Abstract:
Aims: To evaluate the Ovicidal and larvicidal effects of Ricinus communis
(Euphorbiaceae) extracts on Phlebotomus duboscqi.
Study Design: A comparative experimental design using extracts obtained from the leaf and bark
of Ricinus communis plant.
Study Site: Kenya Medical Research Institute, Centre for Biotechnology Research and
Development (CBRD), Nairobi Kenya from January to July, 2015.
Methodology: Aqueous, methanol and ethyl acetate extracts were prepared from
Ricinuscommunis plant. Freshly laid eggs were moistened with 1 ml of each extract separately
during the incubation period. Larvae were also fed on larval food mixed with the powdered crude
extract and a
second group was fed on larval food sprinkled with 5 ml of each extract daily.
Results: No significant difference when bark and leaf extracts were compared (P=0.061).
250 µg/ml and 500 µg/ml of extract eroded all the chorionic membranes of the egg shell while
egg
hatchability was significantly inhibited with only 7%, 9% and 26% of eggs hatching at 500
µg/ml of
aqueous, methanol and ethyl acetate extracts respectively (P<0.001). 100% larval mortality
noted
when at 500 µg/ml methanol extract. The larval period was prolonged to 87 days with the life
cycle
lasting for 101 days.
Conclusion: R. communis extracts have deleterious effects on hatching of eggs, larval and pupal
development and adult emergence of P. duboscqi; hence R. communis should be used
against
sand flies and Leishmania in situ.
