Temporal distribution and behaviour of sand flies (Diptera: Psychodidae) in a cutaneous leishmaniasis focus of the Kani Tribe settlements in the Western Ghats, India.
The temporal distribution of sand flies in relation to environmental factors was studied in the Kani tribe settlements located on the southernmost part of the Western Ghats, Kerala, India, between June 2012 and May 2013. This area is known for occurrence of cutaneous leishmaniasis (CL) cases. Employing hand-held aspirator, light trap and sticky-trap collection methods, a total of 7874 sand fly specimens, comprising 19 species was collected. Sergentomyia baghdadis was predominant species, followed by Phlebotomus argentipes. Sand fly abundance was significantly higher indoors (χ(2)=9241.8; p=0.0001) than outdoors. Mean density of P. argentipes in human dwellings, cattle sheds and outdoors was 7.2±2.9, 27.33±21.1 and 0.64±0.2 females/per man-hour (MHR), respectively. No sand fly species other than P. argentipes was obtained from cattle sheds. Although, sand fly populations were prevalent throughout the year, their abundance fluctuated with seasonal changes. Multiple regression analysis with backward elimination indicated that the increase in precipitation and relative humidity contributed to a significant positive association with the increase in sand fly abundance, while the increase in temperature showed no association. Fully engorged female sand flies tested for blood meal source showed multiple host-blood feeding. Analysis of resting populations of sand flies collected from human shelters indicated that the populations were found maximum on interior walls at 6-8 and >8 ft height, including ceiling during summer (F=83.7, df=6, p=0.001) and at the lower half of the wall at 0 and 0-2 ft height, during monsoon season (F=41.4, df=6, p=0.001). In cooler months, no preference to any height level (F=1.67, df=6, p=0.2) was observed. Proportion of females sand flies with Sella's classification of abdominal stages, namely full-fed, half-gravid and gravid females did not vary significantly (t=1.98, p=0.13827) indoors, confirming their endophilic behaviour. Risk of CL transmission in these tribal settlements is discussed.
Vector Control Research Centre (Indian Council of Medical Research), Pondicherry 605 006, India.
R
R
Srinivasan
Vector Control Research Centre (Indian Council of Medical Research), Pondicherry 605 006, India. Electronic address: pcsaja@gmail.com.
P
P
Jambulingam
Vector Control Research Centre (Indian Council of Medical Research), Pondicherry 605 006, India.
N Pradeep
NP
Kumar
Vector Control Research Centre (Indian Council of Medical Research), Pondicherry 605 006, India.
M
M
Selvakumar
Vector Control Research Centre (Indian Council of Medical Research), Pondicherry 605 006, India.
B
B
Edwin
Directorate of Health Services, Government of Kerala, Thiruvananthapuram 695 035, Kerala, India.
T Dilip
TD
Kumar
D000818:Animals; D001522:Behavior, Animal; D002417:Cattle; D005260:Female; D006798:Housing; D006799:Housing, Animal; D006801:Humans; D007194:India; D016773:Leishmaniasis, Cutaneous / Q000635:transmission*; D008297:Male; D010691:Phlebotomus; D011156:Population Density; D011576:Psychodidae; D012044:Regression Analysis; D012621:Seasons
India; Kani tribe settlements; Sand flies abundance; Temporal distribution; Western Ghats