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14 pages, 4099 KiB

Open AccessArticle

Two Nematicidal Compounds from Lysinimonas M4 against the Pine Wood Nematode, Bursaphelenchus xylophilus

by Yixiu Sun, Chao Wang, Guicai Du, Wenjun Deng, Hong Yang, Ronggui Li, Qian Xu and Qunqun Guo

Forests 2022, 13(8), 1191; https://doi.org/10.3390/f13081191 - 27 Jul 2022

Cited by 5 | Viewed by 2410

Abstract

A rich source of bioactive secondary metabolites from microorgannisms are widely used to control plant diseases in an eco-friendly way. To explore ideal candidates for prevention of pine wilt disease (PWD), a bacterial strain from rhizosphere of Pinus thunbergii, Lysinimonas M4, with [...] Read more.

A rich source of bioactive secondary metabolites from microorgannisms are widely used to control plant diseases in an eco-friendly way. To explore ideal candidates for prevention of pine wilt disease (PWD), a bacterial strain from rhizosphere of Pinus thunbergii, Lysinimonas M4, with nematicidal activity against pine wood nematode (PWN), Bursaphelenchus xylophilus, was isolated. Two nematicidal compounds were obtained from the culture of Lysinimonas M4 by silica gel chromatography based on bioactivity-guided fractionation and were subsequently identified as 2-coumaranone and cyclo-(Phe-Pro) by nuclear magnetic resonance (NMR) and mass spectrometry (MS). The 2-coumaranone and cyclo-(Phe-Pro) showed significant nematicidal activity against PWN, with LC₅₀ values at 24 h of 0.196 mM and 0.425 mM, respectively. Both compounds had significant inhibitory effects on egg hatching, feeding, and reproduction. The study on nematicidal mechanisms revealed that 2-coumaranone and cyclo-(Phe-Pro) caused the accumulation of reactive oxygen species (ROS) in nematodes, along with a notable decrease in CAT and POS activity and an increase in SOD activity in nematodes, which might contribute to the death of pine wood nematodes. Bioassay tests demonstrated that the two compounds could reduce the incidence of wilting in Japanese black pine seedlings. This research offers a new bacterial strain and two metabolites for biocontrol against PWN. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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17 pages, 3391 KiB

Open AccessArticle

Discovery and Biology of Spathius verustus Chao (Hymenoptera: Braconidae), a Potential Biological Agent on Two Monochamus Vectors of the Pinewood Nematode

by Moo-Sung Kim, Jong-Kook Jung, Ki-Jeong Hong, Chang-Jun Kim, Bong-Woo Lee and Il-Kwon Kim

Forests 2022, 13(6), 955; https://doi.org/10.3390/f13060955 - 18 Jun 2022

Cited by 1 | Viewed by 2581

Abstract

Pine wilt disease in Korea can be managed by reducing vector density through chemical application. To reduce the side effects from pesticides, effective natural enemies must be identified and used to reduce the vectors’ natural density. Sentinel logs were used to investigate a [...] Read more.

Pine wilt disease in Korea can be managed by reducing vector density through chemical application. To reduce the side effects from pesticides, effective natural enemies must be identified and used to reduce the vectors’ natural density. Sentinel logs were used to investigate a parasitoid wasp parasitic to Monochamus alternatus and Monochamus saltuarius, the vectors of Bursaphelenchus xylophilus, which causes this disease. During 2016–2017, the parasitoid wasps distributed in the Pinus densiflora and Pinus koraiensis forests were surveyed using sentinel logs at six different areas. An ectoparasitoid wasp Spathius verustus Chao of M. alternatus and M. saltuarius was identified. We showed for the first time that S. verustus was parasitic to M. alternatus in South Korea and to M. saltuarius worldwide. The parasitism rates were affected by region and session but not by the sentinel log height in the tree and the distances between the trap and forest edge locations. Studies also showed that S. verustus appeared to prefer M. alternatus to M. saltuarius as a host. This study unveiled the ecological details of S. verustus. Further research on various environmental factors such as regional differences, host density differences, and the degree of damage from the pine wilt disease is required to understand the effects of environmental or ecological factors on parasitism rates. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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8 pages, 1713 KiB

