The distribution and effect of intracellular rickettsia‐ like micro‐ organisms infecting second‐ stage juveniles of the Potato cyst‐ nematode Globodera rostocbiensis

For the first time rickettsia‐like micro‐organisms are illustrated infecting most tissues of second‐stage juveniles of Globoderu rostochiensis . They were seen only inside host cells, except for the few degenerating forms in the intestinal lumen. They were most common in the non‐contractile (sarcoplasmic) region of body wall muscles. A study of the oesophageal glands of the nematode suggested that micro‐organisms present within these glands would be unlikely to pass out of them and that the nematode would not act as a vector of these micro‐organisms to its host plants. No micro‐organisms were found in the genital primordia of the nematodes. Stored, hatched juveniles appeared to contain more microorganisms than newly hatched juveniles, indicating an increase in the intensity of the infection subsequent to hatching. No obvious signs of pathogenicity were observed in the nematodes. Uninfected juveniles apparently live longer than infected ones in viro , probably because infected juveniles exhaust their lipid reserves sooner than uninfected juveniles. The possible effect of the micro‐organisms on their nematode hosts and their potential as biological control agents are discussed.