Exploring novel pyrethroid resistance mechanisms through RNA-seq in Triatoma dimidiata from Colombia.

Pyrethroids are the most widely used insecticides for controlling insect vectors carrying medically and economically significant pathogens. In Colombia, studies on triatomine insecticide resistance are limited. Due to the increasing challenge of insecticide resistance, this work focuses on determining resistance to different pyrethroid insecticides in populations of Triatoma dimidiata from Colombia. To define the possible causes of resistance, three potential molecular mechanisms were explored: 1) mutations in the coding region of the voltage-gated sodium channel gene (vgsc), the insecticide target site; 2) modulation of enzymatic activity associated with metabolic resistance; and 3) changes in the mRNA profiles using RNA-seq. The results showed that the field population of T. dimidiata was resistant to lambda-cyhalothrin and deltamethrin insecticides. Insects surviving sublethal doses of insecticides did not exhibit the classical mutations in the vgsc gene. Transcriptomic profile analyses of T. dimidiata revealed differentially regulated genes in field and laboratory populations under selective pressure with lambda-cyhalothrin. Gene enrichment analysis showed the positive regulation of transcripts related to detoxifying enzymes and mitochondrial proteins, which could play a significant role in insecticide resistance. This comprehensive investigation is crucial for providing insights into resistance mechanisms and generating strategies to manage these critical vector species.