Search

Forest tree diversity helps shape the assembly of herbivorous insect communities in forests worldwide, and Island biogeography theory explains the role of tree range area as a driver of variation in native insect richness per tree species. However, it is unclear if these biogeographical principles apply to non‐native insect herbivores. We created an extensive list of tree–insect associations for tree species native to Palearctic Europe bioregion, and investigated how both native and non‐native insect herbivore species richness per tree may be influenced by various factors including the range area of the tree and the tree type (conifer or angiosperm). Models were further subsetted to compare drivers for the richness of different feeding guilds (folivores, sap feeders or wood borers) and host breadth (specialist or generalist). Tree range area had a positive effect on native, but not non‐native, insect species richness per tree, while non‐native richness was affected by host type and had a positive correlation with native herbivore richness on the same tree species. Host breadth grouping did not influence the difference in the effect of tree range on native versus non‐native insect richness, but native folivores had a stronger relationship with range distribution area compared to the other groups. We conclude that the assembly of non‐native herbivorous insect species on trees occurs through fundamentally different mechanisms than the co‐evolutionary processes proposed by the framework of Island biogeography theory. [ABSTRACT FROM AUTHOR]

Aim: Forest pathogens, insect pests and parasitic plants are among the most important disturbance agents in forested ecosystems. Understanding where pests occur and where they might occur in the future will be important for understanding their impacts on host trees, and planning for future pest outbreaks. Location: North America. Taxon: Insect pests, pathogens and parasitic plants of forest trees. Methods: Here, we develop and implement a framework to predict the contemporary distributions of 26 pest species that accounts for climate, host abundance and, for non‐native species, their spread on the landscape. Results: We show that pest distributions can be predicted primarily by climatic variables. The abundance of individual host trees had only minor explanatory power, but the summed total of host abundance frequently had greater importance—suggesting forest composition and the relative frequency of hosts and non‐hosts place strong limits on pest distributions. Non‐native pests were strongly impacted by the distance from their original discovery location in North America, which tended to interact with climate variables—suggesting most non‐native pests are not yet at equilibrium with their potential climatic ranges in North America. Main Conclusions: This work helps to clarify the generalised controls on pest distributions and provide a framework for predicting pest distributions in future climates. [ABSTRACT FROM AUTHOR]

Context: Increased cocoa cultivation (Theobroma cacao) has led to the conversion of over 6 million hectares of rainforest to cocoa farmlands in West Africa. Globally, pollinator decline has been driven by land use changes. Though land use change through cocoa expansion may affect insect pollinators and, by extension, pollination services, this has rarely been assessed. Objectives: Our study examined the relationships between the proportion of natural forest in the landscape (reduced primarily due to cocoa expansion) and flower-visiting insect abundance, and bee abundance, richness, diversity and community composition. The effect of pan trap type (aerial or ground) was also tested. Methods: Eighteen sites were selected along a gradient of an increasing proportion of natural forests in the surrounding landscape (from 9 to 100%). Ground and aerial pan traps were deployed in each site to sample flower-visiting insects. Two sampling sessions were conducted; during the rainy season in 2021 and during the dry season in 2022. Results: The abundances of Coleoptera, Hymenoptera and Hemiptera increased with increasing proportion of natural forests in the landscape, while Diptera decreased. Natural forest and trap type did not significantly influence bee abundance, species richness, and Shannon diversity. However, bee community composition differed along the forest gradient, indicating that forests and cocoa farms harbour different bee communities. Ground pan traps captured more insects (61% of 19,927 flower-visiting insects) than aerial pan traps, which was driven by the Diptera as the abundances of the other orders were not significantly related to trap type. Conclusions: Preserving natural forest in cocoa-growing landscapes is important to sustain the coexistence of diverse flower-visiting insect communities owing to their differential responses to the proportions of natural forests. [ABSTRACT FROM AUTHOR]

Timber‐oriented forest management profoundly alters forest structure and composition, with complex effects on associated biodiversity. However, while species' responses to forest management and resulting structural characteristics have been the subject of numerous studies, direct and indirect effects that cascade through trophic levels are rarely disentangled. As insectivorous bats are particularly sensitive to changes in forest structure, that shape their available flight space, we investigated how forest structure, composition and management also indirectly modify their habitats, for example, by affecting important insect prey groups. We used structural equation models (SEMs) to test bat responses to forest composition, structure (forest heterogeneity, old‐growth attributes) and management intensity, quantifying direct and indirect prey‐mediated effects. For that, three bat guilds—short‐ (SRE), mid‐ (MRE) and long‐range echolocating (LRE) bats—and their prey insects (moths and ground beetles) were analysed from 64 sites in the Black Forest, Germany. We found guild‐specific effects on bats: While the structural heterogeneity of forests directly influenced the activity of bat guilds, the main influence of forest management, composition and structure was mediated through their prey‐groups. SRE activity responded to moths and LRE activity was associated with ground beetles, with positive effects of the insect groups' abundance, but negative effects of the same group's species richness. In addition, the SEM approach revealed a negative top‐down relationship between MRE activities and moths, suggesting predation or avoidance behaviour of moths. While forest management directly or indirectly increased prey insect abundance, it negatively affected the availability of roosting structures for bats. Synthesis and applications. The results highlight the indirect and positive effects of forest management on bats and support the important role of bats in insect regulation within continuous cover forests. Although forest management created small gaps that improved foraging habitats for most bats, it compromised the roosting functionality for bats. The ‘close‐to‐nature forestry’ currently prevalent in Europe mainly promotes continuous‐cover forests in mid‐successional stages. Expanding the forest management portfolio towards open and old‐growth forests would increase roosting opportunities and provide complementary foraging habitats for different bat species, while promoting high biodiversity in managed forest landscapes. [ABSTRACT FROM AUTHOR]

The Andean caddisfly genus, Eosericostoma Schmid, 1955, was previously known from two species endemic to Chile and Argentina. In this study, a new species of Eosericostoma was discovered six decades after the last description of a species in the genus. Eosericostoma opposita Desidério, Sganga & Hamada, sp. nov. is described and illustrated based on a single specimen collected close to the Lake Nahuel Huapi, Río Negro Province, in the Valdivian Forest of Argentine Andes. It can be recognised on a combination of abdominal characters, mainly in the tergum X and the inferior appendage. Additionally, a key to identify males of the three species in the genus is provided. Finally, a brief discussion of the biogeography of Eosericostoma is presented. [ABSTRACT FROM AUTHOR]

Simple Summary: Little attention has been paid to the efficiency of trap types in capturing bees across taxonomic and functional groups, nor their suitability under varying environmental conditions. Our study evaluated the efficiency, bias, and complementarity of four trap types: yellow, white, and blue pan traps, and blue vane traps for pollinator monitoring in monoculture and mixed forests. We found that bias in trap types was not only detected in taxonomic but also in functional groups. Differences in bee taxonomic, phylogenetic, and functional diversity were also observed, with blue pan traps yielding the highest species richness and phylogenetic diversity, while blue vane traps captured the highest functional richness. When considering the complementarity of different traps, the combination of blue pan and vane traps outperformed the other two-method combinations. Notably, the bias in trap types was most pronounced in mixed forests. The choice of trap in entomological surveys affects the composition of captured insects, though previous comparative studies have been limited in the types of composition measured, and the effects of environmental context. We assessed the sampling bias of several traps commonly used in pollinator monitoring: blue, yellow, and white pan traps, and blue vane traps, towards different taxonomic and functional groups and their efficiency in measuring taxonomic, phylogenetic, and functional diversity. Analyses were performed in monoculture and mixed forests to understand the environmental context of trap efficiency. We found that blue pan traps generally outperformed other types in bee capture and exhibited a preference for Halictidae bees. Blue pan traps yielded the highest species richness and phylogenetic diversity, while blue vane traps captured the highest functional richness. Bias differences were frequently detected in mixed forests compared with monoculture forests. We also found the combination of blue vane and pan traps consistently correlated highest with a complete survey among two-method combinations. Based on our findings, we recommend a combination of blue vane and pan traps to obtain a more comprehensive bee collection in an efficient manner. Additionally, it is crucial to consider habitat type when designing bee trapping protocols to ensure an accurate representation of bee communities. [ABSTRACT FROM AUTHOR]

