An entomological survey of phlebotomine sand flies (Diptera: Psychodidae) in different areas of Thailand

Abstract

Sand flies (Diptera: Psychodidae) are significant medical vectors of pathogens that cause illness in humans and animals. The most significant of these is the genus Leishmania (Kinetoplastida: Trypanosomatidae). Leishmaniasis is an important vector-borne disease. They are spread throughout the Old and New Worlds by the bites of female phlebotomine sand flies. Despite this importance, certain provinces where autochthonous leishmaniasis has historically existed and is re-emerging are lacking current data regarding their sand fly fauna. To provide a current update on the local sand fly fauna, a comprehensive entomological survey encompassing eight provinces was conducted subsequent to an analysis of past data regarding the species composition and distribution of sand flies in the area. Thus, the purpose of this study was to ascertain the species composition in various locations across eight provinces spread across four regions in Thailand. In order to gather information about the distribution of the phlebotomine sand fly, researchers used modified Centers for Disease Control and Prevention light traps between February 2021 and February 2022. At these 30 trappings in each province, we conducted 240 trapping nights in total. Collected sand flies were morphologically identified. The adult sand flies collected in this study were 8314 and represented 24 species of four genera, including 16 of Sergentomyia, 6 of Phlebotomus, 1 of Idiophlebotomus, and 1 of Chinius. Among these species, Sergentomyia anodontis had the largest population (25.71%), and population peaks were observed in Uthaithani province (51.81%). The collected sand flies’ male-to-female ratio was 1.21:1.00 (4,556:3,758). The study also discovered that Phlebotomus argentipes, a vector of Leishmania spp., was captured in Phayao province, and Phlebotomus major major was majorly found in Uthaithani province. The widespread distribution of sand fly populations in this study may indicate the epidemiologic importance of vector ecology in this habitat. Our results confirm the presence of several sand fly species in different provinces of Thailand and provide valuable information about the distribution and behavior of phlebotomine sand flies, which can be used to develop effective control strategies for the prevention of sand fly-borne diseases. In several Thai provinces, the study also tracked the nocturnal movements of both male and female sand flies. The results showed that phlebotomine sand flies are more active at night, peaking just after dusk.