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Garry oak, Quercus garryana Douglas ex Hooker (Fagaceae), is part of a unique ecosystem in British Columbia, Canada, which is rich in rare and endangered plant species. Garry oak recruitment is critical to the existence of this ecosystem, therefore, the effect of Curculio occidentis (Casey) (filbert weevil; Coleoptera: Curculionidae) and Cydia latiferreana (Walsingham) (filbertworm; Lepidoptera: Tortricidae) on acorn germination is of great interest. Together these two insects infested 80.7%, 75.1%, and 51.3% of acorns collected in 1996, 1997 (low crop years), and 1998 (high crop year), respectively. Filbertworm infestation did not vary with crown level. Filbert weevil infestation did not vary with crown level during poor crop years, but significantly more filbert weevil-infested acorns were found in the lower than the middle and upper portions of the trees during the high crop year. Severely damaged acorns did not germinate, and acorns with light to moderate feeding damage had lower germination success than undamaged acorns, but growth of germinated seedlings in the light to moderate damage category was unaffected. This study showed, for the first time, that these two insect species infested a large proportion of Garry oak acorns on the tree in British Columbia, and that light to moderate damage of the acorn has relatively low impact on seedling growth.

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.

Periodic outbreaks of the Douglas-fir tussock moth (Orgyia pseudotsugata) in forests of western North America generally end with a sudden collapse due primarily to an epizootic caused by a nucleopolyhedrovirus (NPV) that occurs naturally within O. pseudotsugata populations. We genotypically characterized NPV populations from Washington State, Oregon, Idaho, New Mexico and California for the first time. Of 159 infected tussock moth samples, restriction fragment length polymorphism (RFLP) analysis showed that 125 (78.6%) contained single nucleopolyhedrovirus (OpSNPV), 28 (17.6%) contained multiple nucleopolyhedrovirus (OpMNPV), and six (3.8%) contained both OpSNPV and OpMNPV. In comparison, our previous studies in the southern interior of British Columbia showed that all 298 samples examined were infected with OpMNPV, and none were infected with OpSNPV. More than half of the Washington OpSNPV samples shared the same genotype, but most OpSNPV genotypes were rare or unique: across the five states, 31 of the 43 different OpSNPV genotypes were each only found in a single sample. In contrast, only four different OpMNPV genotypes were found, and 29 of the 34 OpMNPV samples shared the same genotype, designated genotype AA. This strain of OpMNPV has been developed, registered and used in both Canada and the United States to control outbreaks of the Douglas-fir tussock moth. It is also the most common genotype in southern British Columbia. The estimated degree of genetic divergence ranged from 0% to 4.19% for the various OpSNPV genotypes and from 0% to 3.16% for the OpMNPV genotypes (based on number of shared bands). This is the first description of the genotypic diversity in a population of OpSNPV, and the first genotypic characterization of NPVs infecting O. pseudotsugata in the USA.

Forest tent caterpillar (Malacosoma disstria Hübner) is a major defoliator of hardwoods throughout North America, including aspen (Populus tremuloides Michx.). M. disstria has been a major concern in many parts of Canada for the last two decades, but until recently in British Columbia it was considered an aesthetic concern only. However, with the increasing interest in the cultivation of hardwoods for fibre, and more recently for fuel, this insect could become a major concern in hardwood management. Records of past M. disstria outbreaks in British Columbia were summarized. The locations and intensity of six outbreaks were overlaid on biogeoclimatic units to determine which biogeoclimatic zones have experienced repeated outbreaks of M. disstria. Between 1944 and 2003, M. disstria outbreaks have become larger in extent and longer in duration. Analysis indicated that aspen stands in the Boreal White and Black Spruce (BWBS), Sub- Boreal Spruce (SBS) and Interior Cedar-Hemlock (ICH) biogeoclimatic zones have been most frequently attacked. In the BWBS zone, most affected areas (93.3%) were defoliated for only one year (lightly). In the SBS and ICH zones, areas attacked by M. disstria tended to be defoliated two or more consecutive years (40.2% and 56.2%, respectively), and had a greater chance of being more severely defoliated than aspen stands in the BWBS zone. Key words: Malacosoma disstria, forest tent caterpillar, damage, outbreaks, hazard rating

We studied Orgyia pseudotsugata multiple nucleopolyhedrovirus (OpMNPV) infections in larvae of the Douglas-fir tussock moth, Orgyia pseudotsugata McDunnough (Lepidoptera: Lymantriidae), to determine the quantity of OpMNPV particles that result in mortality. We observed a bimodal pattern of mortality in Douglas-fir tussock moth larvae that ingested diet plugs contaminated with 9.5 OpMNPV occlusion bodies. A mortality peak (80% of total mortality observed) occurred between day 5 and day 11 post ingestion, and a second, smaller mortality peak coincided with the onset of pupation. Virus loads, defined as the number of OpMNPV occlusion bodies in each sample of tested larval homogenate, were quantified using an indirect ELISA method. Virus loads that resulted in mortality were significantly greater than those quantified in larvae that were sacrificed during and after the peak mortality wave (P < 0.004 and P < 0.0001, Mann–Whitney U two-tailed rank test and SPSS®, respectively). This is the first known attempt to differentiate the quantity of virus produced during lethal infections from the virus loads in larvae that survive infection.