Irruptive forest insects are a leading biotic disturbance across temperate and boreal forests. Outbreaks of forest insects are becoming more frequent and extensive due to anthropogenic drivers (e.g. climate and land‐use), perhaps increasing the likelihood that forests will experience multiple insect‐caused disturbances.Across the fire‐prone Douglas‐fir forests of western North America, recent outbreaks of the western spruce budworm and Douglas‐fir beetle have impacted large expanses of forests, with a higher degree of overlap than expected in some ecoregions. Outbreaks of both insects are positively related to host availability and exhibit density‐dependent population dynamics that are affected by climate and weather.Here, we leverage data from aerial detection surveys, estimates of host availability, climate and weather, and categorized fire severity to describe the spatial overlap between western spruce budworm and Douglas‐fir beetle and assess: (1) how climate and host availability influence the biogeography of outbreaks; (2) how weather incites outbreaks; and finally, (3) how prior disturbances (fire and biotic) affect the subsequent outbreak likelihood of western spruce budworm and Douglas‐fir beetle.Models demonstrate that western spruce budworm and Douglas‐fir beetle share similar predisposing drivers of outbreaks. Outbreaks of both insects were more likely to occur following warm weather, but only beetle outbreaks were more likely following drought. When controlling for differences in outbreak distribution and inciting factors, results indicate that both prior fire and interspecific disturbance altered the likelihood of subsequent insect‐caused disturbance.Specifically, Douglas‐fir beetle outbreaks were more likely to occur for several years following low severity fire, but less likely otherwise. Prior defoliation, especially longer duration defoliation, increased the likelihood of beetle outbreak within stands and across the landscape. On the contrary, western spruce budworm outbreaks were less likely to occur following fire, while prior beetle activity dampened budworm outbreak likelihood for several years, and then eventually increased outbreak likelihood.Synthesis: Biotic–biotic disturbance interactions have the potential to amplify the incidence of insect‐caused disturbance across subcontinental scales. Our findings highlight the need for future work on mechanistic linkages between biotic disturbance agents as well as the ramifications for forest trajectories and function. [ABSTRACT FROM AUTHOR]

Biotic disturbances caused by insects and pathogens have a major impact on forests in the Northern Hemisphere. Knowledge of the effects of increasing temperature on the performance of these forest pests will thus be crucial for predicting future disturbance risks. Here, we systematically review the direct effects of increasing temperatures on four functional subgroups of forest pests, including leaf chewers, sap suckers, bark and wood borers, and pathogens. We considered 118 studies (2003–2022) representing 72 pest species feeding on 33 host genera from sub‐tropical, temperate and boreal forests in Asia, Europe and North America. Based on a subset of 89 studies reporting the required data, we conducted a meta‐analysis 1) distinguishing the functional subgroups, and 2) considering the main life‐history traits, i.e. development, fitness and survival. A temperature corresponding to the expected mean temperature during the growing season in the years 2081–2100 had a significant positive effect on the overall performance of leaf chewers (+18%) and bark and wood borers (+10%), while sap suckers and pathogens remained unaffected. In contrast, performance was not or even significantly negatively affected when a more pronounced temperature increase, i.e. corresponding to the temperature maxima in 2081–2100, was considered. This finding reflects the non‐linear temperature–performance relationship beyond currently evolved temperature optima in insects and pathogens. Furthermore, we showed that differential responses of life‐history traits to increased temperatures may counterbalance each other (e.g. development versus survival), highlighting the importance of a multi‐trait approach to assessing the impact of global warming on pest performance. By quantifying the effects of increasing temperatures on forest pest performance, our results facilitate the prediction of biotic disturbance impacts in a future climate. For instance, they could provide a valuable contribution to the parameterization of large‐scale ecosystem models, which often do not explicitly consider the response of biotic disturbances to climate change. [ABSTRACT FROM AUTHOR]

Engaging ecological resource users in intervention to protect resources is challenging for governments due to the self-interest of users and uncertainty about intervention consequences. Focusing on a case of forest insect infestations, we addressed questions of resource protection and environmentally responsible behavior promotion with a conceptual model. We coupled a forest infestation model with a social model in which a governing agent applies a mechanism for the recognition and promotion of environmentally responsible behavior among several user agents. We ran the coupled model in various scenarios with a reinforcement-learning algorithm for the governing agent as well as best-case, worst-case, and random baselines. Results showed that a proper recognition policy facilitates emergence of environmentally responsible behavior. However, ecosystem health may deteriorate due to temporal differences between the social and ecological systems. Our work shows it is possible to gain insight about complexities of social–ecological systems with conceptual models through scenario analysis. [ABSTRACT FROM AUTHOR]

The impact of climate change on forests is difficult to predict, as it depends on multiple factors and the final effect may vary in different parts of our planet. However, these effects can be sorted in "direct", when they act directly on plants, and "indirect", when they act through other agents. Among the indirect ones, there are those mediated by biotic factors, particularly insect pests. The impact of climate change on insect pests varies depending on the insect species and the type of forest. Some plant-feeding insects may be disfavoured by climate change, with a consequent reduction in population density and thus in damage to forests. However, many outbreaks of forest insects have been recently recorded as related to climate change. In fact, some insect pests, in certain regions of the world, may benefit from higher temperatures, as it has been demonstrated for some devastating defoliators. In addition, more frequent drought and extreme events may favour other pests, particularly bark beetles and wood-boring insects. Bark beetles are the most dangerous ones because their aggressiveness changes with population density. They can attack only stressed trees at low population densities, while, once the populations have reached high density, they are even able to attack healthy trees in widespread areas. [ABSTRACT FROM AUTHOR]

I outline the "definitional problem" in forest insect outbreak analytics and show how it is related to the "counting problem" in dendroentomology and the "forecasting problem" in forest insect population dynamics, through the ubiquitous presence of non-stationary complex periodicity. Using real-world examples from the spruce budworm (Choristoneura fumiferana Clem.) system, I show that regardless how outbreak patterning is characterized—whether by peak impact, cycle frequency, interval duration, or interval severity—the distribution in pattern attributes appears to be extremely variable, regardless how the data are processed through definitional filters. I show that this extreme variability is an unavoidable and key feature of the system's dynamics and argue that it needs to be viewed as an object of study, instead of a nuisance problem to be swept under the rug. The single biggest opportunity for rapid gains in spruce budworm predictive ecology is determining the environmental and ecological factors that separate high-intensity from low-intensity outbreak cycling. [ABSTRACT FROM AUTHOR]

We evaluated the richness, diversity, and assemblage of Carabidae in the Val Grande National Park. Monitoring, by pitfall-trapping, was performed in 2021–2022 in two sites (S1 and S2), and considering six vegetation habitats ("Terraced ferns", "Terraced grassland", "Wood", "Chestnut grove", "Ecotone", and "Grassland"). A total of 2707 carabids consisting of 34 species were collected. The assemblage displayed the dominance of Calathus fuscipes graecus (27%), followed by Carabus glabratus latior (15%), and Carabus problematicus problematicus (15%). Besides the species already known for the Park, seven further species have been recorded. While in S1 the carabid assemblage was unexpectedly poor, a rich biodiversity with an excellent balance among the numerous brachypterous, macropterous, and pteropolymorphous species was recorded in S2. The species recorded in the habitat "Terraced ferns" and in "Ecotone" constituted the dominant groups and they accounted for 51% and 41%, in S1 and S2, respectively. The awareness of the species composition, richness, and ecology can be a useful tool for the Park to address the management of the surfaces in order to avoid disturbing the carabid fauna, especially for carabids of conservation concern, to mitigate their potential decline. [ABSTRACT FROM AUTHOR]

