IMPACT OF SMOKING LOCAL MEDICINAL PLANTS ON INDOOR DENSITY AND FEEDING ACTIVITIES OF MALARIA VECTORS: EVIDENCE FROM FIELD AND TENT EXPERIMENTS IN KOLLA SHARA IN ARBA MINCH AREA, SOUTH WEST ETHIOPIA

Abstract

Malaria has declined in many malaria endemic countries due to the massive scale-up of indoor based vector control interventions. However, the early biting malaria vectors may threaten the gains by maintaining the residual malaria transmission. Hence, supplementary malaria vector control tools are needed to reduce residual malaria transmission. This study aimed to evaluate the impact of smoking Juniperus procera, Eucalyptus globulus and Olea europaea on indoor density and feeding activity of malaria vectors in Kolla Shara village, south west Ethiopia. Five grass thatched traditional huts were selected for the field trial. A Latin square design was used to minimize the bias due to the variation in mosquito catching skills and different sampling nights. Anopheles mosquito larvae and pupae were collected from natural breeding habitats in the village and reared into adults for the tent experiment. Twenty adult An. gambiae complex were released into each tent to evaluate the effect of smoking the plants on knockdown and their feeding activities. An. gambiae s.l., An. demeilloni, An. funestus-group, An. pretoriensis and An. pharoensis were documented in the field collection. J. procera, E. globulus and O. europea significantly reduced indoor density of An. gambiae complex with mean percentage reduction of 80%, 73% and 70% respectively compared to the control. In the tent trial, smoking the plants had significant effect on feeding activity of An. gambiae complex and has induced knockdown effects. The plants significantly inhibited An. gambiae complex attempted to feed on cattle kept inside the tents (F = 383.5, DF =3, P < 0.01). O. europaea (18.9±0.24) induced relatively higher mean feeding inhibition followed by E. globulus (17.9±37) and J. procera (17.2±0.34), while it was 3.9±0.42 in control tents. In conclusion, smoking J. procera E. globulus and O. europea had significant effect on indoor density of host seeking malaria vectors and have inhibited feeding in the tent trials. Therefore, plant-based mosquito control may play role in reducing mosquito biting at early hours and thereby reduce malaria transmission during the early hours of the night. However, further study is recommended for isolation and identification of bio-active molecules of these test plants and their mode of action to prepare products that could be commercialized and used as potent supplementary control options.