CLUMPING OF PLANT PARASITIC NEMATODE DITYLENCHUS DIPSACI IN WATER

Aggregation of D. dipsaci in deep water seems to depend initially on external factors to bring the nematodes into close contact with one another. Clumping does not depend on sensory attraction. A proportion of the nematodes present must be active to form clumps by random interlocking. Accretion of clumps is by chance entry of nematodes whose movement is thereby restrained and by actively ″ hooking″ nematodes within the clump becoming interlocked with some outside it. Clumps are essentially dynamic aggregations and weak convection currents can favour clumping or dispersion according to their direction relative to the largest densities of nematodes. © 1968 BRILL.