Systemic Insecticide Treatment of Chickens Results in Mortality in Triatoma gerstaeckeri, Vector of the Etiological Agent of Chagas Disease

Abstract

Chagas disease remains a persistent vector-borne neglected tropical disease throughout the Americas and threatens both human and animal health. Diverse control methods have been used to target triatomine vector populations, with household insecticides being the most common. As an alternative to environmental sprays, host-targeted systemic insecticides (xenointoxification or endectocides) aChagas disease remains a persistent vector-borne neglected tropical disease throughout the Americas and threatens both human and animal health. Diverse control methods have been used to target triatomine vector populations, with household insecticides being the most common. As an alternative to environmental sprays, host-targeted systemic insecticides (xenointoxification or endectocides) allow for application of chemicals to vertebrate host resulting in toxic bloodmeals for arthropods. In this study, three systemic insecticide products were evaluated for their ability to kill triatomines by treating chickens orally and allowing triatomines to feed on treated birds. The products included: Safe-Guard® Aquasol (fenbendazole), Ivomec® Pour-On (ivermectin), and Bravecto® (fluralaner). Triatoma gerstaeckeri insects were allowed to feed on live birds at 0, 3, 7, 14, 28, and 56 days post-treatment. Triatoma gerstaeckeri survival and feeding status were recorded and analyzed using Kaplan-Meier curves and logistic regression. Fluralaner caused up to 100% mortality in T. gerstaeckeri through 14 days post treatment but not after; in contrast, all insects which fed on fenbendazole and ivermectin-treated birds survived. Liquid chromatography tandem mass spectrometry (LC-QQQ) analysis was used to detect the concentration of each treatment in the chicken plasma. Fluralaner was detected at 3-, 7- and 14 days post treatment, while fenbendazole concentration was below the detectable level. Xenointoxification using fluralaner in poultry is a potential new tool for integrated vector control to reduce risk of Chagas disease.llow for application of chemicals to vertebrate host resulting in toxic bloodmeals for arthropods. In this study, three systemic insecticide products were evaluated for their ability to kill triatomines by treating chickens orally and allowing triatomines to feed on treated birds. The products included: Safe-Guard® Aquasol (fenbendazole), Ivomec® Pour-On (ivermectin), and Bravecto® (fluralaner). Triatoma gerstaeckeri insects were allowed to feed on live birds at 0, 3, 7, 14, 28, and 56 days post-treatment. Triatoma gerstaeckeri survival and feeding status were recorded and analyzed using Kaplan-Meier curves and logistic regression. Fluralaner caused up to 100% mortality in T. gerstaeckeri through 14 days post treatment but not after; in contrast, all insects which fed on fenbendazole and ivermectin-treated birds survived. Liquid chromatography tandem mass spectrometry (LC-QQQ) analysis was used to detect the concentration of each treatment in the chicken plasma. Fluralaner was detected at 3-, 7- and 14-days post treatment, while fenbendazole concentration was below the detectable level. Xenointoxification using fluralaner in poultry is a potential new tool for integrated vector control to reduce risk of Chagas disease.