Laboratory and field evaluation of rodent bait treated with fipronil for feed through and systemic control of Phlebotomus papatasi

The sand fly Phlebotomus papatasi is the main vector of Leishmania major, etiologic agent of zoonotic cutaneous leishmaniasis (ZCL), which is endemic in North Africa, the Middle East, and Asia. In North Africa, Meriones shawi is one of the two main reservoir hosts of L. major. P. papatasi populations are maintained in borrowing rodents such as M. shawi. Three fipronil-treated rodent baits were evaluated for systemic and feed through insecticidal activity against P. papatasi feeding on M. shawi. Through blood feeding bioassays, mortality rates of females P. papatasi increased with the concentration of fipronil in the rodent bait varying from 0.001% to 0.005%. In the laboratory, more than 90.0% of P. papatasi were killed within 48 h after blood feeding on the desertʹs jirds, M. shawi, treated up to 29 days prior with a single application of fipronil at a concentration of 0.001%, 0.0025% and 0.005%. Through larval bioassays, mortality rates of larvae that have fed on faeces of treated bait for M. shawi increase with the concentrations of fipronil. Faeces of orally-treated Meriones were significantly toxic to larvae for 5 weeks with a concentration of 0.005%. In the field, application of treated bait resulted in 80.0% reduction in the populations of P. papatasi up to 6 weeks after a single application of fipronil at a concentration of 0.005%. This is the first study to demonstrate field efficacy of fipronil-treated rodent baits for P. papatasi control and the first study to evaluate this approach in M. shawi, a principal ZCL reservoir host. These results suggest that fipronil-treated rodent baits can be used to effectively reduce the populations of P. papatasi associated with M. shawi in ZCL endemic areas.