Age-grading of Culex pipiens fatigans Wiedemann from different climatic zones in Ceylon
Lambrecht, F.L.; Fernando, J.B.
Southeast Asian Journal of Tropical Medicine and Public Health 5(1): 76-79
1974
ISSN/ISBN: 0125-1562 PMID: 4839085 Document Number: 73048
Culex pipiens fatigans Wied. is found everywhere in Ceylon but filariasis caused by Wuchereria bancrofti is confined to the south-western coastal belt. Samples of C. p. fatigans were collected in this belt and from the dry zones of the country throughout 1971 and dissected for infection with filariae and to determine the number of dilatations in the ovarioles. Females with three or more dilatations were deemed to be potential carriers of infective larvae of W. bancrofti. The average percentages of potential carriers among the total population were 3.3-13.6 in the coastal belt and 1.0-3.0 in the dry zones. The greater mean age of the population in the wetter area was probably the result of the higher rainfall there, but monthly observations in the coastal area over the year point to a negative correlation with rainfall there. Also, the relative humidity readings were similar in the two zones, and probably differences in the microclimate in the resting places is a more likely explanation of the findings.