Effectiveness and public acceptance of a slow release formulation of Bacillus thuringiensis israelensis (Mosquito Dunks^®) in controlling the population density of dengue vectors in Sri Lanka

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.

Keywords:

• Aedes albopictus
• Breteau index
• oviposition activity
• dengue fever
• mosquito control

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.