Population fluctuation of soil and plant parasitic nematodes at Khangabok Wangbal Government silkfarm, Wangbal, Thoubal district Manipur, India.

The population fluctuation of nematodes around the rhizospheric regions of mulberrry plants at Khangabok Wangbal Government Silk farm, Wangbal, Thoubal District, Manipur, India was studied in relation to environmental factors like soil moisture content, soil pH, soil temperature, rainfall and moisture content of air for a consecutive period of three years, 2006-2008. During 2006, nematode population was highest in the month of May with very high rainfall (174.2 mm). Positive correlation of nematode population was found with soil temperature, soil pH, rainfall and relative humidity and negative correlation with soil moisture. During 2007, nematode population was highest in the month of May with least soil moisture and highest rainfall (15.1 p.c. and 190.6 mm). Nematode population had positive correlations with soil moisture, temperature, pH, rainfall and relative humidity of air. During 2008, nematode population was highest in the month of April with highest soil temperature of 24.8 degrees C, 66.0 p.c. moderate relative humidity and 21.0 mm rainfall. There were positive correlation with soil temperature and pH, and negative correlation with soil moisture, rainfall and relative humidity. Lowest nematode population was found during January (2006), and during December (2007, 2008) there were negligible rain and sometimes no rainfall at all. Among all dorylaimids, tylenchids, aphelenchids and mononchids, Helicotylenchus sp. pertain the most numerous nematode species in all the three years and seasons.