Potential lethal and sublethal effects of gypsy moth biological treatments on non-target lepidopterans in two Appalachian forests.

摘要

Eighteen 200 ha plots were established in the Monongahela National Forest (MON), Pocahontas County, West Virginia, and in the George Washington National Forest (GW), Augusta County, Virginia. From 1995 through 1998 black light traps, foliage pruning, and canvas bands were used to collect macrolepidopteran adults and larvae. During 1997 and 1998, 6 plots each were aerially treated with nucleopolyhedrosis virus (Gypchek(TM); GC) and Bacillus thuringiensis var. kurstaki (Btk: Bt). The remaining 6 plots were left untreated (Ref). Leaf samples from Bt plots were analyzed for toxin concentrations using enzyme-linked immunosorbant assay techniques. Results indicated concentrations above 20 ng/cm2 for 90.1% of the samples.;Adults and larvae of 19 species from 5 families were tallied to assess potential treatment effects. Weights of larvae (and their pupae) and wing lengths of adults were measured to assess possible sublethal effects. Analysis of variance indicated a significant interaction (P < 0.05) between pretreatment/treatment years and the 3 treatment groups for 2 species of adults and 3 species of larvae. Fewer individuals were collected from Bt plots than from GC and Ref plots during treatment years, but not during pretreatment years. A similar pattern was observed for the 19 species combined and for the combined sum of all early season non-target macrolepidopteran larvae collected from foliage. Significant forest differences were also observed, with adults of 9 species and larvae of 6 species more numerous in MON catches. Adults of 1 species were more numerous in GW catches.;Sublethal treatment effects of Btk were not identified; however, significant differences between forests were noted. Adults of 13 species from GW catches possessed longer wings than those collected from the MON. One MON species possessed longer wings. Adult males were significantly more numerous and typically possessed shorter wings than females. Significant fluctuations in counts were the result of variation in the number of males. GW larvae (and their pupae) were significantly heavier than MON larvae for 1 species. A comparison of temperatures between forests indicated significantly cooler temperatures on the MON during pretreatment and treatment years.