Abstract
The use of long lasting insecticide nets (LLINs) treated with pyrethroïd is known for its major contribution in malaria control. However, LLINs are suspected to induce behavioral changes in malaria vectors, which may in turn drastically affect their efficacy against Plasmodium sp. transmission. In sub Saharan Africa, where malaria imposes the heaviest burden, the main malaria vectors are widely resistant to pyrethroïds, the insecticide family used on LLINs, which also threatens LLIN efficiency. There is therefore a crucial need for deciphering how insecticide-impregnated materials might affect the host-seeking behavior of malaria vectors in regards to insecticide resistance. In this study, we explored the impact of permethrin-impregnated net on the host attractiveness for Anopheles gambiae mosquitoes, either susceptible to insecticides, or carrying the insecticide resistance conferring allele kdr. Groups of female mosquitoes were released in a dual-choice olfactometer and their movements towards an attractive odor source (a rabbit) protected by insecticide-treated (ITN) or untreated nets (UTN) were monitored. Kdr homozygous mosquitoes, resistant to insecticides, were more attracted by a host behind an ITN than an UTN, while the presence of insecticide on the net did not affect the choice of susceptible mosquitoes. These results suggest that permethrin-impregnated net is detectable by malaria vectors and that the kdr mutation impacts their response to a LLIN protected host. We discuss the implication of these results for malaria vector control.
Highlights
Anopheles gambiae is one of the major mosquito vectors of human malaria parasites in subSaharan Africa
Four insecticide families are available for indoor residual spraying (IRS), whereas only pyrethroïds are recommended for mosquito nets because of their low mammalian toxicity and high insecticidal potency [5]
We examined the long-range host-seeking behavior of An. gambiae mosquitoes to determine whether the attractiveness of a vertebrate host in a dual-choice olfactometer was influenced by physical and/or chemical barriers and by the mosquito kdr (L1014F) genotype
Summary
Anopheles gambiae is one of the major mosquito vectors of human malaria parasites in subSaharan Africa. An. gambiae prefers to bite humans indoors and often rests inside houses after blood feeding [2,3,4]. These behavioral preferences led to the development of insecticide-. Anopheles gambiae behavior based indoor vector control measures, such as insecticide-treated bed nets (ITNs) and indoor residual spraying (IRS), to limit the human-vector contacts and reduce mosquito survival. Four insecticide families are available for IRS (organochlorides, organophosphates, carbamates and pyrethroïds), whereas only pyrethroïds are recommended for mosquito nets because of their low mammalian toxicity and high insecticidal potency [5]
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