Trap Trees Research Articles

Does bark beetle Ips typographus (L.) die after flying away from the poisoned trap tree?

Abstract Ips typographus (L.) is the most significant insect pest in the European spruce forests. Methods of control and monitoring are in the period of Ips typographus (L.) outbreaks supplemented with suppressive procedures applying insecticides. The aim of our study was to determine the necessary length of Ips typographus (L.) imagoes movement across the treated surface, resulting in their death also in the case of their flying away from the trap tree. Insecticides Forester (active substance cypermethrin) and Dinastia (active substance deltamethrin) were tested in laboratory conditions. Exposure times the beetles moved on the intoxicated bark were 30–300 s. Then the beetles were placed in Petri dishes and their survival rate up to twenty-four hours was established. Experiment duration was 8 weeks from spraying with repeated week control tests. High efficiency of tested pyrethroids ensuring the death of also flying away imagoes within six hours after contamination was established at three weeks. The rate of their survival was increasing from Week 4 independently on the exposure times (deltamethrin). In cypermethrin, the survival rate of imagoes was high and dependent on the exposure times. The efficiency of deltamethrin was higher than that of cypermethrin. During the outbreaks, the pheromone-baited poisoned trap trees causing the death also to flying away imagoes of Ips typographus (L.) have to be sprayed with the above-mentioned pyrethroids in a monthly interval at the time of swarming culmination. The efficiency of both insecticides decreased more rapidly on the upper unprotected side of the trap tree.

Interactions at the Oviposition Scar: Molecular and Metabolic Insights into Elaeagnus angustifolia's Resistance Response to Anoplophora glabripennis.

The Russian olive (Elaeagnus angustifolia), which functions as a "dead-end trap tree" for the Asian long-horned beetle (Anoplophora glabripennis) in mixed plantations, can successfully attract Asian long-horned beetles for oviposition and subsequently kill the eggs by gum. This study aimed to investigate gum secretion differences by comparing molecular and metabolic features across three conditions-an oviposition scar, a mechanical scar, and a healthy branch-using high-performance liquid chromatography and high-throughput RNA sequencing methods. Our findings indicated that the gum mass secreted by an oviposition scar was 1.65 times greater than that secreted by a mechanical scar. Significant differences in gene expression and metabolism were observed among the three comparison groups. A Kyoto Encyclopedia of Genes and Genomes annotation and enrichment analysis showed that an oviposition scar significantly affected starch and sucrose metabolism, leading to the discovery of 52 differentially expressed genes and 7 differentially accumulated metabolites. A network interaction analysis of differentially expressed metabolites and genes showed that EaSUS1, EaYfcE1, and EaPGM1 regulate sucrose, uridine diphosphate glucose, α-D-glucose-1P, and D-glucose-6P. Although the polysaccharide content in the OSs was 2.22 times higher than that in the MSs, the sucrose content was lower. The results indicated that the Asian long-horned beetle causes Russian olive sucrose degradation and D-glucose-6P formation. Therefore, we hypothesized that damage caused by the Asian long-horned beetle could enhance tree gum secretions through hydrolyzed sucrose and stimulate the Russian olive's specific immune response. Our study focused on the first pair of a dead-end trap tree and an invasive borer pest in forestry, potentially offering valuable insights into the ecological self-regulation of Asian long-horned beetle outbreaks.

Poisoned trap trees: a positive or negative tool to control Ips cembrae?

Ips cembrae is a destructive forest pest attacking European larch. In 2021 and 2022, effectiveness of poisoned trap trees, trap logs and slot traps baited with the Cembräwit in trapping I. cembrae was tested. The negative impact on the predators of genus Thanasimuswas evaluated. We found that poisoned trap trees and logs are more effective in trapping I. cembrae than slot traps. The aggregation of bark beetles on the trap log edge was significantly lower than in the central part, where the pheromone lure was placed. The application of poisoned trap trees is possible in cases of extreme outbreaks.

