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Southern pine beetle, Dendroctonus frontalis, has expanded its range further into the northeastern United States. This expansion threatens rare and ecologically valuable interior and coastal pitch pine barrens.Pitch pine barrens restoration and southern pine beetle infestation suppression often involve leaving downed dead wood that saproxylic insects can exploit.Semiochemical‐baited traps were used to investigate the response of bark beetles and woodborers to restoration treatments at Rocky Point State Forest and the Albany Pine Bush Preserve, examples of coastal and interior pitch pine forests, respectively.A total of 29,598 saproxylic insects from 116 species of bark beetles and woodborers were captured at Rocky Point State Forest, while 23,117 individuals from 67 species were captured at Albany Pine Bush Preserve.Ips spp. were abundant at both sites with 28%–47% and 42%–74% of total collections at Rocky Point State Forest and Albany Pine Bush Preserve, respectively.Ips grandicollis did not respond to treatments at either site. However, Ips pini was found in higher numbers in thinned blocks in Rocky Point State Forest. [ABSTRACT FROM AUTHOR]

Laurel wilt, caused by the fungus Raffaelea lauricola, has caused widespread mortality to Persea borbonia across the southeastern United States. The invasive ambrosia beetle vector of the pathogen, Xyleborus glabratus, attacks and infects trees, leaving only P. borbonia seedlings, saplings, and stump sprouts in heavily affected areas. To facilitate mitigation of this ecological damage, we initiated a screening program for laurel wilt disease resistance. We established circular field plots (0.08 hectare) in six significantly impacted sites, measured laurel wilt epidemiological characteristics, and selected 61 survivor P. borbonia ortets (≥7.5 cm diameter at breast height [DBH]) for vegetative propagation, screening, and monitoring. Disease incidence in the plots ranged from 50% to 87% of P. borbonia stems thicker than 2.5 cm DBH and ortet survival per site ranged from 0% to 70% a decade after initial selection. Clonal ramets from 38 survivor ortets were out planted and screened for resistance to R. lauricola in a series of field inoculation trials. Results indicate variable levels of host susceptibility and suggest rare individuals exist with tolerance to R. lauricola. Scanning electron microscopy imaging of xylem samples from three infected P. borbonia clones suggests that reduced tylose production and granular deposition in xylem lumina are associated with increased resistance to R. lauricola. Results from this study will aid in the selection of disease‐resistant P. borbonia germplasm for restoration plantings in affected sites and provide new insights into the host–pathogen interaction of this deadly vascular disease. [ABSTRACT FROM AUTHOR]

Insect populations are changing rapidly, and monitoring these changes is essential for understanding the causes and consequences of such shifts. However, large‐scale insect identification projects are time‐consuming and expensive when done solely by human identifiers. Machine learning offers a possible solution to help collect insect data quickly and efficiently.Here, we outline a methodology for training classification models to identify pitfall trap‐collected insects from image data and then apply the method to identify ground beetles (Carabidae). All beetles were collected by the National Ecological Observatory Network (NEON), a continental scale ecological monitoring project with sites across the United States. We describe the procedures for image collection, image data extraction, data preparation, and model training, and compare the performance of five machine learning algorithms and two classification methods (hierarchical vs. single‐level) identifying ground beetles from the species to subfamily level. All models were trained using pre‐extracted feature vectors, not raw image data. Our methodology allows for data to be extracted from multiple individuals within the same image thus enhancing time efficiency, utilizes relatively simple models that allow for direct assessment of model performance, and can be performed on relatively small datasets.The best performing algorithm, linear discriminant analysis (LDA), reached an accuracy of 84.6% at the species level when naively identifying species, which was further increased to >95% when classifications were limited by known local species pools. Model performance was negatively correlated with taxonomic specificity, with the LDA model reaching an accuracy of ~99% at the subfamily level. When classifying carabid species not included in the training dataset at higher taxonomic levels species, the models performed significantly better than if classifications were made randomly. We also observed greater performance when classifications were made using the hierarchical classification method compared to the single‐level classification method at higher taxonomic levels.The general methodology outlined here serves as a proof‐of‐concept for classifying pitfall trap‐collected organisms using machine learning algorithms, and the image data extraction methodology may be used for nonmachine learning uses. We propose that integration of machine learning in large‐scale identification pipelines will increase efficiency and lead to a greater flow of insect macroecological data, with the potential to be expanded for use with other noninsect taxa. [ABSTRACT FROM AUTHOR]

Recent mountain pine beetle (Dendroctonus ponderosae; pine beetle) outbreaks in the western United States have affected nearly 18 million ha of pine (Pinus spp.) forest and are unprecedented in spatial extent, severity, and duration, yet little is known about wildlife responses to large‐scale insect outbreaks. Elk (Cervus canadensis) are important wildlife whose dominant management paradigm on public lands has focused on providing security habitat to increase survival during hunting seasons and to maintain elk presence on public lands to promote hunter opportunity. To assess the effect of pine beetles and associated changes in forest structure on elk security, we used a time series to characterize canopy cover pre‐ and post‐pine beetle outbreak, characterized relative canopy cover among the dominant forest types in the study area post‐pine beetle outbreak, and used global positioning system location data from male and female elk to define habitat relationships and security during the archery and rifle hunting seasons. Our study area was within the Elkhorn Mountains of southwest Montana, USA, 2015–2017, which experienced 80% mortality of lodgepole pine (Pinus contorta) forests during a pine beetle outbreak that peaked in 2008. We observed an 8.5% reduction in canopy cover within pine beetle‐infested lodgepole pine forests, yet canopy cover remained relatively high among other forest types post‐outbreak. The top‐ranked habitat security models contained positive relationships with canopy cover, distance to motorized routes, terrain ruggedness, and slope with few notable differences among sexes and seasons. Across sexes and seasons, 75% and 50% of elk use was within areas with average canopy cover values ≥31 ± 6.65 (SD)% and ≥53 ± 5.7% that were an average of ≥2,072 ± 187.93 m and ≥3,496 ± 157.32 m from a motorized route, respectively. Therefore, we recommend fall elk security be defined as areas that meet these criteria for minimum canopy cover and distance from motorized routes in the Elkhorn Mountains and in other landscapes with similar forest characteristics and hunting pressures. Although we observed expected reductions in canopy cover within pine beetle‐infested forests, defoliation alone did not appear to negatively affect elk security or reduce canopy cover below our management recommendations. Nonetheless, because of the prevalence of standing dead trees in our study area, we recommend future work that investigates the relationships with pine beetle‐infested areas post‐blowdown because changes in ground structure and costs of locomotion may affect elk habitat and security. © 2019 The Authors. Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society. We used a canopy cover time series and global positioning system location data to characterize the loss of security cover resulting from mountain pine beetle infestation, and behavioral responses by male and female elk in the Elkhorn Mountains of southwest Montana, USA. We observed an 8.5% reduction in canopy cover within lodgepole pine forests infested by mountain pine beetles, yet canopy cover remained relatively high among other forest types post‐outbreak resulting in continued use by elk on lands open to public hunting during the hunting seasons. [ABSTRACT FROM AUTHOR]

