A gypsy moth (Lymantria dispar, Lepidoptera : Lymantriidae) multinucleocapsid nuclear polyhedrosis virus from France: comparison with a North American and a Korean strain

As part of a search for natural enemies of the gypsy moth (Lymantria dispar ), virus-infected samples were collected near Toulouse, France. Light and e lectron microscope studies confirmed that the French strain is a multinucle ocapsid nuclear polyhedrosis virus (MNPV). In vivo bioassays using the New Jersey strain oft. dispar, and comparing L. dispar MNPV (LdMNPV) strains fr om France, North America and Korea, showed that the French strain was the l east active, whereas the North American strain had the highest activity. Th e viral efficacy of all strains was enhanced 200 to 1300-fold in the presen ce of 1% fluorescent brightener. The enhancement was highest in the America n strain and lowest in the French strain. French LdMNPV (LdMNPVF) DNA cut w ith four restriction enzymes (BamHI, EcoRI, HindIII, and NotI) revealed min or fragment size differences, but many similarities when compared to the No rth American and the Korean strain. PCR amplification of a LdMNPV early gen e (G22) was detected in the North American and the Korean strain, but not i n the French strain.