Mosquito age and susceptibility to insecticides

Area of Science:

• Medical Entomology
• Molecular Entomology
• Public Health Entomology

Background:

• Insecticides are vital for controlling mosquito-borne diseases.
• Insecticide resistance in mosquitoes poses a significant threat to public health.
• Current World Health Organization (WHO) guidelines for monitoring insecticide resistance use young, non-blood-fed female mosquitoes.

Purpose of the Study:

• To investigate the impact of mosquito age and blood feeding on insecticide-induced mortality.
• To determine if age-related declines in insecticide resistance are a widespread phenomenon.
• To assess the implications of age-dependent resistance for disease vector control strategies.

Main Methods:

• Tested insecticide-induced mortality in six mosquito populations (Aedes aegypti and Anopheles gambiae) across different age groups.
• Analyzed age-dependent changes in the expression of the GSTe2 detoxification gene.
• Investigated the frequency of the kdr 1014F target-site mutation in relation to age.

Main Results:

• Older mosquitoes exhibited higher mortality rates following insecticide exposure in three Aedes aegypti and two Anopheles gambiae populations.
• Significant age-dependent variations were observed in the expression of GSTe2 and the frequency of the kdr 1014F mutation.
• Findings suggest that insecticide resistance may decrease with mosquito age.

Conclusions:

• Mosquito age is a critical factor influencing insecticide efficacy and resistance.
• Current WHO monitoring guidelines may overestimate insecticide resistance levels.
• Further research is needed to refine vector control strategies based on age-dependent insecticide responses.