Search Results (84)

Sclerodermus sichuanensis, a parasitic wasp, plays a significant role in wood-boring forest pest control in China. Research has shown that the photoperiod significantly affects the development and reproduction of parasitic wasps. However, the effects of the photoperiod on S. sichuanensis have not yet been reported. This study investigates the impact of different photoperiods on the developmental duration and reproduction of S. sichuanensis. The wasps were reared under four photoperiod conditions: 0L:24D, 8L:16D, 16L:8D, and 24L:0D. The results show that increased light duration shortened the egg, larval, and pupal stages, with the total developmental period decreasing by up to 17 days. The number of offspring was highest in the 8L:16D and 16L:8D treatments, while constant light (24L:0D) led to a significant decrease in offspring numbers. The parasitism rate and pre-oviposition period were also affected by light exposure, with the longest pre-oviposition period observed in complete darkness. These findings indicate that the photoperiod plays a crucial role in regulating the development and reproductive efficiency of S. sichuanensis, suggesting that appropriate light conditions could enhance the efficiency of its use in pest control. Full article

Wildfires are increasing in extent and severity under anthropogenic climate change, with potential adverse impacts on native pollinators like wild bees. In 2019/2020, wildfires burned swathes of the Australian bushland. Whilst herbaceous angiosperms may flower in the post-fire environment, providing sustenance to native bees, pre-made holes created by wood-boring beetles that obligate cavity-nesting “renter” bees may take a longer time to recover. This may prevent native bees from colonising new areas or reduce the populations that have survived. To date, trap-nests, also known as bee hotels, have never been used as a tool to assist in providing nesting resources in post-fire environments. The project “Bee hotels to boost bees after bushfires” supported the recovery of native bee populations by installing artificial nesting substrates (bee hotels) in areas of high biodiversity value that were impacted by the 2019/2020 bushfires. This was achieved through monitoring of 1000 bee hotels (500 bamboo and 500 wooden) and visual surveys at five burnt sites and three control sites (nearby burnt sites without bee hotels) by a native bee ecologist from September–March 2021/2022. The bee hotel uptake was low initially, but by March, all hotels were occupied. Over 800 nests were created by bees in the bee hotels installed for this project and significantly more bees were observed in sites with bee hotels compared to control sites. Across sites, there was a significant negative association between honeybee density and nest occupancy, suggesting honeybees may be exerting competitive pressure on native bees in post-fire habitats. In conclusion, bee hotels, if designed correctly, can aid in boosting cavity-nesting bee populations following fires. Full article

The Asian longhorn beetle (ALB), Anoplophora glabripennis, and citrus longhorn beetle (CLB), Anoplophora chinensis, are two destructive invasive wood-boring pests, with high similarities in morphology, geographical distribution, host range, life cycle, adult behaviors and male-produced pheromone, implying a potential existence of interspecific interactions. Matings have been found to occur across females and males of the two species when manually paired in confined spaces. However, interspecific mating and its regulating factors are unclear between sympatric populations on hosts. Herein, by observing mountings and tracking the beetles that freely coexisted on host branches in cages, we found that the majority of mountings appeared within species; however, interspecific mountings occasionally occurred between male CLBs and female ALBs. The CLB was more active than the ALB at night. It seems that males actively searched for female ALBs, while the inverse was the case with CLBs. The main release periods of shared pheromone components overlapped between the two species, while compound ratios had significant differences. Our results unveil a trivial and asymmetrical interspecific mating between ALBs and CLBs, implying a risk of co-outbreaks of the two species in either native or invaded areas. Full article

