Changes Associated with Parasitism in Nematodes. I. Morphology and Physiology of Preparasitic and Parasitic Larvae of Meloidogyne javanica

Abstract

Both morphological and physiological changes associated with the onset of the parasitic mode of life were observed in living 2nd-stage larvae of a plant-parasitic nematode. These changes which take place as the preparasitic or infective larvae of Meloidogyne javanica becomes parasitic in the root of its host were observed in living anesthetized larvae under the phase-contrast micro-scope at high magnification. Changes in the mobility and infectivity of these larvae during the same periods were also measured. There is an accumulation of granules in the ducts of the subventral esophageal glands shortly before hatching. These granules appear to be associated with penetration both of the eggshell and the plant cell wall and disappear completely within 1 to 3 days of entry into the host. Within this period of time there is an approximate 3-fold enlargement of the dorsal and subventral esophageal glands. At the same time there is a progressive loss in the ability of the larva to reinfect its host and to move through the soil.