Tomicus Piniperda Research Articles

Hyperspectral evidence of early-stage pine shoot beetle attack in Yunnan pine

Pine shoot beetle (PSB, Tomicus spp.) outbreaks cause widespread Yunnan pine (Pinus yunnanensis Franch) mortality in southwestern China. Early identification of PSB attacks could help forest managers mitigate the infestation before it turns into an outbreak. However, the subtle spectral changes and complex process of PSB-induced crown discoloration make the remote sensing approach difficult.This study employed a manipulated insect infestation experiment to reveal suitable monitoring indicators. Healthy Yunnan pine crowns were infested with PSB adults at different preset densities (light, moderate, and severe) using the bagging method. The crown damage parameters, physiological properties, and corresponding spectral data were systematically measured in time series. Partial least squares regression (PLSR) was used to retrieve crown chlorophylla+b (Cab) and relative water content (RWC) via band reflectance. Random forest (RF) was used to determine the optimum spectral variables capable of capturing dynamic variations in crown shoot damage ratio (SDR).Results showed that (1) after four weeks’ PSB shoot feeding attack, SDR reached saturated (26%-50%) for all damage levels, indicating a crown discoloration “switch point”. (2) A continuous decline was found in Cab and RWC at both shoot and crown levels during the whole infestation process, and the crown level decrease was smaller than the shoot level due to crown heterogeneous discoloration. (3) For PLSR retrieving crown Cab and RWC, estimation accuracy of healthy crowns could reach R2 = 0.70, RMSEcv = 14.60 mg/m2 for Cab, and R2 = 0.82, RMSEcv = 1.25% for RWC, respectively. However, PSB early attack impacted these retrieval accuracies. (4) Spectral differences were evident in the visible region (530–600 nm) and near-infrared (NIR) plateau (780–1300 nm) among the preset damage levels. Significant differences in spectral variables (AMP, CI, OSAVI, RD, and SR) were observed between healthy and moderately damaged crowns. (5) In RF modeling, the importance of spectral variables for SDR estimation varied throughout the shoot feeding process. OSAVI, CI, MSI, PSRI, and SR2 were the top indicators that were suitable for identifying SDR ranging from 5% to 50%. SDR could be estimated with an accuracy of R2 = 0.71, RMSEcv = 8.92%, after 4 weeks’ infestation. Simultaneously, with the RF model, 4 preset damage levels could be differentiated with an out-of-bag error of 14.94% and a kappa coefficient of 0.8835.In conclusion, this study mainly examined the physiological and spectral signatures of PSB early attacked crowns, and provided optimum spectral variables and models which will further help unmanned aerial vehicle (UAV) and satellite remote sensing identify PSB infestation at the early stages.

Using the 3D model RAPID to invert the shoot dieback ratio of vertically heterogeneous Yunnan pine forests to detect beetle damage

As a significant forest disturbance factor, pine shoot beetles (PSB) have caused widespread tree mortality in Yunnan pine forests over southwestern China. Due to significant vertical heterogeneity of tree crowns, empirical remote sensing methods or one-dimensional (1D) radiative transfer (RT) models are not qualified enough to accurately retrieve the damage level of PSB damage. Therefore, three-dimensional (3D) RT models which have the ability to describe vertically complex heterogeneous canopies are more suitable for the damaged forests. In this study, shoot dieback ratio (SDR) was used to parameterize the Radiosity Applicable to Porous IndiviDual Objects (RAPID) model, in order to accurately estimate the PSB damage. Specifically, the vertically heterogeneous characteristics of the biophysical and optical properties within the canopy were carefully considered. First, we developed an approach to reconstruct damaged forest scenes through individual tree segmentation from UAV-lidar data and in situ measurements. Second, the simulated reflectance of forest scenes was compared with the actual hyperspectral and Sentinel-2 (S2) reflectance data to evaluate the performance of the parameterized RAPID. Then, the parameterized RAPID model was used to create a look-up table (LUT) containing the leaf chlorophyll content (Cab), effective leaf area index (LAIe), SDR, and dead needles LAIe (LAIdead, LAIe × SDR) as well as the corresponding simulated canopy reflectance. Furthermore, tree allometric equations were used to regularize the LUT with the intention to improve the estimation accuracy. Good agreement (RMSE: 0.015-0.031, index of agreement: 0.97-0.99) was found between the simulated reflectance and the remote sensing observations. The retrieval accuracy of the biochemical and biophysical parameters using S2 data yielded R2 = 0.55 (normalized RMSE (NRMSE) = 19%) for Cab, R2 = 0.70 (NRMSE = 15%) for the LAIe, R2 = 0.66 (NRMSE = 25%) for SDR, and R2 = 0.82 (NRMSE = 18%) for LAIdead. Using hyperspectral data with higher spatial and spectral resolution yielded better retrieval performance. This study demonstrated that 3D models (such as RAPID) have great potential to accurately invert SDR and LAIdead to assess PSB damage for the forests.