Recent outbreaks of the spruce bark beetle Ips typographus in the UK: Discovery, management, and implications

The eight-toothed spruce bark-beetle Ips typographus is the most damaging insect pest of Norway spruce in Europe, and it poses a serious risk to spruce in other countries where it is not currently present but might be introduced. The beetle is not native to the UK and before 2018 it had not been found established anywhere within the country. In November 2018, however, several adult Ips typographus were found in a billet trap set up as part of annual surveys that the UK carries out to monitor for this and other quarantine bark beetle pests. The finding of adult beetles in the billet trap, a few miles south of Ashford in Kent, led to the discovery of a breeding population in an adjacent woodland. Delimiting surveys to 1 km and further surveys to 50 km showed that the infestation was confined to a single stand of Norway spruce. The stand was felled in January and February 2019, and the material destroyed, and beetles emerging on the site were trapped out using pheromone traps, billet piles and trap trees. These prompt actions eradicated the breeding population, but small numbers of adult Ips typographus continued to be caught on the outbreak site in 2020 and 2021. These captures, and numerous adult Ips typographus caught in pheromone traps set up across the region in response to the outbreak, indicate that incursions of adult Ips typographus are occurring on a regular basis, most likely from source populations in northern France and Belgium. The arrival of adult Ips typographus over a wide area and the potential for further outbreaks represents a continuing threat to spruce woodlands in south-east England, and has important implications for surveillance and monitoring and the management of spruce in this part of the UK.

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AbstractThe Asian longhorn beetle (ALB), Anoplophora glabripennis, is considered one of the most successful and feared invasive insect species globally. In recent decades, extensive research on ALB has captured the attention of scientists worldwide, leading to investigations into various aspects of its biology and strategies for control and management. These comprehensive explorations have been widely reviewed in China (see pages 1534–1551). Specifically, the ecological control of ALB involves planting mixtures of preferred and resistant tree species, which has proven effective in preventing outbreaks. The cover photo depicts an ALB adult feeding on Elaeagnus angustifolia, a type of dead‐end trap tree for ALB. Photo provided by Lixiang Wang.

Time series DNA barcoding provides insight into factors influencing wood-boring and bark-feeding insect communities in Scots pine, Sitka spruce, and Noble fir stands.

Bark-feeding and wood-boring insect pests can have significant negative impacts on conifers and wood production. The damage they cause is expected to increase in the future due to climate change and the growth of international trade. This study employed DNA barcoding of beetle juveniles (Coleoptera) sampled from standing trap trees and cut log piles at regular intervals over a 2-yr period to monitor the beetle community dynamics and associated environmental factors. Tree species was found to have a major influence on beetle communities, most strikingly at the start of early decay stages. Lower species diversity was reported from standing trap tree samples compared to log pile samples, likely due to higher residual defences in dying and recently dead trees. While the species identified from standing trap trees are more likely to be a threat to the forestry sector, the species found in the log piles are more likely to be beneficial due to their high abundance and their ability to compete with pests for breeding substrate. The analysis of beetles collected inside trees revealed additional information on ontogenetic niches and host preferences beyond that acquired solely from flight interception trap data. Our results offer insights on community composition and dynamics of bark-feeding and wood-boring insect species in Welsh conifer forests and provide resources for monitoring and management of potential pest species.

Methyl salicylate improves the effectiveness of the odor-baited trap tree approach for adult plum curculio, Conotrachelus nenuphar (Coleoptera: Curculionidae), monitoring and attract-and-kill.

