Novel Methods for the Control of Phlebotomine Sand Flies (Diptera: Psychodidae)
In arid and semi-arid parts of the Old World, Phlebotomus paptasi is a significant biting pest of man and is the primary vector of Leishmania major, the causative agent of zoonotic cutaneous leishmaniasis (ZCL). Phlebotomus papatasi exhibits a close association with the burrowing rodents that serve as the reservoirs of L. major. Rodent burrows are considered to be the primary habitat of immature P. papatasi in ZCL foci, and sand fly larvae have been observed feeding on rodent feces. In laboratory studies, five insecticides (diflubenzuron, novaluron, methoprene, pyriproxyfen, or ivermectin) were incorporated into the diet of Syrian hamsters and evaluated as feed-throughs to control immature sand flies. Feces of hamsters fed a diet containing approximately 10 mg/kg diflubenzuron, novaluron, or pyriproxyfen, or 20 mg/kg ivermectin killed 100% of sand fly larvae that consumed these feces. Feces of hamsters fed a diet containing up to 978.8 mg/kg methoprene caused significant, but not complete, mortality of sand fly larvae. Feces of novaluron-treated hamsters also were held under simulated field conditions for up to 30 d, and all larvae that consumed these feces died before pupation; a significant reduction in treated larval survival relative to control was observed when the feces were aged for up to 150 d. Novaluron also was shown to be effective as a feed-though larvicide when novaluron-treated food made up only a portion of the diet of hamsters. Ivermectin also was evaluated as a systemic insecticide; ivermectin treatment of hamsters was 100% effective against bloodfeeding sand flies for up to 7 d after hamsters were withdrawn from ivermectin-treated diets. In the final study, proof of concept was established for a novel biomarker system using a feed-through fluorescent dye. The value of this method is that it can mark rodents and their feces to establish the consumption of treated-baits, mark adult female sand flies that feed rodents for the duration of persistence of the dye in rodents, and mark adult male and female sand flies that had fed on feces of bait-fed rodents as larvae.
Advisor:Elzer, Philip; Foil, Lane; Schowalter, Timothy; Kramer, Wayne; Ottea, James
School:Louisiana State University in Shreveport
School Location:USA - Louisiana
Source Type:Master's Thesis
Date of Publication:09/09/2008