This study included one type of forest insect in the Nineveh of northern Iraq, which is plant sap suckers that infect a group of forest trees, including Populus Euphratica and P.deltoides. The results showed a variation in the killing rate resulting from treating poplar leaf nymph aphids with phenols of the study tree species according to the type of tree, concentration, and insect phase. The phenols of the Euphratica poplar leaves excelled on average, with the killing rate of the American type being 62.01 and 56.49% at a concentration of 10%, respectively. For Alkaloids, it was 47.21 and 43.3% for P.euphratica and P.deltoides, respectively. Meanwhile, terpenes were 43.21 and 37.69%. The average percentage of expulsion reached 36.89% in the nymph phase of P. euphratica at a concentration of 10%. The study showed significant superiority of the Alkaloids of Euphratica poplar and the average expulsion percentage over the Alkaloids of the other types. The average percentage of expulsion was 32.69% in the nymph phase at a concentration of 10%. The Euphratica poplar Terpenes outperformed the average kill rate over the Terpenes of the other type, with an average expulsion ratio of 29.92% in the nymph phase at a concentration of 10%. [ABSTRACT FROM AUTHOR]

The highly variable 'leafscapes' of plants across the world represent billions of square metres of mite habitat. The phytoseiid mites (Acari: Phytoseiidae), an extremely species-rich group of mostly generalist predators, are providers of ecosystem services for humanity worth many hundreds of millions of dollars annually by helping suppress phytophagous mites and insects in forests, agro-ecosystems, shade-houses and home gardens. In this study, the phytoseiid mite assemblages on the leaves of four species of common tree species, namely oak (Quercus cerris var. cerris), poplar (Populus deltoides, P. nigra) and walnut (Juglans regia), were compared. The three data sets used were generated in three independent seasonal studies in Samsun Province, Türkiye, between 2018 and 2022. In total, mite species in 18 families, including 15 families on walnut, were recorded. Nineteen phytoseiid species in 13 genera, Amblydromalus, Amblyseius, Euseius, Kampimodromus, Neoseiulella, Neoseiulus, Paraseiulus, Phytoseius, Transeius, Typhlodromina, Typhlodromips, Typhlodromus and Typhloseiulus, were collected. Only Eusieus amissibilis was collected from all three tree genera, whereas 14 species were collected from only one tree genus. Shannon diversity and Jaccard similarity indexes were calculated for mite families and phytoseiid genera and species. Potential reasons for the observed differences in the phytoseiid assemblages on the different host trees are explored in depth. In the 'big picture', global biodiversity, likely including many undescribed phytoseiid species, is threatened by widespread habitat degradation and destruction, especially in the tropics, and accelerating climate change, and rapidly stopping them is imperative. [ABSTRACT FROM AUTHOR]

The recent mountain pine beetle outbreaks have caused widespread mortality among lodgepole pine trees in western North America, resulting in a reduced population of surviving trees. While previous studies have focused on the cascading impacts of these outbreaks on the physiology and growth of the surviving trees, there remains a need for a comprehensive study into the interactions among various physiological traits and the growth in post-outbreak stands. Specifically, the relationship between chemical (primarily terpenes) and anatomical (mainly resin ducts) defences, as well as the allocation of non-structural carbohydrates (NSCs) to support these defence modalities, is poorly understood. To address these gaps, we conducted a field survey of surviving lodgepole pine trees in post-mountain pine beetle outbreak stands in western Canada. Our retrospective analysis aimed at determining correlations between the post-outbreak concentrations of monoterpenes, diterpenes, and NSCs in the phloem and the historical resin duct characteristics and growth traits before and after the outbreak. We detected strong correlations between the post-outbreak concentrations of monoterpenes and historical resin duct characteristics, suggesting a possible link between these two defence modalities. Additionally, we found a positive relationship between the NSCs and the total concentrations of monoterpenes and diterpenes, suggesting that NSCs likely influence the production of these terpenes in lodgepole pine. Furthermore, historical tree growth patterns showed strong positive correlations with many individual monoterpenes and diterpenes. Interestingly, while surviving trees had enhanced anatomical defences after the outbreak, their growth patterns did not vary before and after the outbreak conditions. The complexity of these relationships emphasizes the dynamics of post-outbreak stand dynamics and resource allocations in lodgepole pine forests, highlighting the need for further research. These findings contribute to a broader understanding of conifer defences and their coordinated responses to forest insect outbreaks, with implications for forest management and conservation strategies. [ABSTRACT FROM AUTHOR]

I report on long-term patterns of outbreak cycling in four study systems across Canada and illustrate how forecasting in these systems is highly imprecise because of complexity in the cycling and a lack of spatial synchrony amongst sample locations. I describe how a range of bottom-up effects could be generating complexity in these otherwise periodic systems. (1) The spruce budworm in Québec exhibits aperiodic and asynchronous behavior at fast time-scales, and a slow modulation of cycle peak intensity that varies regionally. (2) The forest tent caterpillar across Canada exhibits eruptive spiking behavior that is aperiodic locally, and asynchronous amongst regions, yet aggregates to produce a pattern of periodic outbreaks. In Québec, forest tent caterpillar cycles differ in the aspen-dominated northwest versus the maple-dominated southeast, with opposing patterns of cycle intensity between the two regions. (3) In Alberta, forest tent caterpillar outbreak cycles resist synchronization across a forest landscape gradient, even at very fine spatial scales, resulting in a complex pattern of cycling that defies simple forecasting techniques. (4) In the Border Lakes region of Ontario and Minnesota, where the two insect species coexist in a mixedwood landscape of hardwood and conifers, outbreak cycle intensity in each species varies spatially and temporally in response to host forest landscape structure. Much attention has been given to the effect of top-down agents in driving synchronizable population cycles. However, foliage loss, tree death, and forest succession at stem, stand, and landscape scales affect larval and adult dispersal success, and may serve to override regulatory processes that cause otherwise top-down-driven periodic, synchronized, and predictable population oscillations to become aperiodic, asynchronous, and unpredictable. Incorporating bottom-up effects at multiple spatial and temporal scales may be the key to making significant improvements in forest insect outbreak forecasting. [ABSTRACT FROM AUTHOR]

Do light vertical gradients in temperate forest structure insect herbivore communities? We tested the hypothesis that the increase in light intensity from understory to forest canopy drives differences in leaf physical traits and bud burst phenology that impact insect herbivores and thus play a role in structuring both herbivore communities and the leaf damage they cause. Understanding these interactions is essential for addressing knowledge gaps in the dynamics of temperate deciduous forest ecosystems. Twelve sugar maple (Acer saccharum) sites were monitored in southern Quebec, examining insect herbivore patterns from understory saplings to mature tree‐shaded and sun canopy (where intensity is highest and canopy cover lowest) over the summers of 2020, 2021 and 2022. Additionally, we recorded leaf physical traits and sun exposure. Our findings revealed that leaf thickness increased along the vertical gradient in 2021, making mature tree leaves in the canopy less favourable to herbivores than understory sapling leaves. Accordingly, we recorded a consistent decrease in insect herbivory damage rates from understory to shaded and to sun canopy in 2020 and 2021, driven by leaf cutters, skeletonizers, stipplers and leaf miners. These results support our hypothesis that variation in leaf physical traits contributes to the vertical stratification of insect damage. This variation in leaf traits can be linked to light levels or to tree ontogeny. In 2022, the gradient of insect herbivore abundance corroborated the observed damage trends from the previous years. We calculated an average annual herbivory rate of 9.1% of the leaf surface in our study site. Overall, our study highlights the importance of vertical gradients in structuring insect herbivore communities and emphasizes the role of leaf traits in mediating these interactions. In addition, the average annual herbivory rate suggests limited evidence supporting a significant contribution of background herbivory to the decline of sugar maple forests. [ABSTRACT FROM AUTHOR]