Open AccessEditor’s ChoiceArticle

Invasion of Emerald Ash Borer Agrilus planipennis and Ash Dieback Pathogen Hymenoscyphus fraxineus in Ukraine—A Concerted Action

by Kateryna Davydenko, Yuriy Skrylnyk, Oleksandr Borysenko, Audrius Menkis, Natalia Vysotska, Valentyna Meshkova, Åke Olson, Malin Elfstrand and Rimvys Vasaitis

Forests 2022, 13(5), 789; https://doi.org/10.3390/f13050789 - 19 May 2022

Cited by 15 | Viewed by 5070

Abstract

Emerald Ash Borer (EAB), Agrilus planipennis, is a beetle that originates from East Asia. Upon invasion to North America in the early 2000s, it killed untold millions of ash trees. In European Russia, EAB was first detected in Moscow in 2003 and [...] Read more.

Emerald Ash Borer (EAB), Agrilus planipennis, is a beetle that originates from East Asia. Upon invasion to North America in the early 2000s, it killed untold millions of ash trees. In European Russia, EAB was first detected in Moscow in 2003 and proved to have the potential to also kill native European ash (Fraxinus excelsior). The beetle has since spread in all geographic directions, establishing itself in eastern Ukraine by 2019 and possessing potential for further westward spread towards the EU. Apart from the approaching EAB, F. excelsior is currently threatened by the dieback disease (ADB) caused by the invasive ascomycete fungus Hymenoscyphus fraxineus. The infestation by EAB combined with ADB infection is expected to be more lethal than either of them alone, yet the potential consequences are unknown. To date, eastern Ukraine represents the geographic area in which both invasions overlap, thus providing the opportunity for related investigations. The aims of the study were to investigate: (i) the EAB expansion range in Ukraine, (ii) the relative susceptibility of F. excelsior and American ash (Fraxinus pennsylvanica) to EAB and ADB, and (iii) the combined effect/impact on ash condition imposed by both the pest and disease in the area subjected to the invasion. The results have demonstrated that (i) the invasion of EAB is currently expanding both in terms of newly infested trees and invaded geographic area; (ii) F. excelsior is more resistant to EAB than F. pennsylvanica, while F. excelsior is more susceptible to ADB than F. pennsylvanica; and (iii) the infection by ADB is likely to predispose F. excelsior to the infestation by EAB. It was concluded that inventory and mapping of surviving F. excelsior, affected by both ADB and EAB, is necessary to acquire genetic resources for the work on strategic, long-term restoration of F. excelsior in devastated areas, thereby tackling a possible invasion of EAB to the EU. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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15 pages, 6552 KiB

Open AccessArticle

Identification of Olfactory Genes in Monochamus saltuarius and Effects of Bursaphelenchus xylophilus Infestation on Their Expression

by Sufang Zhang, Xizhuo Wang, Yanlong Zhang, Yanan Zheng, Zhizhi Fan and Rong Zhang

Forests 2022, 13(2), 258; https://doi.org/10.3390/f13020258 - 7 Feb 2022

Cited by 9 | Viewed by 2529

Abstract

The pine wood nematode (PWN) Bursaphelenchus xylophilus has caused disastrous losses of pine forests in many countries, and the success of PWN depends strongly on interactions with its insect vectors. Monochamus saltuarius is a newly recorded vector in Northeast China. Feeding (i.e., immature) [...] Read more.

