Short-term movement of Phlebotomus argentipes (Diptera: Psychodidae) in a visceral leishmaniasis-endemic village in Bihar, India

Abstract

Visceral leishmaniasis (VL), transmitted by the sand fly, Phlebotomus argentipes, is frequently reported on the Indian subcontinent where its basic ecology is largely unknown. Our objective was to evaluate the effectiveness of sugar solution (10%), containing colored food dye (0.5%) applied to peridomestic vegetation, to mark P. argentipes and subsequently estimate horizontal movement by capturing dye-marked specimens in CDC light traps in a village in Bihar, India. From September 30 to November 27, 2016, a total of 667 captured sand flies were successfully marked using sugar baits, of which 608 were P. argentipes (~91.2%). Although the majority of P. argentipes were captured <100 m from the respective marking sites, a significantly greater proportion of females (15.7%) was captured >100 m from marking sites when compared to males (3.1%). Sand flies that ingested sugar bait were only collected from areas containing >eight vegetation types and mature banana plants. The average number of marked P. argentipes captured per trap-night (±SD) <100 m from respective marking sites was greatest in peridomestic vegetation (Males: 0.9 ± 1.97; Females: 0.63 ± 1.44), followed by areas with livestock (Males: 0.66 ± 2.75; Females: 0.24 ± 0.69), and areas with humans only (Males: 0.1 ± 0.36; Females: 0.11 ± 0.31). To our knowledge, this is the only study in Bihar in which sand flies have been marked with food dyes, and the results demonstrate the potential usefulness of food dyes in estimating short-term movement of P. argentipes. Limitations of this experiment are that the number of each trap location type, vegetation composition at marking sites, and distance of all trap sites from marking sites were not homogenous, and the total number of marked sand flies collected were relatively low. In spite of the above limitations, these data should prove useful in developing a large-scale study addressing the caveats. Results of such a study could provide important information regarding the dynamics of VL transmission and inspire managers to pursue alternative means of sand fly control on the Indian subcontinent.