In commercial apple orchards, the odor-baited trap tree approach involving the synergistic lure composed of benzaldehyde (BEN) and the PC aggregation pheromone grandisoic acid (GA) serves as an effective monitoring tool as well as an attract-and-kill strategy for plum curculio (PC), Conotrachelus nenuphar Herbst. (Coleoptera: Curculionidae), management. However, the relatively high cost of the lure and the degradation of commercial BEN lures by UV light and heat discourage its adoption by growers. Over a 3-yr period, we compared the attractiveness of methyl salicylate (MeSA), either alone or in combination with GA, to plum curculio (PC) with that of the standard combination of BEN + GA. Our main goal was to identify a potential replacement for BEN. Treatment performance was quantified using 2 approaches: (i) unbaited black pyramid traps (2020, 2021) to capture PC adults and (ii) PC oviposition injury (2021, 2022) on apple fruitlets of trap trees and of neighboring trees to assess potential spillover effects. Traps baited with MeSA captured significantly more PCs than unbaited traps. Trap trees baited with a single MeSA lure and 1 GA dispenser attracted a similar number of PCs as trap trees baited with the standard lure composed of 4 BEN lures and 1 GA dispenser based on PC injury. Trap trees baited with MeSA + GA received significantly more PC fruit injury than neighboring trees suggesting no or limited spill-over effects. Our collective findings suggest that MeSA is a replacement for BEN thereby cutting costs of lures by ca. 50% while maintaining trap tree effectiveness.

Patterns of Ips cembrae (Herr) infestation on trap and standing trees of European larch (Larix decidua Mill.)

The large larch beetle, Ips cembrae, is a significant pest causing the death of larch. In 2020, the attack density of I. cembrae on larch trap trees and standing trees was evaluated using sample sections placed along the trunk. As a defensive measure against I. cembrae, trap trees were highly effective in both spring and summer. The attack density increased with increasing trap tree surface area/volume. Galleries were established evenly throughout the entire trunk including the thin upper portion. When the number of trap trees was low and their capacity full, a continual aggregation of adults occurred due to pheromone communication, leading to attacks on healthy standing trees in the immediate vicinity. It was found that I. cembrae attacked standing trees from the trunk base, with a continual colonization of the stem up to 70% of the tree height in a time-differentiated progression of development stages. The attack density of I. cembrae on standing trees was up to 40% lower than on the trap trees.

Precision Detection and Assessment of Ash Death and Decline Caused by the Emerald Ash Borer Using Drones and Deep Learning.

Emerald ash borer (Agrilus planipennis) is an invasive pest that has killed millions of ash trees (Fraxinus spp.) in the USA since its first detection in 2002. Although the current methods for trapping emerald ash borers (e.g., sticky traps and trap trees) and visual ground and aerial surveys are generally effective, they are inefficient for precisely locating and assessing the declining and dead ash trees in large or hard-to-access areas. This study was conducted to develop and evaluate a new tool for safe, efficient, and precise detection and assessment of ash decline and death caused by emerald ash borer by using aerial surveys with unmanned aerial systems (a.k.a., drones) and a deep learning model. Aerial surveys with drones were conducted to obtain 6174 aerial images including ash decline in the deciduous forests in West Virginia and Pennsylvania, USA. The ash trees in each image were manually annotated for training and validating deep learning models. The models were evaluated using the object recognition metrics: mean average precisions (mAP) and two average precisions (AP50 and AP75). Our comprehensive analyses with instance segmentation models showed that Mask2former was the most effective model for detecting declining and dead ash trees with 0.789, 0.617, and 0.542 for AP50, AP75, and mAP, respectively, on the validation dataset. A follow-up in-situ field study conducted in nine locations with various levels of ash decline and death demonstrated that deep learning along with aerial survey using drones could be an innovative tool for rapid, safe, and efficient detection and assessment of ash decline and death in large or hard-to-access areas.

A Non-Invasive Method of Estimating Populations of Tomicus Piniperda on Scots Pine (Pinus Sylvestris L.).

