A novel mosquitocidal Bacillus thuringiensis strain LLP29 isolated from the phylloplane of Magnolia denudata

SummaryEleven Bacillus thuringiensis isolates were recovered from phylloplanes of Magnolia denudata, a specific source of new strains of B. thuringiensis. Among these, a new strain, LLP29, was found to be most toxic to mosquitoes based on the results of preliminary toxicity analysis. Phase contrast microscopy, mosquitocidal activity, polymerase chain reaction (PCR) analysis and parasporal inclusion were performed to learn more about the characteristics of this novel mosquitocidal isolate. The LC50 values of LLP29 against Aedes albopictus and Culex quinquefasciatus were 0.33 and 0.04 ng of protein/ml, respectively. The cyt1 gene, which encodes the Cyt protein that is toxic to mosquitoes, was subsequently detected, cloned, sequenced and expressed in acrystalliferous Bt HD73 Cry−. The results indicated that it might be a member of the cyt1Aa gene group. The novel strain LLP29 appears to be a new subspecies of B. thuringiensis and should prove useful in the control of mosquitoes and mosquito-borne diseases.