Wildfire activity in the western U.S. has highlighted the importance of effective management to address this growing threat. The Lookout Mountain Thinning and Fuels Reduction Study (LMS) is an operational-scale, long-term study of the effects of forest restoration and fuel reduction treatments in ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and mixed-conifer forests in central Oregon, U.S. The broad objectives of the LMS are to examine the effectiveness and longevity of treatments on wildfire risk and to assess the collateral effects. Treatments include four levels of overstory thinning followed by mastication of the understory vegetation and prescribed burning. Stands were thinned to residual densities of 50, 75, or 100% of the upper management zone (UMZ), which accounts for site differences as reflected by stand density relationships for specific plant communities. A fourth treatment combines the 75 UMZ with small gaps (~0.1 ha) to facilitate regeneration (75 UMZ + Gaps). A fifth treatment comprises an untreated control (UC). We examined the causes and levels of tree mortality that occurred 2–9 years after treatments. A total of 391,292 trees was inventoried, of which 2.3% (9084) died. Higher levels of tree mortality (all causes) occurred on the UC (7.1 ± 1.9%, mean ± SEM) than on the 50 UMZ (0.7 ± 0.1%). Mortality was attributed to several bark beetle species (Coleoptera: Curculionidae) (4002 trees), unknown factors (2682 trees), wind (1958 trees), suppression (327 trees), snow breakage (61 trees), prescribed fire (19 trees), western gall rust (15 trees), cankers (8 trees), mechanical damage (5 trees), dwarf mistletoe (4 trees), and woodborers (3 trees). Among bark beetles, tree mortality was attributed to western pine beetle (Dendroctonus brevicomis LeConte) (1631 trees), fir engraver (Scolytus ventralis LeConte) (1580 trees), mountain pine beetle (Dendroctonus ponderosae Hopkins) (526 trees), engraver beetles (Ips spp.) (169 trees), hemlock engraver (Scolytus tsugae (Swaine)) (77 trees), and Pityogenes spp. (19 trees). Higher levels of bark beetle-caused tree mortality occurred on the UC (2.9 ± 0.7%) than on the 50 UMZ (0.3 ± 0.1%) which, in general, was the relationship observed for individual bark beetle species. Higher levels of tree mortality were attributed to wind on the 100 UMZ (1.0 ± 0.2%) and UC (1.2 ± 1.5%) than on the 50 UMZ (0.2 ± 0.02%) and 75 UMZ (0.4 ± 0.1%). Higher levels of tree mortality were attributed to suppression on the UC (0.5 ± 0.3%) than on the 50 UMZ (0.003 ± 0.002%) and 75 UMZ + Gaps (0.0 ± 0.0%). Significant positive correlations were observed between measures of stand density and levels of tree mortality for most causal agents. Tree size (diameter at 1.37 m) frequently had a significant effect on tree mortality, but relationships varied by causal agent. The forest restoration and fuels reduction treatments implemented on the LMS increased resistance to multiple disturbances. The implications of these and other results to the management of fire-adapted forests are discussed. Full article

The fungi residing in the gut and associated habitats play a crucial role in the growth and development of Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), a wood-boring pest. Yet, how they are acquired and maintained across generations, and their respective roles throughout the life cycle, remain unknown. To this end, we used high-throughput ITS sequencing analysis to characterize the fungal composition and diversity associated with A. glabripennis across three different life stages, between sexes, and between its habitats. Overall, the fungi composition was stage specific, with adult gut communities being more diverse than those of larvae and eggs. Male fungal communities differed significantly, while frass and female communities were more similar to each other. The top 10 most abundant genera were investigated, with Fusarium consistently observed in all samples and exhibiting the highest overall abundance. Function predictions revealed the presence of potentially beneficial fungi that may support A. glabripennis invasion across all groups. Additionally, we observed complex network structures in the fungal communities associated with eggs and males, and stronger positive correlations in those of eggs and newly hatched larvae. Source tracking analysis suggested that these fungi were vertically transmitted, following a transmission pathway of ‘female gut–frass–egg–larval gut’, occurring via frass deposited in oviposition sites. Our findings provide a nuanced understanding of the intricate interactions among plants, insects, and fungi, shedding light on the acquisition, maintenance, and roles of gut-associated fungi in A. glabripennis. Full article

