Studies on bionomics of haemadipsa sylvestris blanchard and antileech properties of some plants of Jorhat area of Assam

Abstract

Among the blood sucking animals, leeches occupy a prominent position throughout the world, except in the polar zones, deserts and altitudes exceeding 3700 metres. The common leeches of India belong to the genera viz., HIRUDINARIA Whitman, HAEMADIPSA Tennent, HIRUDO Linn and DINOBDELLA Moore. They thrive in situations where moist humus prevails and are known to be plentiful in rain forests and acidic soils, upto altitudes of 2,500 metres. They are also commonly distributed in Assam over the tea growing areas, humid grazing lands, shrubby undergrowths, rice fields, swamps, buffalo wallows and ponds. Leeches are known for causing great nuisance to man and lifestock. Land leeches belonging to the genus HAEMADIPSA are particularly trouble-some because of their teeming abundance and their wide dissemination particularly with the help of birds and different animals. Haemadipsa sylvestris (Blanchard), Haemadipsa ornata (Moore), Haemadipsa zeylanica montivin-dicis (Moore), and Haemadipsa zeylanica (Moquin Tandon) are the species of land leeches commonly observed in Assam and Arunachal Pradesh (Koshi and Verma, 1965). Like many of the species of land leeches, H. sylvestris (Blanchard) cause very painful bites. There are views that H. sylvestris some times enters water voluntarily during dry season and swims actively (Moore, 1927). About the bionomics and life history of this species adequate elabo-rations are not available, except certain descriptions about the egg capsules and young leeches, including distribution and feeding habits (Stammers, 1950; Koshi and Verma, 1965). Therefore, the present investigation was undertaken to evaluate the bionomics of H. sylvestris under Jorhat conditions of Assam in relation to certain environmental parameters and also to screen some plants possessing anti-leech properties, as plant based chemicals are now globally preferred to the synthetics which are notably poisonous and their use has contaminated the ecosystem to a considerable extent due to their persis-tency and consequent...