A prevailing paradigm in forest ecology is that wood‐boring beetles facilitate wood decay and carbon cycling, but empirical tests have yielded mixed results. We experimentally determined the effects of wood borers on fungal community assembly and wood decay within pine trunks in the southeastern United States. Pine trunks were made either beetle‐accessible or inaccessible. Fungal communities were compared using culturing and high‐throughput amplicon sequencing (HTAS) of DNA and RNA. Prior to beetle infestation, living pines had diverse fungal endophyte communities. Endophytes were displaced by beetle‐associated fungi in beetle‐accessible trees, whereas some endophytes persisted as saprotrophs in beetle‐excluded trees. Beetles increased fungal diversity several fold. Over forty taxa of Ascomycota were significantly associated with beetles, but beetles were not consistently associated with any known wood‐decaying fungi. Instead, increasing ambrosia beetle infestations caused reduced decay, consistent with previous in vitro experiments that showed beetle‐associated fungi reduce decay rates by competing with decay fungi. No effect of bark‐inhabiting beetles on decay was detected. Platypodines carried significantly more fungal taxa than scolytines. Molecular results were validated by synthetic and biological mock communities and were consistent across methodologies. RNA sequencing confirmed that beetle‐associated fungi were biologically active in the wood. Metabarcode sequencing of the LSU/28S marker recovered important fungal symbionts that were missed by ITS2, though community‐level effects were similar between markers. In contrast to the current paradigm, our results indicate ambrosia beetles introduce diverse fungal communities that do not extensively decay wood, but instead reduce decay rates by competing with wood decay fungi. [ABSTRACT FROM AUTHOR]

Insects that depend on microbial mutualists evolved a variety of organs to transport the microsymbionts while dispersing. The ontogeny and variability of such organs is rarely studied, and the microsymbiont's effects on the animal tissue development remain unknown in most cases. Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae or Platypodinae) and their mutualistic fungi are an ideal system to study the animal–fungus interactions. While the interspecific diversity of their fungus transport organ—mycangia—is well‐known, their developmental plasticity has been poorly described. To determine the ontogeny of the mycangium and the influence of the symbiotic fungus on the tissue development, we dissected by hand or scanned with micro‐CT the mycangia in various developmental stages in five Xylosandrus ambrosia beetle species that possess a large, mesonotal mycangium: Xylosandrus amputatus, Xylosandrus compactus, Xylosandrus crassiusculus, Xylosandrus discolor, and Xylosandrus germanus. We processed 181 beetle samples from the United States and China. All five species displayed three stages of the mycangium development: (1) young teneral adults had an empty, deflated and cryptic mycangium without fungal mass; (2) in fully mature adults during dispersal, the pro‐mesonotal membrane was inflated, and most individuals developed a mycangium mostly filled with the symbiont, though size and symmetry varied; and (3) after successful establishment of their new galleries, most females discharged the bulk of the fungal inoculum and deflated the mycangium. Experimental aposymbiotic individuals demonstrated that the pronotal membrane invaginated independently of the presence of the fungus, but the fungus was required for inflation. Mycangia are more dynamic than previously thought, and their morphological changes correspond to the phases of the symbiosis. Importantly, studies of the fungal symbionts or plant pathogen transmission in ambrosia beetles need to consider which developmental stage to sample. We provide illustrations of the different stages, including microphotography of dissections and micro‐CT scans. [ABSTRACT FROM AUTHOR]

Biotic disturbance agents such as insects can be highly responsive to climatic change and have widespread ecological and economic impacts on forests. Quantifying the responses of introduced and native insects to climate, including how dynamics of one agent may mediate those of another, is important for forecasting disturbance and associated impacts on forest structure and function. We investigated drivers of outbreaks by larch casebearer Coleophora laricella, an invasive defoliator, and eastern larch beetle Dendroctonus simplex, a native, tree‐killing bark beetle, on tamarack Larix laricina from 2000 to in Minnesota, USA. We evaluated the utility of temporal, spatial and climatic variables in predicting the presence/absence of outbreaks of each insect in cells of rasterized aerial survey data. The role of defoliation by larch casebearer in outbreaks of eastern larch beetle was also investigated. For both species, the most important predictors of outbreak occurrence were proximity of conspecific outbreaks in space and time. For larch casebearer, outbreak occurrence was positively associated with spring precipitation and warmer growing seasons. Outbreak occurrence of eastern larch beetle was positively associated with warmer and dryer years and was more likely in cells with prior defoliation by larch casebearer. Our results demonstrate that climate can drive large scale outbreaks of introduced and non‐native disturbance agents on a single host species, and that interactions at the tree level between such agents may scale up to manifest across large temporal and spatial scales. [ABSTRACT FROM AUTHOR]

