Comparison of the control effect of mosquito densovirus and Bacillus thuringiensis oil suspension and commonly used mosquito larvicides on mosquito larvae
Objective To evaluate the control efficacy of mosquito densovirus and Bacillus thuringiensis subsp.israelensis(MDV·Bti)oil suspension against the larvae of Culex pipiens pallens and Aedes albopictus under laboratory conditions,providing references for the selection of mosquito larvicidal agents.Methods Thirty larvae of mosquito were placed in enamel pots containing different types of larvicide using the larval dipping method in the laboratory,and the mortality time,pupation,and emergence of the larvae were observed and recorded.The median lethal time(LT50)and 95%confidence interval(CI),along with the toxicity regression equations,were calculated using SPSS 18.0 software for statistical analysis.Results The LT50 of MDV·Bti oil suspension,temephos,and Bacillus sphaericus(Bs)for the early-instar larvae of Culex pipiens pallens were 85.7,73.2,and 109.8 minutes,respectively,and for the late-instar larvae of Culex pipiens pallens were 82.8,71.6,and 128.2 minutes,respectively.The times required for a 100%mortality rate of early-stage larvae of Culex pipiens pallens by MDV·Bti oil suspension,temephos,and Bs were 260,160,and 200 minutes,respectively,and for the late-instar larvae were 240,140,and 300 minutes,respectively.The 24-h mortality rate of both early-instar and late-instar larvae of Culex pipiens pallens by Bti was 0%.The times required for 100%mortality of late-instar larvae of Aedes albopictus by new larvicide 1,2,and 3 were 280,260,and 180 minutes,respectively,with LT50 values of 95.8,68.8,and 54.3 minutes,respectively.The 24-hour mortality rate for Aedes albopictus larvae by temephos and Bti was 100%,with LT50 values of 222.0 and 272.5 minutes,respectively.Conclusions MDV·Bti oil suspension demonstrates a good control effect against the larvae of Culex pipiens pallens and Aedes albopictus under laboratory conditions.Compared with the commonly used larvicides,MDV·Bti oil suspension presents advantages in controlling efficacy,suitable for mosquito larvae control.
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