Bionomics of Leishmaniasis Vector Sand Flies (Psychodidae:Phlebotominae) in Kurunegala District, Sri Lanka

Abstract

Sand flies are responsible for the transmission of leishmaniasis, a disease caused by protozoan parasites of genus Leishmania. Control of the sand fly populations in disease endemic areas is a critical step in the effective disease management which in turn largely depend on the availability of the knowledge on sand fly bionomics. Therefore, this study focuses on the investigation of bionomics of sand flies in three selected disease endemic regions of Kurunegala District, Sri Lanka. Monthly entomological surveillance was conducted from May 2017 – February 2019 using standard entomological techniques. Collected specimens were identified using standard morphological identification keys. The meteorological data were collected for each month from Department of Meteorology, Colombo. A total of 37,955 sand flies were collected during the study. Majority of them were Phlebotomus argentipes (99.43%, n=37,740) while the rest was Sergentomyia punjabensis. Female: male sex ratio for P. argentipes was 0.18, while, it is 0.04 for S. punjabensis. Polpithigama MOH area had the highest abundance of sand flies with a total of 33,374 (87.93%), followed by Maho (9.90%, n=3756), and Galgamuwa (2.17%, n= 825). The variation of sand fly abundance is correlated with climatic variables to some extent. Wind speed has significant negative impacts (r= -0.670, P= 0.002) on the sand fly abundance while, the rainfall (r= 0.349, P= 0.155) and relative humidity (r= 0.107, P= 0.671) positively associated with sand fly abundance though not significant, indicating a possibility of an increased sand fly abundance under rainy, humid conditions with low wind velocities.