สถาบันวิจัยวิทยาศาสตร์สาธารณสุข

National Institute of Health of Thailand

Development of Bti-formulated products and efficacy tests against Aedes aegypti populations

Authors : Kriangkrai Lerdthusnee*, Vichai Ngam-sak**, Prakong Phan-Urai**, Theeraphap Chareonviriyaphap***

 

Affiliations:        *National Center for Genetic Engineering & Biotechnology (BIOTEC),
                         National Science & Technology Development Agency, Rama VI rd
                        Bangkok;
                        **Division of Medical Entomology, Department of Medical Sciences,
                        Ministry of Public Health, Nonthaburi
***Faculty of Liberal Art and Science, Kasetsart University,
Kamphaensean Campus, Thailand
           
Source:            Biopesticides: Toxicity, Safety, Development and Proper Use
Proceedings of the First International Symposium on Biopesticides 1996,
Naresuan University phitsanulok, Thailand
           
Language:       English
 
Abstract:
 
Several Bacillus thuringiensis israelensis (Bti)-formulated products (i.e, sand granules, paper strips and tablets) were developed in order to improve its potency and efficiency in reducing Aedes aegypti larvae. A 1-g tablet, with potency of 500 ITU/mg, demonstrated the best performance among other Bti-formulated products produced in this study. Results from efficacy tests of this product revealed that the tablet was highly toxic to Ae. Aegypti, followed by Culex and Anopheles larvae. Observations on the efficacy of Bti-formulated tablets in the 160-1 water containers showed that the tablets are effective against Ae. Aegypti larvae for as long as 3 mo without changing the water by refilling and removing and about 2 mo in water containers with daily removal/refill of 20% water in volume. In addition to additives of Bti-formulated products, another ingredient, the grounded powder developed from cadavers of mosquito larvae (which were fed on Bti-pure powder) was tested for its efficacy against Ae. Aegypti larvae. Results from the bioassay of such powder demonstrated that there was an adequate amount of toxin retained in the mosquito cadavers, and this can be used as an addition ingredient.