A field release of genetically engineered gypsy moth (Lymantria dispar L.)nuclear polyhedrosis virus (LdNPV)

The gypsy moth (Lymantria dispar L.) nuclear polyhedrosis virus was genetic ally engineered for nonpersistence by removal of the gene coding for polyhe drin production and stabilized using a coocclusion process. A P-galactosida se marker gene was inserted into the genetically engineered virus (LdGEV) s o that infected larvae could be tested for its presence using a colorimetri c assay. In 1993, LdGEV-infected gypsy moths were released in a forested pl ot in Massachusetts to test for spread and persistence. A similar forested plot a km away served as a control. For 3 years (1993-1995), gypsy moths we re established in the two plots in Massachusetts to serve as test and contr ol populations. Each week, larvae were collected from both plots. These fie ld-collected larvae were reared individually, checked for mortality, and th en tested for the presence of beta-galactosidase. Other gypsy moth larvae w ere confined on LdGEV-contaminated foliage for 1 week and then treated as t he field-collected larvae. The LdGEV was sought in bark, litter, and soil s amples collected from each plot. To verify the presence of the LdGEV, polym erase chain reaction, slot blot DNA hybridization, and restriction enzyme a nalysis were also used on larval samples. Field-collected larvae infected w ith the engineered virus were recovered in the release plot in 1993, but no t in subsequent years; no field-collected larvae from the control plot cont ained the engineered virus. Larvae confined on LdGEV-contaminated foliage w ere killed by the virus, No LdGEV was recovered from bark, litter, or soil samples from either of the plots. (C) 1999 Academic Press.