Estimate of survivorship of immature stages of the mosquito Armigeres subalbatus (Coquillett, 1898)

Abstract

The survivorship of immature stages of the mosquito Armigeres subalbatus (Coquillett, 1898) (Diptera: Culicidae) was evaluated under laboratory and field conditions. In the laboratory, the average time taken by the immature stages to reach the adult stage was less in summer (9.1 days) compared to winter (15.3 days), probably owing to seasonal temperature differences. Survival of eggs to the pupal stage varied between 56% and 75% in the laboratory and 9–60% in field conditions, depending on the season. The instar duration and stage-specific survivorship varied significantly with the season. Field data revealed that cohort survival was highest during the monsoon season and lowest in summer. In a sewage drain habitat, the spatial distribution of larvae and pupae remained highly aggregated as reflected in the coefficient of variation values (consistently > 1). A stable age distribution in terms of constancy in proportions of different immature stages over time was lacking in the sewage drains, possibly due to cannibalism and predation by co-occurring predatory mosquito larvae. The life table parameters of A. subalbatus reveal that the abundance of this mosquito varied with season, though a viable population level may exist throughout the year, posing a public health problem as a vector and nuisance pest.