The pine wood nematode (PWN) Bursaphelenchus xylophilus has caused disastrous losses of pine forests in many countries, and the success of PWN depends strongly on interactions with its insect vectors. Monochamus saltuarius is a newly recorded vector in Northeast China. Feeding (i.e., immature) and egg-laying (i.e., mature) Monochamus spp. target different host plants, and olfactory cues play important roles regarding host choice. Whether infestation with PWN affects olfactory mechanisms in M. saltuarius related to feeding and oviposition is of interest as this may affect the spread of nematodes to new healthy hosts. However, little is known about molecular mechanisms of the olfactory system of M. saltuarius. We identified chemosensory-related genes in adult M. saltuarius and examined the influence of B. xylophilus on the respective expression patterns. Fifty-three odorant-binding proteins (OBPs), 15 chemosensory proteins, 15 olfactory receptors (ORs), 10 gustatory receptors, 22 ionotropic receptors (IRs), and two sensory neuron membrane proteins were identified, and sex bias among non-infested beetles was mainly found with respect to expression of OBPs. Interestingly, OBPs and ORs were markedly down-regulated in male M. saltuarius infested with B. xylophilus, which may reduce olfactory sensitivity of male M. saltuarius and affect the spreading of B. xylophilus to new hosts. Our results will help understand the interactions between B. xylophilus and M. saltuarius, which may lead to the identification of new control targets in the olfactory system of M. saltuarius. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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19 pages, 4166 KiB

Open AccessArticle

Evidence for the Widespread Occurrence of Bacteria Implicated in Acute Oak Decline from Incidental Genetic Sampling

by Louise A. P. Gathercole, Gabriele Nocchi, Nathan Brown, Timothy L. R. Coker, William J. Plumb, Jonathan J. Stocks, Richard A. Nichols, Sandra Denman and Richard J. A. Buggs

Forests 2021, 12(12), 1683; https://doi.org/10.3390/f12121683 - 1 Dec 2021

Cited by 10 | Viewed by 3369

Abstract

Acute Oak Decline (AOD) is complex syndrome affecting Britain’s keystone native oak species, (Quercus robur L. and Q. petraea L. (Matt.) Liebl.), in some cases causing mortality within five years of symptom development. The most distinguishable symptom is weeping stem lesions, from [...] Read more.

Acute Oak Decline (AOD) is complex syndrome affecting Britain’s keystone native oak species, (Quercus robur L. and Q. petraea L. (Matt.) Liebl.), in some cases causing mortality within five years of symptom development. The most distinguishable symptom is weeping stem lesions, from which four species of bacteria have been isolated: Brenneria goodwinii, Gibbsiella quercinecans, Lonsdalea britannica and Rahnella victoriana. We do not yet know where else these bacteria exist, and little is known about the relationship of the wider oak leaf microbiome (phyllosphere) to acute oak decline. Here we investigate whether incidental evidence from a large oak genome re-sequencing dataset could be used to detect these bacteria in oak foliage, and whether bacterial incidence co-varied with AOD status or location. Oak leaves and buds were sampled from 421 trees at five sites in England. Whole genomic DNA from these samples was shot-gun sequenced with short reads. Non-oak reads were extracted from these data and queried to microbial databases. Reads uniquely matching AOD-associated bacterial genomes were found to be present on trees from all five sites and included trees with active lesions, trees with historic lesions and trees without AOD symptoms. The abundance of the AOD-associated bacteria did not differ between tree health categories but did differ among sites. We conclude that the AOD-associated bacteria may be members of the normal oak microbiome, whose presence on a tree is not sufficient to cause AOD symptoms. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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14 pages, 2489 KiB

Open AccessArticle

Long-Term Projections of the Natural Expansion of the Pine Wood Nematode in the Iberian Peninsula

by Begoña de la Fuente and Santiago Saura

Forests 2021, 12(7), 849; https://doi.org/10.3390/f12070849 - 28 Jun 2021

Cited by 15 | Viewed by 3271

Abstract

The invasive pine wood nematode (PWN), Bursaphelenchus xylophilus, causal agent of pine wilt disease, was first reported in Europe, near Lisbon, in 1999, and has since then spread to most of Portugal. We here modelled the spatiotemporal patterns of future PNW natural [...] Read more.