The Douglas-fir tussock moth Orgyia pseudotsugata (Lepidoptera: Lymantriidae) is a frequent defoliator of Douglas-fir and true firs in western USA and Canada. A single nucleopolyhedrovirus (SNPV) isolated from O. pseudotsugata larvae in Canada (OpSNPV) was previously analyzed via its polyhedrin gene, but is phylogenetic status was ambiguous. Sequences of four conserved baculovirus genes, polyhedrin, lef-8, pif-2 and dpol, were amplified from OpSNPV DNA in polymerase chain reactions using degenerate primer sets and their sequences were analyzed phylogenetically. The analysis revealed that OpSNPV belongs to group II NPVs and is most closely related to SNPVs that infect O. ericae and O. anartoides, respectively. These results show the need for

This field study was carried out to investigate whether application of an aerial spray containing Bacillus thuringiensis subsp. kurstaki (Btk) to control the western spruce budworm (Choristoneura occidentalis Freeman, 1967) had any measurable effects on aspects of the abundance, distribution, diversity, and feeding behaviour of nontarget soil microarthropods. Although total abundance and species richness (N0) of Collembola declined significantly in samples taken 3 weeks after spraying, this decline occurred in the control plots as well as in plots sprayed with Btk. Values for the diversity indices N1 and N2 were not affected by the treatment. Correspondence analysis did not identify changes in collembolan communities following the aerial application of Btk. Total abundance of mites and populations of different suborders (Prostigmata, Mesostigmata, and Oribatida) were not significantly affected by application of Btk, or by the time of year that the samples were collected. There was no evidence of a selective reduction in the surface-dwelling portions of the collembolan and mite communities following exposure to Btk. Similarly, the experimental spray did not cause a decline in the abundance of the guild of Collembola known to feed on bacteria, and the proportion of bacteria in the diet of these Collembola following application of Btk was also unchanged.

Field trapping trials showed that Cameraria gaultheriella Walsingham and C. lobatiella Opler and Davis (Lepidoptera: Gracillariidae) were attracted in significant numbers in British Columbia, Canada, to sticky traps baited with 10 µg of (E,Z)-8,10-tetradecadienal (E8Z10-14Ald), the sex pheromone of the European horse chestnut leafminer, C. ohridella Deschka and Dimic. There was perfect specificity in captures at habitats located only about 8 km apart from each other: C. gaultheriella was captured exclusively at a humid habitat covered by the shrub salal, Gaultheria shallon Pursh (Ericaceae), whereas C. lobatiella was trapped at an arid location with Garry oak trees, Quercus garryana Dougl. (Fagaceae). Seasonal flight patterns of these two Canadian Cameraria species, as monitored by pheromone traps, indicated differences in their respective flight periods. The possibility of additional cryptic components in the respective pheromones of these three Cameraria species attracted to E8Z10-14Ald is discussed.

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°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 ≈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 effectivenes...

The Douglas-fir tussock moth ( Orgyia pseudotsugata ) multicapsid nucleopolyhedrovirus ( Op MNPV) is periodically applied to suppress Douglas-fir tussock moth populations in British Columbia and in the western United States. The strain of Op MNPV in the product currently used for suppression is not genetically distinct from naturally occurring Op MNPV. To separate the mortality caused by the applied virus from that caused by the naturally occurring virus, a rare and genetically distinct strain of Op MNPV must be applied. To learn more about the genotypic diversity of Op MNPV populations in BC and to identify rare strains in this region, viral DNA was extracted from larvae reared from 208 field-collected egg masses found in five geographic regions of British Columbia and subjected to REN analysis. Nine, 12, and 9 different genotypes were detected using Pst I, Sal I, and Hin dIII, respectively. When the Pst I, Sal I, and Hin dIII profiles for each pure (single strain) isolate were grouped and considered as a combined Pst I– Sal I– Hin dIII genotype, 23 different genotypes were identified among 185 isolates. Nine rare Op MNPV genotypes were selected as ideal candidates for use as a potential ‘marker strain’ to accurately determine the efficacy of the treatment.

Two newly identified geographic isolates of a nucleopolyhedrovirus (LdMNPV-H and LdMNPV-J) were evaluated against Disparvirus (LdMNPV-D), a baculovirus insecticide registered in Canada for the control of gypsy moth (Lymantria dispar (L.) (Lepidoptera: Lymantriidae)). Profiles of HindIII and EcoRI restriction enzyme digests of viral DNA from the three viral isolates are presented. Viral isolates were bioassayed using an inoculated diet plug method to determine the dose- and time-responses of second-instar larvae of both the European and Asian strains of gypsy moth. LdMNPV-D was found to be the most virulent isolate when tested against the European strain of gypsy moth, yielding an LD50 and an LD95 (estimates of the doses required to kill 50% and 95% of the test larvae, respectively) of 95 and 774 occlusion bodies (OBs), respectively. LdMNPV-H was the most virulent isolate when tested against the Asian strain, yielding an LD50 and an LD95 of 648 and 8540 OBs, respectively. Time-response data indicate that the three isolates differ little with respect to their speed of kill (ST50; estimate of the length of time required to kill 50% of the test insects) of either larval strain. These results indicate that both new isolates (LdMNPV-H and LdMNPV-J) should be investigated further for control of the Asian strain of the gypsy moth but not pursued for control of the European strain.

