The effects of temephos, permethrin and malathion selection on the fitness and fecundity of Aedes aegypti

K Gleave,L J Reimer,F Mechan

doi:10.1111/mve.12551

K Gleave, L J Reimer + Show 1 more

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https://doi.org/10.1111/mve.12551

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Abstract

The recent scale-up of insecticide use has led to the rapid spread of insecticide resistance (IR) in mosquito populations across the world. Previous work has suggested that IR mechanisms could influence mosquito life-history traits, leading to alterations in fitness and key physiological functions. This study investigates to what extent mosquito fitness may be affected in a colony of Aedes aegypti after selection with temephos, permethrin or malathion insecticides. We measured immature development, sex ratio, adult longevity, energetic reserves under different rearing conditions and time points, ingested bloodmeal volume, mosquito size, male and female reproductive fitness and flight capability in the unexposed offspring of the three selected strains and unselected strain. We found that insecticide selection does have an impact on mosquito fitness traits in both male and female mosquitoes, with our temephos-exposed strain showing the highest immature development rates, improved adult survival, larger females under crowded rearing and increased sperm number in males. In contrast, this strain showed the poorest reproductive success, demonstrating that insecticide selection leads to trade-offs in life-history traits, which have the potential to either enhance or limit disease transmission potential.

Highlights

Insecticide resistance (IR) in disease vectors is at a crucial tipping point
Within the major arbovirus vector Aedes aegypti, resistance has evolved to the four insecticide classes most commonly used for public health (Ranson et al, 2010; Moyes et al, 2017), with resistance to both larval and adult insecticides well documented in field populations (Montella et al, 2007)
Our study aimed to investigate the fitness costs associated with IR by measuring energetic reserves, development, longevity, reproduction and flight in four strains of A. aegypti with different histories of insecticide exposure

Summary

Introduction

Insecticide resistance (IR) in disease vectors is at a crucial tipping point. The recent scale-up of insecticide-based vector control has protected hundreds of millions of people from disease exposure (Bhatt et al, 2016), but has resulted in the emergence and rapid spread of IR mechanisms across the world (Vontas et al, 2012; Ranson & Lissenden 2016; WHO 2018). Within the major arbovirus vector Aedes aegypti, resistance has evolved to the four insecticide classes most commonly used for public health (Ranson et al, 2010; Moyes et al, 2017), with resistance to both larval and adult insecticides well documented in field populations (Montella et al, 2007). This has led to a reduction in the efficacy of current insecticide-based control strategies (Moyes et al, 2017). Removing insecticide pressures from an environment results in lower frequencies of resistant alleles in mosquito populations, suggesting there is a fitness cost to maintaining these alleles in the absence of insecticide (Coustau et al, 2000; David et al, 2018)

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