Temperature effects on the activity of vectors forLeishmania tropicaalong rocky habitat gradients in the Eastern Mediterranean

Abstract

Cutaneous leishmaniasis caused by Leishmania tropica, transmitted by Phlebotomus sergenti and Phlebotomus arabicus, has been detected in Israel. This research strives to identify the complexity of temperature effects on vectors of L. tropica and to analyze seasonality and distribution across altitudinal levels. Sand fly trappings were conducted monthly during 2015‐2016 in an endemic region for L. tropica in the eastern Galilee. Trappings were conducted in hyrax den sites across a broad topographic and climatic gradient. Using N‐mixture models, we investigated the activity levels of sand flies as related to temporary and periodic climatic variables. We tested generality of climate‐driven models using Root‐Mean‐Square Error (RMSE) values by comparing the 2015‐2016 data with trapping data from 2013. P. sergenti activity was found to be positively and exponentially correlated with early night temperatures and more strongly correlated with average early‐night temperatures for two weeks. P. arabicus exhibited a linear correlation with temperature. Climate‐driven models for both species yielded lower RMSE values for the 2013 data, which validate the generality of the models. Considerable differences were found in slope coefficients of temperature effect on sand fly activity among sites related to elevation levels, implying differential local responses of sand flies to temperature.

Effects of land use type, spatial patterns and host presence on Leishmania tropica vectors activity

“…The traps were set approximately one hour before sunset, and collected half an hour after sunrise, which are the initial and termination activity times of the sand flies [35]. Following the collection, Phlebotomus spp.…”

“…The last group was not included in further analysis. Capture data were used to assess population activity levels of each species and sex at each location using the N-mixture analysis approach [35].…”

“…The traps at each land use type were considered for the repeated observations during the seasonal peak of abundance in the area (see Waitz et al [35]). Activity analyses were conducted using the Unmarked package in R [43].…”

“…Eight possible models were tested to estimate the corrected activity from the samplings: (i) a null model with no land use or trap effect; (ii) trap effect; (iii) land use effect; and (iv) trap and land-use effect. Results of the N-mixture analysis indicate that each of the four models was analyzed under a (i) Poisson or a (ii) negative binomial distribution as detailed by Waitz et al [35].…”

“…Apart from the macro-scale spatial activity patterns, temporal patterns on a daily scale have also been investigated. Nocturnal activity patterns of P. sergenti have been described in several studies, in Israel and elsewhere, as having a higher activity during the hours immediately after dusk; this differs from other species with longer nocturnal activity times [16, 34, 35]. Ecological studies have demonstrated the role of spatial and temporal variability on the sand fliesʼ presence or activity patterns in various habitats.…”