The effect of warmer winters on the demography of an outbreak insect is hidden by intraspecific competition

Warmer climates are predicted to increase bark beetle outbreak frequency, severity, and range. Even in favorable climates, however, outbreaks can decelerate due to resource limitation, which necessitates the inclusion of competition for limited resources in analyses of climatic effects on populations. We evaluated several hypotheses of how climate impacts mountain pine beetle reproduction using an extensive 9‐year dataset, in which nearly 10,000 trees were sampled across a region of approximately 90,000 km², that was recently invaded by the mountain pine beetle in Alberta, Canada. Our analysis supports the hypothesis of a positive effect of warmer winter temperatures on mountain pine beetle overwinter survival and provides evidence that the increasing trend in minimum winter temperatures over time in North America is an important driver of increased mountain pine beetle reproduction across the region. Although we demonstrate a consistent effect of warmer minimum winter temperatures on mountain pine beetle reproductive rates that is evident at the landscape and regional scales, this effect is overwhelmed by the effect of competition for resources within trees at the site level. Our results suggest that detection of the effects of a warming climate on bark beetle populations at small spatial scales may be difficult without accounting for negative density dependence due to competition for resources.     

鹊肾树树皮的化学成分和抗炎作用研究

通过药理实验确定了鹊肾树树皮的乙酸乙酯萃取物为抗炎活性部位,并利用色谱技术从该部位中分离得到了7个化合物,通过UV、IR、NMR、MS等现代谱学方法鉴定化合物的结构分别为:丁二酸(1)、6-乙基-5-羟基-2,7-二甲氧基-1,4-萘醌(2)、3β,20-二羟基-5β-孕甾烷(3)、5-羟基麦芽酚(4)、双[5-甲酰基...     

Attraction of ambrosia and bark beetles to coast live oaks infected by Phytophthora ramorum

1 Sudden oak death is caused by the apparently introduced oomycete, Phytophthora ramorum. We investigated the role of bark and ambrosia beetles in disease progression in coast live oaks Quercus agrifolia. 2 In two Marin County, California sites, 80 trees were inoculated in July 2002 with P. ramorum and 40 were wounded without inoculation. Half of the trees in each group were sprayed with the insecticide permethrin [cyclopropanecarboxylic acid, 3‐(2,2‐dichloroethenyl)‐2,2‐dimethyl‐(3‐phenoxyphenyl) methyl ester] to prevent ambrosia and bark beetle attacks, and then were sprayed twice per year thereafter. After each treatment, sticky traps were placed on only the permethrin‐treated trees. Beetles were collected periodically in 2003. 3 Inoculated trees accounted for 95% of all beetles trapped. The ambrosia beetles Monarthrum scutellare and Xyleborinus saxeseni and the western oak bark beetle Pseudopityophthorus pubipennis were the most abundant of the seven species trapped. 4 Permethrin treatment delayed initiation of beetle attacks and significantly reduced the mean number of attacks per tree. Beetles did not attack any wounded or noncankered inoculated trees. 5 Trees with larger cankers trapped more beetles early in the disease. Once permethrin lost effectiveness, the number of beetle entrance tunnels was a more reliable predictor of subsequent trap catch than was canker size. 6 Beetles were initially attracted to P. ramorum cankers in response to kairomones generated in the host‐pathogen interaction. After beetles attacked the permethrin‐treated trees, aggregation pheromones most probably were the principal factor in beetle colonization behaviour.     

Non-alkaloidal constituents of Virola elongata bark

Eleven of the major non-polar constituents of the dried bark of Virola elongata were isolated. A new neolignan, virolongin, two new lignans, dihydrosesartemin and β-dihydroyangambin, as well as the neolignan, eusiderin, the lignans, epi-sesartemin, epi-yangambin and yangambin, the cis and trans isomers of 3,5,4′-trimethoxystilbene and sitosterol were identified. The structures of virolongin, dihydrosesartemin and β-dihydroyangambin were determined.     

Xanthones from Garcinia smeathmannii (Oliver) and their antimicrobial activity

Two new xanthones, smeathxanthone A (1) (2-(3,7-dimethyl-2,6-octadienyl)-1,3,5,8-tetrahydroxyxanthone) and smeathxanthone B (2) (5,7,10-trihydroxy-2-methyl-2-(4-methylpent-3-enyl)[2H, 6H]pyrano[3,2-b]xanthen-6-one), have been isolated from the stem bark of Garcinia smeathmannii, and their structures elucidated on the basis of 1D and 2D NMR experiments. 1,3,5-Trihydroxyxanthone and 1,5-dihydroxyxanthone were also obtained. The compounds showed only modest activity against a range of bacteria and yeasts.     

