Evaluation of Endod (Phytolacca dodecandra: Phytolaccaceae) as a Larvicide Against Anopheles arabiensis, the Principal Vector of Malaria in Ethiopia.

Malaria control methods rely mostly on adult mosquito control using insecticide-treated nets and indoor residual spraying with insecticides. Plants such as endod (Phytolacca dodecandra) can potentially be used for the control of mosquito larvae as a supplement to adult control methods. Following the discovery of endod, a molluscicide plant, more than 5 decades ago in Ethiopia, subsequent studies have shown that its potency can further be increased by simple procedures such as aging endod berry powder in water. This study was conducted to evaluate the killing effect of fresh and aged endod solution against 4th-stage larvae of Anopheles arabiensis. Laboratory-reared An. arabiensis larvae exposed to different concentrations of endod preparation using distilled or spring water had 50% lethal concentration (LC(50))  =  49.6 ppm and 90% lethal concentration (LC(90))  =  234 ppm for fresh and LC(50)  =  36.4 ppm and LC(90)  =  115.7 ppm for the aged endod solution in distilled water against the laboratory population. Against field-collected larvae of the same species, aged preparations in habitat water resulted in higher LC(50) (472.7 ppm) and LC(90) (691 ppm) values, with only a slight improvement over fresh preparations in habitat water (LC(50)  =  456.2 ppm; LC(90)  =  896.1 ppm). In general, although aged preparations of endod required lower concentrations than fresh to kill at least 90% of the larvae, these concentrations were much higher (12-70×) than that required for schistosome-transmitting snails.

Repellent efficacy of DEET, MyggA, neem (Azedirachta indica) oil and chinaberry (Melia azedarach) oil against Anopheles arabiensis, the principal malaria vector in Ethiopia.

BACKGROUND: In Ethiopia, Anopheles arabiensis is the main vector responsible for the transmission of malaria in the country and its control mainly involves application of indoor residual spraying (IRS) and use of insecticide-treated bed nets (ITNs). OBJECTIVE: Although the role of repellents for reducing man-vector contact is documented in the literature, the response of An. arabiensis to repellents was not previously evaluated under field conditions in Ethiopia. METHOD: The trial was conducted in Sodere village assessing the repellent activities of four repellents, of which, two of them were commercially available DEET (N, N-diethyl-1,3-methylbenzamide) and MyggA (p-methane diol) and the other two were laboratory- produced, 20% neem oil and 20% chinaberry oil. A 6 by 6 Latin square design was employed by involving six volunteers who received rotated treatments of repellents and the Ethiopian Niger seed, noog abyssinia (Guizotia abyssinia), and locally called as noog oil (diluents to the two plant oils). Each volunteer also served as control. Volunteers were positioned at a distance of 20-40 m from each other and each was treated with one of the repellents, Niger seed/noog/ oil or untreated. Landing mosquitoes were collected from dusk to down using tests tubes. The tests were done in three replicates. RESULTS: Both DEET and MyggA provided more than 96% protection. The mean protection time for DEET was 8 hrs while the time for MyggA was 6 hrs. Protection obtained from neem oil and chinaberry oil was almost similar (more than 70%), however, the complete protection time for neem was 3 hrs, while that of chinaberry oil was one hour. CONCLUSION: The commercial products and laboratory-produced repellents can be utilized by individuals to avoid contact with An. arabiensis in Ethiopia.

Laboratory and field evaluation of neem (Azadirachta indica A. Juss) and Chinaberry (Melia azedarach L.) oils as repellents against Phlebotomus orientalis and P. bergeroti (Diptera: Psychodidae) in Ethiopia.

The study evaluated the efficacy of neem (Azadirachta indica A. Juss.) and Chinaberry (Melia azedarach L.) seed oils as repellents against laboratory and field populations of some sandflies in Ethiopia. In the laboratory, concentrations of 2% and 5% neem oil in coconut oil tested against Phlebotomus orientalis (vector of visceral leishmaniasis) provided 96.28% (95% CI=95.60-96.97) protection up to a mean time of 7h and 20 min and 98.26% (95% CI=93.46-104. 07) protection up to 9h, respectively. Similarly, M. azedarach oil at 2% concentration produced 95.13% (95% CI=90.74-99.52) protection for the same duration (7h and 20 min), while the 5% oil gave 96.20 (95% CI=86.98-105.41) protection for 8h and 20 min against the same species with no significant difference in percentage protection between the two oils at 2% and 5% concentrations. In the field tests with only neem oil (A. indica) against field populations of P. orientalis and P. bergeroti, similar high level of repellencies were recorded with about the same duration of protection. Application of both neem and Chinaberry oils can be safe and low-cost means of personal protection against sandfly bites in endemic areas of Ethiopia, if the community is advised and encouraged to grow the plants abundantly.