Invasion of bacteroids and BEV bacterium into oocytes of the leafhopper Euscelidius variegatus Kirschbaum (Homoptera : Cicadellidae): An electron microscopic study

Electron microscopic studies were carried out on the infective stages of sy mbiotic bacteroids a and t, and their chronic pathogen BEV together with ov arioles of the leaf hopper Euscelidius variegatus Kirschbaum fixed in situ. The bacteroids were carried in cluster of host cells in the hemolymph as a n infective mound during the second day of adult emergence. Before entering an ovariole through special wedge cells of the follicular epithelium, they were released as individuals. The BEV bacteria were also carried in infect ive mounds and were released to the hemolymph for oocyte infection. Host he mocytes (probably plasmatocytes) engulfed bacteroids and BEV bacteria in th e hemolymph when they were not protected by host's cell membranes.