EFFECTS OF HOST-CELL DENSITY ON CELL INFECTION LEVEL IN ANTHERAEA-EUCALYPTI (LEPIDOPTERA, SATURNIIDAE) CELL-CULTURES PERSISTENTLY INFECTED WITH NOSEMA-BOMBYCIS (MICROSPORIDA, NOSEMATIDAE)

Spores of Nosema bombycis Y9101, isolated from the beet armyworm, Spod optera exigua, were primed with an alkaline solution and inoculated in to Antheraea eucalypti cell cultures. Infected cells were subcultured every five days at three cell densities (2.5 x 10(3), 5.0 x 10(3), and 1.0 x 10(4) cells/cm(2)). A difference was observed in the spread of N. bombycis Y9101 infection between low density and higher-density cul tures of host cells. The host cell density did not affect the producti vity of secondary infective forms of the parasite. The principal facto r determining the rate of microsporidian infection in vitro was the nu mber of host cells existing within the reach of extruded short-coiled polar tubes from spores germinated intracellularly.