Host selection behavior and incidence of the bark beetle Scolytus kashmirensis (Coleoptera:Curculionidae:Scolytinae) attacking elm (Ulmus spp.) trees in Kashmir

The status of the incidence of the bark beetle Scolytus kashmirensis Schedl on elm （Ulmus spp.） trees was determined in four districts of the Kashmir Valley in 2009. The incidence of the borer was higher in the Anantnag （25.93%） and Shopian （22.35%） districts of the Kashmir Valley, followed by the Ganderbal （17.14%） and Baramulla （16.67%） districts. The overall infestation re- corded in these districts was 20.52%. The beetle under study chewed the scars on twigs of both the host and tentative non-host plants supplied to them in cages but bored and laid eggs in only one of them （the host plant）. Both species of elm, Ulmus wallichiana and U. villosa, were susceptible to borer attacks; however, U. villosa showed low susceptibility and high resistance compared to U. wallichiana. Older, taller elms were preferred for feeding by bark beetles and are therefore much more susceptible to its infestation compared to younger elms. This bark beetle species also preferred to oviposit in branches of the host plants with diameters of 9-12 mm.

Does overshoot in leaf development of ponderosa pine in wet years leads to bark beetle outbreaks on fine-textured soils in drier years?

Background： Frequent outbreaks of insects and diseases have been recorded in the native forests of western North America during the last few decades, but the distribution of these outbreaks has been far from uniform. In some cases, recent climatic variations may explain some of this spatial variation along with the presence of expansive forests composed of dense, older trees. Forest managers and policy makers would benefit if areas especially prone to disturbance could be recognized so that mitigating actions could be taken. Methods： We use two ponderosa pine-dominated sites in western Montana, U.S.A. to apply a modeling approach that couples information acquired via remote sensing, soil surveys, and local weather stations to assess where bark beetle outbreaks might first occur and why. Although there was a general downward trend in precipitation for both sites over the period between 1998 and 2010 （slope =-1.3, R2 = 0.08）, interannual variability was high. Some years showed large increases followed by sharp decreases. Both sites had similar topography and fire histories, but bark beetle activity occurred earlier （circa 2000 to 2001） and more severely on one site than on the other. The initial canopy density of the two sites was also similar, with leaf area indices ranging between 1.7-2.0 m2. m-2. We wondered if the difference in bark beetle activity was related to soils that were higher in clay content at site I than at site II. To assess this possibility, we applied a process-based stand growth model （3-PG） to analyze the data and evaluate the hypotheses. Results： We found that when wet years were followed by drier years, the simulated annual wood production per unit of leaf area, a measure of tree vigor, dropped below a critical threshold on site I but not on site II. Conclusion： We concluded that the difference in vulnerability of the two stands to beetle outbreaks can be explained largely by differences in gross photosynthesis attributed to the fact that an equivalent amount of stored water in the rooting zone （100 mm） is extracted less efficiently from fine-textured soils than from coarse-textured ones.

Effects of bark beetle pheromones on the attraction of Monochamus alternatus to pine volatiles

We evaluated the attraction ofMonochamus alternatus Hope （Coleoptera： Cerambycidae）, Dryocoetes luteus Blandford and Orthotomicus erosus Wollaston （Coleoptera： Curculionidae： Scolytinae） to multiple-funnel traps baited with the pine volatiles, ethanol and （＋）-α-pinene and the bark beetle pheromones, ipsenol and ipsdienol. M. alternatus were attracted to traps baited with ethanol and （＋）-α-pinene but not those baited with ipsdienol and ipsenol. Ipsdienol and ipsenol decreased catches ofM. alternatus in traps baited with ethanol and （＋）-α-pinene. Traps baited with either binary combinations of ethanol and （＋）-α-pinene or ipsdienol and ipsenol were attractive to D. luteus and O. erosus. The addition of ipsenol and ipsdienol to traps baited with ethanol and （＋）-α-pinene synergized attraction of O. erosus but not D. luteus .

Early response of understory vegetation to the mass dieback of Norway spruce in the European lowland temperate forest

Spruce-dominated forests are commonly exposed to disturbances associated with mass occurrences of bark beetles.The dieback of trees triggers many physical and chemical processes in the ecosystem resulting in rapid changes in the vegetation of the lower forest layers.We aimed to determine the response of non-tree understory vegetation to the mass dieback of Norway spruce(Picea abies)in the first years after the disturbance caused by the European spruce bark beetle(Ips typographus)outbreak.Our study area was the Białowieża Biosphere Reserve covering the Polish part of the emblematic Białowieża Forest,in total 597km^(2).The main data source comprised 3,900 phytosociological relevés(combined spring and summer campaigns)collected from 1,300 systematically distributed forest sites in 2016–2018–the peak years of the bark beetle outbreak.We found that the understory responded immediately to mass spruce dieback,with the most pronounced changes observed in the year of the disturbance and the subsequent year.Shade-tolerant forest species declined in the initial years following the mass spruce dieback,while hemicryptophytes,therophytes,light-demanding species associated with non-forest seminatural communities,as well as water-demanding forest species,expanded.Oxalis acetosella,the most common understory species in the Białowieża Forest,showed a distinct fluctuation pattern,with strong short-term expansion right after spruce dieback,followed by a gradual decline over the next 3–4 years to a cover level 5 percentage points lower than before the disturbance.Thus,our study revealed that mass spruce dieback selectively affects individual herb species,and their responses can be directional and non-directional(fluctuation).Furthermore,we demonstrated that the mass dieback of spruce temporarily increases plant species diversity(α-diversity).