The invasive pine wood nematode (PWN), Bursaphelenchus xylophilus, causal agent of pine wilt disease, was first reported in Europe, near Lisbon, in 1999, and has since then spread to most of Portugal. We here modelled the spatiotemporal patterns of future PNW natural spread in the Iberian Peninsula, as dispersed by the vector beetle Monochamus galloprovincialis, using a process-based and previously validated network model. We improved the accuracy, informative content, forecasted period and spatial drivers considered in previous modelling efforts for the PWN in Southern Europe. We considered the distribution and different susceptibility to the PWN of individual pine tree species and the effect of climate change projections on environmental suitability for PWN spread, as we modelled the PWN expansion dynamics over the long term (>100 years). We found that, in the absence of effective containment measures, the PWN will spread naturally to the entire Iberian Peninsula, including the Pyrenees, where it would find a gateway for spread into France. The PWN spread will be relatively gradual, with an average rate of 0.83% of the total current Iberian pine forest area infected yearly. Climate was not found to be an important limiting factor for long-term PWN spread, because (i) there is ample availability of alternative pathways for PWN dispersal through areas that are already suitable for the PWN in the current climatic conditions; and (ii) future temperatures will make most of the Iberian Peninsula suitable for the PWN before the end of this century. Unlike climate, the susceptibility of different pine tree species to the PWN was a strong determinant of PWN expansion through Spain. This finding highlights the importance of accounting for individual tree species data and of additional research on species-specific susceptibility for more accurate modelling of PWN spread and guidance of related containment efforts. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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9 pages, 1343 KiB

Open AccessArticle

The Difficulty of Predicting Eastern Spruce Dwarf Mistletoe in Lowland Black Spruce: Model Benchmarking in Northern Minnesota, USA

by Ella R. Gray, Matthew B. Russell and Marcella A. Windmuller-Campione

Forests 2021, 12(7), 843; https://doi.org/10.3390/f12070843 - 26 Jun 2021

Cited by 5 | Viewed by 2216

Abstract

Insects, fungi, and diseases play an important role in forest stand development and subsequently, forest management decisions and treatments. As these disturbance agents commonly occur within and across landscapes, modeling has often been used to inform forest planning and management decisions. However, models [...] Read more.

Insects, fungi, and diseases play an important role in forest stand development and subsequently, forest management decisions and treatments. As these disturbance agents commonly occur within and across landscapes, modeling has often been used to inform forest planning and management decisions. However, models are rarely benchmarked, leaving questions about their utility. Here, we assessed the predictive performance of a Bayesian hierarchical model through on–the-ground sampling to explore what features of stand structure or composition may be important factors related to eastern spruce dwarf mistletoe (Arceuthobium pusillum Peck) presence in lowland black spruce (Picea mariana (Mill.) B. S. P.). Twenty-five state-owned stands included in the predictive model were sampled during the 2019 and 2020 growing seasons. Within each stand, data related to the presence of eastern spruce dwarf mistletoe, stand structure, and species composition were collected. The model accurately predicted eastern spruce dwarf mistletoe occurrence for 13 of the 25 stands. The amount of living and dead black spruce basal area differed significantly based on model prediction and observed infestation, but trees per hectare, total living basal area, diameter at breast height, stand age, and species richness were not significantly different. Our results highlight the benefits of model benchmarking to improve model interpretation as well as to inform our understanding of forest health problems across diverse stand conditions. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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14 pages, 8195 KiB

Open AccessArticle

Chemical Control of Corythucha arcuata (Say, 1832), an Invasive Alien Species, in Oak Forests

by Flavius Bălăcenoiu, Constantin Nețoiu, Romică Tomescu, Dieter Carol Simon, Andrei Buzatu, Dragoș Toma and Ion Cătălin Petrițan

Forests 2021, 12(6), 770; https://doi.org/10.3390/f12060770 - 11 Jun 2021

Cited by 16 | Viewed by 3342

Abstract

In addition to the classic biotic and abiotic factors that have disrupted the health of forests throughout history, lately, the balance of forest ecosystems has been disturbed by different phenomena such as climate change, pollution, and, especially, biological invasions of invasive alien species. [...] Read more.

