Phenotypic and haplotypic profiles of insecticide resistance in populations of Aedes aegypti larvae (Diptera: Culicidae) from central Lao PDR

• Published in: Tropical Medicine and Health
• Main Authors: Takaki Shimono, Seiji Kanda, Pheophet Lamaningao, Yuki Murakami, Andrew Waleluma Darcy, Nobuyuki Mishima, Somchit Inthavongsack, Odai Soprasert, Thonelakhanh Xaypangna, Toshimasa Nishiyama
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2021
• Subjects: Aedes aegypti; Dengue; Insecticide resistance; Bioassay; Synergist; kdr mutation; Arctic medicine. Tropical medicine; RC955-962; Arctic
• Online Access: https://doi.org/10.1186/s41182-021-00321-3; https://doaj.org/article/bd7b944b140c43ffa6c18d4a61dfb6da

Abstract Background Aedes aegypti, which is widely distributed in the Lao People’s Democratic Republic (PDR), is the primary vector of arboviral diseases. Chemical insecticides have been intensively used to eliminate mosquito-borne diseases, resulting in the development of insecticide resistance. However, little is known about the insecticide resistance of mosquito populations in Lao PDR and the mechanisms responsible for it, which have important implications for vector management programs. Here, we examined the phenotypic and haplotypic profiles of insecticide resistance in populations of Ae. aegypti larvae from central Lao PDR. Methods Ae. aegypti larvae were collected from four sites in Lao PDR, and their susceptibility to temephos, deltamethrin, permethrin, and Bacillus thuringiensis israelensis (Bti) was tested using larval bioassays. Synergistic tests were also conducted to evaluate the activity of insecticide-metabolizing enzymes in the larvae. Deltamethrin-resistant and Deltamethrin-susceptible larvae were then genotyped for knockdown resistance (kdr) mutations to determine the associations between each genotype and resistance. Results Ae. aegypti larvae from central Lao PDR were considered to be “resistant” (<98% mortality) to organophosphates and pyrethroids. The bio-insecticide Bti remains effective against such larvae. The resistance mechanisms of Ae. aegypti larvae were found to vary among populations, especially for pyrethroid resistance. Kdr mutations were significantly associated with deltamethrin resistance in Ae. aegypti from the Xaythany population. In contrast, synergist assays with piperonyl butoxide suggested that cytochrome P450 monooxygenases played an important role in the resistance seen in the Khounkham and Thakhek populations. Conclusion This study obtained information that will aid the design and implementation of insecticide-based vector management of Ae. aegypti in central Lao PDR. Ae. aegypti larvae from central Lao PDR were highly susceptible to Bti, while they were resistant ...