The mating and oviposition behavior of the invasive emerald ash borer (Agrilus planipennis), with reference to the influence of host tree condition

Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive wood-boring beetle first detected in North America in 2002. Relatively little is known about the factors affecting the mating and oviposition behavior of EAB, even though they could have implications for the management of this species. Consequently, we conducted field surveys in Michigan to observe the diurnal behavior of EAB adults, in addition to examining how their behaviors associated with reproduction varied in relation to the size and condition of host trees. We observed most EAB adults between 11:00 and 15:00, and this pattern was the same for both sexes and for all of the specific behaviors examined (feeding, flying, mating, resting, and walking). Regarding host tree size and crown condition, we consistently found that the most EAB eggs, adults, mating pairs, and ovipositing females were observed on intermediately stressed trees with 40–60 % crown reductions (likely resulting from earlier EAB infestations). Additionally, host tree crown condition appeared to be a more important factor than diameter at breast height. Our results therefore provide support to the hypothesis that host tree crown (stressing) condition influences EAB oviposition behavior. Determining which trees are likely to contain the most EAB eggs should help to guide efforts for releasing and promoting the establishment of parasitoids utilized in biologic control. However, future work should attempt to experimentally test the hypothesis that host tree condition (e.g., crown reduction) drives EAB oviposition behavior, and investigate the fitness implications of these host choices.     

花曲柳窄吉丁在不同地区年生活史的补充研究

花曲柳窄吉丁Agrilus planipennis Fairmaire属鞘翅目Coleoptera吉丁科Buprestoidea窄吉丁属Agrilus,是术琴属树木的毁灭性蛀干害虫。调查研究表明,花曲柳窄吉丁以幼虫越冬,但在不同纬度地区其幼虫的越冬虫态、发育历期和年发生代数不同。在河北省唐山市与天津市及其以南地区,花曲柳窄吉丁1a发生1代,以老熟幼虫在浅层木质部蛀建蛹室开始越冬,第2年有1个化蛹、羽化高峰。在辽宁省本溪市也为1a1代,但以不同龄期的幼虫在蛹室或蛀道里越冬,老熟幼虫比例约占90％,相应地第2年有1大1小两个成虫羽化高峰期。在吉林省吉林市有一部分虫体完成1代需要多于1a的时间,可能为1a1代和2a1代混和发生区。在纬度较高的黑龙江省哈尔滨市,发生1代需要2a时间,幼虫发育需要经历2个冬季。随着纬度的增高,花曲柳窄吉丁越冬幼虫中有低龄幼虫所占比例逐渐增加,老熟幼虫的比例逐渐减少的趋势。吉丁虫类昆虫（包括花曲柳窄吉丁）可能为异动态昆虫,其幼虫阶段越冬可能为其化蛹所必需。     

Assessing the potential for ash canopy tree replacement via current regeneration following emerald ash borer-caused mortality on southeastern Michigan landscapes

The emerald ash borer (EAB) has killed millions of ash trees in Michigan and at least fourteen other states since its first detection near its introduction point in metropolitan Detroit in 2002. Despite overstory ash mortality near 100% in many areas, ash seedling and saplings remain unaffected and provide the potential for ash re-establishment into the canopy of deciduous forests of the region. We examined the potential for ash re-establishment in areas of heavy mortality by measuring the status and change of ash regeneration at 45 sites across southeastern Lower Michigan in 2007 and 2009. Ash regeneration was found to be abundant in all forest types, particularly in the smallest height classes, though it was more abundant in ash species of upland forests compared to those of lowland forests. New seedlings 1-2 years old were less common than other regeneration size classes, and declined substantially between 2007 and 2009, suggesting a depletion of the ash seed bank in these forests. Regeneration density was not explained well by the presence of overstory ash prior to EAB introduction, suggesting that competitive interaction with other tree species in higher canopy strata is an important driver of ash regeneration density. Regeneration is sufficient to replenish overstory ash to pre-EAB levels in upland forests, though ecological changes caused by overstory ash mortality in lowland areas may affect local hydrology in a way that reduces opportunities for tree regeneration. Despite abundant ash regeneration, it remains unclear whether ash will recover to the overstory of forests in southeastern Michigan because of uncertainties in the future dynamics of EAB in the region.     