In addition to the classic biotic and abiotic factors that have disrupted the health of forests throughout history, lately, the balance of forest ecosystems has been disturbed by different phenomena such as climate change, pollution, and, especially, biological invasions of invasive alien species. One of the alien species that has invaded Europe relatively quickly is an insect species of North American origin, the oak lace bug (Corythucha arcuata Say, 1832 Heteroptera: Tingidae). In the context of the rapid spread of infestations and the severity of attacks on oak trees in infested forests, this paper aims to assess measures to manage this species in the future. Namely, the effect of aerial chemical treatments on oak lace bug has been investigated with two influencing factors: the mode of insecticide action (contact and systemic) and the treatment volume (low volume and ultra-low volume). The experiment was conducted in two forests over a total area of 350 hectares. The results show that the reduction of the nymph population varied from 91% to 96%. However, the residual population was sufficient to allow differentiated re-infestations over time, more quickly after contact insecticide sprays (22 days after treatment) and slowly after systemic insecticide sprays (more than a month after treatment). This re-infestation time difference had implications on attack intensity as well, with stronger leaf discoloration observed in areas treated with a contact insecticide compared with those treated with a systemic insecticide. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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11 pages, 2821 KiB

Open AccessArticle

The Effects of the Management Strategies on Spruce Bark Beetles Populations (Ips typographus and Pityogenes chalcographus), in Apuseni Natural Park, Romania

by Ciprian George Fora and Adalbert Balog

Forests 2021, 12(6), 760; https://doi.org/10.3390/f12060760 - 9 Jun 2021

Cited by 9 | Viewed by 2869

Abstract

The population densities of I. typographus and P. chalcographus inside the Carpathian Mountains increasing mostly because of the non-synchronized and divers management strategies. The growing loss of trees from one year to another indicates assessment to determine the influence of the current management [...] Read more.

The population densities of I. typographus and P. chalcographus inside the Carpathian Mountains increasing mostly because of the non-synchronized and divers management strategies. The growing loss of trees from one year to another indicates assessment to determine the influence of the current management practices (or the absence of such) on bark beetle densities. A comprehensive tree-year assessment were made inside the Apuseni Natural Park, with a surface of 75,784 ha, to assess the population density of bark beetles. High abundance of both species were detected from one year to another, both in managed and unmanaged forests, the latter explained by the presence of scattered wind falling trees which represent favorable places for oviposition. General linear modelling revealed that the effect of environmental variables (forest mean age, forest density, altitude and slope) on I. typographus density were only significant under management systems, and only forest age has significantly negative effect on bark beetles densities. Overall, we conclude that there is little difference in population between non-intervention and intervention areas and even over a relatively short period of time (2011–2013), the population of both species expanded, and new uninfected habitats were infected both in unmanaged and managed forests, therefore a synchronized management system has to be developed. Climate variables as temperature and precipitations has more significant effects on population density than management. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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10 pages, 2613 KiB

Open AccessArticle

Comparative Efficacy Trials with Two Different Bacillus thuringiensis Serovar kurstaki Strains against Gypsy Moth in Mediterranean Cork Oak Forests

by Maurizio Olivieri, Roberto Mannu, Luca Ruiu, Pino A. Ruiu and Andrea Lentini

Forests 2021, 12(5), 602; https://doi.org/10.3390/f12050602 - 11 May 2021

Cited by 6 | Viewed by 2237

Abstract

The efficacy of two formulations (Foray^® 76B AVIO and Rapax^® AS AIR) containing different Bacillus thuringiensis kurstaki (Btk) strains (ABTS-351 and EG-2348, respectively) was evaluated against Lymantria dispar larval populations in cork oak forests in Sardinia (Italy), in [...] Read more.

