Exposure of Anopheles gambiae larvae to a sub-lethal dose of an agrochemical mixture induces tolerance to Fludora® Fusion and to its neonicotinoid component in adults

ABSTRACT: The heavy use of pesticides in intensive agricultural areas often leads to the contamination of neighbouring mosquito larvae breeding sites. Such exposure to complex agrochemical mixtures can affect the tolerance of mosquitoes larvae to insecticides. The objective of this study was to determine whether agrochemical pollutants found in Anopheline larval breeding sites can affect the tolerance of adults to Fludora® Fusion, a novel vector control insecticide formulation combining two insecticides with distinct modes of action. An. gambiae larvae were exposed to a sub-lethal dose of a mixture of agrochemical pesticides representative of a region with an intense agricultural activity in Ivory Coast. Comparative bioassays with Fludora® Fusion and its two insecticide component (deltamethrine and clothianidin) were carried out between adult mosquitoes exposed or not to the agrochemicals at the larval stage. A transcriptomic analysis through RNA sequencing was subsequently performed in larvae and adults in order to highlight the molecular mechanisms underlying the phenotypic changes observed. Bioessais revealed a significant increased tolerance of adult females to clothianidin (2.5-fold) and Fludora® Fusion (2.2-fold) following larval exposure to agrochemicals. No significant increased tolerance to deltamethrin was observed suggesting that pesticide exposure affects the efficacy of the Fludora® Fusion mixture mainly through mechanisms acting on clothianidin tolerance. Transcriptomic analysis revealed the potential of agrochemicals to induce various resistance mechanisms including cuticle proteins, detoxifications activities and altered insecticide sequestration. These results suggest that though Fludora® Fusion has a good potential for vector control, its efficacy may be locally affected by the ecological context. The present study also suggests that, although the complex interactions between the use of agrochemicals and vector control insecticides are difficult to decipher in the field, they still must be considered in the frame of insecticide resistance management programmes.

ORGANISM(S): Anopheles gambiae

PROVIDER: GSE189345 | GEO | 2022/02/28

REPOSITORIES: GEO