The operational use of Bacillus thuringiensis subsp. kurstaki (Btk) to control the western spruce budworm in the mountainous terrain of British Columbia, Canada, gives variable results at the registered dose of 30 BIU ha − 1 in 2.4 L ha − 1. Btk (Foray 48B®, 60 BIU ha − 1 in 4.8 L ha − 1) was applied experimentally in 1996 over 150-ha of western spruce budworm-infested Douglas-fir forest to determine if increasing both the dose and volume of Btk applications gives more uniform and effective control. We sampled native caterpillars on the shrub Ribes cereum Douglas in this and a similar, untreated area 2 km away from 1996 to 1998 to assess the impact of this high dose and volume Btk application on non-target Lepidoptera. The numerically dominant lepidopteran species were Euhyponomeutoides gracilariella Busck (52%) and Gelechia ribesella Chambers (32%). The remaining 16% of the guild was comprised of numerous sparsely distributed species. Total larval abundance was significantly lower on plants that were spr...

A non-toxic phase separation method was developed for microencapsulation of inoculum used in biological control. Aqueous sodium alginate or gelatin and agar was mixed with inocula of various biopesticides and emulsified in a mixture of corn oil, n-hexadecane, and lecithin. Gelatin and agar globules gelled in the emulsion; alginate globules gelled after settling into a lower phase of aqueous CaCl2. A layer of gelatinous material thus surrounded the inoculum as 'capsules'. Mixing with n-hexadecane reduced the specific gravity and surface tension of the oil, allowing aqueous extraction of the capsules. Successful extraction of alginate capsules depended upon lecithin (>0.17%), n-hexadecane (>30%), and CaCl2 (>0.01 M) concentrations. Alginate-encapsulated macroconidia of Fusarium avenaceum caused 23±3% leaf area damage to seedlings of marsh reed grass, versus 4±3% for unformulated controls. In green foxtail seedlings, gelatin and agar-encapsulated conidia of Bipolaris sorokiniana caused 21.3 vs. 7.9 ...

The abundance of nontarget Lepidoptera on the shrub Ribes cereum Douglas was monitored from 1997 to 2000 in an Interior Douglas-fir forest in British Columbia to assess potential side effects of an operational program to control the western spruce budworm, Choristoneura occidentalis Freeman. The treatment was a single application of Bacillus thuringiensis subsp. kurstaki (Btk) (Foray 48B) at the rate of 30 BIU/ha in 2.4 liter/ha. The guild of leaf-feeding Lepidoptera on R. cereum was dominated by Gelechia ribesella Chambers, and Euhyponomeutoides gracilariella Busck, which made up 24 and 62% of the guild, respectively. The remaining 14% of the guild comprised numerous sparsely distributed species (at least 45 different species based on morphotypes). Total larval abundance was significantly lower on plants that were sprayed with Btk than on plants that were covered to exclude Btk. Covering the plants was a novel approach that enabled us to replicate the treatment within a single spray area. G. ribesella and E. gracilariella were significantly reduced by Btk, but a modest reduction of 'sparsely distributed species' was not significant. Both G. ribesella and E. gracilariella appeared to make a full recovery within 2 yr of the Btk spray, but as a group the abundance of the sparsely distributed species was lowest in the year 2000 in both the Btk sprayed area and an untreated comparison area. This suggests a general decline independent of the treatment. Microscopic examination of cadavers of the two major nontarget species showed the presence of Btk in some of the larvae reared from the treated plot, but Btk was absent in larvae from the reference plot.

Optical brighteners were recently discovered to function as UV protectants for baculoviruses of insects (Shapiro 1992) and, also, to enhance entomopathogenic activity of these viruses (Hamm and Shapiro 1992; Li and Otvos 1999a). Enhancement of viral activity by brighteners varied greatly from one virus–host system to another: for example, from 1500-fold in LdMNPV against Lymantria dispar (L.) (Lepidoptera: Lymantriidae) (Argauer and Shapiro 1997) to 2- to 13-fold in a multicapsid nuclear polyhedrosis virus of Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae) (CfMNPV) against Choristoneura occidentalis Freeman (Li and Otvos 1999a). The reason for this variation in enhancement of viral activity is still unknown. In this study, we used CfMNPV to compare the levels of viral enhancement by an optical brightener between C. occidentalis and C. fumiferana.

Mortality and sublethal effects of different doses of the multicapsid nucleopolyhedrovirus that infects the spruce budworm, Choristoneura fumiferana (Clemens), on the western spruce budworm, Choristoneura occidentalis Freeman, were investigated. C. fumiferana multicapsid nucleopolyhedrovirus (CfMNPV) is known to be more highly virulent to C. occidentalis than to its own host. Larval and pupal mortality were dose-dependent regardless of the age of the larvae challenged. Larval mortality was higher when younger larvae were challenged, whereas pupal mortality among the survivors was higher when older larvae were challenged. Older larvae were less susceptible to CfMNPV than younger larvae treated with the same virus concentration. Sublethal effects were also greater in the insects treated as older larvae. Sublethal effects of CfMNPV on C. occidentalis infected as sixth instars included prolonged developmental time of males to pupation, decreased male pupal weight, decreased longevity of both male and female adults, and a reduced proportion of females among the survivors, even though proportionally more males than females died in the pupal stage. Some of these changes were significant and were age, dose and sex-dependent. Sublethal effects of CfMNPV on survivors challenged as fourth instars were significant in reducing the proportion of females at the highest virus concentration. Fecundity and hatching success of C. occidentalis was not affected by CfMNPV treatment. These findings suggest that CfMNPV should be applied to fourth instars in the field to achieve high larval mortality. Implications of both the combined larval and pupal mortality and sublethal effects of viral application on the population dynamics of C. occidentalis are discussed and compared with previously reported results on other insects.

