Effects of larval and pupal environmental factors on biological status of adults at emergence inAedes taeniorhynchus(Wied.)

Abstract

Adults ofAedes taeniorhynchus(Wied.) were reared from larvae under five environmental variables—quantity of food, density of larvae, salinity of medium, light regime and temperature—singly and in combination. On emergence these adults were analysed for morphological characteristics, dry body weights, energy reserves and autogeny.The minimal expression of adult characteristics and autogeny was effected by lack of food, crowding of larvae, and higher salinity, singly and in combination, at a constant temperature of 27°C. These three factors in turn showed a distinct relationship with delay in onset and prolongation of pupal ecdysis.The maximal expression of adult characteristics and autogeny was found when 75 to 100 larvae per pan were reared on 2 × - or 4 × -basic ration in 10 to 25 per cent, sea water at 27°C. under alternating 12-hr. light-dark cycles. Above the optimal quantity of food,i.e., 2 × -basic ration, there was almost no enhanced effect on the adult characteristics; in fact, with 4 × - and 8 × -basic ration the morphological characteristics were suppressed. Of the three light regimes, continuous light produced adults that were largest, heaviest, had the most energy reserves and the highest level of autogeny. Adults reared on 4 × -basic ration in ten per cent, sea water under alternating 12-hr. light-dark cycles and at temperatures from 24 to 34°C. showed that even though largest mosquitos were obtained at 24°C, the heaviest mosquitos with maximal lipid and glycogen contents and maximal expression of autogeny were found at 28 and 30°C. Temperature changes during the pupal stage did not affect the adult characteristics.Temperature and light regimes show distinct complex effects on adults at emergence, but the quantity of food, density of larvae and salinity of the rearing medium are more important.