Abstract
Studies on Allodorylaimus americanus and Discolaimus silvicolus revealed that these predators are similar in their predatory behaviour and requirements. The predator-prey relationship measured for one species strongly supports the observations made for the other predator. The prey catching and feeding mechanisms consist of five phases viz., encounter with prey, attack-response, attack, extra-corporeal digestion/salivation and ingestion/feeding. Predators were not attracted towards live and intact prey but responded positively towards excised prey. Both species of predators preferred second-stage juveniles of M. incognita, A. tritici, H. mothi and T. semipenetrans. No individual of Hoplolaimus indicus, Helicotylenchus indicus and Hemicycliophora dhirenderi was either injured or killed. Temperature, agar concentration, age of predators, prey density etc., affected predation but starvation of predators did not show any effect. Both predators achieved maximum success on endo-parasitic nematodes (SR = 90%). Cortical and epidermal feeders exhibited maximum resistance (PR = 55-65%). Maximum feeding after wounding occured on endo-parasitic nematodes. Hoplolaimus indicus, Helicotylenchus indicus and H. dhirenderi were 100% resistant to predation. A significant correlation was observed between encounters resulting in attack and attack resulting in wounding and feeding after wounding except for endoparasites for A. americanus and cortical feeders for D. silvicolus. Various physical, chemical and behavioural characteristics are attributed to different degrees of resistance in prey nematodes. Female predators probed their own eggs when they came in contact but attacked, punctured and fed on eggs of prey nematodes (Rhabditis sp.). Predators took maximum time to consume an individual of Longidorus sp. (FT = 61-68m) and minimum time to T. semipenetrans (FT = 22-25m).