Emergence levels of pine shoot beetles from roundwood piles of Scots pine and the cascading damage in the surrounding forests

Bark beetles are amongst the most aggressive pest agents of coniferous forests. Due to this, many boreal countries have designated laws aiming to lower the risk of bark beetle epidemics. Finland’s forest legislation has pre-emptive measures targeted against bark beetles, and for Scots pine ( L.), the law concerns pine shoot beetles ( spp.). This study used data collected around 25 piles of Scots pine roundwood that were harvested in the winter but left in the forest until the following November. Thus, the pine shoot beetles were able to use the piles for breeding. We assessed the number of emerged insects from the piles and the cascading damage they caused in the surrounding forests. All roundwood piles, regardless of their volume, were used by the beetles for breeding. Highest densities of beetle exit holes were found from the parts of the log with thick and intact bark. If the bark of the log was damaged by the harvester head, the number of beetles decreased significantly. Depending on the volume of the roundwood pile, the cascading damage (fallen shoots) was noticeable up to ca. 40–60 m from the roundwood pile. Storing of piles smaller than 50 m did not cause excess damage. The number of fallen shoots per tree was generally below the known thresholds for when growth losses can occur. However, the study was conducted in mature forests, and it can be assumed that the recorded damage levels would severely affect the growth of young pines, raising the question of where to store the roundwood. As with other bark beetles, the role of beetles as damage agents may change in the future, but based on this as well as past studies, the species can be viewed as a notable damage agents only around long-term wood storage sites in the current northern conditions.Pinus sylvestrisTomicus3Tomicus

Tomicus species (Coleoptera: Curculionidae: Scolytinae) as Invasive Forest Pest to Mexico with Ecological Niche Modeling

Scolitine bark beetles of the genus Tomicus (Coleoptera: Curculionidae: Scolytinae) include some forestry pests of major importance worldwide, with the capacity for invading new habitats and threatening native forest populations and are considered as exotic species for America. However, Tomicus piniperda L. the common pine shoot beetle has invaded North America recently and specimens of T. minor Hart have been intercepted in the United States. The possibility for an invasion of Mexico grows day

Discriminant Analysis of the Damage Degree Caused by Pine Shoot Beetle to Yunnan Pine Using UAV-Based Hyperspectral Images

Due to the increased frequency and intensity of forest damage caused by diseases and pests, effective methods are needed to accurately monitor the damage degree. Unmanned aerial vehicle (UAV)-based hyperspectral imaging is an effective technique for forest health surveying and monitoring. In this study, a framework is proposed for identifying the severity of damage caused by Tomicus spp. (the pine shoot beetle, PSB) to Yunnan pine (Pinus yunnanensis Franch) using UAV-based hyperspectral images. Four sample plots were set up in Shilin, Yunnan Province, China. A total of 80 trees were investigated, and their hyperspectral data were recorded. The spectral data were subjected to a one-way ANOVA. Two sensitive bands and one sensitive parameter were selected using Pearson correlation analysis and stepwise discriminant analysis to establish a diagnostic model of the damage degree. A discriminant rule was established to identify the degree of damage based on the median value between different degrees of damage. The diagnostic model with R690 and R798 as variables had the highest accuracy (R2 = 0.854, RMSE = 0.427), and the test accuracy of the discriminant rule was 87.50%. The results are important for forest damage caused by the PSB.

