Seasonal Trends in Population Size and Survivorship of Anopheles Culicifacies, An. Stephensi and An. Subpictus (Diptera: Culicidae) in Rural Punjab Province, Pakistan1

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Abstract
Adult anopheline mosquitoes were collected resting inside houses and cattle sheds at the rural village of Khano-Harni, Punjab Province, Pakistan, during 1978. Anopheles stephensi was collected throughout the year, and showed bimodal population increases during the spring and postmonsoon seasons. Anopheles culicifacies and An. subpictus were first collected at Khano-Harni at the onset of the monsoon season when populations of both species exhibited sharp initial increases, followed by decreases related to flooding and then increases during the postmonsoon season. An. subpictus populations subsequently declined with the onset of cold weather. Absolute population size estimated by Bailey's modification of the Lincoln Index did not differ significantly from concurrent estimates calculated by ltô's modification of Jackson's positive and negative methods. Temporal patterns in population size agreed with changes in the relative abundance (number collected per man-hour) of An. culicifacies and An. stephensi, but not An. subpictus. Collection of relative-abundance data was hampered, in part, by temperature-related changes in mosquito resting behavior, which affected sampling efficiency. The regression of the number of females in each gonotrophic cycle on female age provided the most appropriate estimate of survivorship for epidemiological purposes. Davidson's method provided slightly higher estimates, since survivorship during the nulliparous period was measured. Horizontal survivorship based on the recapture rate of marked specimens provided lower estimates, since losses due to emigration and sampling were included.