High Pyrethroid Resistance in Triatoma infestans Is Strongly Associated with kdr Variants: A Multiplex High-Resolution Melting Tool for Vector Surveillance.

Triatoma infestans is the main vector of Trypanosoma cruzi in the Southern 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 for including strategies for monitoring and management of insecticide resistance as an essential component of control campaigns. Voltage-gated sodium channels are the target site of pyrethroids; non-silent single-nucleotide polymorphisms in specific sites of the gene encoding this channel, called kdr mutations, are associated with resistance to pyrethroids in many insect species, including 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 results indicate that high resistance to pyrethroids is closely related to the presence of kdr variants in T. infestans, and they provide a high-throughput method for vector surveillance and resistance management.