Population Ecology and community structure of plant parasitic nematodes associated with coconut and arecanut in northern West Bengal

Ecological study of plant parasitic nematodes associated with cocount and arecanut in Darjeeling, Jalpaiguri and Cooch Behar districts in the northern parts of West Bengal was undertaken. Pratylenchus coffeae, P. brachyurus, Helicotylenchus elegans, H. mucronatus, Ditylenchus triformis, Criconemella onoensis. Nothotylenchus acutus and Meloidogyne incognita were found associated with coconut and arecanut for the first time in descending order of importance value. Scutellonem brachyurum, Rolylenchulus reniformis, Helicotylenchus elegans were important in coconut. In arecanut, the nematodes of importance were Rolylenchulus reniformis, Hoplolaimus seinhorsti, and Meloidogyne spp. Pratylenchus spp. populations were affected most by rainfall pattern; P. coffeae, P. brachyurus, R. reniformis were more strongly influenced by cropping pattern, plantation age and orchard practices than by other factors; M. incognita was more influenced by topography and soil texture; S. brachyurum by weather and seasonal factors, while P. brachyurus was related to seasonal and vertical distribution. In terms of pathogenic significance ranking. R. reniformis, S. brachyurum, Meloidogyne spp., Helicotylenchus spp. and Pratylenchus spp. in coconut, and Meloidogyne spp., R. reniformis, Pratylenchus zeae and Helicotylenchus spp. in arecanut should receive attention for management. Cluster analysis has been used to determine the levels of agro-ecological similarilies among the sites surveyed.