We studied breeding sites of Phlebotomus orientalis (Diptera: Psychodidae) the vector of visceral leishmaniasis in northern Ethiopia. Although numbers were rather small, 165 sand flies were captured emerging from vertisol cracks. The most productive breeding sites were cracked vertisols, dry river banks and close to trees. No sand flies were caught emerging from sandy clay loam soils in peri-domestic habitats but a few were captured emerging from gaps in a stone wall. Abiotic parameters in vertisols close to trees and in open field from which P. orientalis had emerged, were compared. Soil pH was slightly alkaline and salinity was low. Organic matter contents were similar in both sites. Temperatures and RH remained relatively stable near trees from the end of the rainy season through mid dry season, yet fluctuated markedly at the shallower depth in the open field. During the rainy season, cracks in the soil were sealed resulting in significant lowering of the oxygen concentrations near the tree. Gravimetric water content of soil near trees was lower than open field at shallow depth but similar deeper down. We conclude that ambient conditions suitable for sand fly larvae at shallow depths (45. cm) are restricted to areas close to trees. However, deeper in vertisols (90. cm) suitable conditions are apparently maintained throughout the dry season even in open fallow fields.
Bibliographical noteFunding Information:
This study was supported by the Bill and Melinda Gates Foundation Global Health Program (grant number OPPGH5336 ). We gratefully acknowledge the expert assistance of Tsila Aviad in analyzing soil samples. We also thank Mr. Kiflom Degne and Mr. Henok Tekie for their assistance with the collection of soil samples, and Mr. Aysheshm Kassahun for his assistance in obtaining the permits to export the soil samples.
- Emergence traps
- Phlebotomus orientalis
- Sand fly breeding sites