Susceptibility of Aedes albopictus (Diptera: Culicidae) from Southern Thailand Livestock Farms to Household Larvicides and Adulticides

Abstract

Background:

Aedes albopictus (Skuse) is a major mosquito vector in Southeast Asia, especially in livestock farm environments. This study evaluated the susceptibility of laboratory and field-collected (Songkhla Province) Ae. albopictus to commercial insecticides.

Methods:

Laboratory colony and field population were tested against temephos larvicides, mosquito coils, and aerosol sprays following WHO protocols. Larvicidal efficacy and persistence were assessed in semifield conditions, while adult knockdown and mortality were measured in controlled assays.

Results:

Both laboratory colony and field population exhibited high initial susceptibility to temephos (97.5–100% mortality), but residual efficacy declined rapidly, reaching 0–27% by 30 days. All adulticides achieved 100% mortality. Knockdown times (KT₅₀) ranged 0.58–2.52 min for mosquito coils and 1.09–2.29 min for aerosol sprays. The coil containing 0.03% metofluthrin showed the fastest knockdown (KT₅₀ = 0.58 min laboratory, 1.37 min field).

Conclusions:

Commercial insecticides remain effective against Ae. albopictus in livestock farm settings. However, rapid temephos degradation highlights the need for more frequent larvicide applications or the use of persistent formulations. Integrated approaches combining chemical and nonchemical interventions are recommended to optimize vector control and delay resistance development.