DNA HYBRIDIZATION ASSAY FOR DETECTION OF NUCLEAR POLYHEDROSIS-VIRUS IN TENT CATERPILLARS

A DNA dot-blot hybridization assay to monitor the distribution of nucl ear polyhedrosis virus in populations of tent caterpillars was develop ed and tested. No differences were found between results using DNA ext raction with phenol-chloroform and crudely homogenating caterpillars. Dot-blot hybridization of field-collected caterpillars, frozen immedia tely after collection, showed the same levels of infection as microsco pic examination for polyhedral inclusion bodies of field-collected cat erpillars reared in the laboratory which had died by 5 or 6 days. Howe ver, reared field caterpillars showed higher levels of viral infection on microscopic examination of dead caterpillars by 10 to 13 days. Wit h surface-sterilized eggs reared to third instar and infected with vir us, 79% of infection could be identified by 5 days. Most infected cate rpillars died by 8 days. Molting. to fourth instar was delayed or prev ented in infected caterpillars, suggesting that western tent caterpill ar virus has the egt gene. (C) 1995 Academic Press, Inc.