Bark and Ambrosia Beetles (Coleoptera, Curculionidae: Scolytinae) of Northwest Russia: History of the Study, Composition and Genesis of the Fauna

An essay of the fauna of bark beetles (Coleoptera: Curculionidae: Scolytinae) in five federal subjects of Northwest Russia is presented. The species composition of scolytids in Leningrad, Novgorod, Pskov, and Murmansk provinces as well as the Republic of Karelia is analyzed in comparison with the bark beetle faunas of adjacent Estonia and Finland. The history of investigation of the bark beetle fauna in Northwest Russia starting from the XVIII century and up to date is discussed, and modern knowledge on the regional bark beetle fauna is considered. The distribution of “northern” and “southern” bark beetle species in the region is discussed, and a southward increase in species richness is demonstrated. The genesis of the bark beetle faunas of individual provinces is analyzed with respect to the host plant distribution in the postglacial period (Holocene). It is shown that the border between the middle and the southern taiga subzones running across Leningrad Province is also the northern distribution boundary of numerous bark beetle species. Special attention is paid to expansion of several bark beetle species into Northwest Russia in the last decades caused by different factors; the northward range expansion of the small spruce bark beetle Ips amitinus (Eichhoff, 1872) and elm bark beetles from the genus Scolytus Geoffroy, 1762 is considered in more detail. The absence of monitoring of the elm bark beetle populations has led to uncontrolled reproduction of the pests, spread of Dutch elm disease, and significant economic losses. Rare bark beetle species deserving inclusion in the regional Red Data Lists are named. Attention is drawn to the insufficient knowledge of the bark beetle fauna in nature reserves and other protected areas in Northwest Russia. The damage caused by the most economically important bark beetles, namely the European spruce bark beetle Ips typographus (Linnaeus, 1758) and pine shoot beetles of the genus Tomicus Latreille, 1802, in the boreal forest zone is briefly reviewed. Some taxonomic problems which remain to be solved in order to refine the local bark beetle species lists in Northwest Russia are outlined. The contribution of researchers from St. Petersburg Forest Institute to the knowledge of bark beetle biology in the region and in the whole of Russia is specially considered.

Ecological restoration for biodiversity conservation triggers response of bark beetle pests and their natural predators

Abstract The restoration of forest structure and function is increasingly being used in boreal forests in order to halt the loss of biodiversity. Often ecological restoration is aimed at increasing the volume of dead and dying trees to enhance the biodiversity of deadwood-dependent organisms, but it may also increase population sizes of pest bark beetle species, even several years following restoration. Herein, we used a large-scale restoration experiment in Northern Sweden to assess the 5 years post-restoration effects of restorative gap cutting and prescribed burning on the populations of a set of economically harmful pest bark beetles (Ips typographus, Polygraphus poligraphus, Tomicus piniperda and Pityogenes chalcographus) and the most important predators of bark beetles, Thanasimus spp. In addition, we assessed the effects of forest stand characteristics at stand and landscape scale on the abundance of I. typographus. Five years post-restoration, gap-cut stands supported the highest abundances of P. poligraphus and contained the highest count of spruce trees newly attacked by bark beetles. By contrast, prescribed burning generally sustained the lowest abundances of pest bark beetles, especially I. typographus and P. poligraphus, and the highest abundance of their natural predators Thanasimus spp. The population abundance of I. typographus was also positively affected by the area of clear cuts within a 500 m radius from the stand. In conclusion, prescribed burning appears to be a safer method for ecological restoration than gap cutting in the long-term. According to our results, a risk of a local bark beetle outbreak still remains 5 years following the initiation of ecological restoration treatments on spruce-dominated mature gap-cut stands.

