High Pyrethroid Resistance in Triatoma Infestans is Strictly Associated with kdr Variants: A Multiplex High Resolution Melting Tool for Vector Surveillance

Triatoma infestans is the main vector of Trypanosoma cruzi in the South Cone, where vectorial transmission of Chagas is still occurring despite control campaigns with pyrethroid insecticides. High pyrethroid resistance was detected in T. infestans populations from Argentina and Bolivia. This raises the urgent need of including strategies for monitoring and management of insecticide resistance as an essential component of control campaigns. Voltage-gated sodium channel is the target site of pyrethroids; single-nucleotide polymorphisms in the gene encoding this channel, called kdr variants, are associated with pyrethroid resistance in T. infestans. The early detection of kdr in a population allows taking control decisions timely. In this work, we present the development of a high-throughput assay based on multiplex High Resolution Melting for genotyping kdr variants in this species. We characterized T. Infestans populations according to their toxicological response to deltamethrin, and efficiently used this assay for genotyping. Our work confirms that high pyrethroid resistance is strongly associated with kdr variants in T. Infestans, and provides a high-throughput method for vector surveillance and resistance management.