Spatiotemporal multiple insecticide resistance in Aedes aegypti populations in French Guiana: need for alternative vector control

Abstract

BACKGROUND Aedes aegypti is the sole vector of urban arboviruses in French Guiana. Overtime, the species has been responsible for the transmission of viruses during yellow fever, dengue, chikungunya and Zika outbreaks. Decades of vector control have produced resistant populations to deltamethrin, the sole molecule available to control adult mosquitoes in this French Territory.OBJECTIVES Our surveillance aimed to provide public health authorities with data on insecticide resistance in Ae. aegypti populations and other species of interest in French Guiana. Monitoring resistance to the insecticide used for vector control and to other molecule is a key component to develop an insecticide resistance management plan.METHODS In 2009, we started to monitor resistance phenotypes to deltamethrin and target-site mechanisms in Ae. aegypti populations across the territory using the WHO impregnated paper test and allelic discrimination assay.FINDINGS Eight years surveillance revealed well-installed resistance and the dramatic increase of alleles on the sodium voltagegated gene, known to confer resistance to pyrethroids (PY). In addition, we observed that populations were resistant to malathion (organophosphorous, OP) and alpha-cypermethrin (PY). Some resistance was also detected to molecules from the carbamate family. Finally, those populations somehow recovered susceptibility against fenitrothion (OP). In addition, other species distributed in urban areas revealed to be also resistant to pyrethroids.CONCLUSION The resistance level can jeopardize the efficiency of chemical adult control in absence of other alternatives and conducts to strongly rely on larval control measures to reduce mosquito burden. Vector control strategies need to evolve to maintain or regain efficacy during epidemics.

Impact of selection regime and introgression on deltamethrin resistance in the arbovirus vector Aedes aegypti – a comparative study between contrasted situations in New Caledonia and French Guiana

“…This result is consistent with the massive usage of deltamethrin for years in FG 1,15 and the high frequencies of resistance alleles observed in FG. [4][5][6]15,20,21 Molecular data obtained from each line at the beginning of the experiment (G1) confirmed that most resistance markers monitored in this study were at a higher frequency in the FG line than in the NC line. In the FG line all individuals harbored at least two kdr mutations and seven detoxification genes out of nine tested were overtranscribed as compared to the susceptible strain.…”

Ecology, evolution, and epidemiology of zoonotic and vector-borne infectious diseases in French Guiana: Transdisciplinarity does matter to tackle new emerging threats

“…This information is important to adapt vector control strategies in both countries. Today, the level of resistance in French Guiana is critical with the fixation of target-site mutations and co-occurrence with metabolic mechanisms (Dusfour et al, 2015;Guidez et al, 2020). Other paths are also being investigated to determine the implication of the microbiome in the detoxification of insecticides.…”

“…darlingi, such as Culex quinquefasciatus. This particular Culicid species is known to adapt quickly to insecticide pressure (Guidez et al, 2020). A novel vector in the environment would deeply challenge the wellestablished vector control strategies as developed in French Guiana during the last few decades.…”