Characterization of a new iridovirus isolated from crickets and investigations on the host range

Typical signs of an iridovirus infection were observed in two species of fa tally diseased crickets, Gryllus campestris L. and Acheta domesticus L. (Or thoptera, Gryllidae). The infection was manifested by hypertrophy and bluis h iridescence of the affected fat body cells. Electron microscope investiga tions led to the identification of a new iridovirus, which was termed crick et iridovirus (CrIV). In negatively stained preparations the size of the ic osahedral virus particles ranged from 151 nm (side-side) to 167 nm (apex-ap ex). Assembly of virions occurred in the cytoplasm of hypertrophied fat bod y cells, where they often accumulated in paracrystalline arrays. Genetic an alyses of purified viral DNA using a variety of restriction enzymes reveale d that CrIV is distinct from all other known iridoviruses that have been is olated from insects and reported so far. In host range studies it was shown that CrIV can be transmitted perorally to other orthopteran species, causi ng characteristic symptoms and fatal disease. These species include Gryllus bimaculatus L. (Orthoptera, Gryllidae) and the African migratory locust Lo custa migratoria migratorioides (R. & F.) (Orthoptera, Acrididae), which re presents one of the most important pest insects in developing countries, as well as the cockroaches Blatella germanica L. and Blatta orientalis L. (bo th Orthoptera, Blattidae). Consequently, the isolation and characterization of this new cricket iridovirus is of particular interest in view of its po ssible use in biological or integrated control. (C) 1999 Academic Press.