Evaluation of the predatory behaviour of Dorylaimus stagnalis - Dujardin, 1845 (Nematoda: Dorylaimida )

Abstract

Observations on the predatory behaviour of Dorylaimus stagnalis Dujardin, 1845 were made in agar-plates. Predation was on chance encounters. Predators were not attracted towards live (non-excised) or excised prey. D. stagnalis probed over a short distance along any part of the body of prey and paralysed it by disorganizing its interna1 body organs with the help of their odontostyle. Ingestion of prey contents was intermittent and duration of feeding lasted for 85 mn (25-180 mn) on Rhubditis sp., and 70 mn (15-150 mn) on Hirschmanniella oyzae. Rhabditis sp. was prefered most while Acrobeloides sp., Tylenchorhynchus mashhoodi and Helicotylelzchus indicus the least. No specimen of Hoplolaimus indicus was either injured or killed by the predators. There was no difference in the rate of predation over a period which Iasted for ten days. Adults (male and female) preyed more than their younger stages. Al1 factors viz., prey number, temperature and agar concentration influenced predation by D. stagnalis except the starvation of predators. Maximum predation took place when predators were placed in a population of 125 individuals of prey. Agar conctntrations 1, 2 and 3% and temperatures 25° and 30° were most suitable for predation by D. stagnalis.