Wireworms, the larvae of click beetles (Elateridae), are difficult to manage due to their habitats and behaviour. Wireworms pose a major threat to the wheat crop in the north‐western USA. Seed treatment with neonicotinoids, biological control management and some cultural controls are recommended to manage these pests. Trap cropping is an emerging way to manage wireworms. In strawberry and potato crops, trap cropping has been found effective at attracting wireworms away from the principal crop. An earlier study in the Golden Triangle area of Montana found that pea and lentil could be effective trap crops for managing wireworms in spring wheat. In the present study, experiments were conducted at two locations. The effectiveness of peas and lentils as trap crops with wheat at different seeding densities was assessed [pea at 0, 4, 8, 16 seeds/sq.ft. or 0, 43, 86, 172 seeds/sq.m.; lentil at 0, 6, 12, 18 OR 0, 65, 130, 194 seeds/sq.m.; both with wheat at 0, 11, 22, or 28 seeds/sq.ft. or 0, 120, 230, 300 seeds/sq.m.] in a randomized design where all three crops were intercropped. Both trap crops were found to be effective in protecting wheat at standard seeding rates of 8 seeds/sq.ft. for pea and 12 seeds/sq.ft. for lentils. At these seeding rates, higher numbers of wireworms were found to be attracted to the trap crop, resulting in higher yield (7%–10%) of the associated spring wheat plant stands at 22 seeds/sq.ft. To develop an effective trap crop strategy, the pea–wheat and lentil–wheat spatial patterns that are possible need to be assessed in further field trials. Proper design and evaluation of the cost–benefit ratio of pea and lentil as trap crops are likely to produce good results for wheat crops in Montana. [ABSTRACT FROM AUTHOR]

Abstract: Biotic disturbances (BDs, for example, insects, pathogens, and wildlife herbivory) substantially affect boreal and temperate forest ecosystems globally. However, accurate impact assessments comprising larger spatial scales are lacking to date although these are critically needed given the expected disturbance intensification under a warming climate. Hence, our quantitative knowledge on current and future BD impacts, for example, on forest carbon (C) cycling, is strongly limited. We extended a dynamic global vegetation model to simulate ecosystem response to prescribed tree mortality and defoliation due to multiple biotic agents across United States forests during the period 1997–2015, and quantified the BD‐induced vegetation C loss, that is, C fluxes from live vegetation to dead organic matter pools. Annual disturbance fractions separated by BD type (tree mortality and defoliation) and agent (bark beetles, defoliator insects, other insects, pathogens, and other biotic agents) were calculated at 0.5° resolution from aerial‐surveyed data and applied within the model. Simulated BD‐induced C fluxes totaled 251.6 Mt C (annual mean: 13.2 Mt C year−1, SD ±7.3 Mt C year−1 between years) across the study domain, to which tree mortality contributed 95% and defoliation 5%. Among BD agents, bark beetles caused most C fluxes (61%), and total insect‐induced C fluxes were about five times larger compared to non‐insect agents, for example, pathogens and wildlife. Our findings further demonstrate that BD‐induced C cycle impacts (i) displayed high spatio‐temporal variability, (ii) were dominated by different agents across BD types and regions, and (iii) were comparable in magnitude to fire‐induced impacts. This study provides the first ecosystem model‐based assessment of BD‐induced impacts on forest C cycling at the continental scale and going beyond single agent‐host systems, thus allowing for comparisons across regions, BD types, and agents. Ultimately, a perspective on the potential and limitations of a more process‐based incorporation of multiple BDs in ecosystem models is offered. [ABSTRACT FROM AUTHOR]

Aim A subcontinental-scale outbreak of mountain pine beetle ( MPB; Dendroctonus ponderosae) has affected millions of hectares of forest in the western USA and Canada over the past 15 years. Little research has examined the long-term and broad-scale history of MPB outbreaks, which is necessary to provide a baseline for comparing current and future outbreak extents. We examine the long-term history of MPB outbreaks in western Colorado, and analyse the synchrony of previous outbreaks across western North America. Location Western Colorado for tree-ring analysis; western North America for comparative analysis. Methods We used dendroecological methods to reconstruct the history of MPB outbreaks since the 1700s in lodgepole pine ( Pinus contorta) forests in Colorado. We then combined these new records with previously published data on MPB outbreaks to examine the historical synchrony of outbreaks across western North America. Results The tree-ring record indicated that multiple cross-site MPB outbreaks occurred in Colorado lodgepole pine forests, initiating c. 1760s, 1780s, 1820s-1830s, 1860s, 1910s, 1960s and 1980s. Comparative analysis indicated that these outbreak dates coincide with documented and reconstructed MPB outbreaks in British Columbia, Colorado, Idaho, Montana, Wyoming and Utah. Main conclusions Several subcontinental-scale MPB outbreaks have occurred in lodgepole pine forests over the past three centuries. Although the current study does not address the intensity of past outbreaks, it does indicate that previous outbreaks appear to have been highly synchronous across western North America. The subcontinental, rather than purely local, nature of these outbreaks is important for putting recent and future outbreaks of MPB into a broader ecological context. This study presents the longest tree-ring reconstruction of MPB outbreaks in the southern Rocky Mountains available to date, as well as the first subcontinental long-term comparative analysis of MPB outbreaks in western North America. [ABSTRACT FROM AUTHOR]

91I.91II.92III.92IV.92V.94VI.9696References96 Summary: Recently, widespread piñon pine die‐off occurred in the southwestern United States. Here we synthesize observational studies of this event and compare findings to expected relationships with biotic and abiotic factors. Agreement exists on the occurrence of drought, presence of bark beetles and increased mortality of larger trees. However, studies disagree about the influences of stem density, elevation and other factors, perhaps related to study design, location and impact of extreme drought. Detailed information about bark beetles is seldom reported and their role is poorly understood. Our analysis reveals substantial limits to our knowledge regarding the processes that produce mortality patterns across space and time, indicating a poor ability to forecast mortality in response to expected increases in future droughts. [ABSTRACT FROM AUTHOR]

Pine decline poses a serious threat to forest sustainability in the south-eastern United States. Complex interactions between biotic and abiotic factors are involved in the decline and include root-feeding bark beetles and their associated fungal genera, Leptographium and Grosmannia. A study was conducted to determine the relative tolerance of loblolly pine ( Pinus taeda L.) families when challenged with either Leptographium or Grosmannia species. In the first study, bare root seedlings from 23 loblolly pine families were screened with L. procerum, L. terebrantis, G. huntii and G. alacris using an artificial inoculation method. In a second study, containerized seedlings from 27 loblolly pine families were screened with G. huntii and L. terebrantis. Measured seedling responses to the inoculations included lesion length, lesion width and occlusion of vascular tissues, measured 8 weeks after inoculations. The most common host response was dark brown lesions and resinous occluded stem tissue. Seedling families had a wide range of host responses to the different Leptographium and Grosmannia species and showed that it could be possible to select the families that may be tolerant to Leptographium and Grosmannia fungal species based on these results. [ABSTRACT FROM AUTHOR]