The fully non-invasive method presented here can be used to evaluate Tomicus piniperda L. population sizes in areas subject to strict protection. Data were collected in 2021-2022 in forests containing P. sylvestris, with different stand structures, in the Suchedniowsko-Oblęgorski Landscape Park, Poland. Entomological analyses were carried out on natural traps made from live uncolonised trees. Stepwise regression was used to describe the size of T. piniperda populations. From a set of features representing stem colonisation parameters, stem traits and habitat, the following had a significant effect (p < 0.05) on the total number of galleries of T. piniperda on stems: (1) the number of T. piniperda maternal tunnels in the sixth stem section covering 2.5% of the total length, (2) the length of the stem section with bark thickness greater than 7 mm, and (3) stand structure (homogeneous Scots pine stands). The model can explain 93% (Radj2=0.9333) of the variability in the total number of T. piniperda galleries on trap trees. The mean relative error of estimation is 20.1%. The proposed method is particularly valuable in a climate context. The data obtained enable the prediction of the direct effects of climate change on the population dynamics of T. piniperda in natural forests.

Bursaphelenchus leoni Baujard, 1980 (Tylenchina: Aphelenchoididae)'nin Türkiye'nin Çam Ormanlarından Ilk Kaydı

Several surveys have been performed in Turkey in order to determine a possible presence of Bursaphelenchus xylophilus (Steiner and Buhrer, 1934), Nickle, 1970. As a result, several Bursaphelenchus species have been reported. During a study aimed to identify potential insect vectors of these Bursaphelenchus species using the trap tree method in the western region of Turkey, one Bursaphelenchus species was isolated from a wood chip sample of a Pinus brutia trap log located in Bergama town of the city of İzmir. According to morphological and molecular studies, the species was determined as Bursaphelenchus leoni Baujard, 1980. Morphological characteristics of the species matched well with the original description made by Baujard in 1980. 18S and 28S rRNA genes of B. leoni were sequenced and a phylogenetic tree was constructed that showed B. leoni was clustered with B. leoni in the NCBI database. This is the first report of B. leoni from Turkey. To determine presence of other known Bursaphelenchus species in Turkey, new studies should be performed.

Interception Strategies for Managing Exotic Ambrosia Beetles (Coleoptera: Curculionidae) in Nurseries

Interception Strategies for Managing Exotic Ambrosia Beetles (Coleoptera: Curculionidae) in Nurseries

Managing Thousand Cankers Disease in High-value Plantings of Black Walnut (Fagales: Juglandaceae) in Washington State

Abstract The health and productivity of black walnut (Juglans nigra L.) is currently threatened by Thousand Cankers Disease (TCD), a pest complex comprised of an insect vector, the walnut twig beetle (WTB) (Pityophthorus juglandis Blackman) (Coleoptera: Curculionidae), and associated pathogenic fungi (Geosmithia morbida Kolařík, Freeland, Utley, and Tisserat) (Hypocreales: Bionectriaceae). There is an urgent need for tools to manage TCD and avoid catastrophic losses in high-value plantations of black walnut. In this case study, we evaluated the efficacy of IPM strategies in three TCD-infested black walnut plantations in Walla Walla, WA. At the beginning of our study, average weekly captures of WTB per trap varied across sites; low (~32), moderate (~111), and high (>1,300). Each site received a separate management tactic: 1) girdled trap trees alone; 2) the insecticide emamectin benzoate alone or in combination with the fungicide propiconazole to protect healthy crop trees with superior form; and 3) the combination of girdled trap trees and chemically-protected crop trees. Walnut twig beetle populations remained at consistently low levels at both plantations after girdled trap trees were deployed. In plantations where crop trees were treated, the crown condition of those that received emamectin benzoate alone matched or exceeded that of trees treated with the combination of emamectin benzoate and propiconazole and the untreated control trees. Our findings suggest that using both trap trees and emamectin benzoate in an integrated approach has the most potential to reduce WTB populations and protect valuable crop trees in black walnut stands threatened by TCD.

