Dipanwita  D.¹ , Siddharthasankar B.^1,2 , Anushree S.R.¹ , Soumendranath C.^1,3 , Goutam C.¹

1 Mosquito, Microbiology and Nanotechnology Research Units, Department of Zoology, The University of Burdwan, Burdwan-713104, West Bengal, India
2 Department of Zoology, Netaji Mahavidyalaya, Arambagh, Hooghly-712601, India
3 Parasitology and Microbiology Research Laboratory, Department of Zoology, The University of Burdwan, Burdwan-713104, West Bengal, India
Author    Correspondence author
Molecular Entomology, 2017, Vol. 8, No. 2   doi: 10.5376/me.2017.08.0002
Received: 22 Jun., 2016    Accepted: 03 Aug., 2016    Published: 26 Jan., 2017

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Dipanwita D., Siddharthasankar B., Anushree S.R., Soumendranath C., and Goutam C., 2017, Characterization of a strain of Bacillus sphaericus isolated from local rice field and its virulence against mosquito larvae, Molecular Entomology, 8(2): 1-9 (doi: 10.5376/me.2017.08.0002)

Objective: Classical chemical control to mosquito is a preferable method. But it faces a problem for its increasing resistance against mosquito. To regulate the vector population as an alternative method, non-hazardous biocontrol methods would be the preeminent option to control mosquitoes. Objective of the present study is to examine the virulence of Bacillus sphaericus as an effective biocontrol agent against mosquitoes.Method: A strain of the bacteria Bacillus sphaericus was isolated from the gut of dead Culex quinquefasciatus Say, 1823 (Diptera: Culicidae) larva collected from submerged rice fields, Burdwan, West Bengal, India. The strain was characterized following standard methodologies.Result: The bacterial strain formed crystals, tolerated 4% NaCl, produced protease and sensitive to different known antibiotics. An aqueous preparation of the bacteria revealed that 10ml/L (6.8x10⁶ bacteria/ml) Bs formulation (bacterial broth) killed 100% larvae of Cx. quinquefasciatus, Anopheles subpictus, Armigeres subalbatus within 6 hours of exposure. Field tests showed that by the end of seventh day of application a total reduction of Cx. quinquefasciatus was achieved and 87% and 64% reduction of An. subpictus and Ar. subalbatus immatures were observed respectively. No larval emergence was observed up to tenth day in case of Cx. quinquefasciatus. The results indicate that the isolated strain of B. sphaericus can be a potential larvicide to regulate mosquito populations.Conclusion: Further tests need to be carried out to justify its use against different other mosquito species and insects.

Bacillus sphaericus; Anopheles subpictus; Armigeres subalbatus; Culex quinquefasciatus; Mosquito larvae; Biological control