A Comparative Study of Growth and Development in Florida Mosquitoes1: Part I: Effects of environmental factors on ontogenetic timings, endogenous diurnal rhythm and synchrony of pupation and emergence

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Abstract
A comparative study of 15 mosquito species of Florida showed that at a constant temperature of 27°C under LD 12 : 12, ontogenetic timings. endogenous diurnal rhythm and synchrony of pupation were affected by a combination of environmental factors such as quantity of food, density of larvae and salinity of the medium. The 15 species were reared on the same standard basic ration, showing that qualitative nutritional requirements were similar. The delay in onset of pupation and prolongation of pupal ecdyses were effected by lowering the quantity of food, increasing the number of larvae/pan and increasing the salinity of the medium. The duration of the pupal stage in all these species was temperature dependent, i.e., the resultant pattern of emergence repeated the pupation pattern after a time lapse set by temperature. By manipulatng the rearing environment, 2 distinct aspects of pupation were controlled: (a) diurnal rhythm of pupation and (b) synchronization of total brood. Of the 15 species studied, 4 (A. sollicitans, P. confinnis, C. bahamensis and An. c. bradleyi) showed distinct diurnal rhythmicity in pupation under all combinations of factors in the rearing environment. In C. p. quinquefaciatus a bimodal diurnal rhythm became dear only when larvae were reared on the minimum quantity of food. In the 10 other species no indications of diurnal rhythmicity were evident. In 5 species found exhibiting it the patterns of diurnal rhythm of pupation showed that the mean time of day for the peak of pupation and the S.D. of peak were species-specific at a constant temperature. Increased synchronization of pupal ecdysis was brought about in 4 species under LD 12 : 12 in combination with other factors of the rearing environment, such as higher quantity of food, lesser density of larvae and lower salinity of the medium; whereas in the other 6 species crowding of larvae along with a higher quantity of food enhanced synchronization of the larval population while masking over the effect of LD 12 : 12 regime. In 2 species only, synchronization could not be improved under any combination of rearing factors at 27°C under LD 12 : 12. A growth variability index has been calculated which showed that all the species which possess endogenous diurnal rhythm of pupation exhibit higher values of this index.

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