A release-recapture experiment with the malaria vector, Anopheles stephensi Liston, with observations on dispersal, survivorship, population size, gonotrophic rhythm and mating behaviour.

10 118 female and 10 863 male Anopheles stephensi were released on three successive nights at a breeding site near the village of Sattoki, Punjab Province, Pakistan during early May, 1977. A total of 721 (7.13%) females and 505 (4.65%) males were recaptured resting indoors, feeding on buffaloes and swarming. The average distance dispersed for females and males recaptured resting inside 13 cattle sheds within 2.17 km of the release point was 165.5 m and 184.8 m, respectively. The maximum longevity of the marked females and males was 12 and 13 days, respectively (mean longevity 3.24 and 3.26 days, respectively). Population size was estimated for the first five days after release using the Lincoln Index modified to account for survivorship, and Jackson's positive and negative methods. Estimates of population size at the two cattle sheds nearest the release point ranged from 1294.7--2551.7 for females and from 481.6--1374.3 for males, considerably less than the size of the released cohort. Marked males from all three releases were collected while swarming with wild males. Inseminated marked and unmarked females were captured at male swarms. Females mated on the night of release, some within 15 minutes of release. Mating here presumably occurred while the females were transversing the 45 metres from the release point to the site of the buffalo biting collections. Both inseminated and uninseminated females were collected feeding on buffaloes. The first gonotrophic cycle was completed when the females were three to four days old, i.e. two to three days after release.