Monosteira unicostata (Mulsant & Rey.) (Poplar lace bug) and Melanophila picta Pall. (Poplar wood borer) are significant pests of poplar and willow trees in Hamadan province. The infestation levels of host plants to the pests were assessed across 11 native and exotic Poplar clones at a research station in Hamadan during 2010-2011. The Poplar clones, including species from Populus alba L., P. nigra L., P. deltoides Marsh ., and P. x euramericana (Dode.), were assessed using a randomized complete block design with three replications. For M. unicostata survey, egg counts were conducted on both sides of the leaves by selecting four leaves of uniform size from the four cardinal directions at about 150-200 cm height in July and August. During the M. picta survey, a mesh fabric was wrapped around the main trunk of the trees, covering a height range of 10-110 cm, and the number of beetles present under the net was tallied weekly from June through August. The data were subjected to a mean comparison using Duncan's test using SPSS v.16.0 software. Results indicated a significant variance in infestation rates among the clones. Specifically, Duncan's test revealed that the clones P. deltoides missouriensis, P. x euramericana 214, P. nigra 75/2, and P. nigra 62/167 exhibited the highest to lowest numbers of M. picta on the trunks, respectively. Conversely, the clones P. alba 57/58 and P. nigra 62/149 had the highest and lowest counts of M. unicostata eggs on the leaves, respectively. Based on the findings of this study, P. nigra 62/149, P. nigra 62/167, and P. nigra 74/1 clones demonstrated the greatest adaptability and yeild, exhibiting a less infection to these two critical Poplar pests. [ABSTRACT FROM AUTHOR]

Diapause is a strategy in insects to mitigate seasonal stress and synchronize lifecycles with favorable times. Forests are 3D, dynamic ecosystems with contrasting microhabitats where numerous insects enter diapause and the duration of diapause affects their phenology. Ecologically important forest insects, like defoliators, bark breeders, or soil/litter-dwelling species have diverse diapause strategies. Anthropogenic change, like climate change and urbanization, has and will have substantial impacts on forest insects. Some species may increase their impact on ecosystems, while that of others may be reduced. Understanding how climate change or urbanization factors, like artificial light at night and the urban-heat-island effect, affect diapause may help develop generalizable rules to predict which species will show population expansion and which are likely to contract. Insects have major impacts on forest ecosystems, from herbivory and soil-nutrient cycling to killing trees at a large scale. Forest insects from temperate, tropical, and subtropical regions have evolved strategies to respond to seasonality; for example, by entering diapause, to mitigate adversity and to synchronize lifecycles with favorable periods. Here, we show that distinct functional groups of forest insects; that is, canopy dwellers, trunk-associated species, and soil/litter-inhabiting insects, express a variety of diapause strategies, but do not show systematic differences in diapause strategy depending on functional group. Due to the overall similarities in diapause strategies, we can better estimate the impacts of anthropogenic change on forest insect populations and, consequently, on key ecosystems. [ABSTRACT FROM AUTHOR]

Insect herbivore diet mediates interactions with entomopathogens, yet this is relatively unexplored for microsporidia. Here, we examine a diet‐mediated tri‐trophic interaction between an outbreaking forest defoliator, forest tent caterpillar (FTC) Malacosoma disstria Hübner and Nosema sp. microsporidia.We conducted two experiments where diet quality was manipulated by incorporating lyophilized aspen (Populus tremuloides Michaux) foliage into an artificial diet, which was compared to a standard artificial diet. Diet quantity varied between fully fed and partially starved conditions, simulating an outbreak scenario. Microsporidia infection occurred naturally or was induced via experimental inoculation. We assessed FTC survival, microsporidia infection and load, and sublethal effects of treatments on FTC traits.Plant secondary metabolite concentrations in aspen‐augmented diets varied between experiments. In Experiment 1, the aspen‐augmented diet contained lyophilized aspen foliage with low concentrations of secondary metabolites, which increased FTC survival and reduced microsporidia infection. Diet quality and infection load also interactively influenced adult wing traits in Experiment 1. In Experiment 2, the aspen‐augmented diet contained lyophilized aspen foliage with higher concentrations of secondary metabolites, which negatively affected FTC. No diet‐mediated interactions with microsporidia were observed in Experiment 2.Diet quality (Experiments 1 and 2), diet quantity (Experiment 2) and microsporidia infection (Experiments 1 and 2) directly influenced FTC survival and/or had sublethal effects on FTC that may have cascading effects on population dynamics and dispersal.We demonstrated that diet quality can mediate interactions between FTC and microsporidia, but these interactions depend on the defensive chemistry of the FTC diet. To our knowledge, this is the first study to report diet‐mediated interactions between an outbreaking forest pest and microsporidia and one of only a few studies to examine this tri‐trophic interaction among Lepidoptera. [ABSTRACT FROM AUTHOR]

Urban expansion is an important cause of biodiversity loss due to habitat destruction involving the replacement of the natural environment with anthropic infrastructure. However, recent studies suggest that the harmonious growth of cities could allow the persistence of biological diversity within them. Thus, some cities, especially those that contain remnant forests that preceded their expansion, could harbor high levels of biodiversity. These remnant forests, i.e., urban natural forests (UNFs), are refuges for native species, providing suitable habitat conditions for population stability. However, traditional ecological studies have focused on natural and planted forests, so our knowledge of ecological dynamics in UNFs is still limited. Here, we explore the suitability of a temperate UNF for saproxylic beetles. These beetles are deadwood-dependent, highly diverse trophic groups that commonly inhabit natural forest ecosystems. However, saproxylic beetle diversity has been understudied in urban forest ecosystems. We analyzed the species richness, abundance, and seasonal variation of saproxylic beetles, including their most important trophic guilds, associated with urban forests. For this purpose, we monitored standing dead trees monthly between December 2019 and December 2022, using trunk window (flight interception) traps in the UNF Arboretum of Valdivia, Chile. Additionally, we measured qualitative and quantitative habitat attributes to evaluate the preferences of these insects in the UNF. We used generalized linear models as statistical methods to estimate saproxylic beetle habitat preferences. We collected 1273 individuals, belonging to 43 families and 195 saproxylic species/morphospecies. We found that diversity and abundance were strongly influenced by seasonality and the degree of decomposition of deadwood, with increased diversity and abundance in warmer months and highly decomposed trees. Our data show that UNF Arboretum harbor a high diversity of saproxylic species and are therefore suitable habitats and that the factors that regulate these assemblages are homologous to those of natural forests. Finally, our research provides evidence useful for the establishment of conservation and management practices to promote high diversity in UNFs, for example increasing the deadwood volume and quality of the habitat for saproxylic diversity. [ABSTRACT FROM AUTHOR]

Background: Gonipterus platensis Marelli, 1926 (Coleoptera: Curculionidae) is one of the main defoliating beetles in Eucalyptus plantations. Biological control with egg parasitoids is one of the main control strategies for this pest and a constant supply of fresh host eggs is required to rear the parasitoids. Polyandry can influence Gonipterus oviposition by increasing female fecundity and fertility; however, the high density of individuals in laboratory colonies can lead to male harassment, resulting in lower reproduction rate. The aim of this study was to measure the effects of monoandry and polyandry on the reproduction of G. platensis and the effects of male harassment on laboratory rearing conditions. Methods: Reproductive parameters were compared between three treatments: monoandry, where the female was allowed to mate daily with the same male; no choice polyandry, where the female was allowed to mate daily with a different male; and polyandry with choice, where the female was allowed to mate daily, but with a choice between five different males. Another experiment varying the density of males was conducted to evaluate the effect of male harassment. Results: Polyandry with choice resulted in the longest period of oviposition, highest fecundity and highest number of eggs per egg capsules when compared to monoandrous females. No negative effect related to male harassment in the laboratory, such as decreased fertility, fecundity, or number of eggs per egg capsule, was detected. Conclusion: Polyandry contributes to mass rearing as it increases fecundity and oviposition period on females and there is no evidence of male harassment on G. platensis. [ABSTRACT FROM AUTHOR]

