Recent publications

Linking adaptation, delimitation of evolutionarily significant units (ESUs), and gene function: a case study using hemlock looper ecotypes. 2013. Lumley, L.M.; Cusson, M. Syst. Entomol. 38:428-439.

Mon, 29 Apr 2013 11:51:31 MST

Developing genetic markers for the identification of recently diverged groups, such as ecotypes or species complexes, remains difficult due to challenges with incomplete lineage sorting, hybridization and introgression. Genome-wide scans of single nucleotide polymorphisms (SNPs) have proven useful for inferring patterns of genetic differentiation at the population level. In combination with a new analytical technique, the discriminant analysis of principal components (DAPC), and within the framework of iterative taxonomy, it may also be possible to extract a combination of SNPs as markers for the delimitation of closely related groups. In addition, since DAPC identifies the loci contributing the most to group clustering, it may be possible to link putative biological function to differences that define group boundaries. We tested this technique on two ecotypes of the hemlock looper (Lambdina fiscellaria), which differ in terms of number of larval stadia, developmental rate and fecundity. It was possible to separately cluster the two ecotypes with 95% correct assignment using 27 SNPs. We also determined that a storage hexamerin carried eight of these SNPs, including the two highest contributing loci, of which the top contributor was nonsynonymous. Other studies have found this protein to be highly expressed just before metamorphosis, pointing to a possible connection between its role in clustering ecotypes and its biological function. These SNP markers can now be further developed for high throughput delimitation of individuals of unknown ecotype identity.

Mamidala, P.; Wijeratne, A.J.; Wijeratne, S.; Poland, T.; Qazi, S.S.; Doucet, D.; Cusson, M.; Béliveau, C.; Mittapalli, O. 2013. Identification of odor-processing genes in the emerald ash borer, Agrilus planipennis. PLoS ONE 8:e56555.

Mon, 29 Apr 2013 09:53:23 MST

Background: Insects rely on olfaction to locate food, mates, and suitable oviposition sites for successful completion of their life cycle. Agrilus planipennis Fairmaire (emerald ash borer) is a serious invasive insect pest that has killed tens of millions of North American ash (Fraxinus spp) trees and threatens the very existence of the genus Fraxinus. Adult A. planipennis are attracted to host volatiles and conspecifics; however, to date no molecular knowledge exists on olfaction in A. planipennis. Hence, we undertook an antennae-specific transcriptomic study to identify the repertoire of odor processing genes involved in A. planipennis olfaction.

Methodology and Principal Findings: We acquired 139,085 Roche/454 GS FLX transcriptomic reads that were assembled into 30,615 high quality expressed sequence tags (ESTs), including 3,249 isotigs and 27,366 non-isotigs (contigs and singletons). Intriguingly, the majority of the A. planipennis antennal transcripts (59.72%) did not show similarity with sequences deposited in the non-redundant database of GenBank, potentially representing novel genes. Functional annotation and KEGG analysis revealed pathways associated with signaling and detoxification. Several odor processing genes (9 odorant binding proteins, 2 odorant receptors, 1 sensory neuron membrane protein and 134 odorant/xenobiotic degradation enzymes, including cytochrome P450s, glutathione-S-transferases; esterases, etc.) putatively involved in olfaction processes were identified. Quantitative PCR of candidate genes in male and female A. planipennis in different developmental stages revealed developmental- and sex-biased expression patterns.

Conclusions and Significance: The antennal ESTs derived from A. planipennis constitute a rich molecular resource for the identification of genes potentially involved in the olfaction process of A. planipennis. These findings should help in understanding the processing of antennally-active compounds (e.g. 7-epi-sesquithujene) previously identified in this serious invasive pest.

Charred particle analyses. 2013. Brown, K.J.; Power, M.J. In: Elias, S.A. (ed.) The Encyclopedia of Quaternary Science 2:716-729.

Fri, 26 Apr 2013 11:45:21 MST

Foreward (Editorial) Sleeping Sickness. 2013. Abd-Alla, A.M.M.; Arif, B. Journal of Invertebrate Pathology. 112:S1.