Redbay ambrosia beetle Xyleborus glabratus is an invasive wood boring beetle that has become established in the southeastern U. S.A. and transmits a fungus Raffaelea lauricola that causes lethal laurel wilt. Among susceptible Lauraceae hosts are redbay Persea borbonia and avocado Persea americana., There is a crucial need for detection of this pest as it moves into new areas. Consequently, our goal was to create a better lure for the monitoring and control of redbay ambrosia beetle., We analyzed volatile emissions of R. lauricola, created a synthetic odour blend based on this analysis and tested this odour blend as a potential attractant in a redbay forest infested with X. glabratus. The synthetic Raffaelea odour blend was not attractive to the beetles by itself. However, it synergistically increased attraction to host-mimic volatiles., We tested four commercial release devices for dispensing Raffaelea odour at various release rates. Two prototypes with the highest release rate, when paired with commercial manuka oil lures, captured more beetles than manuka oil lures alone. These results indicate that a synthetic blend of volatiles based on the odour of the symbiotic fungus of X. glabratus may be useful for the development of more sensitive monitoring lures for this invasive pathogen vector. [ABSTRACT FROM AUTHOR]

In Europe and North America, there is growing concern that biodiversity declines associated with agricultural intensification will adversely impact the functioning and sustainability of agricultural ecosystems. Enhancing habitat heterogeneity in agricultural landscapes promotes biodiversity and, whilst erecting fences adjacent to watercourses is widely advocated as a means of mitigating diffuse pollution, associated biodiversity benefits have been largely overlooked., A range of riparian margins and their adjacent grassland fields were investigated to determine the effects of riparian management on the diversity and functional structure of carabid assemblages. Carabid assemblages of fields and open margins (i.e. unfenced watercourses) were more diverse and species rich than those of fenced margins., The functional structure of carabid assemblages in fenced margins differed from grassland fields and open margins. This disparity was greater in wide margins (i.e. fences erected over 5·4 m from watercourses) than narrow margins (i.e. fences erected within 2·6 m of watercourses). Wide margins had the highest relative proportions of carabids which had pushing body forms, were flightless, very small in size and Collembola specialists. During early summer, wide margins also had the highest proportion of carabids that overwinter as adults., The taxonomic and functional structure of carabid assemblages was more sensitive for detecting impacts of agricultural management than measurements of diversity. It is likely that this also applies to other taxa, thus emphasising the need to consider a wide range of assemblage attributes when investigating agricultural impacts on biodiversity., Synthesis and applications. Fenced riparian margins, particularly those over 5·4 m wide, harbour carabids with poor dispersal ability which are vulnerable to habitat fragmentation. While lack of management benefits sedentary species, a wider range of taxa (e.g. pollinators, foraging birds and flowering plants) are enhanced by management to obtain a more open vegetation structure (e.g. restricted grazing or mowing). It is important that management practices are implemented at a sufficiently fine spatial scale to allow recolonisation of species with restricted dispersal from adjacent undisturbed habitats. Wide riparian margins have the potential to enhance taxonomic and functional diversity at the landscape scale. Management actions must, however, be carefully balanced to ensure that they promote a wide range of taxa without unduly interfering with the margin's ability to mitigate diffuse pollution. [ABSTRACT FROM AUTHOR]

1. Species incidence is influenced by environmental and intrinsic factors operating at multiple scales. The incidence of a dispersal-limited beetle, Odontotaenius disjunctus (Coleoptera: Passalidae), was surveyed within hierarchically nested organisational levels of its environment (log sections < logs < 10-m radius subplots < 0.66-ha plots) in Louisiana, U.S.A. The finest level was the size of a single territory. Passalid beetles are an ecologically prominent group, but little is known of the factors affecting their incidence. 2. Three scale-sensitive aspects of O. disjunctus incidence were evaluated: (i) the extent (52-3600 ha) within which forest cover was most associated with incidence; (ii) the hierarchical level at which environmental variables best predicted incidence; and (iii) the hierarchical level at which incidence exhibited the greatest spatial autocorrelation as a result of intrinsic factors (e.g. dispersal limitation). 3. Forest cover best predicted incidence at 225 ha, but accounted for only 1.2% of variation in incidence. Incidence was most sensitive to environmental factors measured at the finest scale (i.e. territories). Incidence was positively associated with moderately decayed wood and increased surface area of logs (9.9% and 3.1% of variance, respectively). When environmental factors were accounted for, spatial autocorrelation in incidence was greatest within subplots and logs, consistent with the hypothesis that intrinsic autocorrelation is associated with O. disjunctus average dispersal distance (<5 m). 4. This study indicates the influences of factors acting at multiple scales, but suggests that environmental conditions at the scale of territories may be most important for species incidence. [ABSTRACT FROM AUTHOR]

In Canada and the United States pressure to recoup financial costs of wildfire by harvesting burned timber is increasing, despite insufficient understanding of the ecological consequences of postfire salvage logging. We compared the species richness and composition of deadwood-associated beetle assemblages among undisturbed, recently burned, logged, and salvage-logged, boreal, mixed-wood stands. Species richness was lowest in salvage-logged stands, largely due to a negative effect of harvesting on the occurrence of wood- and bark-boring species. In comparison with undisturbed stands, the combination of wildfire and logging in salvage-logged stands had a greater effect on species composition than either disturbance alone. Strong differences in species composition among stand treatments were linked to differences in quantity and quality (e.g., decay stage) of coarse woody debris. We found that the effects of wildfire and logging on deadwood-associated beetles were synergistic, such that the effects of postfire salvage logging could not be predicted reliably on the basis of data on either disturbance alone. Thus, increases in salvage logging of burned forests may have serious negative consequences for deadwood-associated beetles and their ecological functions in early postfire successional forests. [ABSTRACT FROM AUTHOR]

