Mitochondrial DNA haplotypes indicate two postglacial re‐colonization routes of the spruce bark beetle Ips typographus through northern Europe to Scandinavia

Species in northern Europe re‐colonized the region after the last glacial maximum via several routes, which could have lingering signatures in current intraspecific trait variation. The spruce bark beetle, Ips typographus, occurs across Europe, and biological differences have been found between southern and northern Scandinavian populations. However, the postglacial history of I. typographus in Scandinavia has not been previously studied at a fine geographical scale. Therefore, we collected specimens across northern Europe and analysed the genetic variation in a quite large mitochondrial fragment (698 bp). A high genetic diversity was found in some of the most northern populations, in the Baltic States, Gotland and central Europe. Detected genetic and phylogeographic structures suggest that I. typographus re‐colonized Scandinavia via two pathways, one from the northeast and one from the south. These findings are consistent with the re‐colonization history of its host plant, Picea abies. However, we observed low haplotype and nucleotide diversity in southern Scandinavian populations of I. typographus, indicating that (unlike P. abies) it did not disperse across the Baltic Sea in multiple events. Further, the divergence among Scandinavian populations was shallow, conflicting with a scenario where I. typographus expanded concurrently with its host plant from a ‘cryptic refugium’ in the northwest.     

Vegetational changes in the montane grassland zone of the High Bieszczady mountains (southeast Poland) during the last millennium—pollen records from deposits in hanging peat-bogs

The pollen analytical investigations of hanging peat bogs in the summit zone of the Polish east Carpathians show that the absence of the upper montane spruce zone in the western Bieszczady mountains is a phenomenon that has been historically stable at least for the last millennium and probably also in earlier times. At altitudes corresponding to the spruce zone in other parts of the Carpathians, dwarf beech woods form here a low-lying upper tree limit. The montane grassland zone occurring above this tree line did not result from human activities, although it has been extended by human activity. Besides, it is shown how far it is possible to reconstruct from a pollen diagram the differentiation of vegetation surrounding the site of profile collection located in the upper montane zone when the present-day local plant communities are well known, in spite of pollen from long distance transport always being present at the summits of mountain ranges.     

Comparison of methods to evaluate the potential of fungal growth on decay of spruce wood after short-time treatment

Several analytical methods were compared to evaluate characteristic wood decaying fungi for their potential to depolymerise lignin on spruce wood particles. Wood samples were treated with the white rot fungi Phlebia brevispora, Ceriporiopsis subvermispora, Merulius tremellosus, Pycnoporus sanguineus, Trametes pubescens and with the brown rot fungus Gloeophyllum trabeum. The UV absorbancies of crude ethanol extracts, total extractives content from sequential extraction, ligninolytic enzyme activities, lignin solubilisation and decrease of lignin content were compared. It was shown, that, in early decay stages, UV absorbancies of crude ethanol extracts and total extractives content correlate well with lignin degradation, increase of acid soluble lignin and increased production of ligninolytic enzymes (total peroxidase). Lignin content was determined using FT-NIR spectroscopy as well as by wet-chemical analysis, indicating a very good correlation between the two methods. According to the different analytical methods, the tested fungi can be classified into three categories based on their characteristic behaviour: brown rot, “slow” and “fast” white rot.     

The effects of host plant on the coccinellid functional response: Is the conifer specialist Aphidecta obliterata (L.) (Coleoptera: Coccinellidae) better adapted to spruce than the generalist Adalia bipunctata (L.) (Coleoptera: Coccinellidae)?

