Control of aquatic leeches (Lymnatis nilotica) using Phytolacca dodecandra (Endod) in Sodo District, Gurage Zone, Southern Nations, Nationalities and Peoples Region, Ethiopia

Abstract

Infestation of cattle by leeches and occasional attack of humans is becoming serious problem in some parts of the country. The objective of this study is to investigate the prevalence of leech in selected streams in Sodo district, Southern Nations, Nationalities and Peoples Region and to evaluate the efficacy of endod on leech in field condition and its impact on other non-target aquatic fauna following the request of the district craving for intervention. Estimation of prevalence of leech was assessed before application; 24 hrs, 10 days and 30 days post application of endod based on the number of leeches collected per person per 5 minutes. Findings
from interview of the local communities revealed that 95% of the respondents rated leech as the major animal health problem in the district and 65% of them have seen human infested by leech at least once in their life. The mean leech count per person per 5 minutes before application of endod ranged from 16.8-38 in different streams. Stock solution of endod berries suspended in water for 16 hrs was continuously applied to various streams so as to maintain concentration of 20 g/m3 of water for 6 hrs. Application of endod caused mortality of most of the leech population resulting in 97-100% reduction which persisted for minimum of 30 days post application in most of the streams. Most of the local communities witnessed that endod rendered the treated water bodies free of leech for 2-3 months. It has also caused mortality of tadpoles, frogs and round worms found in streams while it doesn’t cause any visible toxicity to different water insects. Moreover, no livestock toxicity due to endod was recorded post application. In conclusion, endod can be used to control leech without causing serious toxicity to most of the aquatic fauna, human and livestock with continuous application for 6 hrs at concentration of 20 g/m3. However, care should be taken in using appropriate concentration and it should not be used in water bodies that contain fish because it is toxic to fish at the dose required to control leeches.

Keywords: Aquatic Leech/Lymnatis nilotica; Cattle; Phytolacca dodecandra/Endod; Stream; Sodo district