Emerald ash borer (EAB, Agrilus planipennis Fairmaire) is an Asian woodborer that is a destructive pest of ash (Fraxinus spp.) trees throughout North America and in parts of Asia and Europe. It has killed hundreds of millions of ash trees worldwide in the past two decades and has shown some ability to infest novel hosts, most notably white fringetree (Chionanthus virginicus L.). Here, I review the evidence that this beetle can succeed on cultivated olive (Olea europaea L), a close relative of white fringetree. Studies and observations thus far indicate that, while young trees are largely resistant to EAB larval development, adults will oviposit on olive trees, can feed on their foliage and produce viable eggs, and that larger, older and possibly stressed trees have the potential to support larval development to the adult stage in the field. Emerald ash borer will soon interact with cultivated olive trees in the wild in parts of the U.S. and in Europe, and the realized risk to olives by this beetle will be revealed. Full article

Subcortical beetle communities interact with a wide range of semiochemicals released from different sources, including trees, fungi, and bark beetle pheromones. While the attraction of bark beetles, their insect predators, and competitors to bark beetle pheromones is commonly studied, the attraction of these beetle communities to other sources of semiochemicals remains poorly understood. We tested the attraction of bark and wood-boring beetles and their predators to host stress volatiles, fungal volatiles, and a mountain pine beetle lure in the field. Host stress volatiles were derived from lodgepole pine trees stressed by three fungal symbionts of mountain pine beetle and two common phytopathogens. Our results showed that bark beetles, particularly mountain pine beetles, show a preference for a combination of fungal volatiles, particularly 2-methyl-1-butanol and its lures. Without the addition of lures, 2-methyl-1-butanol was also identified as a key fungal volatile in the attraction of mountain pine beetle competitors from the Cerambycidae and Buprestidae families. Predators in the Elateridae and Staphylinidae families showed attraction to host stress volatiles and the healthy tree volatile profiles. These findings suggest that these semiochemicals warrant further field testing for potential use in monitoring and management of subcortical beetle populations. Full article

The early identification of forest wood-boring pests is essential for effective pest management. However, detecting infestation in the early stages is difficult, as larvae, such as the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), usually feed inside the trees. Acoustic sensors can detect the pulse signals generated by larval feeding or movement, but these sounds are often weak and easily masked by background noise. To address this, we propose a dual-branch time-frequency multi-dilated dense network (DBMDNet) for noise reduction. Our model decouples two denoising training objectives: a magnitude masking decoder for coarse denoising and a complex spectral decoder for further magnitude repair and phase correction. Additionally, to enhance global time-frequency modeling, we use three different multi-dilated dense blocks to effectively separate clean signals from noisy data. Given the difficult acquisition of clean larval activity signals, we describe a self-supervised training procedure that utilizes only noisy larval activity signals directly collected from the wild, without the need for paired clean signals. Experimental results demonstrate that our proposed approach achieves the optimal performance on various evaluation metrics while requiring fewer parameters (only 98.62 k) compared to competitive models, achieving an average signal-to-noise ratio (SNR) improvement of 17.45 dB and a log-likelihood ratio (LLR) of 0.14. Furthermore, using the larval activity signals enhanced by DBMDNet, most of the noise is suppressed, and the accuracy of the recognition model is also significantly improved. Full article

This paper presents a method for detecting holes and grooves made by wood-boring pests. As part of the production process automation, wood delivered from sawmills is checked for defects visible on its surface. One of the critical defects that disqualifies wood from further processing is the presence of feeding marks left by various types of pests on its surface. This paper proposes a method for detecting this type of damage based on analysis of three-dimensional images of the wood surface. Three-dimensional imaging methods and the image resolutions resulting from the adopted imaging system’s configurations are discussed. An analysis of the advantages and disadvantages of the methods investigated is presented, together with an assessment of their potential use in the implementation of the assigned control task, i.e., the detection of holes and grooves made by pests. Three-dimensional image parameters and interferences affecting the quality of the recorded image are described, along with the designed algorithm for identifying holes and grooves and the parametric description of the identified defect. The imaging effects for selected surfaces bearing signs of pest damage and the parameters describing the effectiveness of the present industrial solution are also presented. This paper demonstrates that it is possible to build a three-dimensional image to identify damage effectively within a minimum diameter of 1mm. It makes it possible to observe the damage carried out by most wood-boring pests. Full article

