PROPAGATION OF FLAVESCENCE DOREE MLO (MYCOPLASMA-LIKE ORGANISM) IN THE LEAFHOPPER VECTOR EUSCELIDIUS-VARIEGATUS KBM

Flavescence doree (FD) MLO is experimentally maintained in broadbean a nd transmitted by the leafhopper vector Euscelidius variegatus. Indire ct ELISA allowed the study, according to time after feeding access, of the distribution of MLO in the different organs of the vector. Colloi dal gold indirect immunolabeling was used to visualize the MLO cells i n the FD-infected organs. The alimentary tract was the first organ to become infected. Infected cells were not numerous but were crowded wit h MLO particles. Infection did not seem to be localized in specific ce lls. MLO multiplied in the cytoplasm of midgut cells and reached the h emolymph either by crossing between two cells or through individual in fected cells. By circulating in the hemolymph, MLO infected salivary g lands, in which they subsequently multiplied. Abdomen fat bodies and f inally brain were infected; an increase in the number of MLO was obser ved in these organs. Observation by electron microscopy showed that ML O infection in fat bodies was important, with no particular localizati on. In contrast, MLO infection in the brain was low. Mycetomes were oc casionally infected. No MLO particles were detected in malpighian tubu les or in male and female genital organs. (C) 1994 Academic Press, Inc .