Relationships between the emergence and oviposition of ectoparasitoid Spathius agrili Yang and its host emerald ash borer, Agrilus planipennis Fairmaire

Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), (= A. marcopoli Obenberger), is an important bark beetle attacking ash trees (Fraxinus spp.). It is very difficult to detect and control because of its highly concealed life history. This pest mainly distributed in partial Asian countries (China, Japan, Korea, Mongolia) and Far East Russia, while in China it presented in Heilongjiang, Jilin, Liaoning, Shandong, Inner Mongolia, Hebei, Taiwan Provinces and Tianjin City, etc. The important timber species F. mandshurica and gardening tree F. velutina were damaged severely in northern China. Spathius agrili Yang (Hymenoptera: Braconidae) is an important ectoparasitic wasp of the EAB larvae. This parasitoid has the potential to use as an excellent biological control agent for suppressing populations of EAB. The differences of emergence date between overwintered S. agrili and its host, parasitism rates at different periods, relations between parasitism rates and host densities, and relationships between ovipositions of braconid wasp and body sizes of host larvae were studied using methods of regular surveys in forests and observations in laboratory. Results revealed that the emergence of S. agrili was more than one month later than that of its host. It suggests good synchrony between parasitoid emergence and host availability. The overwintered S. agrili emerged from mid June to mid August with the peak in July in 2003, and it lasted from late May till late July with the peak during late June to early July in 2004. While the EAB emergence period ranged from mid May to late May in 2003, it ranged from mid April to mid May in 2004 (in laboratory). The emergence date of parasitoid asynchronously inosculated with the optimum developmental instars of the earliest host larvae, which was the result of a long-term co-evolution between the two species. It was also suggested that the parasitoid S. agrili could be a specialized natural enemy for EAB. The natural parasitism rates on the whole gradually increased in field with time. The body sizes of host larvae, i.e. larval instar, affected the decision of parasitoid S. agrili to lay eggs or not. Under natural conditions, this parasitoid usually oviposited only on those host larvae with a prontum and body width more than 1.5 mm, and a body length in excess of 12 mm, i.e. the third or fourth instar larvae. These findings would consequentially contribute to the further successfully biological control of the trunk borer. __________ Translated from Acta Ecologica Sinica, 2006, 26(4): 1,103–1,109 [译自: 生态学报]     

Estimating stemwood nutrient concentration with an increment borer: a potential source of error

Two methods of sampling stemwood nutrients have been comparedon 10 Pinus pinaster (Ait.) trees: the increment borer method(non-destructive but producing samples which are not weighedaccording to the tissues' proportion) and the disc method (destructivebut producing weighed samples). The samples were divided intosapwood and heartwood, and nutrient concentrations were determinedfor major nutrients (N, P, K, Ca, Mg). Compared with the discsampling method, the increment borer sampling method significantlyunderestimated N, P and K concentration in sapwood, whereasit overestimated Ca and Mg concentration in heartwood. The meanerror ranged from –13 per cent (N and P in sapwood) to+14 per cent (Ca in heartwood). These results were in agreementwith previous studies which showed horizontal variations inthe nutrient concentration of stemwood.     

Potential for combined use of parasitoids and generalist predators for biological control of the key invasive tomato pest Tuta absoluta

The tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) has recently invaded Mediterranean countries and is a major pest in tomato crops. Trichogrammatid oophagous parasitoids have shown promising potential for controlling the pest before the yield decreases in the greenhouse. In protected tomato crops (greenhouse), mirid predators are commonly used for biological control of whiteflies and they also prey on T. absoluta. These predators do not attack Trichogramma adults but they may partially decrease the overall impact of parasitoids on T. absoluta if intraguild predation (IGP) occurs on parasitized eggs. Under laboratory conditions, we tested if the mirid predator Macrolophus pygmaeus shows preference between parasitized and unparasitized T. absoluta eggs. We also tested if the predator reduces the number of parasitized eggs on caged tomato plants (microcosms) and assessed the efficacy of natural enemies used alone or together in limiting T. absoluta populations. We found that IGP is inflicted on the parasitoid Trichogramma achaeae by M. pygmaeus and that the risk of IGP depends on the developmental stage of T. achaeae inside the egg because the larva is at risk mostly early in its development (when parasitized egg is still yellow). In addition, we observed that non-consumptive events, likely probing of the predator on parasitized eggs, may induce mortality in parasitoid offspring without actual feeding on parasitized eggs. However, both IGP and non-consumptive events decreased when the predator was not confined with parasitized eggs in small arenas. Despite negative effects of the predator to the parasitoid, results demonstrate that adding Trichogramma parasitoids may significantly increase the level of control of the pest over what could be attained when only the mirid predator M. pygmaeus is present on tomato. Implications of results are discussed regarding potential of these natural enemies for biological control of T. absoluta in greenhouse tomato crops.     