In this study, methods are proposed for analyzing the susceptibility of forest stands to attacks by forest insects on the basis of Earth remote sensing data. As an indicator of the state of forest stands, we proposed to use a parameter of the sensitivity of a vegetation index (normalized difference vegetation index; NDVI) during a vegetative period to changes in the radiative temperature of the territory (land surface temperature; LST) determined from satellite data of the Terra/Aqua system. The indicator was calculated as a spectrum of a response function in an integral equation linking changes of NDVI to those of LST. Backtesting was carried out using data from two outbreaks of the Siberian silk moth Dendrolimus sibiricus Tschetv. and outbreaks of the white mottled sawyer Monochamus urussovi Fischer and of the four-eyed fir bark beetle Polygraphus proximus Blandford in taiga forests of Krasnoyarsk Territory in Russia. In addition, the state of fir stands in the year 2023 was examined when damage to the forest stands was not yet noticeable, but Siberian silk moth adults were found in pheromone traps. It was shown that the proposed indicator of susceptibility of forest stands changed significantly 2–3 years before the pest outbreak in outbreak foci of the studied areas. Thus, the proposed indicator can be used to predict outbreaks of insect pests. The proposed approach differs from commonly used remote sensing methods in that, rather than using absolute values of remote indicators (such as, for example, NDVI), it focuses on indicators of the susceptibility of these remote indicators to the characteristics of the natural environment. Since any given point on the planet is characterized by a seasonally varying temperature, it is always possible to determine the sensitivity of a remote sensing indicator to changes in the environment that are not directly related to the absolute value of the indicator. Future studies are expected to examine susceptibility indices as a function of forest stand location and species, and to examine the length of spatial correlation of susceptibility indices, which may provide information on the possible extent of future insect outbreaks. [ABSTRACT FROM AUTHOR]

Insects live in a wide range of thermal environments and have evolved species- and location-specific physiological processes for survival in hot and cold extremes. Thermally driven dormancy strategies, development rates and thresholds are important for synchronizing cohorts within a population and to local climates and often vary among populations within a species. Mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae, Scolytinae), is a widely distributed forest insect native to North America with clinal genetic differentiation in thermally dependent traits. MPB development occurs in Pinus phloem beneath the bark, and its cryptic habitat makes experimentation difficult, particularly for the adult stage. We describe a novel method for modeling MPB adult development following pupation and terminating in emergence from a brood tree. We focus on an Arizona (southern) MPB population with previously described preadult development rates. Field-observed tree attack, adult emergence, and phloem temperature data are combined in a parameterized cohort model and candidate rate curves are evaluated to describe adult emergence timing. Model competition indicates that the Brière rate curve provided the best fit to field data and performed well under cross-validation. Results confirm that the development of Arizona MPB adults is slower than the previously described development rate of more northern Utah adults. Using the estimated adult rate curve in a scenario of increasing mean temperatures, we show that the timing of second-generation adult emergence in the same year would result in cold-intolerant lifestages during winter, limiting the success of bivoltine populations. [ABSTRACT FROM AUTHOR]

Simple Summary: Simple Summary: Acoustic communication is present in different groups of insects and is used in different contexts during their life cycle. Bark beetles are a group of insects of ecological importance, because they can kill a large number of trees and affect forest succession These insects communicate using chemical signals for long distances, but while on or in the tree, they use acoustic communication to interact between individuals during the colonization of their host trees. A series of sounds have been described for bark beetles, which are produced by specialized anatomical structures under different conditions, such as stress, courtship, and territoriality. In this study, we worked with males of Dendroctonus adjunctus, and we described the stridulatory structures using optical and electron microscopy. In addition, we recorded and characterized the types of calls and their spectral and temporal characteristics under stress conditions, female–male, and male–male interactions. Results showed that the shape of the stridulatory apparatus is like males of other beetle species in the genus, and we identified single– and multi–noted calls with differences in temporal and spectral characteristics under three behavioral contexts. Finally, a new type of withdrawal call was identified in male–male interactions. The acoustic communication system (ACS) in bark beetles has been studied mainly in species of the genera Dendroctonus, Ips and Polygraphus. Specifically, ACS of the roundheaded pine beetle, Dendroctonus adjunctus, has been little studied. In this study, we described the stridulatory apparatus of this beetle using optical and scanning electron microscopy and recorded the call types produced by males in three behavioral contexts: stress, female–male–, and male–male interactions. From the spectrograms and waveforms, call types, as well as temporal (tooth strike, tooth strike rate, and intertooth strike interval) and spectral features (minimum, maximum and dominant frequency), were determined. Males have a functional elytro–tergal stridulatory apparatus—females do not—consisting of a file for the pars stridens and two lobes for the plectrum. Most of spectro–temporal features were statistically different between single– and multi–noted calls and across the three behavioral contexts. In the male–male interaction, a new type of call named "withdrawal" was produced by the male withdrawing or fleeing. Our results suggest that the spectro–temporal features of single– and multiple–noted calls in the three behavioral conditions are specific and different from each other. Yet, the combination of single and multiple calls determines an overall calling pattern characteristic of the tested behaviors and, therefore, is species–specific. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of constructing a mathematical model of population density dynamics and the dynamics of forest areas damaged by spongy moth (Lymantria dispar L.) outbreaks in the United States, Europe, Russia, and Japan. The key variable of the model is either the pest population density or the area of forests damaged by spongy moths during a season. This variable can be considered proportional to the total current pest abundance in the study area. For the purposes of modeling, data from a number of different authors was used (see bibliography), as well as data from surveys conducted at the egg or caterpillar stage. The complexity of modeling the dynamics of L. dispar abundance is largely due to the fact that, when studying the dynamics of spongy moth population density, the values of external factors such as parasites, predators, and the amount of available food are often unknown. A simple model was proposed using only two types of data: population density and monthly weather characteristics. Our analysis demonstrated that, even in the absence of knowledge regarding the characteristics of ecosystem components interacting with the spongy moth population (parasites, predators, and the state of forage trees), it is possible to introduce models that characterize the regulatory processes in the population in terms of (i) the presence of negative and positive feedbacks in the system and (ii) the influence of external weather factors. The system under investigation was described as an autoregressive system, whereby the current state of the population is dependent on its state in previous years. The order of autoregression in the system was estimated using the order of the maximum significant partial autocorrelation function. It was found that the regulation of spongy moth population density was characterized by the presence of two feedback loops: positive feedback between the current population density and the population density in the previous season and negative feedback between the current population density and the population density two years ago. To evaluate the model, its stability margin was calculated and found to be directly proportional to the positive feedback coefficient and inversely proportional to the negative feedback coefficient. The model was demonstrated to explain up to 90% of the observed variance of real data. Although the model coefficients for different local populations (North America, Europe, and Asia) differ, the general form of the equation describing both direct data on population densities and indirect data on pest dynamics characterized by areas of stand damage is consistent. Consequently, the form of the ADL model is general, irrespective of the location of the local population. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to study a class of forest disease and insect infection models with time delay. The exact solutions are successfully obtained by using the homotopy perturbation method. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The most important aim of the integrated management of forest insect pests remains the prevention of insect outbreaks, which are a consequence of the interaction of many factors in forest ecosystems, including species composition, age and health of the forest, soil type, the presence of natural enemies, and climatic factors. Integrated pest management until now has been achieved using measures aimed at shaping the functioning of stands in a changing environment. The aim of this review is to summarize research on the use of entomopathogens (microorganisms and nematodes) in the management of forest insect pests and to identify the principal knowledge gaps. We briefly describe the main research directions on the use of pathogens and nematodes to control insect pests and discuss limitations affecting their implementation. Research on entomopathogens for the biocontrol of forest insects has provided a wealth of knowledge that can be used effectively to reduce insect populations. Despite this, few entomopathogens are currently used in integrated pest management in forestry. They are applied in inoculation or inundation biocontrol strategies. While the use of entomopathogens in forest pest management shows great promise, practical implementation remains a distant goal. Consequently, sustainable reduction of forest pests, mainly native species, will be largely based on conservation biological control, which aims to modify the environment to favor the activity of natural enemies that regulate pest populations. This type of biocontrol can be supported by a range of silvicultural measures to increase the resilience of stands to insect infestations. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Engaging ecological resource users in intervention to protect the resource is challenging for governments due to self-interest of users and uncertainty about intervention consequences. Focusing on a case of forest insect infestations, we addressed questions of resource protection and environmentally responsible behavior promotion with a conceptual model. We coupled a forest infestation model with a social model in which a governing agent applies a mechanism for recognition and promotion of environmentally responsible behavior among several user agents. We ran the coupled model in various scenarios with a Reinforcement Learning algorithm for the governing agent as well as best-case, worst-case, and random baselines. Results showed that a proper recognition policy facilitates emergence of environmentally responsible behavior. However, ecosystem health may deteriorate due to temporal differences between the social and ecological systems. Our work shows it is possible to gain insight about complexities of social-ecological systems with conceptual models through scenario analysis. [ABSTRACT FROM AUTHOR]

