The impact of sublethal permethrin exposure on susceptible and resistant genotypes of the urban disease vector Aedes aegypti

Abstract

BACKGROUND: In urban environments, some of the most common control tools used against the mosquito disease vector Aedes aegypti are pyrethroid insecticides applied as aerosols, fogs or residual sprays. Their efficacy is compromised by patchy deployment, aging residues, and the evolution and invasion of pyrethroid-resistant mosquitoes. A large proportion of mosquitoes in a given environment will therefore receive sublethal doses of insecticide. The potential impact of this sublethal exposure on the behaviour and biology of Ae. aegypti carrying commonly reported resistance alleles is poorly documented. RESULTS: In susceptible insects, sublethal exposure to permethrin resulted in reductions in egg viability (13.9%), blood avidity (16.7%) and male mating success (28.3%). It caused a 70% decrease in the lifespan of exposed susceptible females and a 66% decrease in the insecticide-resistant females from the parental strain. Exposure to the same dose of insecticide in the presence of the isolated kdr genotype resulted in a smaller impact on female longevity (a 58% decrease) but a 26% increase in eggs per female and a 37% increase in male mating success. Sublethal permethrin exposure reduced host-location success by 20-30% in all strains. CONCLUSION:The detrimental effects of exposure on susceptible insects were expected, but resistant insects demonstrated a less predictable range of responses, including negative effects on longevity and host-location but increases in fecundity and mating competitiveness. Overall, sublethal insecticide exposure is expected to increase the competitiveness of resistant phenotypes, acting as a selection pressure for the evolution of permethrin resistance.

Sublethal exposure to spinetoram impacts life history traits and dengue virus replication in Aedes aegypti

“…, 2021), whereas the sublethal effects of insecticides have been neglected for a long time (Rigby et al. , 2021). This study links the traditional sublethal effects of insecticides with the impact on viral replication in the primary vector Ae.…”

“…, 2019; Rigby et al. , 2021). However, most studies on the sublethal effects of insecticides focused on few life history traits of mosquito vectors and only limited studies examined the sublethal effect of insecticides on mosquito susceptibility to arboviruses (Alto et al.…”

“…Thus, this has raised concern that mosquito vectors can be exposed to sublethal levels of insecticides in different ways (Rigby et al. , 2021); for instance, several studies have shown that mosquito larvae in aquatic habitats are frequently subject to the sublethal exposure of insecticides in nature (Muturi et al. , 2010; Russo et al.…”

“…Moreover, the insecticide concentrations that mosquitoes are exposed to can vary greatly in actual field conditions depending on the application technique and frequency, local environment, and time after the initial (i.e., lethal) application (Guedes et al, 2017). Thus, this has raised concern that mosquito vectors can be exposed to sublethal levels of insecticides in different ways (Rigby et al, 2021); for instance, several studies have shown that mosquito larvae in aquatic habitats are frequently subject to the sublethal exposure of insecticides in nature (Muturi et al, 2010;Russo et al, 2018). However, to date, most researchers focus only on the lethal effects of insecticides in mosquito vectors with a limited investigation of the sublethal impact of insecticides despite their potential to influence interactions between mosquito vectors and pathogens (Guedes et al, 2017;Rigby et al, 2021).…”

“…Several different studies show that sublethal exposure to different insecticides (pyrethroids, permethrin, spinosad, etc.) can significantly reduce the fecundity of Aedes aegypti (Fernandes et al, 2019;Rigby et al, 2021). However, most studies on the sublethal effects of insecticides focused on few life history traits of mosquito vectors and only limited studies examined the sublethal effect of insecticides on mosquito susceptibility to arboviruses (Alto et al, 2008;Muturi et al, 2011b;Moltini-Conclois et al, 2018).…”