Evaluating the impact of nitisinone at mosquito-lethal doses on Lutzomyia longipalpis

Nitisinone, a systemic inhibitor of tyrosine catabolism, has recently emerged as a promising endectocide with demonstrated lethality against mosquitoes and tsetse flies. To assess its efficacy against Lutzomyia longipalpis , an important vector of Leishmania infantum —the causative agent of zoonotic visceral leishmaniasis prevalent in the Mediterranean basin, Latin America, and parts of the Middle East—, we exposed sand flies to a concentration previously shown to be lethal to Anopheles mosquitoes (250 ng/mL). Survival was monitored over 14 days and showed no significant difference between treated and control groups, indicating a lack of insecticidal effect at this dose. These findings suggest that Lu. longipalpis exhibits tolerance to nitisinone, likely due to species-specific metabolic differences. Although nitisinone remains a promising tool for systemic vector control, its effectiveness against sand flies may require higher doses or alternative compounds.