Efficacy and Toxicity of 20 Commercial Aerosol Insecticide Brands to Anopheles gambiae Mosquitoes in Lagos State.

Abstract

Aim: This study was conducted with a focus on assessing the susceptibility of the Anopheles gambiae mosquitoes in Lagos state to twenty commercial aerosol insecticides brands.
Study design: An entomological survey and a conventional bioassay.
Place and Duration of Study: The study was carried out between May and December 2025 in the Department of Zoology and Environmental Biology, Lagos State University, Nigeria.
Methodology: Entomological surveys were conducted in the urban and rural areas of Lagos state using 105 structured questionnaire to understand the public opinion on the use of aerosol insecticides in controlling mosquitoes. The efficacy of the twenty aerosol insecticides was assessed using a conventional bioassay on adult Anopheles gambiae by exposing twenty adult Anopheles mosquitoes to 0.5ml of each of the insecticides; after the bioassay, Probit 1.5 software was used to determine the lethal concentrations of the insecticides that can knockdown and bring about mortality of 50% and 99% of exposed insects.
Results: Findings revealed that about 96.19% residents of Lagos State prefer aerosol insecticides to other forms of vector control; while 3.81% do not use aerosol at all. The study further revealed that all aerosol insecticides marketed in Lagos State contained pyrethroids as the active ingredient, and Anopheles gambiae populations in the State remained susceptible to them, though toxicity levels varied. The most toxic was found to be Specimen A while the least toxic is V. All twenty test aerosol insecticides were able to cause 100% mortality in twenty exposed Anopheles gambiae mosquitoes after 60 minutes exposure period.
Conclusion: The study discovered that aerosol insecticides are both the first choice of Lagos State residents and is equally effective at controlling Anopheles gambiae mosquitoes. It is therefore suggested that pyrethrum based aerosol insecticides should be used in place of other toxic chemical insecticides; while putting into consideration safety precautions during and after use.