The enhancement of Choristoneura fumiferana (Clemens) multicapsid nuclear polyhedrosis virus (CfMNPV) activity by 4 optical brighteners was compared in the laboratory between nondiapausing laboratory and diapausing field strains of the western spruce budworm, C. occidentalis. The laboratory strain was 2.7 times as susceptible to the virus as the field population in terms of LD 50 (dose at which 50% of the tested larvae died). When a 1% concentration of optical brightener was added to the virus, lethal doses for both strains were significantly reduced, indicating that all 4 brighteners acted as activity enbancers for CfMNPV. In terms of LD 50 , brighteners enhanced viral activity against the field strain more (7.6-11.0 times) than the laboratory strain (2.5-3.5 times). Although there were differences in larval susceptibility to CfMNPV between the 2 strains, LD 50 values for both strains were reduced to the same levels when 1% brightener was added to the virus. Furthermore, the larvae died more quickly with the addition of brighteners. The time required to kill 50% of the larvae was reduced by 39-60% for the field strain, and by 43-57% for the laboratory strain by the addition of 1% brightener.

Nine optical brighteners were tested using diet-plug bioassays in the laboratory to determine their effects on the activity of Choristoneura fumiferana (Clemens) multicapsid nuclear polyhedrosis virus ( Cf MNPV) against 4th instars of C. occidentalis Freeman. Five brighteners (Blankophor RKH, Tinopal LPW, Blankophor BBH, Blankophor P167, and Blankophor HRS) enhanced viral activity, whereas 4 did not (Blankophor BSB, Blankophor DML, Blankophor LPG, and Blankophor BSU). The effective brighteners enhanced viral activity 1.76–13.08 times. The optimal concentration of brightener for enhancing viral activity was 1%. Adding brightener reduced the time required for the virus to kill larvae by 30–72%. Further studies are required to determine whether active brighteners may enhance efficacy of Cf MNPV against C. occidentalis in the field.

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.

Fifth-instar larval mortality was compared between male and female Choristoneura occidentalis Freeman exposed in the laboratory to sublethal doses of Choristoneura fumiferana (Clem.) multicapsid nuclear polyhedrosis virus (CfMNPV) with or without optical brighteners. More females than males died when the virus was used alone, but differences were not significant. When 1% brightener was added to CfMNPV suspension, differences in larval mortality between males and females were significant for three of the four brighteners tested. In addition, times at which 50% of the larvae died indicated that female larvae died 23 and 39% more quickly than male larvae, respectively, when brightener Blankophor HRS and Tinopal LPW were added to the virus, whereas at times at which 95% of the larvae died indicated that females died 33 and 54% faster than males. Alteration of sex ratio favoring male survival can play a significant role in the biological control of C. occidentalis by the virus.

Three types of burlap traps were designed and tested for the western hemlock looper, Lambdina fiscellaria lugubrosa, in the interior of British Columbia from 1993 to 1994. While the first two trap types provided the means for examining the responses of pupating larvae to various layers of burlap band and pocket structure, the third trap type, which had the desirable burlap layers and structure, was used as a sampling tool for the insect. The effects of tree diameter, crown ratio, crown class, defoliation class and basal areas on trap capture appeared to vary with locations. However, a high correlation between trap capture and actual population density was consistently present. Therefore, trap capture can be used as an estimator of actual population density.

The roadside sampling method, in which sampling is conducted along a road has the advantage that large areas can be quickly surveyed. The method is particularly useful for forest areas where accessibility to trees within a stand can be a problem. In this study, larvae and adults of the western hemlock looper were sampled along forest roads and the data were examined with spatial statistics. The results indicated spatial continuity of insect counts along the forest roads, although the range and magnitude varied significantly between years and among sites. At Sugar Lake Forest Road, larvae and adults were spatially dependent within a distance of 7.25 km. In the three Vancouver watersheds, a significant spatial autocorrelation of male adult counts occurred when traps were up to 3 km apart. In addition, insect densities along the roads were closely related to those within the stands. The implications of these results to the management of the western hemlock looper are discussed.

