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Seasonal abundance of Lutzomyia longipalpis (Diptera: Psychodidae) at an endemic focus of visceral leishmaniasis in Colombia

Morrison, A.C., Ferro, C., Pardo, R., Torres, M., Devlin, B., Wilson, M.L., Tesh, R.B.
Journal of medical entomology 1995 v.32 no.4 pp. 538-548
Lutzomyia longipalpis, disease vectors, leishmaniasis, population dynamics, temperature, relative humidity, rain, seasonal variation, rural areas, time series analysis, Colombia
Ecological studies on the sand fly Lutzomyia longipalpis (Lutz & Neiva) were conducted during 1990-1993 in a small rural community in Colombia where American visceral leishmaniasis is endemic. Standardized weekly sand fly collections made from pigpens and natural resting sites displayed a bimodal annual abundance cycle, with a small peak occurring in October-November and a larger one in April-May. Time series analysis was employed to quantify the associations between sand fly abundance and weather factors (temperature, relative humidity, and rainfall). In addition to a prominent 6-mo cycle, Fourier analysis of the collection data demonstrated that the L. longipalpis population also exhibited a 5- to 8-wk cycle that may represent the length of larval development. Autoregressive moving average models were fit to weekly collection data and their residuals were regressed against rainfall, temperature, and relative humidity. A significant positive association between female L. longipalpis abundance and the relative humidity and rainfall recorded 3 wk earlier was found, indicating that these factors may be of value in predicting sand fly abundance. Additionally, these data indicated that L. longipalpis larvae may become quiescent during adverse conditions.