Abstract
American Cutaneous Leishmaniasis, ACL, is a zoonotic disease with a large richness of co-occurring vector species in transmission foci. Here, we describe changes in patterns of phlebotomine sand fly (Diptera: Psychodidae: Phlebotominae) species composition at the village of Trinidad de Las Minas, Capira, Panamá, a hyperendemic focus of ACL transmission, subjected to a vector control intervention with insecticide thermal fogging (ITF). Our study setting consisted of 24 houses, 12 subjected to two rounds of ITF and 12 kept as control. During 15 months (April 2010– June 2011) we monitored sand fly species composition and abundance with modified HP light traps inside (domicile) and outside (peridomicile) the studied houses. From 5628 sand flies collected, we were able to identify 5617 of the samples into 24 species, a number of species close to 25±1.6, the estimate from the Chao2 Index. The most abundant species were Lutzomya trapidoi (20%), Lu. gomezi (20%) and Lu. triramula (20%). Cluster analyses showed that most of the 24 houses had high similarity in relative abundance patterns of the six most common species, with only few peripheral houses not following the main cluster pattern. We also found that species richness was decreased to 22 species in the fogged houses, of which only 19 were found in the domiciliary environment. Changes in species richness were especially notorious at the end of the wet season. Our results suggest that species richness can decrease following ITF in domiciliary environments, primarily affecting the less common species.
Highlights
American Cutaneous Leishmaniasis (ACL) is an increasing public health problem in Panama, and other neo-tropical countries [1]
The flat slope of the Species accumulation curves (SAC) after 400 trap nights (Fig. 4A), the plateau of 25 species in the SAC, the Chao2 estimate of 25 species, and the convergence of the cumulative Chao2 index to 25 species, when all houses were considered in the analysis (Fig. 4B), were all values extremely close to the species that we recorded, which could potentially be assuming some of the unidentifiable individuals belonged to a different species
We found 24 of the 74 native species of phlebotomine sand flies reported for Panama [4,33,43,49] and the slope of the species accumulation curve, for all the traps (Fig. 4A), flattened as expected when an exhaustive sampling is done [44]
Summary
American Cutaneous Leishmaniasis (ACL) is an increasing public health problem in Panama, and other neo-tropical countries [1]. Besides passive detection and specific treatment of human cases, no measures are currently being undertaken to control the vectors of this parasitic infection It has been suggested a change in the epidemiologic pattern of transmission, with the possibility of peridomestic and/or domestic transmission in endemic areas of Panama [2], moving away from the paradigmatic ‘‘sylvatic’’ transmission [4]. This group of medically and veterinary important insects is notorious by the co-occurrence of a large number species across the different natural habitats they colonize in the new world [20,21,22,23,24,25,26,27], such as the tropical agro-forest landscape matrices of Panama [2,4,28,29,30,31,32,33]
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