The eastern hemlock looper (EHL), Lambdina fiscellaria fiscellaria, the western hemlock looper (WHL), L. fiscellaria lugubrosa, and the western oak looper (WOL), L. fiscellaria somniaria, are closely related insects that are pests in Canadian forests. We have used restriction endonuclease (REN) and Southern blot analyses to characterize DNA of nuclear polyhedrosis viruses (NPVs) isolated from each of the three subspecies of L. fiscellaria. REN analysis of EHL-NPV, WHL-NPV, and WOL-NPV DNAs revealed that they have nonidentical REN-banding patterns. NPV DNA extracted from WOL larvae collected from Douglas fir trees had a different REN pattern than NPV DNA extracted from WOL larvae collected from Garry oak trees. Hybridization of radiolabeled EHL-NPV genomic DNA revealed that the EHL- and WHL-NPVs share considerable DNA sequence similarity, as radiolabeled EHL-NPV DNA hybridized strongly with all WHL-NPV DNA bands. The EHL-NPV polyhedrin gene hybridized strongly with WHL-NPV DNA, but the hybridization patterns of the two NPVs were different. Very weak hybridization was detected between the EHL-NPV polyhedrin gene and DNAs of the two WOL-NPVs. Nucleotide sequence analysis revealed that the polyhedrin genes of EHL-NPV and WHL-NPV differ in sequence by only eight nucleotide substitutions (five third position and three second position changes, resulting in four amino acid substitutions). Phlyogeneitc analysis using the polyhedrin genes of EHL-NPV and WHL-NPV indicate that these two viruses cluster with the Group II NPVs as described by Zanotto, Kessing, and Maruniak (1993, J. Invertebr. Pathol. 62, 147).

An egg sampling study of the western hemlock looper, Lambdina fiscellaria lugubrosa (Hulst), was conducted in mature western hemlock stands from 1992 to 1994 in British Columbia, Canada. Egg density of the looper was homogenous within a tree crown, suggesting that lower-crown sampling is effective for egg density estimation on the entire tree. Both the Taylor power law and the Iwao patchiness regression described egg distribution as aggregated. This aggregated distribution was further delineated as negative binomial distribution by chi-square test. Based on the Iwao model, the optimal sample size required to reach a predetermined precision level was calculated. To reduce egg-counting time, the relationship between mean egg density and proportion of lichen samples containing a specified number of eggs was established. The effect of tree height, diameter at breast height, crown width, crown length, and presence of heartrot on egg density was also examined. The results indicated no significant effect on egg density of these variables.

Larvae of the Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), were reared from egg masses collected at 10 locations in 6 geographic regions of British Columbia. DNA of O. pseudotsugata nuclear polyhedrosis virus (OpMNPV) extracted from these larvae and from commercial OpMNPV viral-insecticide preparations (Virtuss, and TMBioControl-1) were subjected to restriction endonuclease (REN) analysis with Pst I and SaI I. Southern blot analyses of the REN cleavage products revealed polymorphisms in 54.5% of samples digested with Pst I and 43.3% of samples digested with SaI I. Five Pst I genotypes and 2 Sal I genotypes were detected. Each of the five Pst /I REN patterns demonstrated either one or the other of the Sal I REN patterns, creating 10 possible combined genotypes, 8 of which were actually detected. Hare and common genotypes were mapped to each of the 6 geographic regions.

We have examined the geographic distribution and prevalence of insect-specific viral infections in Douglas-fir tussock moth populations in British Columbia. Nucleic acids extracted from field collected egg masses from 10 different locations in British Columbia were subjected to agarose gel electrophoresis and Southern blot analysis. Electrophoresis of nucleic acids after digestion with RNase A at high and low ionic strengths showed that the extra bands detected in agarose gels were double-stranded RNA (dsRNA). The dsRNA banding pattern was similar to the electropherotype of cytoplasmic polyhedrosis virus type 5. CPV infections were found in 27 of 170 DFTM larvae reared from field collected egg masses from four of 10 sites examined in three geographic regions of British Columbia. The CPV-infection rate for the DFTM larvae ranged from 10 to 86% depending on the location of the site.

Erannis tiliaria Harr. and Erannis defoliaria Cl. are closely related species (Rindge 1975) that have similar external appearance and flight period. Erannis tiliaria occurs in North America, whereas E. defoliaria is confined to Europe. Erannis defoliaria occasionally damages oak, Quercus spp. L. (Fagaceae), and cheny, Prunus spp. L. (Rosaceae) (Reichart 1993). During its 1975 outbreak, E. tiliaria severely defoliated 200 000 ha of white and yellow birch, Betula alleghaniensis Britt. and Betula papyrifera Marsh. (Betulaceae), respectively (Howse et al. 1995).

An integrated, long-term system to detect and treat infestations of Douglas-fir tussock moth in the Southern Interior of British Columbia was successfully implemented between 1984 and 1999. All aspects of recent research were implemented during an integrated control program conducted between 1991 and 1993. Many localized, incipient outbreak populations of tussock moth were detected prior to significant defoliation and treatments of a nuclear polyhedrosis virus (NPV) were applied. The application of NPV to sites with increasing tussock moth populations effectively terminated the localized infestations. The combination of early detection and application of NPV greatly reduced damage when compared to previous tussock moth outbreaks. Other program components were evaluated during the outbreak including: 6-trap cluster pheromone monitoring sites and singlet pheromone monitoring sites that correctly predicted outbreak level tussock moth populations; comparison between stored and new virus; comparison between virus formulations (Virtuss® versus TM Biocontrol-1®); evaluation of alternate swath versus entire coverage application of virus; and reduced dosages of virus. All virus trials were effective in reducing tussock moth populations to pre-outbreak levels. Future research and applications of the methodology are discussed.

