Predatory nematodes associated with polyhouse grown flower crops in Himachal Pradesh

Four predatory nematodes (mononchids) viz., Mylonchulus (M. brachyuris), Iotonchus (I. monhystera), Mononchus (M. truncatus) and Clarkus (C. papillatus) were found harbouring the rhizosphere of flower crops (carnation, rose and chrysanthemum), along with plant parasitic nematodes, viz., root-knot nematode (Meloidogyne incognita) spiral nematode (Helicotylenchus dihystera), stunt nematode (Tylenchorhynchus mashhoodi), lesion nematode (Pratylenchus coffeae) and pin nematode (Paratylenchus curvitatus). Among mononchids, highest incidence was recorded for Mononchus (in 73% localities and 34% samples) followed by the Mylonchulus (54% localities and 33% samples), Iotonchus (54% localities and 25% samples) and Clarkus (9% localities and 2% samples). Maximum population density was recorded for Mylonchulus (400 nematodes/200 cc soil), followed by the Iotonchus (180) and the Clarkus (180) while it remained minimum for Mononchus (120). With highest average population of 55, the Mylonchulus dominated the other mononchids. In all the polyhouses sampled, there was recorded reduction in the overall population of plant parasitic nematodes with the increase in mononchid population. Statistically also, negative correlation was being recorded between predatory and parasitic populations in all the localities sampled, which indicated high predatory potential of mononchids against plant parasitic nematodes.