Phytonematode Pathology: Ultrastructural Studies. II. Parasitism of Meloidogyne arenaria Eggs and Larvae by Paecilomyces lilacinus

Abstract

An isolate of Paecilomyces lilacinus (Thom) Samson, from mature cysts of Heterodera glycines Ichinohe, was evaluated in vitro for its ability to parasitize eggs of Meloidogyne arenaria (Neal) Chitwood. Hyphae of the fungus readily penetrated the egg shell through small pores dissolved in the vitelline layer. Invaded eggs became swollen as a result of a change in shell permeability. Once inside, a penetrating hypha enlarges, crushes the chitin and lipid shell layers in its immediate proximity, and permeates the egg content, including developing larvae whose cuticles are disrupted. Endogenous hyphae reemerge by tearing the egg shell and produce conidiophores bearing chains of conidia on the shell surface. Shells of eggs containing fungal hyphae undergo a number of ultrastructural changes. The vitelline layer splits into three discrete membranes which appear unevenly thickened, the chitin layer becomes vacuolated, and the lipid layer largely disappears. Similar disorganization of the la