A naturally occurring virus often leads to the development of an epizootic late in the outbreak cycle of the Douglas-fir tussock moth, but not before significant damage occurs to the trees. This virulent virus can be mass-produced in the laboratory and, when applied early in the outbreak cycle, can prevent severe defoliation. This, however, requires that an early-warning system be integrated with a virus treatment. The development and integration of a pheromone monitoring system with a virus treatment is described. Stands susceptible to Douglas-fir tussock-moth outbreaks are defined by overlying maps of past outbreaks, forest and habitat types, and climatic zones. Pheromone-baited traps are placed and monitored annually at permanent locations in the susceptible areas. Measuring annual trends of moth density indicates the time and location of the next outbreak. Trap-catch data provide an early warning of impending outbreaks. This is confirmed by ground reconnaissance. Insect density and defoliation is predicted from egg-mass and larval sampling. The virus then can be applied from the air or from the ground into threatened stands to initiate an epizootic to prevent the development of an outbreak and to minimize tree damage. The virus appears to spread, and field tests with reduced dosages indicate that that small amount of virus applied can still decimate larval populations and prevent tree mortality, at considerably reduced cost.

Infections of two heterologous insect cell lines derived from Malacosoma disstria (Md108) and Choristoneura fumiferana (Cf70) by the Lambdina fiscellaria lugubrosa nucleopolyhedrovirus (LafiNPV-W) were characterized. Cytopathic effects characteristic of LafiNPV-W infection, including rounding of cells, nuclear hypertrophy, and occlusion body (OB) production, were observed in both cell lines. Budded virus titers were slightly higher in Md108 cells than Cf70 cells (5.8 x 10(7) versus 3.1 x 10(7) TCID(50) units mL(-1)). Viral replication kinetics and cytopathic effects induced by LafiNPV-W infection were very similar in both cell lines. Actin rearrangements and redistribution of heterochromatin and euchromatin were observed within 24 h post-inoculation (hpi), and large quantities of nucleocapsids and virions were observed by electron microscopy at 48 hpi in both cell lines. Cf70 cultures produced OBs with numerous embedded virions, while OBs in Md108 cultures contained few virions or were empty with nucleocapsids packed in the nucleoplasm between OBs. In bioassays against second instar L. fiscellaria lugubrosa, OBs derived from LafiNPV-W-infected Md108 cells induced significantly lower levels of mortality than OBs derived from LafiNPV-W-infected Cf70 cells or from infected L. fiscellaria fiscellaria larvae.

Various molecular methods are used to detect pathogenic microorganisms and viruses within their hosts, but these methods are rarely validated by direct comparison. Southern hybridization, enzyme-linked immunosorbent assay (ELISA), and a novel DNA extraction/PCR assay were used to detect Orgyia pseudotsugata multiple nucleopolyhedrovirus (OpMNPV) in Douglas-fir tussock moth larvae. PCR was more sensitive than Southern hybridization and ELISA at detecting semipurified virus. ELISA, however, was the most accurate method for detecting virus within larvae, given that Southern hybridization and PCR produced false-negative results (31% and 2.5%, respectively). ELISA may be preferable in some applications because virus infections can be quantified ( r 2 = 0.995). These results may be applicable to both applied and academic research that seeks to accurately identify the incidence of viruses and microorganisms that regulate insect populations.

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.

Capacity building in environmental biomonitoring is a key component of sustainable development. This paper addresses this subject in relation to: practical methods for general and specific monitoring of environmental biohazards; conductance of compliance monitoring of large-scale releases of microbe-based contaminants, and risk/benefit analysis of biotechnology products such as biopesticides used in “greening” the environment. In addition to providing an environmental toxicology perspective to “what do we really know about the environmental“(59), we discuss the safety and utility of Bacillus thuringiensis-based, commercial pesticides (BT products) for developing and validating environmental dosimetry methods and strategies. A performance evaluation of “conventional” and “advanced” molecular dosimetry methods is made from a large data set based on an aerial spray calibration. The latter methods are by no means as “advanced” as those under development for climate control and defense research (42; see authors in this NATO ASI edition), but they are often regarded at the limit of capacity (molecular skills and specialty equipment) in most field work conducted in developing and developed countries.

Two viruses, one a nuclear polyhedrosis virus and the other a granulosis virus, were applied in an attempt to initiate epizootics in populations of western spruce budworm, Choristoneura occidentalis Freeman, on Douglas-fir trees, Pseudotsuga menziesii (Mirb.) Franco, in southeastern British Columbia. Two 172-ha plots were aerially treated in 1982 with 9.0 kg of lyophilized, virus-infected larval powder that was formulated in an emulsifiable oil tank mix and applied at 9.4 L per hectare. Each plot was treated when larval populations were at the peak of the fourth instar. The nuclear polyhedrosis virus was applied at 5.4 × 1011 polyhedral inclusion bodies per hectare and the granulosis virus at 1.7 × 1014 capsules per hectare. Results showed that the granulosis virus treatment caused 34.6% population reduction (Abbott’s formula) and the nuclear polyhedrosis virus 51.8%. Larvae from treated and check plots were reared individually in the laboratory and the incidence of viruses, parasitoids, and successful adult emergence was recorded. Studies m these plots continued in 1983 and 1984. Although vertical transmission of both viruses was evident, their impact on budworm mortality was less than in 1982. Consequently, the epizootics were not sufficiently intense to control the target insect population.

