Influence of larval diet and population density on pre-adult developmental rate of laboratory populations of Culex quinquefasciatus (Diptera: Culicidae

Abstract

The influence of larval diet and population density on pre-adult developmental rate, adult population sizes, pre-adult survival and sex ratio was investigated. Mean developmental period varied significantly with low larval densities. Similarly, there were significant variations of developmental periods with different diets. A comparison of the survival rate of larvae fed with the three types of diets showed significant variations (P<0.05). Sex ratio varied significantly from 1:1 ratio in adult raised from larvae fed with milk powder while those raised from liver and liver/milk powder varied non significantly. Mean pre-adult developmental period of larvae fed with milk, liver and milk/liver powder were 15.55±0.76, 9.54±0.32 and 9.68±0.14 days respectively and those for densities of 30L/300ml, 60L/300ml, 150L/300ml and 300L/300ml were 10.60 ±1.36, 11.68 ±2.10, 11.70 ±2.30 and 12.39 ±2.17 days respectively. The mean pre-adult survival for larvae fed with milk, liver and milk/liver powder were 22.88±3.19%, 68.13±6.20% and 66.53±4.75 respectively and those for densities of 30L/300ml, 60L/300ml, 150L/300ml and 300L/300ml were 65.57±17.31%, 49.43±15.68%, 47.4±11.39% and 47.57 ±15.21% respectively. Analysis of the results showed that intra-specific competition was high for diet (food) and effect of density was greater at extreme densities.


KEY WORDS: Larval diet, population density, Pre-adult developmental rate, Laboratory populations, Culex quinquefasciatus.


Tropical Freshwater Biology, 10 (2001) 1 – 8