Female Aphidecta obliterata consumed an average of 26.6 ± 5.8 Elatobium abietinum and males consumed an average of 19.9 ± 3.2 Elatobium abietinum, but there was no significant difference in the number consumed between the sexes. In Petri dish trials, the larval stages of A. obliterata and all stages of Adalia bipunctata appeared to exhibit a Type II response to prey density, although A. obliterata adults showed a more linear response to prey density. There was no significant difference between the functional responses of the 3rd instars of the two coccinellid species, but there was a significant difference between the responses shown by the 1st instars, with A. obliterata larvae consuming more than those of A. bipunctata, especially at low densities, suggesting that the two species respond differently to an increase in prey density.At low prey densities, adults and 4th instars of both species exhibited a similar response to an increase in prey density but at higher densities the 4th instars and adult stages of A. bipunctata showed higher attack rates when compared with the same stages of A. obliterata.Adult and 4th instar A. obliterata exhibited Type II functional responses on spruce sections. The 4th instar A. obliterata larva appeared to be a more effective predator than the adult of the species, and was more effective when compared with adult A. bipunctata at lower prey densities but A. bipunctata adults appeared to be a more effective predator at higher prey densities.The host plant affected the rate of consumption by adult A. obliterata as adults on Sitka spruce sections consumed significantly higher numbers of aphids than their counterparts on Norway spruce. This was most noticeable at densities above 16 aphids.The distributions of the two coccinellid species in the olfactometer were significantly affected by the presence of host plant material. Aphidecta obliterata adults were found in significantly higher numbers in the Sitka spruce chambers than the control chambers (those without plant material). Adalia bipunctata adults were found in significantly lower numbers in the Norway spruce chamber than the control chamber.Although A. bipunctata has a higher level of voracity than A. obliterata, the latter is more adapted to the spruce environment and the boom and bust population dynamics of E. abietinum.     

Food consumption and utilization by 6th-instar larvae of spruce budworm, Choristoneura fumiferana: a comparison on three Picea (spruce) species

The effects of tree species, shoot age, and sex of larvae on food consumption and utilization were investigated in a factorial experiment. Diets prepared from lyophilized and powdered current-year shoots, from two age classes (sample dates) of Picea glauca (Moench) Voss, Picea rubra, Sarg., and Picea mariana (Mill.) B.S.P., were evaluated for eight performance criteria. All factors had significant effects on all criteria except for tree species on assimilation efficiency, shoot age on development time, and sex on net growth efficiency. Eight of the possible 24 two-factor interactions and one of the possible eight three-factor interactions were significant. Food utilization efficiencies and relative growth rate were in the low and moderate characterization limits for immature arthropods; relative consumption rates were high. The higher performance values on Picea glauca were related to this species greater vulnerability to spruce budworm. Performance criteria of similar larvae on an artificial diet were compared with those on the foliage-diets.

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Résumé L'auteur a déterminé la quantité d'aliments utilisées, à 22±0,5 °C, par des larves de Tordeuse des bourgeons de l'épinette parvenues à leur sixième stade de développement qui s'étaient nourries d'un régime artificiel et d'aiguilles de l'année en cours lyophilisées et réduites en poudre, prélevées à deux dates différentes, à 10 jours d'intervalle, et provenant d'épinettes blanchés (Picea glauca [Moench] Voss), d'épinettes rouges (Picea rubra Sarg.) et d'épinettes noires (Picea mariana [Mill.] B.S.P.). Les femelles ont invariablement ingéré une quantité significativement plus importante de tous les régimes que les mâles, consommant 24% de plus d'aiguilles d'épinette noire et 73% de plus d'aiguilles d'épinette blanche.Les femelles prenaient en général plus de temps pour parvenir au stade de chrysalide et avaient un taux d'utilisation des aliments significativement plus élevé. L'efficacité nette de la croissance chez les deux sexes ne présentait toutefois aucune différence significative. La performance des larves ayant ingéré des aiguilles provenant de deux classes d'âge différait de façon significative mais non pas uniforme d'un régime à l'autre: les aiguilles d'épinette blanche plus récentes donnaient une performance généralement plus élevée contrairement aux aiguilles plus jeunes d'épinette rouge et d'épinette noire. Les larves ingéraient une quantité significativement plus élevée, avaient un taux de consommation et de croissance supérieur et augmentaient davantage leur biomasse avec des aiguilles d'épinette blanche. L'efficacité d'utilisation des aliments et le taux de croissance relatif étaient de faibles à modérément faibles pour un lépidoptère arboricole phyllophage; la vitesse d'ingestion relative était élevée. La qualité des aiguilles des trois essences d'épinettes était faible. Les aiguilles d'épinette blanche permettaient aux larves d'avoir une performance significativement plus élevée, performance mesurée à partir de plusieurs critères, alors que les aiguilles d'épinette rouge et d'épinette noire donnaient une performance égale. La supériorité des performances obtenues avec l'épinette blanche explique la plus grande vulnérabilité de cette essence à la Tordeuse des bourgeons de l'épinette.