Distribution of endemic bark beetle attacks and their physiological consequences on Pinus halepensis

One factor that determines a tree’s resilience capacity to drought is its level of interaction with aggravating biotic factors, such as bark beetles, which in turn depends on whether insect populations are at an endemic or epidemic stage. In a Mediterranean natural forest ecosystem, we investigated the ecophysiological characteristics of trees which (i) predispose Pinus halepensis to attacks of endemic populations of bark beetles (Tomicus destruens) and (ii) that arise as a result of these attacks. The annual life cycle of Tomicus destruens features an initial dispersal phase of sexually mature adults towards pine trunks for the purposes of brood production, and a second dispersal phase of callow adults from trunks to pine shoots for sexual maturation. During a three-year survey of endemic bark beetle attacks in a stand of 178 trees, we found that trees targeted for trunk attacks showed a more aggregated distribution pattern than those targeted for shoot attacks. Moreover, shoot-attacked trees were clearly larger and taller, had lower wood density, and were less exposed to competition than non-attacked trees. No differences were found between the characteristics of trunk-attacked trees and non-attacked ones. We found crown defoliation, lower primary growth and alteration of trunk non-structural carbon in phloem in the year following trunk attacks, although this did not affect vulnerability to cavitation of the vascular system, secondary growth, wood density, and xylem starch. Conversely, the health status and physiological variables of the shoot-attacked trees were not altered, which may be explained by their initial vigor. We conclude that the distribution of Tomicus destruens attacks at the plot level was independent of the ecophysiological traits of the host trees. It was mainly determined by the dispersal strategy of the endemic bark beetle population especially during brood production as only trunk attacks significantly weakened the trees.

Niche‐based relationship between sympatric bark living insect pests and tree vigor decline of Pinus yunnanensis

AbstractForest stands of Pinus yunnanensis Franch in southwestern China are seriously damaged by several bark living insect pests. These pests commonly exist in the same host tree and exploit limited phloem resources. In this study, we hypothesized that sympatric pests would occupy different ecological niches to reduce interspecific competition, and their coordinated attack would aggravate the tree vigor decline of P. yunnanensis. To quantify the ecological niches, we used a sampling method involving three dimensional divisions of tree resource states: (a) sample plot dimension (to evaluate the extent of pest colonization at plot scale), (b) trunk height dimension, and (c) tree vigor dimension. Those attacked pine canopies and colonized trunks were analysed in the field study. The results showed that Tomicus minor and Tomicus yunnanensis both widely and uniformly distributed in lightly, moderately and heavily damaged canopies while they aggregated on particular trunks of dying and withered trees. Lower and middle trunk sections (1–4 m) were mainly occupied by Monochamus alternatus and T. minor, yet T. yunnanensis dominated the upper parts (5–6 m). There was an overlap of the pine shoot beetles in the middle sections (2–4 m), whereas all three species were ecologically segregated in other trunk sections. During the shoot feeding phase, tree vigor declined with pine shoot beetles' increasing shoot feeding density. They coexisted in the same host tree, while M. alternatus only attacked dying and withered tree trunks, causing a greater infestation. Colonization of pine shoot beetle then followed by M. alternatus could be the major causes of tree mortality. This study highlights the resource utilization pattern of sympatric bark living insect pests corresponding with tree vitality. Those findings would help to understand the mechanisms of pest outbreak in P. yunnanensis ecosystem and provide potential guidance for developing an early monitoring pest warning system.

Зміни вмісту монотерпенів живиці сосни у звʼязку з ураженням кореневою губкою (Heterobasidion annosum (Fr.) Bref.)

За допомогою газорідинної хроматографії виявлено тенденції змін вмісту монотерпенів у складі живиці дерев сосни IV класу віку, уражених кореневою губкою у різному ступені. Виявлено, що з розвитком хвороби вміст α-пінену і камфену знижується. Найменший їхній уміст, якщо порівняти зі здоровими деревами, виявлено у дерев, що знаходяться в активній зоні осередку всихання, ступінь ураження коріння яких становить 11–30 %. Уміст ∆3-карену в складі живиці цих дерев проти неуражених є, навпаки, вищим на 15–16 %. Уміст β-пінену в уражених кореневою губкою дерев був в 1,8–2,0 разу вищим, ніж у неуражених. Відзначено, що зміни в складі ефірних олій дерев в активній зоні осередку хвороби є сигналом щодо ослаблення дерева та можливості його заселення лубоїдами. Зміни в складі ефірних олій живиці в осередках кореневої губки провокують як патологічні процеси, так і зміни екології дерев унаслідок розвитку хвороби.

