Responses of the plant parasitic nematodes Rotylenchulus reniformis, Anguina agrostis and Meloidogyne javanica to chemical attractants.

Rotylenchulus reniformis, Anguina agrostis and Meloidogyne javanica respond differently to gradients of chemical attractants. In chemotaxis assays performed on agarose plates, R. reniformis L2 larvae oriented their movement to several common inorganic salts, cyclic AMP and AMP, as well as to germinated host plant seeds. M. javanica L2 larvae were attracted to germinated seeds, but not to the salts tested, and A. agrostis dauer larvae were not strongly attracted to any of 12 different tested agents, including host root or shoot tips. Attraction of R. reniformis to salts was measured by comparing different pairwise combinations of ions at equivalent concentrations. The indicated order of attractiveness was: Cl- greater than Na+ greater than C2H3O2- greater than Mg2+, NH4+, SO4(2-). The least attractive salts, (NH4)2 SO4 and MgSO4, were weakly attractive at an orientation threshold of 1 mM, whereas the most attractive salt, MgCl2, was strongly attractive at a threshold of 0.2 mM Cl-. 3',5' cyclic AMP was strongly attractive at a threshold of 0.05 mM, whereas 5'-AMP was a weak attractant. Some of these responses may affect the distribution of R. reniformis in its natural environment.