     

Copper-chelatin: isolation from various eucaryotic sources.

Bovine factor V was treated with highly purified neuraminidase to yield asialo factor V. Different preparations of factor V were found to exhibit heterogeneity with respect to the content of sialic acid, which ranged from 5% to 12%. The activity of asialo factor V in accelerating blood coagulation was found to be significantly greater than native factor V; thus, sialic acid is not essential for activity but may modulate its function. Asialo-factor V was 3.8 times more stable as calculated from the thermal decay constant at 37 °C. when compared to unmodified factor V.The increase in activity of factor V by thrombin was biphasic after removal of all sialic acid residues. The binding of asialo-factor V to phosphatidyl ethanolamine, as, characterized both by kinetics and by sucrose density gradient ultracentrifugation, resulted in an inactive complex. Double immunodiffusion shows that the sialic acid component of factor V is not necessary for its antigenicity.     

Physiological and biochemical analysis of overwintering and cold tolerance in two Central European populations of the spruce bark beetle, Ips typographus

Overwintering success is one of the key aspects affecting the development and outbreaks of the spruce bark beetle, Ips typographus (L.) populations. This paper brings detailed analysis of cold tolerance, and its influence on overwintering success, in two Central European populations of I. typographus during two cold seasons. Evidence for a supercooling strategy in overwintering adults is provided. The lower lethal temperature corresponds well to the supercooling point that ranges between −20 and −22 °C during winter months. The supercooled state is stabilized by the absence of internal ice nucleators and by seasonal accumulation of a mixture of sugars and polyols up to the sum concentration of 900 mM. The cryoprotective function of accumulated metabolites is probably based on increasing the osmolality and viscosity of supercooled body fluids and decreasing the relative proportion of water molecules available for lethal formation of ice nuclei. No activity of thermal hysteresis factors (stabilizers of supercooled state) was detected in hemolymph. Lethal times for 50% mortality (Lts50) in the supercooled state at −5, −10 or −15 °C are weeks (autumn, spring) or even months (winter), suggesting relatively little mortality caused by chill injury. Lts50 at −15 °C are significantly shorter in moist (6.9 days) than in dry (>42 days) microenvironment because there is higher probability of external ice nucleation and occurrence of lethal freezing in the moist situation.     

Genomic selection accuracies within and between environments and small breeding groups in white spruce

Background

Genomic selection (GS) may improve selection response over conventional pedigree-based selection if markers capture more detailed information than pedigrees in recently domesticated tree species and/or make it more cost effective. Genomic prediction accuracies using 1748 trees and 6932 SNPs representative of as many distinct gene loci were determined for growth and wood traits in white spruce, within and between environments and breeding groups (BG), each with an effective size of N_e ≈ 20. Marker subsets were also tested.

Results

Model fits and/or cross-validation (CV) prediction accuracies for ridge regression (RR) and the least absolute shrinkage and selection operator models approached those of pedigree-based models. With strong relatedness between CV sets, prediction accuracies for RR within environment and BG were high for wood (r = 0.71–0.79) and moderately high for growth (r = 0.52–0.69) traits, in line with trends in heritabilities. For both classes of traits, these accuracies achieved between 83% and 92% of those obtained with phenotypes and pedigree information. Prediction into untested environments remained moderately high for wood (r ≥ 0.61) but dropped significantly for growth (r ≥ 0.24) traits, emphasizing the need to phenotype in all test environments and model genotype-by-environment interactions for growth traits. Removing relatedness between CV sets sharply decreased prediction accuracies for all traits and subpopulations, falling near zero between BGs with no known shared ancestry. For marker subsets, similar patterns were observed but with lower prediction accuracies.

