sentences:  Several studies conducted in the 1970s and 1980s have showed that the beet leafhopper is a vector (epidemiology) of the "Spiroplasma citri" prokaryote which is the causal agent of the Citrus Stubborn Disease.The bacterium "S. citri" is initially acquired by the leaf hopper through feeding on a plant that has already been infected.Through feeding, the prokaryote enters the gut of the beet leafhopper where most of its cells are killed, but some do survive.