A preliminary analysis on the effect of copper on Anopheles coluzzii insecticide resistance in vegetable farms in Benin

Abstract

The use of agrochemicals in vegetable production could influence the selection for insecticide resistance in malaria vectors. Unfortunately, there is a dearth of information on the potential contribution of agrochemicals to insecticide resistance in Anopheles mosquitoes breeding on vegetable farms in southern Benin. A Knowledge, Attitudes and Practices study was conducted with 75 vegetable farmers from Houeyiho and Seme to determine the main agrochemicals used in vegetable production, and the concentration and frequency of application, among other details. Mosquitoes and breeding water were sampled from the farms for analysis. Bioassays were conducted on mosquitoes, while breeding water was screened for heavy metal and pesticide residue contamination. Lambda-cyhalothrin was the main insecticide (97.5%) used by farmers, and Anopheles coluzzii was the main mosquito identified. This mosquito species was resistant (30-63% mortality rate) to λ-cyhalothrin. It was also observed that 16.7% of the examined breeding sites were contaminated with λ-cyhalothrin residues. Furthermore, copper contamination detected in mosquito breeding sites showed a positive correlation (r = 0.81; p = 0.0017) with mosquito resistance to λ-cyhalothrin. The presence of copper in λ-cyhalothrinfree breeding sites, where mosquitoes have developed resistance to λ-cyhalothrin, suggests the involvement of copper in the insecticide resistance of malaria vectors; this, however, needs further investigation.

Pyrethroid Resistance Situation across Different Eco-Epidemiological Settings in Cameroon

“…The resistance profile detected during the present study, was in accordance with studies conducted so far across the country, suggesting rapid expansion of insecticide resistance in vector populations [ 5 , 7 , 35 ]. Similar evolution of pyrethroid resistance patterns have been reported across Africa [ 6 , 18 , 25 ]. The high pyrethroid resistance profile detected in vector populations could result from the prevailing insecticide selective pressure on mosquitoes following regular scaling up since 2010 of pyrethroid-treated nets across the country.…”

“…It is possible that the increasing use of LLINs may have contributed to increase insecticide selective pressure on mosquito populations. Moreover, the uncontrolled use of pesticides in agriculture is also considered to contribute to vector resistance to pyrethroids [ 5 , 6 , 7 ].…”

Colonization and Authentication of the Pyrethroid-Resistant Anopheles gambiae s.s. Muleba-Kis Strain; an Important Test System for Laboratory Screening of New Insecticides

“…Third, by exerting the selection pressure to the aquatic stage of the mosquitoes, there is assurance for successive selection as it is impossible for larvae to survive subsequent selections but only through developing resistance [67]. Additionally, many reports have associated larvae exposure to trace amounts of pesticides with the development of insecticide resistance in malaria vectors [68][69][70][71].…”

Indoor and outdoor malaria transmission in two ecological settings in rural Mali: Implications for vector control

“…In Dangassa, the peak in the dry season could be explained by the availability of productive larval sites created in the river bed of River Niger when water recedes as reported by many studies across Africa [32,34,39,40]. In Koïla Bamanan the dry season peak could be explained by vegetable cropping which creates suitable water puddles for larval development [41] .…”