North Carolina State University Raleigh, North Carolina
A sustainable alternative to the delivery of an insecticide to the vector is to bring the vector to the insecticide using attractants. In this project, we applied a multi-disciplinary approach to identify attractive materials, microbes and semiochemicals for Phlebotomus papatasi sand flies (a vector of Old-World cutaneous leishmaniasis [CL]) for surveillance and control tools. We identified larval conditioned rearing medium as a potent source for oviposition attractants and stimulants, which harbor highly attractive bacterial strains that produce several volatile compounds. We also found that conspecific eggs and first instar larvae were highly attractive and stimulated oviposition. Conspecific eggs induced attraction at low-intermediate doses and repellence at high doses. This attraction pattern was mediated by dodecanoic acid as an egg and larval pheromone. Isovaleric acid was also an important attractant produced by both young conspecific stages and the most attractive bacterial isolate. In addition to these olfactory-driven processes, attraction to potential oviposition sites is mediated by visual cues with gravid females attracted to dark oviposition cups. Furthermore, when gravid females were presented with a black oviposition cup the attractive olfactory effect of organic matter was diminished. Finally, our study also described the circadian rhythm of P. papatasi oviposition behavior, with gravid females increasing their affinity to volatile oviposition attractants at the later part of the night whereas actual egg-laying tend to mostly occur at the earlier part of the night. These findings are instrumental in guiding us through the development of attractive lures for surveillance and managing P. papatasi populations.