Plant-Feeding Behaviour and its Efects on the Fitness and Competence of the Malaria Vector Anopheles Gambiae (Diptera: Culicidae)

Malaria remains a serious threat in sub-Saharan Africa Available control tools are now largely ineffective. Because of the role of vectors in malaria transmission, integrated vector management strategies that are environmentally safe, economically feasible and acceptable to resource-limited communities are one way to achieve effective malaria control. However, adequate knowledge of the biology, behaviour and ecology of the malaria vectors are imperative. Sugar-feeding from plants is a basic requirement for adult mosquitoes, and so far have received little attention. The present study, conducted in Suba district (a malaria endemic area of western Kenya), aimed to investigate the plant-feeding behaviour and its effects on the fitness and competence of Anopheles gambiae. Females of two species of Anopheles gambiae s.l. namely Anopheles gambiae s.s ., and Anopheles arabiensis were sampled during both dry and wet seasons. Approximately 12% were fructose-positive at the time of collection, indicating recent plant-feeding. Proportions of plant-fed mosquitoes were similar in all the 2 Anopheles species (P=0.90), at all their gonotrophic status (unfed, blood-fed, half-gravid, and gravid) (P=0.69), at all ages (parous and nulliparous) (P=0.98), and during both seasons (P=0.06). However, more mosquitoes had fed on plants when collected far from larval habitats (P=0.001). When offered 13 dominant plant species [Cassia hirsuta L., Senna bicapsularis L., Senna didymobotrya F. (Leguminosae), Datura stramonium L. (Solanaceae), Flaveria trinervia M., Parthenium hysterophorus L., Psiada punctulata V., Tithonia diversifolia H. (Asteraceae), Hamelia patens J. (Rubiaceae), lpomea hildebrandtie V. (Convolvulaceae), Lantana camara L. (Verbenaceae), Ricinus communis L. (Euphorbiaceae), Tecoma stans L. (Bignoniaceae)] growing around human dwellings and mosquito larval habitats in the study area, behavioural responses of mosquitoes to those candidate plants were recorded in the greenhouse, each plant being presented to mosquitoes singly, and concurrently with other plants species in the no-choice and choice bioassays respectively. Gas chromatography analysis was carried out to determine and compare plants and mosquito sugar profiles. Five plants species were found to be most preferred by Anopheles gambiae, namely; Ricinus communis L., Senna didymobotrya F., Parthenium hysterophorus L., Tecoma stans L., and Hamelia patens J (P