NUMERICAL ANALYSIS OF THE PREDATORY RELATIONS BETWEEN MESODORYLAIMUS BASTIANI (NEMATODA: DORYLAIMIDA) AND DIFFERENT PREY TROPHIC CATEGORIES

Abstract

Numerical analysis of relations between the predator Mesodorylaimus bastiani and prey nematodes belonging to five trophic groups viz., bacteriophagous, endoparasitic, ectoparasitic-epidermal feeders, ectoparasitic-cortical feeders and predaceous nematodes was made. Predators were most successful on endo-parasitic nematodes. Predaceous nematodes as prey exhibited high degree of resistance against predation by M. bastiani. Only 11% attacks resulted in wounding out of 31% encounters that resulted in attacks. Physical characteristics viz., thick body cuticle, body annulations, thick longitudinal cuticular folds are hyptothesised as the cause of 100% resistance of Hoploaimus indicus, Hemicriconemoides mangiferae, Hemicycliophora dhirenderi and Dorylaimus stagnalis. Mononchoides fortidens, M. longicaudatus and Mylonchulus minor also appeared to have resisted predation by their cuticular characteristics and behavioural patterns. Low strike rate of M. bastiani and less feeding after wounding on Helicotylenchus indicus has been attributed to repulsive/unattractive prey secretions (chemical resistance). Feeding time required to consume an individual depended upon size of the prey, maximum being on Paralongidorus citri and minimum on Cephalobus sp. The body cuticle, cuticle texture, quality, quantity and chemical composition of prey contents also influenced feeding by predators on different prey.