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.
