The effectiveness of mosquito coils containing esbiothrin under laboratory and field conditions

Tests were made to correlate the chemical content of mosquito coils with the knockdown and bite-inhibitory action of the smoke in the laboratory and with the protective effect in field use. Smoke from a blank coil, containing no pyrethroid, gave no knockdown, 10% inhibition of biting in the laboratory using Aedes aegypti, and 39% protection in field tests in village huts on the Kenyan coast with a mixed population of mosquitoes including 71% Anopheles gambiae. Coils containing low experimental contents of 0.044% and 0.099% Esbiothrin, an isomer blend rich in the D-allethrolone ester of D-trans-chrysanthemic acid, gave rapid knockdown in both small chamber and 25 m3 room tests, and 71% and 94% inhibition of biting respectively in the laboratory. In the field they gave 74% and 84% protection from mosquitoes alighting. Chemical content was therefore a good guide to knockdown and bite inhibition in the laboratory and also to the considerable protection found in the field.