Динаміка популяцій короїдів у соснових лісах Житомирської області

Установлено, що у всиханні соснових насаджень Житомирської області відіграють роль короїди, які заселяють дерева, ослаблені внаслідок посух і надмірного антропогенного навантаження. Висловлено гіпотезу, що після посухи 2009 р. відбулося два спалахи різних угруповань короїдів. Для підтвердження цієї гіпотези проаналізовано динаміку за 2013-2019 рр. популяційних показників найпоширеніших видів під час їхнього масового розмноження у лісах Житомирської області: великого (Tomicus piniperda) та малого (T. minor) соснових лубоїдів, а також верхівкового (Ips acuminatus) й шестизубчастого (I sexdentatus) короїдів. Під час аналізу даних стосовно поширеності, щільності поселення, продукції й енергії розмноження цих видів, одержаних на 550 палетках із 61 модельного дерева, з'ясовано, що в комплексі короїдів в осередках всихання до 2014 р. переважали соснові лубоїди, а з 2015 р. – верхівковий і шестизубчастий короїди, які мають декілька поколінь на рік. Показано, що основні тенденції розвитку комплексу короїдів у соснових насадженнях Житомирської області в роки досліджень визначала динаміка популяцій домінантного виду – верхівкового короїда. Значення показників поширеності, щільності поселень, продукції та енергії розмноження короїдів свідчать про посилення з 2016 р. внутрішньовидової конкуренції в популяції верхівкового короїда, а у 2018-2019 рр. – також міжвидової конкуренції. З огляду на дію конкуренції та накопиченням ентомофагів в осередках всихання варто очікувати згасання спалахів масового розмноження короїдів.

Detection of Pine Shoot Beetle (PSB) Stress on Pine Forests at Individual Tree Level using UAV-Based Hyperspectral Imagery and Lidar

In recent years, the outbreak of the pine shoot beetle (PSB), Tomicus spp., has caused serious shoots damage and the death of millions of trees in Yunnan pine forests in southwestern China. It is urgent to develop a convincing approach to accurately assess the shoot damage ratio (SDR) for monitoring the PSB insects at an early stage. Unmanned airborne vehicles (UAV)-based sensors, including hyperspectral imaging (HI) and lidar, have very high spatial and spectral resolutions, which are very useful to detect forest health. However, very few studies have utilized HI and lidar data to estimate SDRs and compare the predictive power for mapping PSB damage at the individual tree level. Additionally, the data fusion of HI and lidar may improve the detection accuracy, but it has not been well studied. In this study, UAV-based HI and lidar data were fused to detect PSB. We systematically evaluated the potential of a hyperspectral approach (only-HI data), a lidar approach (only-lidar data), and a combined approach (HI plus lidar data) to characterize PSB damage of individual trees using the Random Forest (RF) algorithm, separately. The most innovative point is the proposed new method to extract the three dimensional (3D) shadow distribution of each tree crown based on a lidar point cloud and the 3D radiative transfer model RAPID. The results show that: (1) for the accuracy of estimating the SDR of individual trees, the lidar approach (R2 = 0.69, RMSE = 12.28%) performed better than hyperspectral approach (R2 = 0.67, RMSE = 15.87%), and in addition, it was useful to detect dead trees with an accuracy of 70%; (2) the combined approach has the highest accuracy (R2 = 0.83, RMSE = 9.93%) for mapping PSB damage degrees; and (3) when combining HI and lidar data to predict SDRs, two variables have the most contributions, which are the leaf chlorophyll content (Cab) derived from hyperspectral data and the return intensity of the top of shaded crown (Int_Shd_top) from lidar metrics. This study confirms the high possibility to accurately predict SDRs at individual tree level if combining HI and lidar data. The 3D radiative transfer model can determine the 3D crown shadows from lidar, which is a key information to combine HI and lidar. Therefore, our study provided a guidance to combine the advantages of hyperspectral and lidar data to accurately measure the health of individual trees, enabling us to prioritize areas for forest health promotion. This method may also be used for other 3D land surfaces, like urban areas.

