Electroantennographic and behavioral responses of Rhodnius prolixus (Stal 1872) to xenobiotics reveal carvone and IR3535 as potential repellent candidates

Electroantennography (EAG) is a valuable approach for monitoring the sensory responses of insects to insecticidal and repellent molecules and an effective tool for early screening of compounds aimed at controlling and protecting against medically important insect vectors. However, its predictive potential for repellent efficacy in triatomine vectors remains poorly explored. The objective of this study was to evaluate the EAG responses to different xenobiotics as a preliminary selection strategy for compounds with potential repellent action against triatomines. For this purpose, the antennae of adult triatomines subjected to prolonged fasting ([≥]30 days) were exposed to repellent molecules. In parallel, repellency bioassays were conducted using a live bait (Gallus gallus) and a newly designed laboratory device to validate the electroantennographic results. EAG recordings showed a significant reduction in olfactory capacity of> 60% in response to the chemical compounds IR3535 and carvone, consistent with the protection times observed in the repellency tests (135.6 {+/-} 43.29 min and 108 {+/-} 26.33 min, respectively). In conclusion, the compounds with the highest repellent activity were clearly discriminated by the insects olfactory system, a finding corroborated by the decrease in electrical signals recorded in the EAG bioassays.