboratory investigation was carried out on 2^nd instar larvae of Diacrisia obliqua with two commercial microbial pesticides viz., Btk 55000 SU/mg and avermectin 1.8% w/v separately and in combination with different synthetic insecticides. Among the microbials avermectio @ 0.0018% and Btk @ 0.2% provided 100 and 80% mortality after 48 h of treatment respectively. However, at 96 h after treatment Btk@ 0.2% gave the highest mortality of 93.33% being significantly superior to all other treatments except endosulfan @ 0.052%, monocrotophos 0.04%, acetamiprid 0.002%, dichlorvos @ 0.057% and avermectin 0.0018%. Thus, both the microbial pesticides Btk and avermectin are effective in control of the pest. The best result in the joint effect with different insecticides revealed that Btk (0.1%) with endosulfan (0.026%) mixture, Btk (0.1%) and acetamlprid (0.001%) mixture provided 100% initial larval mortality. Whereas avermectin In combination with the synthetic insecticides provided initial 100% larval mortality in all the treatments except cartap hydrochloride combination.