Cinnamomum camphora is a broad-spectrum insect-repelling tree species because of its high content of terpenoids. However, it is curious that Pagiophloeus tsushimanus, a recently recorded wood-boring pest, has widely infested C. camphora plantations across various administrative districts in Shanghai. The larvae, being concealed within the trunk of C. camphora trees, exhibit characteristics such as hidden activity, strong destructiveness, and being difficult to control. While the primary host plant for P. tsushimanus is C. camphora, preliminary observations have shown that the pest can also complete its life cycle on Cinnamomum chekiangensis and Phoebe chekiangensis. To explore the host selection preference of this beetle, the present study aimed to investigate the olfactory selection behavior of P. tsushimanus adults towards C. camphora, C. chekiangensis, and P. chekiangensis. Results from choice and no-choice tests indicated that both male and female adults exhibited a feeding preference for C. camphora twigs, with females showing a preference for laying eggs on camphor tree twigs as well. Volatile compounds unique in camphor trees were significantly higher in relative content than those on the other two plants that were detected. The Y-shaped olfactometer experiments and electroantennography measurements results showed that male and female adults of P. tsushimanus had a positive chemotaxis towards volatiles released by C. camphora and a negative chemotaxis towards volatiles released by C. chekiangensis or P. chekiangensis. Overall, the findings suggest that both male and female adults have a selective preference for volatiles released by the camphor tree, and this provides a theoretical basis for monitoring and controlling the occurrence of this weevil pest. Full article

The weevil Eucryptorrhynchus brandti (Harold, 1880), a wood-boring pest of Ailanthus altissima (Mill.) Swingle, has caused significant ecological damage and economic loss in China. Physical control was effective against the related species Eucryptorrhynchus scrobiculatus (Motschulsky). One type of trunk trap net controlled the adult weevil population through blocking and trapping. However, the effectiveness of this device was compromised by their tendency to escape when encountering such trapping nets. Therefore, it is crucial to enhance and optimize both the material composition and structural design of trap nets to enhance weevil capture rates by mitigating escape behavior. In this study, we compared the capture efficacy of an anti-escape trap net (AETN) with novel materials (Velcro) and a double-layer trap net (DLTN). The results indicate that the mean recapture rate of AETNs (50%) was significantly higher than that of DLTNs (3%) in laboratory tests. The total number of E. brandti captured using AETNs was 11 times higher than that of DLTNs in field marker recapture tests and 4 times higher in capture tests on field populations. The new AETN structures could effectively prevent the escape behavior of E. brandti and capture weevils. The use of Velcro made the AETN easier to manufacture, more convenient to use, and less costly. Overall, the AETN is an economical and environmentally friendly physical control device. Full article

Wood-boring pests are one of the most destructive forest pests. However, the early detection of wood-boring pests is extremely difficult because their larvae live in tree trunks and have high invisibility. Borehole listening technology is a new and effective method to detect the larvae of insect pests. It identifies infested trees by analyzing wood-boring vibration signals. However, the collected wood-boring vibration signals are often disturbed by various noises existing in the field environment, which reduces the accuracy of pest detection. Therefore, it is necessary to filter out the noise and enhance the wood-boring vibration signals to facilitate the subsequent identification of pests. The current signal enhancement models are all designed based on deep learning models, which have complex scales, a large number of parameters, high demands for storage resources, large computational complexity, and high time costs. They often run on resource-rich computers or servers, and they are difficult to deploy to resource-limited field environments to realize the real-time monitoring of pests; as well, they have low practicability. Therefore, this study designs and implements two model lightweight optimization algorithms, one is a pre-training pruning algorithm based on masks, and the other is a knowledge distillation algorithm based on the separate transfer of vibration signal knowledge and noise signal knowledge. We apply the two lightweight optimization algorithms to the signal enhancement model T-CENV with good performance outcomes and conduct a series of ablation experiments. The experimental results show that the proposed methods effectively reduce the volume of the T-CENV model, which make them useful for the deployment of signal enhancement models on embedded devices, improve the usability of the model, and help to realize the real-time monitoring of wood-boring pest larvae. Full article

