Occurrence and composition of Phlebotomine sandflies (Diptera, Psychodidae) in selected areas along the East Africa Great Rift Valley ecosystem, Tanzania

Abstract

Sandflies are dipterans of medical significance, well-known for transmitting Leishmania parasite. This study investigated the occurrence, composition and distribution of sandflies. Sandflies were collected for three consecutive nights each week at each sampling point using CDC miniature light traps, sticky traps and manual aspiration. Captured sandflies were morphologically identified, based on head structure and terminalia, following standard keys. A generalised linear model was used to determine the effects of explanatory variables on sandfly abundance. Shannon-wiener and Jaccard’s similarity indices were utilised to calculate species diversity and community similarity, respectively. A total of 586 Phlebotomine sandflies were collected, comprising eight species; Sergentomyia freetownensis (38.74%), Se. antennata (49.49%), Se. schwetzi (4.61%), Se. bedfordi (3.75%), Se. adleri (1.19%), Grassomyia squamipleuris (0.68%), Phlebotomus martini (0.85%) and Ph. vansomerenae (0.68%). Sandfly abundance was significantly influenced by habitat type ( X 2 = 71.6, df = 2, P < 0.001), altitudinal range ( X 2 = 46.85, df = 2, P < 0.001), average temperature ( X 2 = 39.16, df = 1, P < 0.001) and average relative humidity ( X 2 = 41.03, df = 1, P < 0.001). Sandfly diversity was higher in farmland (H’ = 1.149) and at mid-altitude areas (H’ = 1.079). The presence of competent and susceptible vectors species in the study villages underscores the necessity for surveillance, including vectorial capacity and bloodmeal sources as fundamental factors in incriminating the vector in areas considered non-endemic.