Bark beetle epidemics result in tree mortality across millions of hectares in North America. However, few studies have quantified impacts on carbon (C) cycling. In this study, we quantified the immediate response and subsequent trajectories of stand-level aboveground tree C stocks and fluxes using field measurements and modeling for a location in central Idaho, USA that experienced an outbreak of mountain pine beetle ( Dendroctonus ponderosae Hopkins). We measured tree characteristics in lodgepole pine ( Pinus contorta) plots spanning a range of structure and mortality conditions. We then initialized the forest vegetation simulator, an individual tree-based model, with these measurements and simulated the response of aboveground production of C fluxes as well as trajectories of C stocks and fluxes in the coming decades. Mountain pine beetles killed up to 52% of the trees within plots, with more larger trees killed. C stocks in lodgepole pine were reduced by 31-83% following the outbreak, and plot-level C fluxes decreased 28-73%. Modeled C stocks increased nearly continuously following the infestation, recovering to preoutbreak levels in 25 years or less. Simulated aboveground tree C fluxes increased following the immediate postoutbreak decrease, then subsequently declined. Substantial variability of C stocks and fluxes among plots resulted from the number and size of killed and surviving trees. Our study illustrates that bark beetle epidemics alter forest C cycling unlike stand-replacement wildfires or clear-cut harvests, due in part to incomplete mortality coupled with the preference by beetles for larger trees. The dependency of postoutbreak C stocks and fluxes on stand structure suggests that C budget models and studies in areas experiencing mountain pine beetle disturbances need to include size distribution of trees for the most accurate results. [ABSTRACT FROM AUTHOR]

Modification of dispersal behaviour is a common response of insects to food and water deprivation. The literature suggests that different insects respond with different strategies: changing walking parameters, switching dispersal mode (walking to flight or vice versa), or changing the host searching path. The goal of this study was to add to the limited literature on the subject by investigating, whether the walking parameters of adult male Colorado potato beetles, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), change in response to food and water deprivation. Observations on the distance walked, the travel speed, and the frequency of walking bouts were carried out in laboratory arenas using motion monitoring equipment. Summer and overwintered beetles were exposed to short starvation periods (2, 4, 8, 24 h) and two ranges of long starvation periods (1, 2, 4, 8 days and 1, 2, 4, 8, 16, and 32 days). Only the longest food deprivation periods of 16 and 32 days significantly reduced the walking distance, speed, and frequency of walking bouts of summer beetles. No changes were observed with overwintered beetles. The tolerance of the beetles without access to water to the different periods of food deprivation was similar to that for beetles with water except after a starvation period of 32 days, when the travel speed of summer beetles was significantly reduced by 33%. The absence of increased walking parameters found in this study and earlier observations of increased flight frequency suggest that the strategy of summer beetles will be to change the dispersal mode from walking to flight and/or to change the walking host searching path. The same results of this study and earlier observations of a decrease in the mean frequency of daily flights suggest that the strategy of overwintered L. decemlineata, exposed to food deprivation, will be to change the host search walking path rather than the walking parameters themselves. [ABSTRACT FROM AUTHOR]

1 Abiotic conditions within logs can affect pine engraver Ips pini (Say) reproductive success, and slash management techniques have been developed that exploit these relationships to reduce brood production. In the present study, we investigated the affect of sunlight exposure on phloem temperature and moisture in logs of two diameters and the subsequent effects on pine engraver reproduction. 2 Logs, 30 cm in length, with diameters of 10 and 15 cm, were cut, left in the field for natural colonization by I pini, and then placed in an open meadow and under shade cloth, providing 27% and 66% shade, until offspring beetles had left the logs. Phloem temperature and moisture were recorded over the duration of the experiment and, at the end of the field experiment, logs were dissected and galleries were measured to gauge beetle reproductive success. 3 As sunlight exposure increased, phloem temperatures increased and potentially lethal temperatures were often reached in the high-sunlight exposure but seldom in the low-sunlight. Smaller diameter logs had drier phloem than larger diameter logs. All logs dried with time but sunlight level did not affect desiccation rates. Ips pini preferred attacking larger logs and the bottom side of logs. Sunlight exposure had a significant effect on net reproductive success in smaller diameter logs, with very little net reproductive success in high-sunlight exposed logs, and the highest reproductive success was found in small diameter logs in the low-sunlight treatments. 4 Management implications of these results are discussed. [ABSTRACT FROM AUTHOR]

1. Understanding species-specific habitat requirements is important in insect ecology. Co-occurrence of closely related species can provide insight into microhabitat segregation. Tiger beetles are well suited for such studies, as they occur in multi-species assemblages, exhibit species-specific habitat requirements, and are sensitive to anthropogenic modifications of the environment. 2. This study investigated ovipositional microhabitat choice of two sympatric tiger beetles at Point Reyes National Seashore, California, U.S.A., and evaluates how human activity affects that choice. Cicindela oregona is widespread and common whereas C. hirticollis, an undescribed subspecies, is locally threatened. Laboratory experiments tested oviposition-site selection of the two species in response to variations in moisture, pH, salinity, and grain size. Field experiments tested larval burrow location in response to experimental shading and experimental human disturbance. 3. Laboratory results indicated that while C. hirticollis females preferred a narrow range of moisture levels and fine sands, C. oregona females had more specific pH and salinity requirements and preferred coarser sands. They also differed in timing of activity. Preferences are probably related to prevention of fungal or bacterial infection and avoidance of desiccation and immersion. 4. In the field, significantly more larval burrows were found under experimental shading for both species. In addition, repeated human compaction of the sand significantly decreased the number of larval burrows. 5. Results suggest that protection of microhabitat, restoration of native plants, and limitation of human traffic are vital in the conservation management of tiger beetles. [ABSTRACT FROM AUTHOR]

1. Climate change has been occurring at unprecedented rates and its impacts on biological populations is beginning to be well documented in the literature. For many species, however, long-term records are not available, and trends have not been documented. 2. Using museum specimens from southern USA, we show that the stream-dwelling beetle Gyretes sinuatus has shown an 8% increase in body size and change in body shape (fineness ratio) from 1928 to 1988. Any directional morphological change observed over time could be an indicator of a microevolutionary response. 3. During these 60 years, there have also been changes in temperature, precipitation, and location of collection sites. Unlike the global trend, mean annual temperature in the region has decreased, and furthermore, total annual precipitation has increased. By investigating how these various ecological and geographical variables may affect body size and shape, we can examine which pressures may promote larger and/or thinner beetles. 4. Results indicate that mean annual temperature was the most predictive variable for the change in size and shape. We suggest there is an adaptive role for temperature on body size and shape of stream dwelling organisms. 5. We found that museum specimens can be invaluable resources of information when collection date and location information is available. We promote the use of such specimens for future studies of the morphological response to climate change. [ABSTRACT FROM AUTHOR]