Ophiostomatales (Ascomycota) associated with Tomicus species in southwestern China with an emphasis on Ophiostoma canum

Ophiostomatalean fungi may facilitate bark beetle colonization and reproduction. In the present study of the fungal community associated with bark beetle species belonging to Tomicus in Yunnan, China, six ophiostomatalean fungi (Ophiostoma canum, O. ips, O. tingens, Leptographium yunnanense, Leptographium sp. 1 and Leptographium sp. 2) were isolated from the beetles or their galleries; O. canum was the most common fungal species. The distribution of O. canum was associated with stands heavily damaged by Tomicus species and a higher percentage of valid galleries of Tomicus yunnanensis and T. minor in Yunnan pine (Pinus yunnanensis). After inoculation of Yunnan pine with the fungus, a phloem reaction zone formed and monoterpenes accumulated in the phloem. These results suggested that O. canum was pathogenic to Yunnan pine and that the wide distribution of the fungus might be beneficial to reproduction of pine shoot beetles in Yunnan pine. However, because the reaction zone and monoterpene accumulation were mild, fungal damage of Yunnan pine might be limited. A more integrated study considering all the fungal species should be done to better understand the interactions among bark beetles, blue-stain fungi, and the tree hosts in the region.

Factors affecting the occurrence of bark- and wood-boring beetles on Scots pine logging residues from pre-commercial thinning

A total of480 Scots pine (Pinus sylvestris L.) trees felled during pre-commercial thinning in a single stand in the Drahanska Highlands in the Czech Republic were examined for the occurrence of bark- and wood-boring beetles. Thinning was performed on different dates during 2006 and 2007 (February, May, August and November). Half of the felled trees were cut into 1 m-long sections, and the rest were left whole. The fauna inhabiting the logging residues were investigated by peeling off the bark ofthe felled trees during the first six months of the vegetative period following felling. The studied logging residues hosted species-rich assemblages of bark- and wood-boring beetles (28 species identified), including numerous populations of several pest species (Pityogenes chalcographus, Tomicus minor and Tomicus piniperda). The occurrence of species was significantly affected mainly by the part of the tree and its diameter and bark thickness and by the felling date and post-felling cutting of the trees.

Semiochemical Regulation of the Intraspecific and Interspecific Behavior of Tomicus yunnanensis and Tomicus minor during the Shoot-Feeding Phase.

Two pine shoot beetles, Tomicus yunnanensis and Tomicus minor, are the most destructive pests of Pinus yunnanensis in southwestern China. We investigated behavioral responses within and between these two species during the shoot-feeding phase using walking bioassays. We also identified the pheromonal aspects of beetles by static solid phase microextraction (SPME) and hindgut extraction following interactive communication by gas chromatography-mass spectroscopy (GC-MS). Both species were significantly attracted by their own species and the same sex, and attraction was inhibited by exposure to additional beetles or to the hindgut extracts of beetles which had shown interaction. Female and male T. minor and T. yunnanensis hindguts contained 0.19, 0.09, 0.22, and 0.05ng/individual of (-)-trans-verbenol, respectively; following interaction with additional beetles, this increased to 16.74-292.71ng/individual in T. minor females. Mean concentration of verbenone detected in the hindguts of female/male individuals of T. minor and T. yunnanensis under natural conditions were 0.16, 0.06, 0.03, and 0.05ng/individual, respectively, but these correspondingly increased to 5.90, 2.43, 0.06, and 0.19ng/individual after exposure to additional insects. In T. yunnanensis, the amounts of detectable (-)-trans-verbenol and verbenone extracted from hindguts were lower than those from T. minor. The levels of cis-verbenol and (-)-trans-verbenol most attractive to walking T. yunnanensis and T. minor were 0.1 and 1.0ng/μl, respectively. Verbenone was not attractive at any of the concentrations tested. The addition of verbenone to cis-verbenol or (-)-trans-verbenol reduced the attraction responses. We conclude that the (-)-trans-verbenol produced by these two pine shoot beetles is attractive at low concentrations and repellant at high concentrations, thereby fostering intraspecific competition. Verbenone is produced to prevent overcrowding via interspecific inhibition, and to expel beetles during shoot-feeding.