Climate Change Induced Tree Mortality in a Relict Scots Pine (Pinus sylvestris L.) Forest

Mortality appeared in a relict Scots pine (Pinus sylvestris L.) forest where the sandy pine forest association (Pinetum-Festuco vaginatae sylvestris) is unique in the Carpathian Basin. To identify the complex causes of tree mortality, we analysed the climatic and soil conditions completed with bryological and biotical (pests) surveys. Altogether the results show that unfavourable soil conditions (coarse sand) and increasing aridity have led to a decline in tree vitality. Bark beetles have a high population density in the stand, and they have colonised both the felled trap trees and the standing trees, where the beetles contributed to tree mortality. New spreading invasive moss species have appeared in the recently formed gaps, where crone projection is low. The disappearance of this relict forest stresses the urgent need for Hungarian forest management to prepare strategies for adaptive tree species selection.

Comparison of Two Treatment Regimes for Managing Western Balsam Bark Beetle

The efficacy of pheromone-baited, standing subalpine fir Abies lasiocarpa (Hook) Nutt. and felled green trap trees was tested in southern British Columbia as potential manage- ment techniques for containing western balsam bark beetle Dryocoetes confusus Swaine populations prior to logging. In the year treatments were deployed, standing trees in close proximity to baited trees had significantly higher levels of current attack than those near felled trap trees or in control blocks. The control blocks had the lowest level of current at- tack. Diameters of attacked trees were significantly greater than unattacked trees in all treatments. Naturally attacked, standing subalpine fir had high levels of occupation (number of nuptial galleries) along the full length of the bole. Baited trees had similar levels of occupancy up to six metres in height. Felled green trees had lower occupancy than the baited or naturally attacked trees. Although baited trees concentrated attack into a discrete area, they did not artificially trigger an outbreak or further population expansion in the year following treatment. Felled trap trees appeared less attractive to western balsam bark beetle than natural, susceptible, standing subalpine fir; they are more difficult to de- ploy and therefore not recommended as a means of containing western balsam bark beetle prior to logging.

Weather conditions and host characteristics drive infestations of sessile oak (Quercus petraea) trap trees by oak bark beetles (Scolytus intricatus)

The European oak bark beetle (Scolytus intricatus) has the potential to impact forest structures through its selection of certain trees. We investigated potential S. intricatus colonisation densities by setting up 150 trap trees and analysing them in 5-metre sections during a three-year period from 2014 to 2016 in a temperate forest in Slovakia, Central Europe. Understanding the population dynamics of S. intricatus and the drivers of its colonization density on trees is necessary if attempts to control or manage populations of S. intricatus in managed forests are to succeed.To explain the population dynamics of S. intricatus, ANOVA was used to assess the colonisation densities in the stem , and generalized linear mixed effect models (GLMMs) were used to analyse the main characteristics of the host trees and the meteorological variables. Structural equation modelling (SEM) was then used to explain the multitude of relationships among the predictor variables and bark beetle populations.Scolytus intricatus reached higher population levels under dry and warm conditions, when trees were prone to drought stress. The highest colonization densities at the trap trees occurred in May and June of 2014 and 2016; in 2015, the highest densities were reported in August and a second generation of S. intricatus was observed. This is unusual, as this species is usually univoltine, i.e. has one generation per year under Central European conditions.Population levels differed in different months during the 3-year study period, i.e. patterns of population dynamics and phenology are not repeating. The mixed-effects models demonstrated that the seasonal temperature influenced the occupation of trap trees by S. intricatus and that the lengths of the galleries were affected by the section surfaces.We conclude that environmental stress hastens the rate of drought stress in oak trees, resulting in faster population growth and higher survival of S. intricatus.