Thu, 25 Apr 2013 09:36:49 MST

Forest inventory stand height estimates from very high spatial resolution satellite imagery calibrated with lidar plots. 2013. Mora, B., M.A. Wulder, G. Hobart, J.C. White, C.W. Bater, F.A. Gougeon, A. Varhola, N.C. Coops. International Journal of Remote Sensing. 34(12):4406–4424.

Wed, 24 Apr 2013 12:04:31 MST

Many areas of forest across northern Canada are challenging to monitor on a regular basis as a result of their large extent and remoteness. Although no forest inventory data typically exist for these northern areas, detailed and timely forest information for these areas is required to support national and international reporting obligations. We developed and tested a sample-based approach that could be used to estimate forest stand height in these remote forests using panchromatic Very High Spatial Resolution (VHSR, < 1 m) optical imagery and light detection and ranging (lidar) data. Using a study area in central British Columbia, Canada, to test our approach, we compared four different methods for estimating stand height using stand-level and crown-level metrics generated from the VHSR imagery. ‘Lidar plots’ (voxel-based samples of lidar data) are used for calibration and validation of the VHSR-based stand height estimates, similar to the way that field plots are used to calibrate photogrammetric estimates of stand height in a conventional forest inventory or to make empirical attribute estimates from multispectral digital remotely sensed data. A k-nearest neighbours (k-NN) method provided the best estimate of mean stand height (R2 = 0.69; RMSE = 2.3 m, RMSE normalized by the mean value of the estimates (RMSE-%) = 21) compared with linear regression, random forests, and regression tree methods. The approach presented herein demonstrates the potential of VHSR panchromatic imagery and lidar to provide robust and representative estimates of stand height in remote forest areas where conventional forest inventory approaches are either too costly or are not logistically feasible. While further evaluation of the methods is required to generalize these results over Canada to provide robust and representative estimation, VHSR and lidar data provide an opportunity for monitoring in areas for which there is no detailed forest inventory information available.

Insect cell culture: virus replication and applications in biotechnology. 2013. Arif, B.; Pavlik, L. 112(Suppl):S136-S141.

Wed, 24 Apr 2013 08:40:12 MST

Insect cell lines have been initiated since the 1930s and were used to replicate insect baculoviruses as well as arboviruses. Since the latter group of viruses cause serious diseased in man and equines, efforts were expended to characterize the viruses in the new cell lines in attempts to understand the replication cycle at the cellular and molecular levels. Soon it was realized that insect baculoviruses have a potential as viable alternatives to chemicals in the control of agricultural and forest insect pests. The cell lines provided excellent tools to understand the molecular biology of baculoviruses before wide-scale use in the field. During these investigations, it came to light that baculoviruses can be exploited as vectors for the expression of exogenous proteins and vaccines. The amenability of the virus to genetic modifications and the increasing numbers of permissive cell lines opened new avenues in protein expression. However, not all baculoviruses were able to replicate in cell lines. Indeed, there are no cell lines permissive to viruses belonging to the genera Gammabaculvirus and Deltabaculovirus. Some entomopoxviruses have been replicated in a few cell lines and this paper reports the replication of an entomopoxvirus from the spruce budworm in a homologous cell line.

Activity of Bacillus thuringiensis cytlBa crystal protein against hymenopteran forest pests. 2013. van Frankenhuyzen, K.; Tonon, A. Journal of Invertebrate Pathology. 113:160-162.

Wed, 24 Apr 2013 05:58:39 MST

A crystal-spore suspension of PS201T6 was toxic to larvae of Diprion similis (Hymenoptera: Diprionidae). Toxicity was at least in part attributable to the Cyt1Ba crystal protein, as demonstrated by bioassays of solubilized protein produced by Escherichia coli expressing PS201T6's cyt1Ba gene. PS201T6 reduced survival and growth of D. similis in a 2-week field experiment. In laboratory bioassays, both toxin and parental strain affected Acantholyda erythrocephala (Pamphiliidae), Pikonema alaskensis (Tenthredinidae), and Neodiprion sertifer (Diprionidae), as well as spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae). Affecting insects across at least four orders (Diptera, Coleoptera, Hymenoptera, Lepidoptera), Cyt1Ba has the broadest insecticidal activity spectrum among Bacillus thuringiensis crystal proteins documented to date.