Vol. 8, Issue 1, Part A (2021)

Author(s): Dr. Milagros M Greif

Abstract: A new application technique for the control of mosquito larvae under tropical conditions was conducted in Cebu City, Philippines. The study used silica granules to evaluate a totally new technique to embed, store, and release the endotoxins of microbial agents. A bacterium, Bacillus thuringiensis israelensis was embedded in silica granules. It further assessed the efficacy of the embedded bacterium in silica granules (product) under laboratory and field conditions. Six concentrations were prepared. Each of the concentration was tested with 25 3^rd instar larvae of Aedes aegypti. Results show that in laboratory test, LC₅₀, LC₉₀ and LC₉₉ of 0.593, 2.226 and 6.543 granules are needed to eliminate 50%, 90% and 99%, respectively of the mosquitoes exposed to the product. Moreover, the number of granules continues to increase until the 16th day after treatment except for the LC₉₀ and LC₉₉ that it subsides during the 16th day. Field test shows LC₅₀, LC₉₀ and LC₉₉ of 0.290, 2.640 and 15.975 granules which are needed to terminate 50%, 90% and 99% of mosquito larvae. The product is proven to kill the larvae of mosquito with mortality rate that varies in relation to the number of granules applied and to the number of days the granules present in the water. Further, it is proven to be environmental friendly, less expensive, easy to produce and apply.