Pine defenses against the pitch canker disease are modulated by a native insect newly associated with the invasive fungus

Tomicus piniperda (Coleptera, Curculionidae) is a native insect in Europe and now potential enabler of the invasive fungal pathogen of pines, Fusarium circinatum. The co-occurence of T. piniperda and F. circunatum could increase disease incidence via (1) insect wounding when they bore galleries into shoots of healthy trees, and (2) by acting as vectors that introduce fungal propagules directly. The extent of damage by F. circinatum is likely to be influenced by tree defenses, which can depend upon pine species, environmental conditions, and responses to other biotic and abiotic challenges. Indirect interactions among plant enemies can arise when the attack by one enemy alters the shared host plant in a way that affects a second enemy. We tested for indirect interactions between T. piniperda and F. circinatum mediated by plant defenses. Our study employed 100 potted, identically treated, seedlings of Pinus pinaster and P. radiata. Plants were randomly allocated to one of five different treatments: inoculation with T. piniperda alone, inoculation with F. circinatum alone, inoculation with T. piniperda and F. circinatum together, a mock treatment with sterilized water, and true controls. We assessed plant mortality, and measured plant height and diameter, crown size, resin flow after T. piniperda attack, the size of lesions from fungal infection, and phloem chemistry (terpenes and nitrogen). There were conspicuous differences between pine species in their defensive responses to inoculations: P. pinaster showed increases in numerous terpenes following attack by T. piniperda but was unresponsive to F. circinatum, while P. radiata increased terpene concentrations with exposure to either F. circinatum or T. piniperda. In P. radiata, fungal growth within the plant (as reflected by lesion size) was reduced by coincident insect attack. This suggests that plant defensive responses against the insect also functioned as deterrents to a fungal enemy. Thus the combination of T. piniperda and F. circinatum should not be as dangerous to pine stands as if the insect disabled defences against the fungus. Nonetheless, the insect can only increase fungal introductions by increasing wounds and moving propagules. There is a need for field studies of damage from F. circinatum in different pine species with low vs. high abundance of T. piniperda. Better understanding of pine defenses against F. circinatum, and genetic variation in defense responses, would contribute to the development of safe, effective, and sustainable tactics for managing damage from F. circinatum to pine forests in Spain and elsewhere.

Bark Beetles of Balikesir Region in Turkey

The aim of this study was to determine species of bark beetles in the coniferous forests of Bahkesir. Five pheromone and two log traps were established in six plots and set 40 meters apart for each site. At the conclusion of the study, 15 species belonging to 4 tribes Hylastini, Ipini, Pholeosinini and Tomicini of Scolytinae were identified as follows: Hylastes angustatus, H. linearis, Ips sexdentatus, Orthotomicus erosus, O. longicollis, Pityogenes bistridentatus, P. pennidens, Pityokteines curvidens, P. vorontzowi, Phloeosinus aubei, Hylurgus ligniperda, H. micklitzi, Tomicus destruens, T. minor and T. piniperda.

Bark Beetle-Associated Blue-Stain Fungi Increase Antioxidant Enzyme Activities and Monoterpene Concentrations in Pinus yunnanensis.

Yunnan pine is the most important tree species in SW China in both economical and ecological terms, but it is often killed by pine shoot beetles (Tomicus spp.). Tomicus beetles are secondary pests in temperate regions and the aggressiveness of the beetles in SW China is considered to be due to the warm subtropical climates as well as the beetles’ virulent fungal associates. Here, we assessed the virulence of three blue-stain fungi (Leptographium wushanense, L. sinense and Ophiostoma canum) associated with pine shoot beetles to Yunnan pine (Pinus yunnanensis) in SW China. Following fungal inoculation, we measured necrotic lesion lengths, antioxidant enzyme activities and monoterpene concentrations in the stem phloem of Yunnan pine. Leptographium wushanense induced twice as long lesions as L. sinense and O. canum, and all three fungi induced significantly longer lesions than sterile agar control inoculations. The activity of three tested antioxidant enzymes (peroxidase, polyphenol oxidase, and superoxide dismutase) increased after both fungal inoculation and control inoculation. However, L. wushanense and L. sinense generally caused a greater increase in enzyme activities than O. canum and the control treatment. Fungal inoculation induced stronger increases in six major monoterpenes than the control treatment, but the difference was significant only for some fungus-monoterpene combinations. Overall, our results show that L. wushanense and L. sinense elicit stronger defense responses and thus are more virulent to Yunnan pine than O. canum. The two Leptographium species may thus contribute to the aggressiveness of their beetle vectors and could damage Yunnan pine across SW China if they spread from the restricted geographical area they have been found in so far.

