Species Composition of Sand Fly (Diptera: Psychodidae) in Khartoum State, Sudan, during 2013- 2016

Abstract

The aim of this study was to identify the fauna and the abundance of phlebotomine sand flies in the study area followed by molecular identification of the most common species. This study was carried out during 2013- 2016 in different sites in Khartoum State that represent all Nile environments including El-Hrizab, Surogia, Tuti, Al-Ozuzab, Soba, Abo-roaf, and Al-Sheikh Yusuf. Sand flies were collected using sticky papers traps (STs) and CDC light traps (LTs) which were fixed on the bordering areas between residence and farms overlooking the river. All collected specimens were subjected to the microscopic morphological identification, but only females were subjected to molecular identification using Polymerase Chain Reaction (PCR). DNA was extracted from 173 female specimens using G-spin kits and STE extraction protocol and Another 34 specimens were subjected to direct amplification to identify vector species in Khartoum State using molecular tools. The total number of collected sand flies during this study using STs was 6483 while those collected by LTs were 417 females. The STs collection included seven species; these were Phlebotomus papatasi, S. clydei, S. antennata, S. squamipleuris, S. adleri, S. schwetzi, and S. africana. P. papatasi, the proven vector for cutaneous leishmaniasis, was the only recorded species belonging to the genus Phlebotomus and comprised 3.82% of the total collection. The most abundant sand fly species was Sergentomyia antennata (2879; 44.41%) followed by S. clydei (2850; 43.96%), S. squamipleuris (275; 4.2%), P. papatasi (221; 3.4%), S. adleri (179; 2.8%), S. schwetzi (64; 1.0%), and S. africana (15; 0.2%). P. orientalis was not recorded in the area. The majority of sand flies were collected from El-Hrizab (459.4 samples/ visit) followed by Tuti (323.7 samples/ visit), while the lowest number was collected in Abo-roaf (12 samples/ visit). Most of the collected females using LTs were S. clydei females (281; 62.86%) followed by S. antennata (114; 25.50%), No S. africana were found in this collection. The values of diversity (H, D) and richness indices (R1, R2) fluctuated in a narrow ranges indicating that, the sites in Khartoum State are similar to each other regarding their species diversity and richness (Shannon index {H}= 0.5- 1.5, Simpson index {D}= 1.9- 3.6, Margalef index {R1} = 1.7- 2.6, Menhinick index {R2} = 0.12- 0.56). The abundance of S. antennata was found to be significantly different between study sites for both STs and LTs (Kruskal-Wallis test P. value= 0.001 and 0.016 for STs and LTs, respectively). There were no significant difference in the mean number of collected females neither between STs and LTs nor between indoor and outdoor settings. S. clydei and S. squamipleurisiv revealed a significant difference regarding their seasonal patterns (Kruskal-Wallis test P. value=0.011 and 0.004 for S. clydei and S. squamipleuris, respectively). More S. adleri males were collected, and more females of S. africana (Kruskal-Wallis test P. value=0.02 and 0.001 for S. adleri and S. africana, respectively). Only 20 specimens (11.5 %) for ITS2 and 2 specimens (15.4 %) for Cyt b were successfully amplified by PCR. For direct amplification, 10 (31.2 %) specimens out of 32 specimens were successfully amplified for ITS2, and 2 (25 %) specimens out of 8 specimens were successfully amplified for Cyt b, beside 9 (17.6%) specimens for S. clydei and 4 (16.0%) for S. antennata. In conclusion, the findings of the present study reflect that the abundance of several sand fly species is different between areas of Khartoum State and this may be attributed to some environmental factors such as soil type, temperature and humidity. Based on this, many ecological aspects are still waiting to be covered through basic or operational studies investigating sand fly bionomics, in addition to the necessity for developing standardized morphological and molecular approaches for species identification.