Long-term monitoring of sand fly populations: temporal responses to land-use change and climatic variability.

BACKGROUND

Phlebotomine sand flies are the sole vector of leishmaniasis and other sand fly-borne diseases, and their populations are shaped by climate and human-driven environmental change. While warming is expected to expand sand fly ranges, the joint effects of long-term climatic variability and land-use change on population dynamics remain poorly understood, largely owing to limited long-term monitoring.

METHODS

We analyzed an 18-year dataset (2005-2021) from a site in semi-arid Ma'ale Adumim, Israel, using CO2-baited traps. Land-cover change was quantified using remote sensing, focusing on the establishment of a managed urban park near the site. Climatic variables from the Israel Meteorological Service and ERA5 were related to interannual variation in abundance and seasonal phenology characters (median seasonal timing and peak timing).

RESULTS

A marked land-cover transformation associated with an irrigated park was identified, increasing dry-season vegetation. Sand fly species showed contrasting long-term trends and phase-dependent responses: Phlebotomus sergenti and P. papatasi were most abundant immediately after landscape modification and declined later, whereas P. tobbi and P. syriacus increased after park establishment. Seasonal activity was strongly species-specific with limited interspecific synchrony. Climatic variability explained little interannual variation overall; only P. tobbi maximum abundance and timing of within-season population increase were associated with the timing of thermal onset.

CONCLUSIONS

Anthropogenic land-use change dominated long-term sand fly population dynamics, often exceeding climatic effects, and altered habitat suitability in species-specific, phase-dependent ways. Integrating land management and spatial planning into prevention strategies is critical for reducing leishmaniasis risk in human-modified landscapes.