Fungal Communities Associated with Bark Beetles in Pinus radiata Plantations in Northern Spain Affected by Pine Pitch Canker, with Special Focus on Fusarium Species

Fusarium spp., as well as other endophytic or pathogenic fungi that form communities, have been reported to be phoretically associated with bark beetles (Coleoptera; Scolytinae) worldwide. This applies to Fusarium circinatum Nirenberg and O’Donnell, the causal agent of pine pitch canker (PPC), which threatens Pinus radiata D. Don plantations in northern Spain. The main objective of this study was to study the fungal communities associated with bark beetles and their galleries in stands affected by PPC, with special attention given to Fusarium species. Funnel traps and logs were placed in a P. radiata plot known to be affected by F. circinatum. The traps were baited with different attractants: four with (E)-pityol and six with ethanol and α-Pinene. In addition, fresh green shoots with Tomicus piniperda L. feeding galleries were collected from the ground in 25 P. radiata plots affected by PPC. Extracts of whole insects and gallery tissues were plated on agar medium to isolate and identify the associated fungi. A total of 24 different fungal species were isolated from the bark beetle galleries constructed in logs and shoots, while 18 were isolated from the insect exoskeletons. Ten different Fusarium species were isolated from tissue and insects. Fusarium circinatum was isolated from bark beetle exoskeletons (1.05% of the Pityophthorus pubescens Marsham specimens harboured F. circinatum) and from the galleries (3.5% of the T. piniperda feeding galleries harboured the pathogen). The findings provide information about the fungal communities associated with bark beetles in P. radiata stands in northern Spain.

Health Condition and Colonization of Stem Insects in Scots Pine after Ground Fire in Central Polissya

Abstract Over the past decades, the increase in occurrence of fires has caused degradation of the forest ecosystem and caused impacts to the environment. The aim of this study was to reveal the peculiarities of Scots pine health condition dynamics in the first 2 years after August fire and to estimate the rate of tree colonisation by stem insects in Central Polissya. Scots pine health condition for the first 2 years after summer ground fire in August 2016 and the rate of tree colonisation by stem insects was studied in Zhytomyr region, Western Ukraine. Stem scorch height was measured for every fire-damaged tree, and the index of fire damage severity was calculated. Vital trees health condition worsened more intensively in the sample plot with the lowest relative stocking density and the highest stem scorch by fire. Generally, the forest health condition has worsened in post-fire period in fire damaged stands. However, 23.1% of trees recovered health condition from category ‘drying-up’ to ‘severely weakened’. In fire-damaged stands, the number of species of stem insects has increased from 8 to 11 during the first 2 years of fire damage. Bark beetles were represented by Tomicus piniperda (Linnaeus, 1758), Tomicus minor (Hartig, 1834), Ips acuminatus (Gyllenhal, 1827) and Ips sexdentatus (Boerner, 1767). Jewel beetles included Anthaxia quadripunctata (Linnaeus, 1758), Phaenops cyaneus (Fabricius, 1775), Melanophila acuminata (DeGeer, 1774) and Chalcophora mariana (Linnaeus, 1758). Longhorn beetles included Monochamus galloprovincialis (Olivier, 1795), Pogonocherus fasciculatus (Degeer, 1775) and Acanthocinus aedilis (Linnaeus, 1758). Tree colonisation by stem insects in the year of fire damage was comparable with control stand, because insect swarming completed before this disturbance. Maximal occurrence of stem insects in 2017 in fire-damaged stand increased up to 66.7% (for I. sexdentatus). The percentage of trees colonised by any insect species at fire-damaged and healthy pine stands differed significantly. The occurrence of stem insects depended mainly on the ratio of trees with different health condition. Our results demonstrate data of tree damage from fire and tree health index as a strong predictor of post-fire mortality of Scots pine and bark beetle occurrence.