The establishment of the multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), in North America has resulted in negative impacts on fruit production. We investigated the overwintering survival of H. axyridis after feeding on four diets: injured wine grape berries, 25% sucrose solution, water, and a control containing no food or water. After being exposed to these diets for 6 days, live individuals were transferred to clean plastic Petri dishes, and held at 5 ± 1 °C in growth chambers throughout the winter. Survival was recorded every month. Adult lady beetles collected during the overwintering flight in mid-October had higher survival rates than beetles collected from soybean fields in mid-August. These results suggest that an adaptation period prior to diapause increases the chances of lady beetle survival over the winter. In addition, injured wine grape berries, sugar, and water decreased beetle mortality during the overwintering months. Our results also showed that under similar conditions, females have higher survival during the winter than males. The importance of sugar and water on winter survival may drive H. axyridis adults to vineyards for feeding on wine grapes. Finally, we tested if adults of H. axyridis and the European paper wasp, Polistes dominulus Christ (Hymenoptera: Vespidae), were able to break the grape skin. Harmonia axyridis adults and paper wasps were not able to cause the primary injury to berries of Frontenac grapes under laboratory conditions. These results suggest that control of paper wasps in vineyards may not affect H. axyridis aggregations, and that H. axyridis feeding on wine grapes depends on previous injury to grape berries. [ABSTRACT FROM AUTHOR]

The southern pine beetle ( Dendroctonus frontalis) and western pine beetle ( Dendroctonus brevicomis) cause significant mortality to pines in the southern and western United States. The effectiveness of commercial lures at capturing these bark beetles in Arizona has not been tested and may vary from other regions of their distribution. We conducted experiments using baited Lindgren funnel traps to investigate (i) if D. frontalis is more attracted to the standard commercial lure for D. brevicomis (frontalin + exo-brevicomin + myrcene) than the D. frontalis lure (frontalin + terpene blend), (ii) whether replacement of myrcene with α-pinene changes trap catches of Dendroctonus and associated insects, and (iii) whether the attraction to these lures varies across the geographical range of ponderosa pine forests throughout Arizona. In 2005, we tested various combinations of frontalin, exo-brevicomin, myrcene and α-pinene to D. frontalis, D. brevicomis and associated species. Dendroctonus frontalis, D. brevicomis and the predator Temnochila chlorodia were most attracted to lures with exo-brevicomin. The replacement of the myrcene component with α-pinene in the D. brevicomis lure resulted in the capture of twice as many bark beetles and Elacatis beetles. However, T. chlorodia did not differentiate between monoterpenes. In 2006, traps were set up in 11 locations around Arizona to test the relative attraction of lure combinations. In 9 out 11 locations, the D. brevicomis lure with α-pinene was more attractive than the lure with myrcene or a terpene blend. These results suggest that the D. brevicomis lure with α-pinene rather than myrcene is more effective lure to capture D. brevicomis and D. frontalis in Arizona. However, geographical variation in attractiveness to lures is evident even within this region of the beetles’ distributions. Differential attraction of Dendroctonus and their predators to these lures suggests potential use in field trapping and control programmes. [ABSTRACT FROM AUTHOR]

Skunk vine, Paederia foetida (Rubiaceae), is native to Asia and has been recognized as an invasive weedy vine of natural areas in Florida and Hawaii. Two insects, Trachyaphthona sordida and Trachyaphthona nigrita (Coleoptera: Chrysomelidae) from Japan are being considered as potential biological control agents against skunk vine. To gather fundamental information on their biology, we carried out field surveys and laboratory experiments in Kyushu, southern Japan, between 2003 and 2006. We found that T. sordida is commonly distributed in Kyushu and T. nigrita is restricted to the southern parts of Kagoshima Prefecture on the southern part of Kyushu. These species are fundamentally univoltine and adults appear in late April to early July. Trachyaphthona sordida overwinters as mature larvae and T. nigrita as mature larvae or rarely as adults. Larvae of both species feed on fine roots of P. foetida in the field and Serissa foetida (Rubiaceae) under rearing conditions, and they appear to have tribe-level host specificity in their host range. On the basis of these results, we suggest that both species are suitable as biological control agents. [ABSTRACT FROM AUTHOR]

1. Resource regulation by insects is the phenomenon by which herbivory enhances resources for the progeny of the herbivore. This report provides an example of resource regulation with implications for desertification in the Chihuahuan Desert of North America. 2. Female Oncideres rhodosticta beetles chew girdles around mesquite ( Prosopis glandulosa) stems before ovipositing in those stems. The mesquite plants respond by producing compensatory stems below the girdle. Mesquite volume was significantly correlated with the total number of beetle girdles across a suite of low shrub density grassland and high shrub density dune sites, and plants in dune sites had more old and new girdles than mesquite in grasslands. 3. Smaller, younger shrubs in grassland responded more vigorously to girdling than did larger, older shrubs in dune landscapes. Stems on shrubs within grassland produced significantly more and longer compensatory stems per girdle than stems on shrubs in dunes. Soil capture by individual plants positively correlated with stem density, and stem density is increasing in the younger plants as a response to beetle damage. 4. This study suggests that the interaction between O. rhodosticta and mesquite is an example of resource regulation that increases the stem density and soil capture ability of mesquite. Because the conversion of productive grasslands to mesquite dune landscapes is one of the most important drivers of desertification in the Chihuahuan Desert, feedbacks between organisms that promote an increase in the size and soil capture ability of mesquite may exacerbate desertification. [ABSTRACT FROM AUTHOR]

