Acaricidal Activity of Tephrosia vogelii Extracts on Nymph and Adult Ticks.

Abstract

Botanical pesticides exist within nearly all vector disease endemic communities of the world. Natural/' botanical tick control methods offer several advantages over synthetic tick control including environmental preservation smce they have sh01ter residual periods with rapid action. Tephrosia vogelñ a shmbby, legummous and woody plant is one of the potential candidates to provide afforthble botanical acaricides. However, its effectiveness in the control of Acarina has not been fully explored in developing countries. Tephrosia vogelii plant materials were collected from two selected sites, one on a higher altitude than the other. The air-dry plant material was cmshecl into powder; and extracted with a known volume of solvent. The mixture was left to stand for seven days with daily stilTing for at least 2 h. Extracts from shoot, cortex and roots have an average yield of 0.06, 0.05 and 0.015 g per one gram of plant raw material, respectively. Shoot and cortex plant parts accumulate relatively high amounts of the active ingredients in Tephrosia compared to the roots• probably explaining why leaves (shoot) are prefe1Tecl by the local fanners for effective pest control. Methanol, Petroleum ether and Chlorof01Ä11 yield 0.0875, 0.0142 and 0.0172 g per one gram of plant raw material, respectively, indicating a significantly valuable yield when methanol is used for extraction than any of the other two solvents or water. All extracts killed 100% of the exposed ticks but variations where noted in the time taken to achieve 100% exposed tick death Petroleum ether, chloroform, methanol and water extracts killed 1 0 of the ticks in an average time of 8.3, 9.7, 10.3 and I .3 days, respectively; Implying that ticks are more susceptible to the active ingredient extracted usl_ng petroleum ether relative to the other solvents. Tephrosia crude extracts can potentially, therefore, be used to effectively control ticks in the Ugandan animal production systems. Photosynthesis and plant respiration seem to have an effect on the production and storage of the active ingredients in Tephrosia with the more effective active ingredients being found in the early moml_ng. Key words: Acaricithl activity, vector disease, cholorofomm, photosynthesis, plant respiration