Two different application methods were tested using a nuclear polyhedrosis virus as a control agent at an early stage in the outbreak cycle of Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), in south central British Columbia in 1981. The virus, which often leads to the development of an epizootic late in the outbreak cycle, was propagated in whitemarked tussock moth, Orgyia leucostigma (J. E. Smith). A helicopter fitted with a boom and nozzle was used for treating four plots (total area 19.8 ha) at a dosage of 2.2 × 1011 polyhedral inclusion bodies (PIB) in an emitted volume of 11.3 L ha−1. Five to eight weeks after spraying, microscopic examination of live larvae showed that 77 to 100% were infected. In ground-spray applications of two other plots, a modified orchard-type sprayer was used to apply 2.4 × 1010 PIB in a volume of 4.5 L per tree. Microscopic diagnosis of live larvae at 8 weeks post-spray revealed 83 and 85% infection.In autumn 1981, no egg masses could be found in the plots treated earlier that year and no larvae were found on the sample trees in 1982 or 1983. The treatment was effective over a range of initial mean larval densities of 41 to 206 m−2 of foliage. At the same time, populations in nearby untreated areas increased in 1982. Little foliage protection was obtained the year of application due to the lengthy virus incubation period, but the trees recovered quickly when populations disappeared due to the virus epizootic.

Several host–parasitoid models were examined to assess the feasibility of parasitoid inundation as a means of pest control or eradication. The approach is comparative, to assess independently the effects of various ecological factors on the ease of control by this means. For most of the models, there exists a critical inundation rate, I*, above which the host population is eradicated, provided inundative releases continue beyond the time of eradication. The existence of density-dependent mortality in the hosts reduces the time to eradication but does not affect I*. Density dependence in the parasitoids, however, usually increases I*. The existence of hyperparasitoids appears to have no effect on the ease of host eradication.

Pyemotes barbara, n. sp., is illustrated and described. This species is parasitic on pupae of Barbara colfaxiana (Kearfott), one of the important cone and seed pests of Douglas-fir, Pseudotsuga menziesii (Mirbel) Franco. The Pyemotes mite considered here is a candidate for the biological control of forest insects.

A sequential egg-mass sample system for Douglas-fir tussock moth, Orgyia pseudotsugata McDunnough (Lepidoptera: Lymantriidae), was designed, based on visual scanning of the lower branches of Douglas-fir trees, Pseudotsuga menziesii (Mirb.) Franco. A branch was removed from each quadrant from the upper, middle and lower crown level, and from the lowest whorl of a total of 59 non-defoliated trees in 10 areas. No consistent trend in egg-mass density per branch could be found between crown levels and no level proved superior as a representative of the tree. Therefore, the lower whorl of branches was selected for survey purposes because of sampling efficiency. Sample stop lines were determined from egg-mass density and variability data collected on 55 sites and subsequent defoliation estimates were related to these densities. The system is designed as an early detection tool to be used only in non-defoliated stands at the incipient stage of an impending outbreak.

The diets of 25 species of forest-inhabiting birds were examined in California from 1962 to 1968. Coleoptera and Hymenoptera comprised the bulk of the diets. Coleopterans were, in decreasing amounts, the most common food of the three-toed woodpecker, Steller's jay, American robin, brown creeper, hairy woodpecker (both sexes), dark-eyed junco, downy woodpecker (both sexes), olive-sided flycatcher, western wood-pewee, and white-headed woodpecker (both sexes). Hymenopterans, mainly ants, were the most common food of the northern flicker, Williamson's sapsucker, red-breasted sapsucker, and acorn woodpecker. White-headed woodpecker (both sexes) also ate ponderosa-pine seeds in the fall. Hairy woodpecker (both sexes) fed on the seeds of ponderosa pine and sugar pine. Detailed estimates of foods consumed by item and volume from analyses of stomach contents of 241 specimens are presented.

Four 10-ha plots located in Kamloops Forest District, British Columbia, containing Douglas-fir trees infested with Douglas-fir tussock moth were aerially sprayed with nuclear polyhedrosis virus (Virtuss) in 1982 when most larvae were in the first instar. A dosage of 2.5 × 1011 polyhedral inclusion bodies (PIB) per hectare was applied in an emulsifiable oil tank mix to one plot and the same dosage in an aqueous tank mix containing molasses was applied to a second plot. The remaining two plots were treated with dosages of 8.3 × 1010 and 1.6 × 1010 PIB per hectare, respectively, in the oil mix. The treatments were applied with a fixed-wing aircraft fitted with boom and nozzle equipment and calibrated to deliver 9.4 L/ha. A further four plots were selected as checks.Population reduction at 6 weeks post-spray (calculated using a modified Abbott’s formula) was 65% in the plot receiving the lowest dosage and from 87 to 95% in the remaining three plots. Incidence of virus infection, determined microscopically, peaked at 5–6 weeks post-spray with 85–100% of the larvae scored as positive. Levels of naturally occurring virus remained low in the check plots. Adult emergence from the pupae collected in the treated plots ranged from 4 to 19% and from 28 to 43% in the check plots. Reduction in egg-mass density attributed to the treatments was 97% in one plot, 99% in two others, and not determined for the fourth.A virus dosage of 8.3 × 1010 PIB per hectare, which is one-third of the previously recommended dosage, is adequate, and either tank mix is acceptable.