History, Present and Expected Future of Forests in Slovakia

In this paper, we briefly summarize the problems that have been affecting Slovakian forestry in the past, in the present and are expected in the future. In the past, the forests in Central Europe were significantly harmed by the development of mining, metallurgy, wood processing industry, agriculture and grazing of sheep and cattle. Many areas have been completely deforested. Fundamental change occurred in the 18th Century, when the regulations about forest management, declared by Empress of the Austro-Hungarian monarchy Maria Therese, came into force. With the changing level of forest cover, there have been changing as well the problems in the forestry. Forests in Slovakia are nowadays dealing with the climate change, which is causing extreme weather fluctuations. It is connected with the emergence of abiotic disturbances after which usually occurs activation of biotic harmful agents. We expect that the most serious problem of forests in the future will be their state of health. We expect an increase representation of thermophilic tree species (beech and oak) at the expense of upland trees such as spruce. An important role will be played by the invasive species of plants, fungi and animals that can compete with native species and their habitats or in the situation of the absence of their reducents these can cause serious economic and environmental damage.

Spatial Distribution of Mountain Pine Beetle Outbreaks in Relation to Climate and Stand Characteristics： A Dendroecological Analysis

Principal components analysis, followed by K-means cluster analysis, was used to detect variations in the timing and magnitude of Pinus contorta Dough ex Loud. growth releases attributed to mountain pine beetle outbreaks in 31 stands of central British Columbia. Four major growth release patterns were identified from 1970 to 2000. Variations in the timing of growth releases among clustered stands corresponded well to aerial survey data indicating the timing of beetle outbreaks in the study area. Redundancy analysis was used to determine how variations in the timing and magnitude of growth releases attributed to beetle outbreaks changed with variations in climate or stand conditions over the study area. The first RDA axis, which accounted for 39% of the variations in growth patterns among stands, was significantly （P〈0.05） correlated with gradients in the percentage of pine in stands killed by mountain pine beetle, summer aridity, variation in summer precipitation, distance from initial infestation site, average pine age, and maximum August temperatures. The second RDA axis explained 6% of the variations and was significantly correlated with gradients in the beetle climate suitability index, extreme cold month temperatures, and site index. Comparisons of growth release patterns with aerial survey data and redundancy analyses indicated that dendrochronological techniques are useful for identifying mountain pine beetle outbreaks in central British Columbia, particularly among stands that had a density high enough to produce a growth release signal. Provided future studies account for interannual weather fluctuations, identification of growth increases due to stand thinning caused by beetle outbreaks will be useful for reconstructing the history of beetle outbreaks over much longer time periods.

Effect of associated fungi on the immunocompetence of red turpentine beetle larvae, Dendroctonus valens （Coleoptera： Curculionidae： Scolytinae）

Abstract Dendroctonus-fungus symbioses are often considered as the ideal model sys- tems to study the development and maintenance ofectosymbioses, and diverse interactions, including antagonism, commensalism and mutualism, have been documented between these organisms. The red turpentine beetle, Dendroctonus valens LeConte （Coleoptera： Curculionidae： Scolytinae） is a pine-killing invasive beetle in northern China. Fungi species Ophiostoma minus, Leptographium sinoprocerum, L. terebrantis and L. procerum were associated with this bark beetle. Antagonistic interactions between D. valens and its as- sociated fungi, such as O. minus and L. sinoprocerum, have been demonstrated, but the underlying causes of this phenomenon are unknown. Here, we first found the two tested fungi species retarded the net weight gain of D. valens larvae after completing 3-day feeding on their media. Furthermore, we provide direct evidence indicating the effect of associated fungi on the immunocompetence olD. valens larvae to explain the documented antagonism. Our results showed that the activity of phenoloxidase and total phenoloxi- dase in D. valens larvae were significantly upregulated by two strains of associated fungi, O. minus and L. sinoprocerum as compared with the controls. The phenoloxidase ratio increased significantly in the larvae which had fed for 3 days on media inoculated with O. minus. Because insect immtme defenses are costly to be deployed, these results could be explored as one of the underlying mechanisms of the documented antagonism.