The efficacy of two formulations (Foray^® 76B AVIO and Rapax^® AS AIR) containing different Bacillus thuringiensis kurstaki (Btk) strains (ABTS-351 and EG-2348, respectively) was evaluated against Lymantria dispar larval populations in cork oak forests in Sardinia (Italy), in 2018 and 2019. The experimental design involved the following treatments: (I) untreated control; (II) Foray^® 76B at the dose of 2.0 L/ha; (III) Foray^® 76B at the dose of 2.5 L/ha; (IV) Rapax^® AS AIR at the dose of 2.0 L/ha. Aerial applications were carried out using a helicopter equipped with four electronic rotary atomizers adjusted to sprinkle 160 micron-sized drops. Btk efficacy was evaluated by assessing the larval density reduction 7, 14, and 21 days after the application in each experimental plot in comparison with an untreated check. In addition to field surveys, the mortality of second and third instar larval samples, randomly collected from each plot after treatment and fed with foliage from the same plot, was determined in the laboratory. All Btk treatments were similarly effective, and no differences in larval density reduction among Btk strains and doses were found in either year. Twenty-one days after application, the average larval density reduction in the field was approximately 70% in all treated plots in 2018, whereas in 2019 it reached 80% only in areas treated with Foray 76B at 2.5 L/ha. Laboratory observations showed that all Btk-based products were effective against gypsy moth larvae, with significant differences in mortality between untreated control and the different Btk treatments. Our results shed light on the possibility of alternating different Btk strains for resistance management purposes and of applying lower doses than labeled, in order to achieve cost savings for product shipment and distribution and to reduce the environmental impact. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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8 pages, 3396 KiB

Open AccessCommunication

Quantification of One-Year Gypsy Moth Defoliation Extent in Wonju, Korea, Using Landsat Satellite Images

by Won-IL Choi, Eun-Sook Kim, Soon-Jin Yun, Jong-Hwan Lim and Ye-Eun Kim

Forests 2021, 12(5), 545; https://doi.org/10.3390/f12050545 - 27 Apr 2021

Cited by 17 | Viewed by 2715

Abstract

We quantified the extent and severity of Asian gypsy moth (Lymantria dispar) defoliation in Wonju, Korea, from May to early June in 2020. Landsat images were collected covering Wonju and the surrounding area in June from 2017 to 2020. Forest damage [...] Read more.

We quantified the extent and severity of Asian gypsy moth (Lymantria dispar) defoliation in Wonju, Korea, from May to early June in 2020. Landsat images were collected covering Wonju and the surrounding area in June from 2017 to 2020. Forest damage was evaluated based on differences between the Normalized Difference Moisture Index (NDMI) from images acquired in 8 June 2020 and the prior mean NDMI estimated from images in June from 2017 to 2019. The values of NDMI ranged from −1 to 1, where values closer to 1 meant higher canopy cover. The NDMI values for 7825 ha of forests were reduced by more than 0.05 compared to the mean NDMI values for the prior 3 years (2017 to 2019). The NDMI values of 1350 ha of forests were reduced by >0.125 to 0.2, and the NDMI values for another 656 ha were reduced by more than 0.2. A field survey showed that these forests were defoliated by gypsy moth and that forests with NDMI reductions of more than 0.2 were heavily defoliated by gypsy moth. A 311 ha area of Japanese larch (Larix kaempferi) was severely damaged by gypsy moth and the proportion of larch damaged was higher than that of other tree species. This intense damage to larch suggests that gypsy moths preferentially attack Japanese larch in Wonju. Our study shows that the use of NDMI values to detect areas defoliated by gypsy moth from satellite images is effective and can be used to measure other characteristics of gypsy moth defoliation events, such as host preferences under field conditions. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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19 pages, 5061 KiB

Open AccessArticle

Assessment of Machine Learning Algorithms for Modeling the Spatial Distribution of Bark Beetle Infestation

by Milan Koreň, Rastislav Jakuš, Martin Zápotocký, Ivan Barka, Jaroslav Holuša, Renata Ďuračiová and Miroslav Blaženec

Forests 2021, 12(4), 395; https://doi.org/10.3390/f12040395 - 27 Mar 2021

Cited by 17 | Viewed by 3087

Abstract

Machine learning algorithms (MLAs) are used to solve complex non-linear and high-dimensional problems. The objective of this study was to identify the MLA that generates an accurate spatial distribution model of bark beetle (Ips typographus L.) infestation spots. We first evaluated the [...] Read more.

