Life-table analysis of Anopheles malaria vectors: generational mortality as tool in mosquito vector abundance and control studies.

BACKGROUND & OBJECTIVES Vector control will for sometime remain a primary weapon in the war against vector borne diseases. Malaria is of paramount importance in this with its associated high morbidity and mortality especially in sub-Saharan Africa. This study on generational mortality associated factors in Anopheles mosquitoes life-table analysis was designed to investigate the fecundity, levels of mortality and mortality associated factors at the aquatic stages of anopheline malaria vectors. METHODS Mortality associated factors were investigated at the eggs, I and II instar larval, III and IV instar larval and pupal stages of two anopheline species--Anopheles pseudopunctipennis (Theobald) and An. gambiae life-cycles in screen cages. Adult male and female mosquitoes were membrane filter-fed and algae in culture medium formed the bulk of food substances for the larval stage. Environmental temperature of culture media, pH and some associated physio-chemical factors were also determined. RESULTS Results showed significant mortality rates at various aquatic stages. Infertility, cannibalism and environmental factors were the major factors responsible for mortality at the egg, larval and pupal stages respectively. INTERPRETATION & CONCLUSION The aquatic stages of Anopheles mosquito mortality factor K and the mortality factors at the various stages investigated k1, k2, k3 and k4 are discussed. Our recommendations include further studies on the possible genetic modification of predacious An. pseudopunctipennis larvae and/or its modification for the production of sterile/infertile eggs as possible alternatives in the reduction and control of anopheline malaria burden.