OCCURRENCE, BIOLOGICAL-ACTIVITY, AND HOST-RANGE OF ENTOMOPOXVIRUS-B FROM OCNOGYNA-BAETICA (LEPIDOPTERA, ARCTIIDAE)

Several populations of the winter webworm, Ocnogyna baetica (Rambur), were surveyed in southern Spain during 1989-1992 for pathogenic microo rganisms. A virus infection caused by a new Entomopoxvirus B (ObEPV) w as first recorded in 12 of 1238 larvae collected in 1989 at Cordoba. I n 1992 the ObEPV infection was recorded in two other populations, whil e at Cordoba a heavy epizootic in the host field population was observ ed at the maximum infection level of 67.4%. The LD(50) value of ObEPV for third-instar O. baetica larvae was 6663 spheroids/larva. Mortality time was not related to dosage, and the LT(50) values were calculated as 15-16 days. In laboratory tests ObEPV showed low infectivity to Ag rotis segetum and Spodoptera littoralis but was not infectious to thre e other tested lepidopterans and one orthopteran. Some features of the O. baetica life cycle and ecology which contribute to the development of ObEPV epizootic are discussed. (C) 1991 Academic Press, Inc.