Machine learning algorithms (MLAs) are used to solve complex non-linear and high-dimensional problems. The objective of this study was to identify the MLA that generates an accurate spatial distribution model of bark beetle (Ips typographus L.) infestation spots. We first evaluated the performance of 2 linear (logistic regression, linear discriminant analysis), 4 non-linear (quadratic discriminant analysis, k-nearest neighbors classifier, Gaussian naive Bayes, support vector classification), and 4 decision trees-based MLAs (decision tree classifier, random forest classifier, extra trees classifier, gradient boosting classifier) for the study area (the Horní Planá region, Czech Republic) for the period 2003–2012. Each MLA was trained and tested on all subsets of the 8 explanatory variables (distance to forest damage spots from previous year, distance to spruce forest edge, potential global solar radiation, normalized difference vegetation index, spruce forest age, percentage of spruce, volume of spruce wood per hectare, stocking). The mean phi coefficient of the model generated by extra trees classifier (ETC) MLA with five explanatory variables for the period was significantly greater than that of most forest damage models generated by the other MLAs. The mean true positive rate of the best ETC-based model was 80.4%, and the mean true negative rate was 80.0%. The spatio-temporal simulations of bark beetle-infested forests based on MLAs and GIS tools will facilitate the development and testing of novel forest management strategies for preventing forest damage in general and bark beetle outbreaks in particular. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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17 pages, 7567 KiB

Open AccessArticle

Comparison of Ips cembrae (Coleoptera: Curculionidae) Capture Methods: Small Trap Trees Caught the Most Beetles

by Karolina Resnerová, Jaroslav Holuša, Peter Surový, Jiří Trombik and Emanuel Kula

Forests 2020, 11(12), 1275; https://doi.org/10.3390/f11121275 - 28 Nov 2020

Cited by 8 | Viewed by 2353

Abstract

Ips cembrae is the most important bark beetle pest of larches and has had several local outbreaks in recent decades in Europe. In this study, we compared the numbers of I. cembrae captured by pyramid-trap piles, trap trees, pheromone traps, and poisoned and [...] Read more.

Ips cembrae is the most important bark beetle pest of larches and has had several local outbreaks in recent decades in Europe. In this study, we compared the numbers of I. cembrae captured by pyramid-trap piles, trap trees, pheromone traps, and poisoned and baited tripods. We also studied how the properties of trap trees and trap logs (volume, sun exposure, and position relative to the ground once deployed) affected the trapping of I. cembrae. We found that both sexes avoided infestation at the bottom of the logs and more than 15 times the number of beetles were captured by traditional trap trees than by pheromone traps or baited and insecticide-treated tripods. The number of I. cembrae per trap tree did not decrease with trap volume; therefore, it is appropriate to use traps of small dimensions. Baited tripods, pyramid-trap piles, and pheromone traps could be useful for detection of the beginning of flight activity, but trap trees are the most useful for reducing I. cembrae numbers. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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Review

Jump to: Research

13 pages, 3266 KiB

Open AccessReview

Oak Decline Syndrome in Korean Forests: History, Biology, and Prospects for Korean Oak Wilt

by Won Il Choi, Dong-Hyeon Lee, Jong Bin Jung and Young-Seuk Park

Forests 2022, 13(6), 964; https://doi.org/10.3390/f13060964 - 20 Jun 2022

Cited by 3 | Viewed by 3361

Abstract

Oak decline syndrome has been observed in South Korea and Japan and variously referred to as Korean oak wilt (KOW) and Japanese oak wilt (JOW). We reviewed aspects of the historical occurrence of KOW, disease cycle, and its potential causes. KOW has been [...] Read more.

