_____________________________________________________________________________________________________ *Corresponding author: Email: stephensonlawson@yahoo.com; South Asian Journal of Research in Microbiology 10(2): 17-21, 2021; Article no.SAJRM.70886 ISSN: 2582-1989 Isolation and Use of Bacillus thuringiensis for the Production of Bio-Insecticide in Control of Mosquito Larvae A. A. Ibiene 1 , S. D. Lawson 2* , S. O. Enyinnaya 2 , F. E. Amos 1 , L. Nnodim 3 and G. A. Uzah 1 1 Department of Microbiology, Faculty of Sciences, University of Port Harcourt, Port Harcourt, Rivers State, Nigeria. 2 Department of Medical Microbiology and Parasitology, Faculty of Basic Clinical Sciences, College of Medical Sciences, Rivers State University, Port Harcourt, Rivers State, Nigeria. 3 Department of Microbiology, Faculty of Sciences, Rivers State University, Port Harcourt, Rivers State, Nigeria. Authors’ contributions This work was carried out in collaboration among all authors. All authors read and approved the final manuscript. Article Information DOI: 10.9734/SAJRM/2021/v10i230225 Editor(s): (1) Dr. Chamari Hettiarachchi, University of Colombo, Sri Lanka. Reviewers: (1) Dan Răzvan Popoviciu, “Ovidius” University, Romania. (2) Poornachandra Rao K, University of Mysore, India. Complete Peer review History: https://www.sdiarticle4.com/review-history/70886 Received 26 May 2021 Accepted 02 August 2021 Published 04 August 2021 ABSTRACT Bacillus thuringiensis is a widely studied bacterium and it is known for its use in pest management. It is selectively active on pests and less likely to cause resistance; hence it is considered a suitable replacement to chemical pesticides. The study assessed the potential of Bacillus thuringiensis in controlling mosquito larvae. Bacillus thuringiensis isolates selected were tested against secondary stage larvae of mosquito. Thirty-six larvae (6 each) were transferred into each test tubes (7 x 9) cm with 30ml sterile distilled water. The stock suspension of cultures of Bacillus thuringiensis in broth was diluted to 10 7 , 10 6 , 10 5 , 10 4 , 10 3 and 10 2 in sterile water, following the McFarland standard method for microbial load count. The test tubes were kept at room temperature, larval mortality was observed over time within 24hrs. The results showed that all mosquito larvae died at the 10 7 and 10 6 dilutions but at dilutions 10 5 , 10 4 and 10 3 though affecting mosquito larvae, it was highly Original Research Article