NOCTURNAL ACTIVITY PATTERNS OF LUTZOMYIA-LONGIPALPIS (DIPTERA, PSYCHODIDAE) AT AN ENDEMIC FOCUS OF VISCERAL LEISHMANIASIS IN COLOMBIA

Nocturnal activity of the sand fly Lutzomyia longipalpis (Lutz and Nei va) was studied from August 1991 to July 1992 in a small rural communi ty in Colombia where American visceral leishmaniasis is endemic. Durin g 2 or 3 nights each month, sand flies were collected with hand-held a spirators each hour between 1730 and 0630 hours, from a pigpen and a c attle corral located 30 m apart. Host-seeking activity of L. longipalp is adults was characterized by 2 general patterns: (1) adult sand fly activity increased shortly after sunset and continued until just after sunrise, and (2) peak sand fly activity was greatest early in the eve ning (1830-2330 hours) and then declined steadily tow ard morning. Fem ale L. longipalpis activity generally increased after 2030 hours, wher eas that of males remained constant or declined as the evening progres sed. There were seasonal differences in sand fly abundance between the 2 sites: peak abundance in the cattle corral occurred during hot, dry periods, whereas maximum abundance in the pigpen occurred when relati ve humidity uas higher. Influence of relative humidity on activity var ied with season. Sand fly activity tended to decrease at temperatures below 24 degrees C and increase in the presence of moonlight.