Oak decline syndrome has been observed in South Korea and Japan and variously referred to as Korean oak wilt (KOW) and Japanese oak wilt (JOW). We reviewed aspects of the historical occurrence of KOW, disease cycle, and its potential causes. KOW has been seen principally in Mongolian oak (Quercus mongolica Fisch. ex Ledeb.). The first occurrence of KOW was in 2004 in Seongnam, South Korea. KOW is associated with the fungus Raffaelea quercus-mongolicae, which is vectored by the ambrosia beetle Platypus koryoensis. In addition, it has been suggested that yeasts have evolved a symbiotic relationship with the vector without antagonism for the pathogenic fungus. The number of trees in Korea killed by KOW increased to about 331,000 in 2011, but then decreased to about 157,000 in 2019. We hypothesized that trees infected by R. quercus-mongolicae accumulate phenolic compounds in the sapwood and the vector (P. koryoensis) beetles then avoid these trees. Therefore, the number of hosts available for the beetle after a KOW outbreak decrease due to accumulation of phenolic compounds in the wood, although most oak trees survive outbreaks. Therefore, P. koryoensis beetles move longer distances after outbreaks to find susceptible host trees. Novel occurrence of KOW in Korea may be due to either (1) an increase in tree age (size) in Korean oak stands, for which the beetle has a known preference or (2) climate change, which may be increasing the number of weakened or stressed trees, for which P. koryoensis also shows a preference. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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60 pages, 10957 KiB

Open AccessReview

Invasive Insect Pests of Forests and Urban Trees in Russia: Origin, Pathways, Damage, and Management

by Dmitry L. Musolin, Natalia I. Kirichenko, Natalia N. Karpun, Evgeniy V. Aksenenko, Viktor B. Golub, Ivan A. Kerchev, Michail Y. Mandelshtam, Rimvys Vasaitis, Mark G. Volkovitsh, Elena N. Zhuravleva and Andrey V. Selikhovkin

Forests 2022, 13(4), 521; https://doi.org/10.3390/f13040521 - 28 Mar 2022

Cited by 31 | Viewed by 11755

Abstract

Invasive alien insects cause serious ecological and economical losses around the world. Here, we review the bionomics, modern ranges (and their dynamics), distribution pathways, monitoring, and control measures of 14 insect species known to be important invasive and emerging tree pests in forest [...] Read more.

Invasive alien insects cause serious ecological and economical losses around the world. Here, we review the bionomics, modern ranges (and their dynamics), distribution pathways, monitoring, and control measures of 14 insect species known to be important invasive and emerging tree pests in forest and urban ecosystems of Russia: Leptoglossus occidentalis (Hemiptera: Heteroptera: Coreidae), Halyomorpha halys (Hemiptera: Heteroptera: Pentatomidae), Corythucha arcuata (Hemiptera: Heteroptera: Tingidae), Agrilus fleischeri, A. mali, A. planipennis, Lamprodila (Palmar) festiva (Coleoptera: Buprestidae), Ips amitinus, Polygraphus proximus (Coleoptera: Curculionidae: Scolytinae), Cydalima perspectalis (Lepidoptera: Crambidae), Acrocercops brongniardella, Cameraria ohridella, Phyllonorycter issikii, and P. populifoliella (Lepidoptera: Gracillariidae). We identified three major scenarios of tree pest invasions in the country and beyond: (1) a naturally conditioned range expansion, which results in the arrival of a pest to a new territory and its further naturalization in a recipient region; (2) a human-mediated, long-distance transfer of a pest to a new territory and its further naturalization; and (3) a widening of the pest’s trophic niche and shift to new host plant(s) (commonly human-introduced) within the native pest’s range frequently followed by invasion to new regions. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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