A LIGHT AND ELECTRON-MICROSCOPIC INVESTIGATION OF THE OCCURRENCE OF NOSEMA SP (MICROSPORIDA, NOSEMATIDAE) IN THE ABDOMEN OF THE PARASITIC WASP PEDIOBIUS-FOVEOLATUS (HYMENOPTERA, EULOPHIDAE)

The occurrence of Nosema sp. (Microsporida: Nosematidae) in cells in several tissues in the abdomen of the parasitic wasp, Pediobius foveolatus (Hymenoptera: Eulophidae), is described from light and electron microscopy of thin and ultrathin sections. Infected wasps showed no outward signs of infection. The ultrastructural features of the sporonts and immature spores indicate the designation Nosema sp. (probably N. varivestis). The nuclei of the sporonts and immature spores are diplokaryotic, and the microsporidia develop directly in the host cell cytoplasm. Adipose tissue, intrinsic midgut muscle, gut epithelium, Malpighian tubules, and egg cells all are invaded by the microsporidia. The spores are ovocylindrical and measure about 2.0 x 4.5 mum. They Contain a polar tube with 17-19 coils. The plasmalemma of the sporonts is coated with a thin layer (about 200 nm) of electron-dense material interrupted by electron-lucent vesicles or tubules. The coating material gives rise to strands, individual or chains of granules or tubules, and larger clumps of electron-dense material. Microsporidia are noted intranuclearly in cells of the visceral muscle.