MOVEMENT OF EELWORMS II. A COMPARATIVE STUDY OF THE MOVEMENT IN SOIL OF HETERODERA SCHACHTII SCHMIDT AND OF DITYLENCHUS DIPSACI (KUHN) FILIPJEV

Studies of mobility in horizontal tubes containing different soil fractions at different suctions and in single layers of particles, showed that the optimum particle size for movement of Heterodera schachtii and Ditylenchus dipsaci was 150-250 and 250-500 mu, respectively. In both species mobility was greatest when (a) there were few pores smaller in diameter than the eelworm width, (b) the pore diameter was narrow enough to restrict lateral movement, (c) the tortuosity of the channels between particles was such that the body form of the eelwom had waves of long wave-length and short amplitude. By plotting tracks among water droplets it was possible to show quantitatively the relationship between the form of the body waves and the speed of the eelworms. The optimum temperature for movement was 15 degrees C. for H. schachtii and 15-20 degrees C. for D. dipsaci. The comparative study suggested that there was a simple relationship between body length, particle size and speed.