Felled and Lure Trap Trees with Uncut Branches Are Only Weakly Attractive to the Double-Spined Bark Beetle, Ips duplicatus

Bark beetles are the most important forest pests in the Northern Hemisphere. The range of Ips duplicatus, an invasive bark beetle in central Europe, has been steadily expanding, and it is now responsible for a high proportion of the spruce wood infested by bark beetles. Apart from searching for and eliminating infested trees, there is no effective control method. The aim of this study was to determine whether trap trees with a pheromone evaporator can be used to capture I. duplicatus. Felled trap trees with branches and with pheromone lures (ID Ecolure®) were infested by I. duplicatus, at a median density of 1 nuptial chambers per 0.1 m2 (median); similar trees without lures and lying at a distance of 1, 5, or 10 m from the lure trees were rarely infested by I. duplicatus. The entire surface of the lure trees could capture <400 beetles per tree. The results indicate that lure trap trees (felled and with branches attached) could only be used in a limited number of situations; one such situation would involve forests that suffered wind damage and contained very high numbers of I. duplicatus.

Modelos para estimativas de ataque de <i>Sirex noctilio</i> (Fabricius) em povoamentos de <i>Pinus taeda</i> L.

Uma das principais pragas dos plantios florestais de Pinus spp. é Sirex noctilio (Fabricius), conhecida popularmente como vespa-da-madeira. Este trabalho tem por objetivo desenvolver um modelo matemático para estimar o número de árvores atacadas por Sirex noctilio em povoamentos de Pinus taeda L. baseado nos métodos de monitoramento e nas características dendrométricas do reflorestamento. Selecionaram-se, para a coleta de dados, cinco áreas localizadas no município de Palmas - PR. Foram utilizadas como variáveis independentes do modelo a serem selecionadas pelo método Stepwise a amostragem sequencial, número de indivíduos da parcela, árvores-armadilha, diâmetro a altura do peito (DAP) médio, altura média, volume médio individual, volume da parcela, idade, espaçamento, sítio, área basal da parcela, área transversal média, diâmetro médio quadrático e o DAP estratificado em três classes de diâmetro. A maior influência sobre a estimativa de ataque (Y) foi exercida pelas variáveis número de árvores atacadas detectadas na amostragem sequencial (AS) (p-valor 0,001) e o número de indivíduos da parcela (n) (p-valor 0,05). O modelo mais adequado para a obtenção da variável resposta foi δ = β0 + β1AS+β2n + ε, o qual apresentou coeficiente de determinação ajustado (R²adj) de 0,965 e erro padrão de estimativa (Syx%) de 18,65% obtendo o melhor desempenho na análise gráfica dos resíduos. O modelo pode ser utilizado pelos gestores florestais como uma ferramenta na tomada de decisões quanto ao manejo do povoamento.

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

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.

Metabolic Profiling of Hybrids Generated from Pummelo and Citrus latipes in Relation to Their Attraction to Diaphorina citri, the Vector of Huanglongbing.

The citrus industry at present is severely affected by huanglongbing disease (HLB). HLB is caused by the supposed bacterial pathogen “Candidatus Liberibacter asiaticus” and is transmitted by the insect vector, the Asian citrus psyllid, Diaphorina citri Kuwayama. Developing new citrus hybrids to improve HLB management is much needed. In this study, we investigated the metabolomic profiles of three new hybrids produced from the cross of C2-5-12 Pummelo (Citrus maxima (L.) Osbeck) × pollen from Citrus latipes. The hybrids were selected based on leaf morphology and seedling vigor. The selected hybrids exhibited compact and upright tree architecture as seen in C. latipes. Hybrids were verified by simple sequence repeat markers, and were subjected to metabolomic analysis using gas chromatography-mass spectrometry. The volatile organic compounds (VOCs) and polar metabolites profiling also showed that the new hybrids were different from their parents. Interestingly, the levels of stored VOCs in hybrid II were higher than those observed in its parents and other hybrids. The level of most VOCs released by hybrid II was also higher than that released from its parents. Additionally, the preference assay showed that hybrid II was more attractive to D. citri than its parents and other hybrids. The leaf morphology, compact and upright architecture of hybrid II, and its attraction to D. citri suggest that it could be used as a windbreak and trap tree for D. citri (double duty), once its tolerance to HLB disease is confirmed. Our results showed that metabolomic analysis could be successfully used to understand the biochemical mechanisms controlling the interaction of D. citri with its host plants.