Abstract
A slow release, solid formulation of Bacillus thuringiensis israelensis (Bti)-Mosquito Dunks® was evaluated for its effectiveness in controlling of dengue vectors in Sri Lanka. A small-scale simulation field study showed a high effectiveness of 98–100% mortality at 15 days post-treatment and the mortality rate started to drop down by 30 days post-treatment. The larval density in the large-scale field study showed a progressive drop during the post-treatment period achieving the highest by 30 days (62.5%) and a subsequent increase by 45 days post-treatment, while in the control area showed a continuous increase. Reduction in the mean number of positive breeding places per house among sampling bouts was highly significant (p = 0.016). In the control area, oviposition activity showed a marked reduction 15 days post-treatment (71.4% Ovi-trap index, 82.3% Egg density index) after an initial increase at 8 days post-treatment. Mean number of eggs per trap showed a highly significant difference among the sampling bouts in the test area. Public acceptance of the product was very high (93.3%). A single selective application of the Bti-Mosquito Dunks® when used at recommended dosage is effective in controlling population densities of vectors of dengue approximately up to 30 days.
Acknowledgements
Dr. Amal Harsha De Silva, the Provincial Director of Health Services/Western Province, Sri Lanka, Entomological Assistants/Western Province, Sri Lanka and the supportive communities at two study areas are acknowledged. This is a research report only and specific mention of the product does not imply endorsement by the authors.
Disclosure statement
The authors declare no conflict of interest.