肉桂油的提取及其抑菌活性研究

本文用水蒸汽蒸馏法蒸馏经微波预处理的肉桂粉得到肉桂油,并采用滤纸片法、固相扩散法、气相扩散法研究了肉桂油对6种细菌、1种酵母、4种霉菌的抑菌活性及其最低抑菌浓度(MIC)。结果表明:肉桂油经固相和气相扩散对细菌、酵母、霉菌的抑制活性均较强,并且对真菌的抑菌活性更强一些,其次是G ,对所有供试菌种的最低抑菌浓度(MIC)<63mL/L,且真菌的MIC<细菌的MIC。     

Resistance of fast- and slow-growing subalpine fir to pheromone-induced attack by western balsam bark beetle (Coleoptera: Scolytinae)

Abstract 1 We investigated the resistance of fast‐ and slow‐growing subalpine fir to pheromone‐induced attack by western balsam bark beetle at two sites in the interior of British Columbia, Canada. 2 Attack success by the beetle and subsequent tree mortality were higher in slow‐growing trees than in fast‐growing trees. 3 Fast‐growing trees were more likely to produce secondary resin, and in greater quantities, than slow‐growing trees after attack. 4 Host vigour (indicated by recent radial growth) was positively related to the induced defense response and resistance of subalpine fir to bark beetle attack. These results are discussed in the context of plant defense and plant–herbivore interaction hypotheses. 5 Given the preference of western balsam bark beetle for weakened trees, as well as the reduced defenses and increased mortality rates in less vigorous trees, effective management tactics for this beetle may include strategies that increase the growth and vigour of its subalpine fir host.     

An ordinal day model of spruce beetle trap capture phenology in northern Colorado

Spruce beetle populations (Dendroctonus rufipennis) (Coleoptera: Scolytinae) in Engelmann spruce (Picea engelmannii) stands were monitored at twelve sites for 6 years in northern Colorado using pheromone‐baited Lindgren funnel traps. During the trapping period, over 30,000 beetles were captured, and beetle abundance data were used to construct empirical models of trap capture phenology based on day of year, accumulation of thermal units and thermal day thresholds, with the goal of informing future regional trapping efforts and producing a simple model for use by forest managers. Ordinal day models outperformed thermal accumulation and thermal threshold models in both predictive power and parsimony. Mean date of earliest capture was Day 153 (June 2) and ranged from Day 126 to Day 161 (May 6–June 10), and mean date of final capture was Day 243 (August 31) and ranged from Day 220 to Day 286 (August 8–October 13). A two‐parameter logistic function was the most parsimonious of several ordinal day models, accounting for 81% of the variance in cumulative trap capture across all sites and dates. The model predicts 50% of trap captures to occur by Day 181 (June 30). This model has application as a decision support tool for forest ecosystem managers concerned with the timing of trap deployment or D. rufipennis mitigation treatments.     

Growth and Wood/Bark Properties of Abies faxoniana Seedlings as Affected by Elevated CO2

Growth and wood and bark properties of Abies faxoniana seedlings after one year's exposure to elevated CO2 concentration (ambient 350 (=1= 25) μmol/mol) under two planting densities (28 or 84 plants/mz) were investigated in closed-top chambers. Tree height, stem diameter and cross-sectional area, and total biomass were enhanced under elevated CO2 concentration, and reduced under high planting density. Most traits of stem bark were improved under elevated CO2 concentration and reduced under high planting density. Stem wood production was significantly increased in volume under elevated CO2 concentration under both densities, and the stem wood density decreased under elevated CO2 concentration and increased under high planting density. These results suggest that the response of stem wood and bark to elevated CO2 concentration is density dependent. This may be of great importance in a future CO2 enriched world in natural forests where plant density varies considerably. The results also show that the bark/wood ratio in diameter, stem cross-sectional area and dry weight are not proportionally affected by elevated CO2 concentration under the two contrasting planting densities. This indicates that the response magnitude of stem bark and stem wood to elevated CO2 concentration are different but their response directions are the same.