Crop rotation has been a valuable technique for control of Diabrotica virgifera virgifera for almost a century. However, during the last two decades, crop rotation has ceased to be effective in an expanding area of the US corn belt. This failure appears to be due to a change in the insect's oviposition behaviour, which, in all probability, has an underlying genetic basis. A preliminary genome scan using 253 amplified fragment-length polymorphism (AFLP) markers sought to identify genetic variation associated with the circumvention of crop rotation. Samples of D. v. virgifera from east-central Illinois, where crop rotation is ineffective, were compared with samples from Iowa at locations that the behavioural variant has yet to reach. A single AFLP marker showed signs of having been influenced by selection for the circumvention of crop rotation. However, this marker was not diagnostic. The lack of markers strongly associated with the trait may be due to an insufficient density of marker coverage throughout the genome. A weak but significant general heterogeneity was observed between the Illinois and Iowa samples at microsatellite loci and AFLP markers. This has not been detected in previous population genetic studies of D. v. virgifera and may indicate a reduction in gene flow between variant and wild-type beetles. [ABSTRACT FROM AUTHOR]

1 Natural and recurring disturbances caused by fire, native forest insects and pathogens have interacted for millennia to create and maintain forests dominated by seral or pioneering species of conifers in the interior regions of the western United States and Canada. 2 Changes in fire suppression and other factors in the last century have altered the species composition and increased the density of trees in many western forests, leading to concomitant changes in how these three disturbance agents interact. 3 Two- and three-way interactions are reviewed that involve fire, insects and pathogens in these forests, including fire-induced pathogen infection and insect attack, the effects of tree mortality from insects and diseases on fuel accumulation, and efforts to model these interactions. 4 The emerging concern is highlighted regarding how the amount and distribution of bark beetle-caused tree mortality will be affected by large-scale restoration of these fire-adapted forest ecosystems via prescribed fire. 5 The effects of fire on soil insects and pathogens, and on biodiversity of ground-dwelling arthropods, are examined. 6 The effects of fire suppression on forest susceptibility to insects and pathogens, are discussed, as is the use of prescribed fire to control forest pests. [ABSTRACT FROM AUTHOR]

Ecological patterns and processes often change with scale, and determining how they do so is a necessary first step in understanding these relationships. We documented how the spatial patterns of beetle species richness, environmental variables, and correlations between the two change with spatial scale. Tenebrionid beetles and vegetation coverage were sampled on the shortgrass steppe of northeastern Colorado during June and August 1998. We used triplet quadrat variance (tQV) and triplet quadrat covariance (tQC) to evaluate the spatial patterns of beetle distribution and environmental variables. As revealed by tQV, spatial patterns of beetle species richness and environmental measures were scale dependent but differed among transects. Bare ground exhibited significant patchiness at spatial scales in the 460-500-m range, grass at 460-540 m, and shrubs at 420-620 m. Tenebrionid species richness in June showed significant patchiness in the 400-420-m and 560-640-m range, while August patch dimensions were in the 200-360-rn and 400-520-m ranges. As revealed by tQC, correlations between tenebrionid species richness and environmental measures were not scale dependent, nor was there much variation between transects. Univariate, multiscaled analyses revealed potentially significant scales; however, covariate, multiscaled analyses revealed no scale dependence of interaction. These analyses showed (1) that while spatial scale is important, it is often unpredictable and (2) that multiscaled analysis in realistic settings may not capture species' relevant heterogeneity. [ABSTRACT FROM AUTHOR]

1 Carpophilus sayi, a nitidulid beetle vector of the oak wilt fungus, Ceratocystis fagacearum, was shown to have a male-produced aggregation pheromone. 2 Six male-specific chemicals were identified from collections of volatiles. The two major compounds were (2 E,4 E,6 E,8 E)-3,5-dimethyl-7-ethyl-2,4,6,8-undecatetraene and (2 E,4 E,6 E,8 E)-3,5,7-trimethyl-2,4,6,8-undecatetraene, in a ratio of 100 : 18. These compounds, in a similar ratio, were previously reported to be the pheromone of Carpophilus lugubris, a closely related species. The four minor C. sayi compounds (less than 4% as abundant as the first) were also alkyl-branched hydrocarbons and consisted of two additional tetraenes and two trienes. 3 The pheromone of C. lugubris was re-examined to refine the comparison with C. sayi, and C. lugubris was found to have the same additional, minor tetraenes as C. sayi, but not the trienes. 4 A synthetic mixture of the two major compounds was behaviourally active for both sexes of C. sayi in oak woodlands in Minnesota. The pheromone was tested in combination with fermenting whole wheat bread dough (a potent synergist of nitidulid pheromones). The combination of the 500-µg pheromone dose and dough attracted at least 30-fold more C. sayi than either pheromone or dough by itself. The synergized pheromone has potential as a tool for monitoring insect vector activity in an integrated management program for oak wilt. 5 Although C. lugubris was not present at the Minnesota test sites, two other Carpophilus species, Carpophilus brachypterus and Carpophilus corticinus, were clearly cross-attracted to the synergized pheromone of C. sayi. [ABSTRACT FROM AUTHOR]

The problem of invasive species has reignited interest in biological control as a management tool. Classical biological control involves deliberate release of exotic natural enemies into new environments in an attempt to limit the density of an invasive species. Persistent, sustained limitation of invasive species by coevolved natural enemies is a seductive concept. Evidence now suggests, however, that biological control through the release of natural enemies can carry unanticipated ecological risks. There have been ecological side effects of distributing a deliberately introduced weevil ( Rhinocyllus conicus ) and an adventitious weevil ( Larinus planus ) for the biological control of exotic thistles. Both weevils have had major direct effects on key population-growth parameters of native thistles, and R. conicus has had an indirect effect on the interaction between a thistle and a native insect. These findings led us to review how ecological risk is evaluated, and to ask whether pre-release tests can predict the types of ecological effects documented. We conclude that, when done thoroughly, the tests used can determine host specificity by identifying physiological host range, but the usual tests cannot be relied upon to predict the ecological host range or impact on populations of less-preferred but accepted native species. Our data provide support for suggestions that the behavioral and developmental data now taken need to be supplemented with additional data on population parameters to better predict field-host use, population growth, interaction strengths, and ecological outcomes for native species that are potential hosts. [ABSTRACT FROM AUTHOR]