Remote sensing is a well-established tool for detecting forest disturbances. The increased availability of uncrewed aerial systems (drones) and advances in computer algorithms have prompted numerous studies of forest insects using drones. To date, most studies have used height information from three-dimensional (3D) point clouds to segment individual trees and two-dimensional multispectral images to identify tree damage. Here, we describe a novel approach to classifying the multispectral reflectances assigned to the 3D point cloud into damaged and healthy classes, retaining the height information for the assessment of the vertical distribution of damage within a tree. Drone images were acquired in a 27-ha study area in the Northern Rocky Mountains that experienced recent damage from insects and then processed to produce a point cloud. Using the multispectral data assigned to the points on the point cloud (based on depth maps from individual multispectral images), a random forest (RF) classification model was developed, which had an overall accuracy (OA) of 98.6%, and when applied across the study area, it classified 77.0% of the points with probabilities greater than 75.0%. Based on the classified points and segmented trees, we developed and evaluated algorithms to separate healthy from damaged trees. For damaged trees, we identified the damage severity of each tree based on the percentages of red and gray points and identified top-kill based on the length of continuous damage from the treetop. Healthy and damaged trees were separated with a high accuracy (OA: 93.5%). The remaining damaged trees were separated into different damage severities with moderate accuracy (OA: 70.1%), consistent with the accuracies reported in similar studies. A subsequent algorithm identified top-kill on damaged trees with a high accuracy (OA: 91.8%). The damage severity algorithm classified most trees in the study area as healthy (78.3%), and most of the damaged trees in the study area exhibited some amount of top-kill (78.9%). Aggregating tree-level damage metrics to 30 m grid cells revealed several hot spots of damage and severe top-kill across the study area, illustrating the potential of this methodology to integrate with data products from space-based remote sensing platforms such as Landsat. Our results demonstrate the utility of drone-collected data for monitoring the vertical structure of tree damage from forest insects and diseases. [ABSTRACT FROM AUTHOR]

Evidence for widespread declines in arthropods is growing and climate change is one of the suspected drivers. Recent droughts in Europe were unprecedented in the previous centuries and we are only beginning to understand the impacts on ecosystems. We analysed a 24‐year dataset of carabid beetles from a temperate forest area in northeast Germany and investigated linear and non‐linear trends in carabid abundance, biomass, diversity and species traits. We were especially interested if and how these were linked to droughts at different temporal scales using the standardized precipitation evapotranspiration index (SPEI). We found significant linear declines in abundance and biomass with annual rates of −3.1% (0.95 CI [−5.3, −1]) and –4.9% (0.95 CI [−9.4, −1.6]), respectively. Non‐linear trends were closely related to the SPEI when considering the climatic water balance of the previous six years and showed severe declines between 2015 and 2022 (−71% abundance, 0.95 CI [−84, −61] / −89% biomass, 0.95 CI [−97, −59]). However, there remained a significant annual background‐decline of −2.1% (0.95 CI [−5.7, −0.2]) and −3.1% (0.95 CI [−6.5, −0.1]), respectively, which occurred independently of drought. We observed negative trends in standardized carabid diversity metrics and a shift in species assemblage that were less directly linked to droughts. Declining and drought‐sensitive species tended to be larger predators with low dispersal abilities. This study is among the very first to investigate the impacts of the current unprecedented drought on forest insects in central Europe. Our findings add to the concerning amount of evidence for widespread declines in arthropods while pointing towards weather anomalies and climate change as one important driver. [ABSTRACT FROM AUTHOR]

Forest insect outbreaks cause large changes in ecosystem structure, composition, and function. Humans often respond to insect outbreaks by conducting salvage logging, which can amplify the immediate effects, but it is unclear whether logging will result in lasting differences in forest structure and dynamics when compared with forests affected only by insect outbreaks. We used 15 years of data from an experimental removal of Tsuga canadensis (L.) Carr. (Eastern hemlock), a foundation tree species within eastern North American forests, and contrasted the rate, magnitude, and persistence of response trajectories between girdling (emulating mortality from insect outbreak) and timber harvest treatments. Girdling and logging were equally likely to lead to large changes in forest structure and dynamics, but logging resulted in faster rates of change. Understory light increases and community composition changes were larger and more rapid in the logged plots. Tree seedling and understory vegetation abundance increased more in the girdled plots; this likely occurred because seedlings grew rapidly into the sapling‐ and tree‐size classes after logging and quickly shaded out plants on the forest floor. Downed deadwood pools increased more after logging but standing deadwood pools increased dramatically after girdling. Understory light levels remained elevated for a longer time after girdling. Perhaps because the window of opportunity for understory species to establish was longer in the girdled plots, total species richness increased more in the girdled than logged plots. Despite the potential for greater diversity in the girdled plots, Betula lenta L. (black birch) was the most abundant tree species recruited into the sapling‐ and tree‐size classes in both the girdled and logged plots and is poised to dominate the new forest canopy. The largest difference between the girdling and logging treatments—deadwood structure and quantity—will persist and continue to bolster aboveground carbon storage and structural and habitat diversity in the girdled plots. Human responses to insect outbreaks hasten forest reorganization and remove structural resources that may further alter forest response to ongoing climate stress and future disturbances. [ABSTRACT FROM AUTHOR]

The choice of trap in entomological surveys affects the composition of captured insects, though previous comparative studies have been limited in the types of composition measured, and the effects of environmental context. We assessed the sampling bias of several traps commonly used in pollinator monitoring: blue, yellow, and white pan traps, and blue vane traps, towards different taxonomic and functional groups and their efficiency in measuring taxonomic, phylogenetic, and functional diversity. Analyses were performed in monoculture and mixed forests to understand the environmental context of trap efficiency. We found that blue pan traps generally outperformed other types in bee capture and exhibited a preference for Halictidae bees. Blue pan traps yielded the highest species richness and phylogenetic diversity, while blue vane traps captured the highest functional richness. Bias differences were frequently detected in mixed forests compared with monoculture forests. We also found the combination of blue vane and pan traps consistently correlated highest with a complete survey among two-method combinations. Based on our findings, we recommend a combination of blue vane and pan traps to obtain a more comprehensive bee collection in an efficient manner. Additionally, it is crucial to consider habitat type when designing bee trapping protocols to ensure an accurate representation of bee communities.