Wood-boring pests are difficult to monitor due to their concealed lifestyle. To effectively control these wood-boring pests, it is first necessary to efficiently and accurately detect their presence and identify their species, which requires addressing the limitations of traditional monitoring methods. This paper proposes a deep learning-based model called BorerNet, which incorporates an attention mechanism to accurately identify wood-boring pests using the limited vibration signals generated by feeding larvae. Acoustic sensors can be used to collect boring vibration signals from the larvae of the emerald ash borer (EAB), Agrilus planipennis Fairmaire, 1888 (Coleoptera: Buprestidae), and the small carpenter moth (SCM), Streltzoviella insularis Staudinger, 1892 (Lepidoptera: Cossidae). After preprocessing steps such as clipping and segmentation, Mel-frequency cepstral coefficients (MFCCs) are extracted as inputs for the BorerNet model, with noisy signals from real environments used as the test set. BorerNet learns from the input features and outputs identification results. The research findings demonstrate that BorerNet achieves an identification accuracy of 96.67% and exhibits strong robustness and generalization capabilities. Compared to traditional methods, this approach offers significant advantages in terms of automation, recognition efficiency, and cost-effectiveness. It enables the early detection and treatment of pest infestations and allows for the development of targeted control strategies for different pests. This introduces innovative technology into the field of tree health monitoring, enhancing the ability to detect wood-boring pests early and making a substantial contribution to forestry-related research and practical applications. Full article

The introduction of wood-boring insects to non-native areas can pose a significant threat to global forest ecosystems. Aromia bungii and Massicus raddei, native to Asia including Korea but potentially important in urban forestry worldwide, are severe trunk borers that have recently infested host trees in urban landscapes of Korea. The signs of external injury can help identify cerambycid-infested trees. However, assessing the internal condition of trees without causing damage is challenging, which hinders the management of infested trees that are still alive. This study evaluated the potential use of sonic tomography to assess injury characteristics in the woody parts of trees, such as Prunus × yedoensis and Quercus palustris infested by A. bungii and M. raddei, respectively. Among the 45 investigated trees, the number of holes on external parts was recorded by visual examination. Sonic tomography images revealed decayed areas, allowing for a comparison of internal damage between infested and non-infested trees. The internal status of trees infested by the two cerambycid beetles differed from that of healthy trees. While some healthy trees exhibited minimal internal damage, those that were not infested by beetles showed decayed areas, potentially caused by non-biological factors such as frozen cracks. In conclusion, sonic tomography equipment can potentially be used for non-invasive assessment of internal injuries caused by wood-boring insects in urban trees. Full article

Sirex noctilio, a European woodwasp, occasionally shares resources with the native S. nitobei and other colonizers in northeast China. The impact of its coexistence on individual species remains unclear. Random sampling was conducted to assess the patterns and extent of insect co-colonization across various spatial scales. Additionally, we analyzed wood sections to determine the density, adult size, and distribution of the two Sirex species. Spatial scales revealed negative associations (Asemum striatum and Phaenops sp.) and neutral ones (Ips acuminatus) between woodwasps and other co-colonizers. Clustering of woodwasps and Phaenops sp. occurred at a small scale (0–7.3 m). Regression analysis showed a positive correlation between the chance of woodwasp attacks and past attacks on the same host, with little impact from other colonization factors. The distribution and body size of S. noctilio within the tree appeared unaffected by S. nitobei’s presence. In the presence of S. noctilio, S. nitobei tended to lay eggs in damaged sections. At the stand level, the overall impact of S. noctilio on S. nitobei population density is likely positive because S. nitobei prefer weaker trees, a preference potentially influenced by initial attacks from S. noctilio on healthier hosts. Full article