Natural plant diet impacts phenotypic expression of pyrethroid resistance in Anopheles mosquitoes

Abstract

Success in reducing malaria transmission through vector control is threatened by insecticide resistance in mosquitoes. Although the proximal molecular mechanisms and genetic determinants involved are well documented, little is known about the influence of the environment on mosquito resistance to insecticides. The aim of this study was to assess the effect of plant sugar feeding on the response of Anopheles gambiae sensu lato to insecticides. Adults were fed with one of four treatments, namely a 5% glucose control solution, nectariferous flowers of Barleria lupulina, of Cascabela thevetia and a combination of both B. lupulina + C. thevetia. WHO tube tests were performed with 0.05% and 0.5% deltamethrin, and knockdown rate (KD) and the 24 h mosquito mortality were measured. Plant diet significantly influenced mosquito KD rate at both concentrations of deltamethrin. Following exposure to 0.05% deltamethrin, the B. lupulina diet induced a 2.5 fold-increase in mosquito mortality compared to 5% glucose. Species molecular identification confirmed the predominance of An. gambiae (60% of the samples) over An. coluzzii and An. arabiensis in our study area. The kdr mutation L1014F displayed an allelic frequency of 0.75 and was positively associated with increased phenotypic resistance to deltamethrin. Plant diet, particularly B. lupulina, increased the susceptibility of mosquitoes to insecticides. The finding that B. lupulina-fed control individuals (i.e. not exposed to deltamethrin) also displayed increased 24 h mortality suggests that plant-mediated effects may be driven by a direct effect of plant diet on mosquito survival rather than indirect effects through interference with insecticide-resistance mechanisms. Thus, some plant species may weaken mosquitoes, making them less vigorous and more vulnerable to the insecticide. There is a need for further investigation, using a wider range of plant species and insecticides, in combination with other relevant environmental factors, to better understand the expression and evolution of insecticide resistance.

Transfluthrin and Metofluthrin as Effective Repellents against Pyrethroid-Susceptible and Pyrethroid-Resistant Aedes aegypti (L.) (Diptera: Culicidae)

“…aegypti USDA. These differences could be explained by the testing methods, the size and volume of the chamber, larval rearing conditions, such as overcrowding or poor diet [ 50 , 51 ], the time of day for testing [ 52 ], a decrease in temperature [ 53 ], an increase in humidity during insecticide susceptibility testing, the natural plant diet of the adults [ 13 ], and the genotypic background of the inbred mosquito strain. It is crucial that these physical and environmental conditions be kept constant while carrying out the HITTS-TOX bioassay to minimize multiple potential sources of variability, which can influence the result of the bioassay.…”

“…As the effectiveness of VPSRs depends on the volume of indoor or outdoor space to be protected and the dose of the active ingredients (AIs), it is crucial to choose the appropriate AI based on its chemical and physical properties, the application platform, and local environmental conditions. Transfluthrin (TFT) and metofluthrin (MFT) are two of the main highly volatile pyrethroids (VPs) which have been applied in various formats, such as coils [ 12 ], kerosene mixture for lamps [ 13 ], electro-vaporizers [ 14 ], multi-layer paper strips [ 15 ], and hessian strips [ 16 ]. Like conventional insecticides, these volatile pyrethroids are subject to an increased risk of resistance [ 17 , 18 ].…”

The paradox of plant preference: The malaria vectors Anopheles gambiae and Anopheles coluzzii select suboptimal food sources for their survival and reproduction

“…Between 7 and 10 freshly cut stems of flowering plants were arranged in a bouquet (with leaves removed) and introduced into the cages. The base of the bouquet was wrapped in moistened paper towels and covered with an aluminum sheet so that mosquitoes had no access to the moistened paper (Hien et al., 2016 ; Paré et al., 2022 ). A 5% glucose solution was used as a positive control by soaking a cotton pad with this solution and placing it on top of the control cage.…”

The paradox of plant preference: the malaria vectorsAnopheles gambiaeandAnopheles coluzziiselect suboptimal food sources for their survival and reproduction

“…Between seven and ten freshly cut stems of flowering plants were arranged in a bouquet (with leaves removed) and introduced into the cages. The base of the bouquet was wrapped in moistened paper towels and covered with an aluminum sheet so that mosquitoes had no access to the moistened paper 25,40 . A 5% glucose solution was used as a positive control by soaking a cotton pad with this solution and placing it on top of the control cage.…”