Termites are amongst the most abundant and ecologically-important groups of insects in tropical forests. However, the destructive potential of some species amounts to billions of dollars in damage each year. Despite their economic and ecological impacts, only a limited number of invasive termite species have been studied using distribution modelling and no studies have taken trade, transport and demography variables into account. We used Species Distribution Models (SDMs) to investigate the potential distribution of 10 highly-invasive termites. Our study includes bioclimatic conditions, landuse patterns, elevation and connectivity predictors (i.e. urban areas, human population, accessibility to cities and private vessels), alongside different climatic and socioeconomic change scenarios. The distribution of the termite species hinges on bioclimatic and connectivity variables, highlighting the significance of these latter factors in invasive species analyses. Our models demonstrate the potential of these invasive termites to thrive in large urbanised and connected areas within tropical and subtropical regions and to a lesser extent within temperate regions. As climate changes and urbanisation intensifies, most species' range could expand, particularly under a "fossil fuel-driven development" scenario. Furthermore, while some species may have a slightly reduced range, they could extend their presence into more urbanised and connected areas, increasing the risks and costs associated with termite damages. Our models highlight the anticipated role of growing connectivity and climate change dynamics in facilitating the widespread proliferation of invasive termites in the coming years. [ABSTRACT FROM AUTHOR]

We report observations of Onnia subtriquetra on bishop pine (Pinus muricata) and shore pine (Pinus contorta var. contorta) from north coastal California. Our identification of this fungus is supported by molecular information, morphological characteristics, and and a description of the observed range of the fungus on the West Coast. These observations represent an expansion of the geographic and host ranges of Onnia subtriquetra, which on the observed sites is generally associated with declining tree condition and the presence of other native forest pathogens and insects. [ABSTRACT FROM AUTHOR]

Aim: Biological invasions are an escalating environmental challenge due to their substantial ecological and socio‐economic consequences. Accurate near‐term forecasts of future areas occupied by an invasive species could enhance the efficiency and efficacy of invasion monitoring and management but spread forecasting models have been developed and tested for few invasive species thus far. Location: Northeastern USA. Methods: We developed a quantitative model to forecast 1‐year‐ahead occupancy of Lymantria dispar dispar, an expanding invasive forest insect introduced into the eastern United States in 1869 that causes large‐scale defoliation of forests. We validated and tested the model using historical distribution and density data from a large‐scale network of pheromone‐baited traps. We first assessed how forecast accuracy depended on trap catch density thresholds for determining occupancy and on the spatial scale of local connectivity measures. Next, we tested how increasing the computational complexity and biological detail encoded in the models affected prediction accuracy. Results: Models using lower occupancy thresholds and measuring connectivity over shorter distances tended to perform best. A simple model using only coarse and generic representations of habitat suitability and local diffusive spread potential performed at least as well as more complex models. Our best models achieved total accuracy and true‐positive rates exceeding 95%. Conclusions: Our baseline model illustrates the utility of a mechanistic model to forecast year‐to‐year occupancy dynamics of L. dispar. Near‐term spread forecasting can be a valuable tool for invasion management, even for species without detailed a priori ecological knowledge. [ABSTRACT FROM AUTHOR]

Defoliators cause extensive damage in boreal and temperate forests of the world. Considerable effort has been invested to understand their individual population dynamics, and despite ample theorising, there is little empirical evidence on factors causing spatial synchrony of pest eruptions at landscape scales.We report on the landscape‐level effect of forest configuration and composition on the intensity of outbreaks of spruce budworm and forest tent caterpillar in a mixedwood boreal forest in northern Minnesota (USA) and adjacent Ontario (Canada), and how this is related to the degree of spatial synchrony in each species' outbreak cycling.Using a large spatiotemporal tree‐ring reconstruction of outbreak impacts across these two systems, we evaluate two contrasting theories governing defoliator outbreaks: harmonic oscillation (a.k.a. 'clockwork') and relaxation oscillation (a.k.a. 'catastrophe'), each with consequences linked to top‐down versus bottom‐up influences on outbreak behaviour in time and space.We find synchrony varies temporally, among outbreak cycles and in direct proportion to cycle peak intensity; however, cycle peak intensities are distributed bimodally in time, and so, therefore, are synchrony coefficients. Spatially, the area where each pest species currently cycles with the greatest peak intensity and synchrony is where their preferred host trees are currently found in greatest proportion.Despite overall synchrony in cycling, we found, in both systems, a persistent negative spatial correlation among successive eruptive pulses of defoliation. Many of these eruptions failed to spread spatially and to coalesce with other spot eruptions to form extensive area‐wide outbreaks. Eruptions often fail to spread at the hardwood‐conifer interface, resulting in outbreak pulses that systematically bounce back and forth between landscape types, particularly when systems were cycling at low amplitude. These over‐dispersed spatial patterns of pulse impact are consistent with a contagious theory of eruption and outbreak spread. They could be considered consistent with harmonic oscillation theory only for populations cycling at different frequencies, with cycling frequency determined by host forest landscape structure.Synthesis. We find that defoliator outbreak dynamics across systems include spatiotemporal signatures of each theoretical paradigm—suggesting a hybrid approach will better characterise outbreak behaviour. Host concentration influences which paradigm dominates the spatial dynamics in any given forest landscape context. Because of the synchronising effect of host concentration on forest insect spatial dynamics, mixedwoods appear to be less prone to intense, synchronised defoliator attack than forests of pure hardwood or pure conifer. [ABSTRACT FROM AUTHOR]

Forest soil and leaf litter support diverse arthropod mesofauna for which diversity dynamics is challenging to study due to the high number of species and specimens, small body size and limited taxonomic knowledge.Immature stages (larvae) are even harder to identify than adults, as their morphology is largely unknown. Therefore, larvae are often ignored, even though they may form a substantial proportion of specimens collected, are less mobile than adults and their exclusion may provide an incomplete diversity profile.Here, we use Oxford Nanopore DNA barcoding to investigate whether the inclusion of larvae provides a more complete taxonomic, phylogenetic and functional diversity profiles in leaf litter beetles (Coleoptera) from a subtropical forest in Taiwan.Our results indicate that larvae represent up to 38% of beetle specimens per sample, but most of them belong to 2–3 common species. Larvae of most beetle species are rarely collected repeatedly or in multiple specimens, possibly due to special habitat requirements or high seasonality.Taxonomic, phylogenetic and incidence‐based functional diversity measures were not affected by the exclusion of larvae in the Staphylinidae dataset but were strongly biased in all‐beetle dataset, especially when only common or abundant species were considered. Taxonomic beta diversity was not affected by the omission of larvae.Our results indicate that immature stages may be omitted in ecological studies of arthropods in case both adults and larvae co‐occur in the same habitat, and the sites are sampled repeatedly. Caution is needed (1) in groups in which larvae and adults do not inhabit the same environment or strongly differ in biology, (2) when rare species are omitted or (3) when functional diversity is calculated from abundance data. [ABSTRACT FROM AUTHOR]

Climatic chances, and most precisely extended drought, have a negative impact on forests ecosystems. Such conditions can increase the incidence of pests and diseases in the forests, and change the behavior of saproxylic insects and fungi, which migrate from the dead wood to the stressed trees. The aim of this study is to reveal the fungal species associated with saproxylic insects collected from debilitated trees found in the strictly protected area of the Plaiul Fagului Nature Reserve. A total of 21 fungal strains were isolated from the insects' body of coleopteran species Platypus cylindrus, Scolytus carpini, Stereocorynes truncorum and Xyleborus monographus collected from Quercus petraea trees - edifier of the European-type natural forests in the Republic of Moldova. This study is the first one describing the fungal diversity associated with saproxylic insects in the Republic of Moldova. [ABSTRACT FROM AUTHOR]

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Effective management of forest insects and diseases requires detection of abnormal mortality, particularly among a single species, sufficiently early to enable effective management. Remote detection of individual trees crowns requires a spatial resolution not available from satellites such as Landsat or Sentinel-2. In the United States, there are currently few operational systems capable of effectively and affordably detecting and mapping tree mortality over broad landscapes using high-resolution imagery. Here, we introduce the Tree Condition and Analysis Program (TreeCAP), an open-source system that uses freely available imagery from the National Agriculture Imagery Program (NAIP) to create maps of tree condition (healthy or damaged). We demonstrate the potential applications of TreeCAP in four study sites: (1) beetle-killed pines in California, (2) emerald ash borer progression in Wisconsin, (3) hemlock wooly adelgid mortality in Pennsylvania, and (4) drought damage in Texas. We achieved an average overall accuracy of 87% across all study sites. [ABSTRACT FROM AUTHOR]

Copyright of Revista Colombiana de Entomología is the property of Universidad del Valle and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article titled "New record of Giant Redeye Gangara thyrsis thyrsis (Fabricius, 1775) (Lepidoptera: Hesperiidae) from Garhwal region of western Himalaya, India" discusses the discovery of the Giant Redeye butterfly in the Garhwal region of the western Himalayas in India. The Giant Redeye is the largest skipper butterfly in India, known for its quick darting flight. The butterfly was previously only found in the Indian peninsular region, but this new record expands its known distribution. The article provides details about the physical characteristics and habitat preferences of the butterfly, as well as information about its larval host plants. This is the first authentic record of the Giant Redeye in the Garhwal region of Uttarakhand, India. [Extracted from the article]