Carrion beetles depend on vertebrate carcasses to rear their young. Carcasses are a limited resource with patchy distribution, and there is an intense competition among many species for these carcasses. This situation is expected to lead to niche partitioning, such that different beetle species use different resources and thus escape direct competition. Our project used a geographic information system (GIS) and pitfall sampling to characterize carrion beetle preferences for soil texture and land use in Kearney County, Nebraska. The GIS was used to select sites where sampling was conducted using pitfall traps baited with rat carcasses. Attracted beetles were counted, identified to species, and released. The resulting data were used to construct occurrence maps of eleven species of carrion beetles by overlaying soil texture and land use. We then compared the results of EcoSim (an ecological simulation model of niche overlap) with GIS–generated maps of probability of carrion beetle occurrence. Our results are consistent with landscape–level niche partitioning by seven of the eleven examined species. Our application of GIS to the spatial analysis of carrion beetle distributions demonstrates how this technology can be used to test ecological and evolutionary hypotheses, predict habitat associations, and examine the effects of land use on a community of insects. This work could easily be extended to study the habitat preferences of the federally endangered American burying beetle, Nicrophorus americanus. [ABSTRACT FROM AUTHOR]

Abstract 1 One expected effect of global climate change on insect populations is a shift in geographical distributions toward higher latitudes and higher elevations. Southern pine beetle Dendroctonus frontalis and mountain pine beetle Dendroctonus ponderosae undergo regional outbreaks that result in large-scale disturbances to pine forests in the south-eastern and western United States, respectively. 2 Our objective was to investigate potential range shifts under climate change of outbreak areas for both bark beetle species and the areas of occurrence of the forest types susceptible to them. 3 To project range changes, we used discriminant function models that incorporated climatic variables. Models to project bark beetle ranges employed changed forest distributions as well as changes in climatic variables. 4 Projected outbreak areas for southern pine beetle increased with higher temperatures and generally shifted northward, as did the distributions of the southern pine forests. 5 Projected outbreak areas for mountain pine beetle decreased with increasing temperature and shifted toward higher elevation. That trend was mirrored in the projected distributions of pine forests in the region of the western U.S. encompassed by the study. 6 Projected outbreak areas for the two bark beetle species and the area of occurrence of western pine forests increased with more precipitation and decreased with less precipitation, whereas the area of occurrence of southern pine forests decreased slightly with increasing precipitation. 7 Predicted shifts of outbreak ranges for both bark beetle species followed general expectations for the effects of global climate change and reflected the underlying long-term distributional shifts of their host forests. [ABSTRACT FROM AUTHOR]

The once-extensive tallgrass prairie community of North America has been reduced to small remnants, many of which are surrounded by intensive corn ( Zea mays) agriculture. We investigated adult corn-rootworm beetles (Chrysomelidae: Diabrotica spp.), important pests of corn, on sunflowers (Asteraceae: Helianthus spp.) in prairie remnants in southeast Minnesota. Large numbers of beetles invaded the prairie from surrounding corn fields in late summer. D. barberi and D. virgifera were captured on sticky traps in all locations in the prairie, but abundance was much greater near the edge adjacent to corn. We observed D. barberi ( but not D. virgifera) feeding extensively on sunflower pollen and occasionally on other flower parts, such as petals. Sunflowers located nearer corn fields sustained more floral damage than those farther from corn. To determine the effect of beetle damage on seed set, we enclosed sunflower heads in bags with either zero, two, or four D. barberi adults. Seed set was reduced in heads enclosed with D. barberi. Thus, this agricultural pest may interfere with the successful reproduction of sunflowers and possibly other prairie composites that flower in late summer. Given the small size of most prairie remnants and the abundance of this flower-feeding beetle in landscapes dominated by corn agriculture, D. barberi may affect the sustainability of prairie plant populations. [ABSTRACT FROM AUTHOR]

Summary1. Food resources for rearing young may influence insect populations. This is particularly true for insects that breed obligately on rare, ephemeral resources such as dung, fungi, or carrion. 2. Beetles in the genus Nicrophorus bury small vertebrate carcasses for rearing their young. Studies reviewed by have found a positive relationship between carcass mass and total brood size. It is likely that access to carcasses suitable for breeding, and not food or mates, limits reproduction in both male and female Nicrophorus. Thus, small mammal densities could determine Nicrophorus population sizes. 3. The work reported here examined the relationship between Nicrophorus investigator (Coleoptera: Silphidae) population size and small mammal abundance at two sites over a 4-year period. 4. Nicrophorus investigator buried and reared young on all the native small rodent species trapped at two sites in south-western Colorado, U.S.A. (Peromyscus maniculatus, Microtus montanus, Zapus princeps, Tamias minimus, Thomomys talpoides). They preferred to bury and reproduce on rodent carcasses weighing between 16 and 48 g; rodents of this size represented 82% of captures. 5. Population sizes of N. investigator and small rodents were estimated simultaneously using mark-recapture censuses over a 4-year period. Considering only rodents within the size range used by N. investigator, the estimated small mammal biomass per hectare in one year and the beetle population size in the following year were correlated significantly. [ABSTRACT FROM AUTHOR]

This article studies survival of Ceratocystis fagacearum in branches of treeskilled by oak wilt in Minnesota. The survival of Ceratocystis fagacearum in branches of Quercus ellipsoidalis killed by oak wilt in Minnesota depends on the time of year when the trees die. In trees, which wilt in May or June, the pathogen can be isolated from the xylem for only 1-2 months. In trees which die later in the summer it may persist through to the following spring. Observations on oak bark beetles breeding in the dead trees do not suggest that these beetles are important vectors of the disease in Minnesota.

1. Scirtid beetles (Coleoptera: Scirtidae) are common inhabitants of water-filled treeholes and interact with other detritivores in a processing chain commensalism. The strength of the commensalism is determined by resource quantity and the organisms involved have different tolerances to low pH. To determine the effects and interactions of resource quantity and pH on one of these leaf-shredding scirtid beetles, Helodes pulchella (Guerin), leaf litter and pH were varied independently in experimental microcosms which mimic treehole habitats. 2. Helodes pulchella growth was affected by both resources and pH in two similar experiments conducted in different years. Scirtid larvae grew more slowly in low resource treatments and also grew more slowly in low pH treatments. Scirtid survival was not affected by pH, but was lower in high resource microcosms in the 1997 experiment. Consumption of leaf litter was much higher in high resource microcosms, even though not all leaf litter was consumed in low leaf litter treatments. 3. Thus, water chemistry and leaf litter quantity could have strong effects on resource availability through effects on these beetle facilitators, in turn affecting other insects living in these detritus-based communities. [ABSTRACT FROM AUTHOR]