The observations reported here were made while I attended the Tropical Entomology Course offered by the Organization for Tropical Studies in Costa Rica sponsored by the National Science Foundation. In spite of the brevity of the study, I believe that the results are a useful addition to the scant knowledge on food and feeding habits of tropical woodpeckers and woodcreepers. Observations on bird predation were made during the wet season in 1965 in three forest types (Holdridge, 1964): tropical dry forest (Playa Coco in Guanacaste), tropical moist forest (Puerto Viejo in Heredia and Palmar Sur in Puntarenas), and the subtropical wet forest life zone (Turrialba in Cartago). These locations represented four of Costa Rica's seven provinces. Visual observations of the species of woodpeckers and woodcreepers present, their feeding habits, and behavior were made at various times of the day. Specimens of 6 of the 16 species of woodpeckers and 2 of the 16 species of woodcreepers were studied and collected in the various locations. Stomach analyses were made from a total of 21 stomachs representing 8 of these species. Estimates were made on a visual examination of the entire stomach content, spread out in a petri dish; a piece of graph paper underneath provided a grid. The percentage of the identifiable portions was estimated from the area occupied on the grid. These figures seldom represent the actual volume of arthropods taken at the time of feeding because of autolysis. Although Martin (1949) claims that there is no need of preservatives if the stomachs are examined within 24 hours, Koersveld (1950) and Dillery (1965) found that digestion and autolysis of food continues for some time after death, depending on temperature and time interval between the death of the bird and examination of the stomach content. Immediate fixing of the stomach contents after killing is, therefore, desirable. Scientific names of woodpeckers of the genus Centurus follow Selander and Giller (1963); all other names of birds follow Peters' check lists (1948, 1951) and Mayr and Greenway (1960).

Four species of woodpeckers (family Picidae) are definitely known to be predaceous on the western pine beetle in the Central Sierra Nevada Mountains in California. These are: Dendrocopus villosus, Dendrocopus pubescens, Dendrocopus albolarvatus and Dryocopus pileatus. The red-shafter flicker (Colaptes cafer, Picidae), creepers (Certhiidae), nuthatches (Sittidae), and flycatchers (Tyrannidae) are thought to be predators on the western pine beetle.Predation by woodpeckers reduced the western pine beetle population by (a) actual consumption of 31.8% in two generations studied, and (b) by increasing parasite densities in the order of 3.85 factor. The increase in parasite density was believed to have been caused by bark removal to a near uniform thickness enabling a higher parasitism by those parasites with short ovipositors, such as Cecidostiba and Roptrocerus spp.One adverse effect of woodpecker predation was a reduction or a depression of insect predation. Highly mobile insect predators may have been driven away by woodpecker activity, actually consumed, or both.Bark flakes, chipped or pried off by the woodpeckers during their feeding activity, contained but few insects and it is doubtful that these could survive on the ground and reach the adult stage.

Western false hemlock looper, Nepytia freemani Munroe, is a cyclical pest in British Columbia which defoliates mainly Douglas-fir, Pseudotsugata menziesii (Mirb.) Franco, often near residential areas. Outbreaks were recorded from 1947 to 1949, 1963 to 1964, and 1972 to 1976; the current outbreak started in 1980 and, in 1982, covered 1,100 ha near Tappen, Canoe, Enderby, and Carquile (Ferris and Woensdregt 1983).

Three types of traps were tested in 1969 and 1970 for collecting pupae of the eastern hemlock looper, Lambdina fiscellaria fiscellaria (Guen.). Highest numbers of pupae were obtained with burlap traps made from 2-ft-wide bands wrapped around trunks of infested trees. The proportion of the pupae in the burlap traps was estimated. Some of the potential uses for pupae collected by the method are mentioned.

Insectivorous birds play an important role in the forest ecosystem. They have a significant influence on the population dynamics of many forest insects. Birds act as direct mortality agents of insect pests, and they can also affect their prey indirectly through influencing insect parasites and predators of the prey, by spreading entomogenous pathogens, or in some cases by altering the microhabitat of the prey. Birds exert the greatest influence on insect populations at endemic levels; they suppress and delay population build-up to epidemic levels, and thus may increase the interval between insect outbreaks. Insectivorous birds may also accelerate the decline of an outbreak. They may also have an effect on the forest ecosystem by feeding on and by dispersing seeds of various forest trees and shrubs. Some birds may be involved in the spreading of wood rotting fungi and thus contribute to the nutrient recycling.

Winthemia occidentis Rhn. was introduced into Newfoundland to strengthen the parasite complex of the eastern hemlock looper. This tachinid has two emergence periods, one in the fall, the other in the following spring. A method was developed for rearing overwintering tachinid larvae to the adult stage. The best rearing results were obtained when the larvae were stored outdoors in jars of peat moss for the fall and winter period and removed to controlled temperature and humidity conditions in the spring, to complete development.