This article discusses the challenges posed by non-native forest insects and the importance of risk mapping approaches to address this threat. It highlights the impacts of invasive forest insects on forest health, ecosystem services, and the economy. The article emphasizes the importance of pest risk models and maps in assessing the risk posed by invasive pests and guiding management and surveillance strategies. It also presents various modeling methods and tools that have been developed to predict the phenology, climate suitability, and spread of invasive insects. The article concludes by emphasizing the need for engagement with end users and improving outreach and training to ensure the broader uptake of pest forecasting tools and map products. The given text consists of a list of references and citations related to the topic of invasive forest insects and their impact on ecosystems. The references cover various aspects of the issue, including the ecological and economic impacts of invasive insects, the role of climate change in facilitating their spread, and the development of decision support systems for risk assessment and management. The text emphasizes the need for surveillance and early detection of high-consequence pests and pathogens to prevent their establishment and spread. It also highlights the importance of accurate species distribution modeling and phenology forecasting in managing invasive forest pests. [Extracted from the article]

Simple Summary: Insects are a significant cause of harm and mortality to forest areas. In particular, the forests of Siberia, covering over 2.4 million square kilometers with a low or non-existent pest insect population, are at high risk. Under such conditions, observing insects from the ground is nearly impossible. Consequently, remote sensing techniques are the sole feasible option. However, many remote indicators only change after significant damage occurs to the stands of trees, making it too late to implement protective measures. The objective of this study was to construct distance indicators that could identify areas where forest stands have lost resistance to attacks by such a dangerous pest of Siberian forests as the Siberian silk moth Dendrolimus sibsiricus Tschetv. To create indicators, it has been suggested that estimations rely on the reaction of stands to weather conditions during the season, instead of absolute values. Such remote indicators were constructible, and these indicators in the areas of future outbreaks had changed already two or three years before the outbreak. Remote sensing data allow the development of complex indicators of forest stands' insect resistance anywhere in the world, thus making it possible to monitor large areas to identify risk of pest outbreaks. The feasibility of risk assessment of a Siberian silk moth (Dendrolimus sibiricus Tschetv.) outbreak was analyzed by means of landscape and weather characteristics and tree condition parameters. Difficulties in detecting forest pest outbreaks (especially in Siberian conditions) are associated with the inability to conduct regular ground surveillance in taiga territories, which generally occupy more than 2 million km2. Our analysis of characteristics of Siberian silk moth outbreak zones under mountainous taiga conditions showed that it is possible to distinguish an altitudinal belt between 400 and 800 m above sea level where an outbreak develops and trees are damaged. It was found that to assess the resistance of forest stands to pest attacks, researchers can employ new parameters: namely, characteristics of a response of remote sensing variables to changes in land surface temperature. Using these parameters, it is possible to identify in advance (2–3 years before an outbreak) forest stands that are not resistant to the pest. Thus, field studies in difficult-to-access taiga forests are not needed to determine these parameters, and hence the task of monitoring outbreaks of forest insects is simplified substantially. [ABSTRACT FROM AUTHOR]

Population outbreaks of such species as Dendrolimus sibiricus Tschetv., in Siberian taiga forests begin with areas of several hectares and develop up to hundreds of thousands of hectares, resulting in significant damage to forests. Boundaries of foci change with time depending on external factors, population dynamics, and the state of forage trees. In this regard, it is important to determine the beginning of an outbreak and the affected area in advance as predictors of increasing pest numbers. To assess necessary conditions for an outbreak, a method for assessing the state of forest stands is proposed based on remote sensing data. In this regard, it is important to assess risks of outbreaks and to determine in advance their onset times and starting zones. In order to evaluate necessary conditions for an outbreak, a "cascade" of factors is considered: geophysical (solar activity), weather, and the state of forest stands. Each of these factors is characterized by its own area, within the bounds of which any changes in this particular factor affect the insect population. [ABSTRACT FROM AUTHOR]

During the growth of a forest insect outbreak epicenter, there are processes that involve the formation and expansion of the primary epicenter of forest damage, as well as secondary epicenters—both connected and unconnected to the primary one. This study characterizes outbreak epicenters in terms of their fractal dimensions and "viscous finger" parameters at the epicenter boundary, highlighting their significance in the context of forest insect management. Local outbreak epicenters were found to be characterized by fractal dimension D = 1.4–1.5, and the boundaries of the epicenters were described using the "viscous finger" model. Proposed models were constructed and validated using remote sensing data obtained from MODIS and Sentinel-2 satellites at epicenter sites and boundaries during the outbreak of the Siberian silk moth Dendrolimus sibiricus Tschetverikov from 2014 to 2020 in the Krasnoyarsk region of Russia. The study revealed that the frequency of the mode spectrum of one-stage spatial series of "viscous fingers" corresponds with the data on the development of the outbreak foci area. [ABSTRACT FROM AUTHOR]

Using multi-scale trembling aspen tree-ring width data from Alberta, we show that scaling has a profound influence on dendroecological inferencing. At all scales of sampling, there is a significant climatological signal whose strength is nevertheless superseded by the pervasive effect of insect herbivory. At the smallest spatial scale, 20 km × 20 km, we demonstrate a quasi-periodic pattern of sharp growth reductions and the existence of negative spatial correlations among successive outbreaks. At the intermediate spatial scale of 20 km × 80 km, we show that the period 1930–1963 was marked by extremely low correlations in aspen ring widths, with much higher correlations occurring both before and after, despite high variance in precipitation that might have caused ring widths to correlate under moisture limitation. At the largest spatial scale of the entire province, aspen ring widths in the boreal forest became decorrelated abruptly in 1916, after cycling synchronously for the previous 80 years. This occurred despite a warming climate that heightened moisture limitation. Something in the environment prevents some outbreak cycles from rising to maximum intensity and from spreading to maximum extent. This appears to be the key to better predictability and management of forest insects and forests at short and long time-scales. [ABSTRACT FROM AUTHOR]

Insect and disease outbreaks in forests are biotic disturbances that can profoundly alter ecosystem dynamics. In many parts of the world, these disturbance regimes are intensifying as the climate changes and shifts the distribution of species and biomes. As a result, key forest ecosystem services, such as carbon sequestration, regulation of water flows, wood production, protection of soils, and the conservation of biodiversity, could be increasingly compromised. Despite the relevance of these detrimental effects, there are currently no spatially detailed databases that record insect and disease disturbances on forests at the pan‐European scale. Here, we present the new Database of European Forest Insect and Disease Disturbances (DEFID2). It comprises over 650,000 harmonized georeferenced records, mapped as polygons or points, of insects and disease disturbances that occurred between 1963 and 2021 in European forests. The records currently span eight different countries and were acquired through diverse methods (e.g., ground surveys, remote sensing techniques). The records in DEFID2 are described by a set of qualitative attributes, including severity and patterns of damage symptoms, agents, host tree species, climate‐driven trigger factors, silvicultural practices, and eventual sanitary interventions. They are further complemented with a satellite‐based quantitative characterization of the affected forest areas based on Landsat Normalized Burn Ratio time series, and damage metrics derived from them using the LandTrendr spectral–temporal segmentation algorithm (including onset, duration, magnitude, and rate of the disturbance), and possible interactions with windthrow and wildfire events. The DEFID2 database is a novel resource for many large‐scale applications dealing with biotic disturbances. It offers a unique contribution to design networks of experiments, improve our understanding of ecological processes underlying biotic forest disturbances, monitor their dynamics, and enhance their representation in land‐climate models. Further data sharing is encouraged to extend and improve the DEFID2 database continuously. The database is freely available at https://jeodpp.jrc.ec.europa.eu/ftp/jrc‐opendata/FOREST/DISTURBANCES/DEFID2/. [ABSTRACT FROM AUTHOR]