Effect of attachment of Corynebacterium rathayi on movement of Anguina agrostis larvae

Bird A. F. and Riddle D. L. 1984. Effect of attachment of Corynebacterium rathayi on movement of Anguina agrostis larvae. International Journal for Parasitology 14: 503–511. The movement of freshly hatched larvae (FHL₂) and dauer larvae (DL₂) of Anguina agrostis was compared on ‘agarose’ plates. The DL₂S moved faster and over greater distances. They were not attracted to Corynebacterium rathayi on agar plates, but contact with this bacterium, in most instances, markedly reduced their speed of movement. This reduction was found to be approximately proportional to the concentration of the bacteria (from 8 × 10⁵ to 8 × 10⁸ per ml) to which the DL₂ were exposed prior to observation of their movement, as was the number of bacteria observed to be adhering when viewed under the light microscope. This type of bacterial attachment appeared to be largely stage specific as it was much more pronounced and characteristically different in the DL₂ from that in the FHL₂. This interaction between the DL₂ and the bacterium was similar in material from fresh and from rehydrated nematode galls so that it was apparently not dependent on any surface cuticular changes associated with anhydrobiosis. Furthermore, pretreatment of the nematodes with the surfactant SDS did not influence attachment. An electron microscope study of sections cut through DL₂ exposed to bacteria showed that this interaction was indeed not a surface phenomenon but that the bacteria exerted a pathological effect on the nematode. The bacterium's capsular material actually penetrated and broke down the nematode epicuticle and part of the cortical zone. These observations make it easier to understand the dramatic physiological responses of this nematode to these bacteria.