Posture changes in Helicotylenchus indicus as influenced by copper sulphate and temperature

Abstract

Nematodes upon relaxation assume a posture which is characteristic and thus may be useful in their identification. The plant parasitic nematodes of the genera Rotylenchus Filipjev, 1936 and Helicotylenchus Steiner, 1945 are typical examples of posture characteristics, as they assume a spiral posture upon death or on relaxation with gentle heating. Helicotylenchus indicus Siddiqi, 1963 assumes a characteristic flat spiral posture when relaxed. Any change in the media (environment) in which they live disturbs their normal spiral posture. The posture of nematodes is influenced by physical and chemical stimuli due to abnormal neuro-muscular activity and hence such changes provide a useful tool for the study of nematode behaviour. Recently Keeth (1974) has studied the effect of aldicarb on the posture of Aphelenchus avenae. Jairajpuri et al. (1975) have studied the effect of copper sulphate on some nematodes and came to the conclusion that lower concentrations (0.025 M) of this salt is not very toxic to H. indicus. The postural patterns of nematodes show its activity viz., resting or locomotory state. A sudden change in the temperature produces marked changes in their posture. The present paper deals with the changes that occur in the posture of H. indicus when treated with copper sulphate solution, and also in response to very high or very low temperatures.