Field testing Chinese and Japanese gypsy moth nucleopolyhedrovirus and disparvirus against a Chinese population of Lymantria dispar asiatica in Huhhot, Inner Mongolia, People's Republic of China.

The activity of three geographic isolates of the gypsy moth nucleopolyhedrovirus (LdMNPV) was evaluated in field trials against larvae of the Chinese population of Lymantria dispar asiatica Vnukovskij in Inner Mongolia, People's Republic of China, in 2004, 2005, and 2006. Although the Chinese isolate of the virus, LdMNPV-H, was the most pathogenic of the isolates tested, having the lowest mean lethal concentration causing 50% and 95% larval mortality, the increase in efficacy that would be obtained by incorporating this isolate into a commercial product does not justify the time or expense required to register it for use in the United States or Canada. The commercially available North American isolate, LdMNPV-D, was moderately pathogenic, whereas the Japanese isolate, LdMNPV-J, was the least pathogenic. The slopes of the dose-response regression lines for the three virus isolates indicated that the Chinese gypsy moth larvae were more homogenously susceptible to LdMNPV-H and LdMNPV-D than to LdMNPV-J. Time-response data showed that LdMNPV-J was significantly more virulent, but at a much higher dose, than the other two isolates, causing 50% mortality in the shortest time, followed by LdMNPV-H and LdMNPV-D. Rainfall immediately after the application of LdMNPV-D in 2005 resulted in significantly reduced gypsy moth larval mortality.

Effects of long-term storage on potency of TM Biocontrol-1, the registered viral insecticide of Orgyia pseudotsugata (Lepidoptera: Lymantriidae).

The article presents the results of bioassaying 39 samples of TM Biocontrol-1, a viral insecticide, from 10 different lots and various sizes of vacuum-sealed packages that were stored at -10 degrees C for 5-15 yr. This is the first study to present potency data for a registered virus product stored for this length of time. Laboratory bioassays in insects from the same colony from which the TM Biocontrol-1 was produced showed that the stored viral insecticide is still effective, although it lost approximately 30% of its effectiveness during storage. A direct correlation of this loss with the length of time in storage is not apparent. Bioassays also showed that there are significant differences in the susceptibility of Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), larvae from different geographic regions to OpMNPV (family Baculoviridae, genus Nucleopolyhedrovirus) infection. Package size did not affect the potency of stored TM Biocontrol-1. There were no clear, significant differences in the effectiveness among lots of TM Biocontrol-1 processed by different organizations.

Effects of long-term storage on the stability of OpMNPV DNA contained in TM Biocontrol-1.

Orgyia pseudotsugata multicapsid nucleopolyhedrovirus (OpMNPV) DNA was extracted from samples representing 10 lots of TM Biocontrol-1 stored at -10 degrees C for 5-15 years and digested with the restriction enzymes BglII, PstI, and SalI. DNA from the OpMNPV virus strain (MEM-75-STANDARD) used to produce the TM Biocontrol-1 lots was also extracted and digested. No restriction fragment length polymorphisms were observed in any of the samples and there was no evidence of DNA degradation. This indicates that long-term cold storage of TM Biocontrol-1 had no adverse effect on the quality of the OpMNPV DNA. In addition to the expected >23 kb OpMNPV DNA, extracts from lots 4a, 5b, and 6 contained 10 additional nucleic acid segments, ranging in size from 0.9 to 4.2 kb. The electrophoretic profile of these segments was characteristic of O. pseudotsugata cypovirus (OpCPV). RNase A/DNase I treatment showed that the nucleic acid contaminants were composed of RNA, suggesting that lots 4a, 5b, and 6 contained OpCPV as well as OpMNPV. Bioassay results have shown that there is a decrease in efficacy of stored TM-biocontrol-1, but this did not appear to be directly correlated with the length of time in storage.

Mitochondrial DNA sequence variation among populations and host races of Lambdina fiscellaria (Gn.) (Lepidoptera: Geometridae).

The hemlock looper, Lambdina fiscellaria (Gn.), is a recurring major forest pest that is widely distributed in North America. Three subspecies (L. f. fiscellaria, L. f. lugubrosa (Hulst) and L. f. somniaria (Hulst)) have been recognized based on larval host or adult pheromone differences, but no consistent morphological differences have been reported. To clarify their taxonomic status, we surveyed mitochondrial DNA (mtDNA) sequence and restriction site variation in two protein coding genes, cytochrome oxidase I and II (COI and COII), in populations across the range of L. fiscellaria. In addition to variation in COI and COII, we found an intergenic spacer region of 20-23 bp located between the tRNA tyrosine gene and the start of COI. Of the 141 specimens of L. fiscellaria assayed, 137 were grouped into two distinct mtDNA lineages, one of which was disproportionately associated with eastern populations and one with western populations. However, single specimens and two populations in eastern Canada had mtDNA resembling that of western populations. Three divergent and rare haplotypes had basal affinities to the two common lineages. The two major lineages of L. fiscellaria were diverged by approximately 2% from each other, as well as from the mtDNA of two outgroup species, L. athasaria (Walker) and L. pellucidaria(G. & R.). The two outgroup species had essentially the same mtDNA and may be conspecific. We interpret the pattern of mtDNA variation within L. fiscellaria as indicating genetic polymorphism within a single species without clear subspecific divisions, rather than evidence of multiple cryptic species.