Conclusions

Given the need for high relatedness between CV sets to obtain good prediction accuracies, we recommend to build GS models for prediction within the same breeding population only. Breeding groups could be merged to build genomic prediction models as long as the total effective population size does not exceed 50 individuals in order to obtain high prediction accuracy such as that obtained in the present study. A number of markers limited to a few hundred would not negatively impact prediction accuracies, but these could decrease more rapidly over generations. The most promising short-term approach for genomic selection would likely be the selection of superior individuals within large full-sib families vegetatively propagated to implement multiclonal forestry.     

Small gap dynamics in the southern boreal forest of eastern Canada: Do canopy gaps influence stand development?

Question: To what extent do small‐scale disturbances in the forest canopy, created by natural disturbance agents, affect stand development? Doubts exist as to whether small canopy openings have any real effect on the understory tree recruitment, especially in boreal forests. Location: Conifer and mixed stands in the Gaspesian region in eastern Québec. The main natural disturbance agents are recurring outbreaks of Choristoneura fumiferana (eastern spruce budworm) and winds. Methods: Linear transects in 27 sites were used to describe the gap (< 0.1 ha) regime parameters, including gap fraction, gap size and change in disturbance severity through time. Three stand types were distinguished, based on a gradient of abundance of tree host species for the eastern spruce budworm. The impact of gaps was evaluated on the basis of changes in the number, the period of recruitment, and the composition of tree saplings present within gap areas. Changes were measured along the gap size gradient, and according to the pattern of recent budworm epidemics. Results: The gap fraction is highly variable (18%‐64%) and is on average relatively high (42%). Gap sizes have a positively skewed distribution. In most cases the growth rate among gap filling saplings increased sufficiently to date disturbance events. The composition and the structure of understory trees were affected by gap formation. The number of shade‐intolerant tree species did increase during or following periods of particularly severe canopy disturbances. However, the establishment or survival of shade intolerant species was not restricted to larger gaps or more intensely disturbed periods. Conclusions: In sub‐boreal forests of Eastern Canada, small scale disturbances in the tree canopy influence stand regeneration dynamics, but not to the extent that parameters such as sapling composition and recruitment patterns depend on gap regime characteristics.     

Strategies of carbon and nitrogen acquisition by saprotrophic and ectomycorrhizal fungi in Finnish boreal Picea abies-dominated forests

We compared the δ¹³C and δ¹⁵N of forest material with an extensive sporocarp collection to elucidate the role of litter, wood and soil as fungal carbon and nitrogen sources in Finnish boreal Picea abies-dominated forests. Ectomycorrhizal Hydnum and Cortinarius had higher δ¹⁵N than other ectomycorrhizal fungi, suggesting use of ¹⁵N-enriched, deeper nitrogen. Russula had lower δ¹⁵N than other ectomycorrhizal fungi and resembled some litter decay genera, suggesting use of litter-derived nitrogen. There was little variation in δ¹⁵N among other genera of ectomycorrhizal fungi, indicating limited functional diversity in nitrogen use. Saprotrophic Leotia, Gymnopus, Hypholoma, Pholiota, Rhodocollybia and Calocera had δ¹⁵N values similar to ectomycorrhizal fungi, indicating overlap in use of older nitrogen from soil or roots or use of newly fixed nitrogen. Genera of litter and wood decay fungi varied up to 6‰ in δ¹³C and 10‰ in δ¹⁵N, suggesting large differences in carbon and nitrogen sources and processing. Similar δ¹³C between white and brown rot wood decay fungi also suggest that white rot fungi do not use lignin-derived carbon. Together, these δ¹³C and δ¹⁵N patterns of fungi from Finnish boreal forests enhance our knowledge of fungal functional diversity and indicate broad use of litter, wood and soil resources.