Insecticide-treated rodent baits for sand fly control

Rodent baits containing systemic insecticides are potential tools to interrupt the cycle of transmission of Leishmania parasites by killing sand flies that take bloodmeals from rodents as adults. Bio-indicators that can be used in conjunction with rodent-targeted sand fly control methods also have been developed to demonstrate that the insecticide treatments are reaching the targeted life stages of sand flies and to quantify the effect of the insecticide treatments on sand fly populations. This article presents new results from a field study on the use of rodent bait containing a systemic insecticide in Kenya. The objective of this field study was to incorporate the fluorescent dye rhodamine B into rodent baits to determine the level of blood feeding by the sand fly Phlebotomus duboscqi on targeted rodents, and to demonstrate the effect of rodent bait containing the systemic insecticide ivermectin on bloodfeeding adult females of P. duboscqi. Over 50% of the bloodfed females of P. duboscqi collected at sites that were treated with rodent baits containing rhodamine B alone were positive for the presence of rhodamine B while no bloodfed females of P. duboscqi collected at the sites treated with rodent baits containing rhodamine B plus ivermectin were positive for the presence of rhodamine B. The results of this field trial constitute proof of concept for the targeted control of an epidemiologically significant portion of the population of the sand fly vector of Leishmania major, and demonstrate the potential for the interruption of the transmission of L. major using applications of systemic insecticide-treated rodent baits. © 2013