Effect of feeding by the western conifer seed bug, Leptoglossus occidentalis, on the major storage reserves of developing seeds and on seedling vigor of Douglas-fir

The impact of feeding by the western conifer seed bug (Leptoglossus occidentalis Heidemann) on storage reserves of developing seeds of Douglas-fir (Pseudostuga menziesii (Mirb.) Franco) was studied by caging nymphal and adult seed bugs on cones during late-season development, and nymphs on cones during early, mid- and late-season development. Analysis of the major storage reserves of partially damaged seeds revealed that late-season feeding by each life stage and feeding by nymphs at all three stages of cone development significantly reduced the amounts of lipid and buffer-insoluble (crystalloid) protein in seeds at harvest by up to 78 and 97%, respectively. Seeds showing light to moderate damage on radiographs did not exhibit a reduction in the amount of buffer-soluble (matrix) protein. Seeds damaged by feeding during early development compensated in part by continuing to synthesize lipid and crystalloid protein. Light or moderate damage to mature Douglas-fir seeds exposed to L. occidentalis in the laboratory reduced seedling emergence by > 80%, but the seedlings that emerged successfully appeared to suffer no adverse effects when grown under standard nursery conditions.     

Changes in volatile terpene and diterpene resin acid composition of resistant and susceptible white spruce leaders exposed to simulated white pine weevil damage

Induced (traumatic) resin in white spruce (Picea glauca (Moench) Voss) leaders resistant or susceptible to the white pine weevil (Pissodes strobi Peck) was analyzed for volatile terpenes and diterpene resin acids after simulated white pine weevil damage. Leaders from 331 trees were wounded just below the apical bud with a 1-mm diameter drill, coinciding with the natural time of weevil oviposition in the spring. Leaders were removed in the fall, and the bark and xylem from the upper and lower regions of the leader extracted and analyzed by gas chromatography. Unwounded trees had low amounts of resin in xylem compared with bark. In response to wounding, volatile terpenes and diterpene resin acids increased in the upper xylem (area of wounding), with resistant trees showing a greater increase than susceptible trees. Wounding caused monoterpenes in particular to decrease in the lower region of the leader (away from the drilled area) in greater amounts in susceptible trees than in resistant trees. In response to wounding, the proportion of monoterpene to resin acid increased in the upper and lower xylem of resistant trees, and slightly increased in the upper xylem of susceptible trees. Monoterpene-enriched resin is more fluid than constitutive resin, and probably flows more readily into oviposition cavities and larval mines, where it may kill immature weevils. Loss of resin components in the lower xylem suggested catabolism and transport of these materials to the site of wounding; however, energetic and regulatory data are necessary to confirm this hypothesis. This study provides a basis for measuring the ability of a tree to undergo traumatic resinosis that could be used to screen for resistance to white pine weevil.     

Estimating coarse root biomass with ground penetrating radar in a tree-based intercropping system

Conventional measurements of tree root biomass in tree-based intercropping (TBI) systems can be inadequate in capturing the heterogeneity of rooting patterns or can be highly destructive and non-repeatable. In this study, we estimated coarse root biomass using ground penetrating radar (GPR) of 25-year-old trees inclusive of five species (Populus deltoides × nigra clone DN-177, Juglans nigra L., Quercus rubra L., Picea abies L. Karst, and Thuja occidentalis L.) at a TBI site in Southern Ontario, Canada. Subsurface images generated by GPR were collected in grids (4.5 × 4.5 m) centred on tree stems. The predictive relationship developed between GPR signal response and root biomass was corrected for species effects prior to tree-scale estimates of belowground biomass. Accuracy of the tree-scale estimates was assessed by comparing coarse root biomass measured from complete excavations of the corresponding tree. The mean coarse root biomass estimated from GPR analysis was 54.1 ± 8.7 kg tree^?1 (mean ± S.E.; n = 12), within 1 % of the mean coarse root biomass measured from excavation. Overall there was a root mean square error of 14.4 kg between measured and estimated biomass with no detectable bias despite variable conditions within the in-field and multi-species study. Root system C storage by species, calculated with species-specific root carbon concentrations, is estimated at 5.4 ± 0.7–34.8 ± 6.9 kg C tree^?1 at this site. GPR is an effective tool for non-destructively predicting coarse root biomass in multi-species environments such as temperate TBI systems.     

Conception rates and calving intervals of different beef breeds at a farm in the semi-arid region of Namibia

Tropical Animal Health and Production - A retrospective study from 2004 to 2017 investigated the effect of bull age, cow age and breed on conception rates, and calving intervals of beef cattle at...     

Three-dimensional deformation measured in an alaskan glacier

Measurements of movement along 28 boreholes reveal the three-dimensional flow field in a 6 million cubic meter reach of Worthington Glacier, a temperate valley glacier located in Alaska. Sliding at the bed accounted for 60 to 70 percent of the glacier's surface motion. Strain rates in the ice were low from the surface to a depth of about 120 meters, but then increased rapidly toward the bed. Ice deformation was not affected by temporal changes in the sliding rate. The three-dimensional pattern of motion indicates that plane strain, which is often assumed by models, is a poor approximation of this viscous flow.     

Echocardiographic evaluation of the effects of medetomidine and xylazine in dogs

The echocardiographic effects of medetomidine and xylazine were evaluated in 6 healthy dogs. Values for echocardiographic variables were significantly different from pre-treatment values after administration of both drugs. The effects of medetomidine were similar to that of xylazine. Because of their cardiac depressant effects, both drugs should be used with care in sick dogs.     

Potential for Nonhost Volatiles as Repellents in Integrated Pest Management of Ambrosia Beetles

Semiochemical-based mass trapping of the striped ambrosia beetle, Trypodendron lineatum (Olivier) (Coleoptera: Scolytidae), has been the cornerstone of an integrated pest management (IPM) programme for ambrosia beetles on the British Columbia coast since 1981. However, there is no available tactic of protecting logs from attack that could be incorporated into the IPM programme. We tested nonhost volatiles (NHVs) from the bark of angiosperm trees for their ability to disrupt catches of T. lineatum in multiple-funnel traps baited with the aggregation pheromone lineatin. In one set of experiments, a blend of 1-hexanol and benzyl alcohol caused 77.9% and 80.0% reduction in captures of males and females, respectively, and in another a blend of methyl salicylate and salicylaldehyde caused reductions of 65.0% for males and 66.9% for females. All four NHVs combined caused reductions in captures for males and females of 82.3% and 81.4%, respectively, not much greater than to the blend of 1-hexanol and benzyl alcohol. However, because both blends were active alone, their redundancy when combined lends confidence to the selection of the four-component blend for operational testing. Although disruption was increased when a 16-component NHV blend was tested, or when (±)–(E)-conophthorin was added to the four-component blend, addition of more compounds to the four-component blend was not considered operationally or economically justifiable. When deployed from low-density polyethylene tubes stapled along the length of pheromone-baited conifer logs, this blend caused prolonged and significant reductions in landing by T. lineatum and also by Gnathotrichus sulcatus (LeConte) and G. retusus (LeConte) (Coleoptera: Scolytidae). However, attacking beetles generally overcame the NHV treatment by the end of the flight period, leading to similar attack densities on treated and control logs. Therefore, we recommend that further operational investigations explore using repellent NHVs in combination with disruptive visual, tactile or gustatory stimuli.