北美木地板行业发展综述

与前几年相比,2011年全球地板行业的发展相对平稳,全球经济开始缓慢恢复,房地产、装修也在逐渐的增长,如北美的装修指数达到了5年来的最高水平。地板企业也对未来充满了希望,地板展览已经充分体现了这一点,德国Domotex吸引了4.5万人,增长了19％,2012年初的Surface吸引了2．7万人参加,与2011年相比增长了10％,是继2008年3．454万人后参加人数最多的一年。     

Life cycle assessment of windows for the North American residential market: Case study

Abstract

A life cycle assessment (LCA) of residential windows was conducted to evaluate the environmental impacts of those made with aluminum-clad wood, polyvinyl chloride (PVC) and fiberglass frames for sale in North America. The LCA was a case study in which specific-site data were used for the manufacturing stage of each window, while published data were adapted to complete the life cycle inventories using Sima Pro software. These inventories were grouped into impact categories and scaled based on IMPACT 2002+ version 2.1 characterization and damage factors. The damage modeling indicated that the life cycle impacts are dominated by the combustion of non-renewable energy resources. The PVC life cycle used the most non-renewable energy and caused the most damage owing to that window's shorter service life. The disposal of aluminum cladding in the municipal waste stream caused greater aquatic ecotoxicity for the wood window. The sensitivity analysis revealed that replacing the virgin material in aluminum cladding with recycled content improved the life cycle impacts of the wood window. Using fiberglass or PVC to clad the wood window also improved the environmental performance. Other potential improvements to the life cycle impacts of the three windows include improving energy efficiency, particularly during the secondary manufacturing.     

Extending rotation age for carbon sequestration: A cross-protocol comparison of North American forest offsets

Through carbon offset programs, forest owners can be offered financial incentives to enhance the uptake and storage of carbon on their lands. The amount of carbon that can be claimed by an individual landowner will ultimately depend on multiple factors, including the productivity of the forest, the management history of the stand, and the program in which the landowner is participating. This project presents a modeling framework for forest carbon accounting which is driven by forest yield curves and carbon pool partitioning. Within this model the amount of creditable carbon generated from adjusting the rotation age of multiple forest stands can be estimated for 46 distinct North American forest types. The model also provides a comparison of total creditable carbon generated under three carbon accounting methodologies: the Department of Energy 1605b Registry, the Chicago Climate Exchange, and the Voluntary Carbon Standard. In our evaluation of a 5-year rotation extension across 102 unique modeling scenarios, we find large differences among the carbon accounting schemes. This has implications for both forest landowners and policymakers alike. In particular, methodologies to account for such issues as leakage, permanence, additionality, and baseline establishment, while potentially increasing the overall legitimacy of any forest carbon offset program, can reduce creditable carbon to the forest owner (by up to 70%). Regardless of the protocol used, we also note strong regional differences, with Pacific Northwest forests of fir, spruce, hemlock, alder and maple being the most effective at sequestering carbon on a per area basis.     

Characterization of North American Armillaria species: genetic relationships determined by ribosomal DNA sequences and AFLP markers

Phylogenetic and genetic relationships among 10 North American Armillaria species were analysed using sequence data from ribosomal DNA (rDNA), including intergenic spacer (IGS‐1), internal transcribed spacers with associated 5.8S (ITS + 5.8S), and nuclear large subunit rDNA (nLSU), and amplified fragment length polymorphism (AFLP) markers. Based on rDNA sequence data, the nLSU region is less variable among Armillaria species than the ITS + 5.8S and IGS‐1 regions (nLSU < ITS + 5.8S < IGS‐1). Phylogenetic analyses of the rDNA sequences suggested Armillaria mellea, A. tabescens and A. nabsnona are well separated from the remaining Armillaria species (A. ostoyae, A. gemina, A. calvescens, A. sinapina, A. gallica, NABS X and A. cepistipes). Several Armillaria species (A. calvescens, A. sinapina, A. gallica, NABS X and A. cepistipes) clustered together based on rDNA sequencing data. Based on the isolates used in this study, it appears that techniques based on IGS‐1, ITS + 5.8S, and/or D‐domain/3′ ends of nLSU are not reliable for distinguishing A. calvescens, A. sinapina, A. gallica and A. cepistipes. However, AFLP data provided delineation among these species, and AFLP analysis supported taxonomic classification established by conventional methods (morphology and interfertility tests). Our results indicate that AFLP genetic markers offer potential for distinguishing currently recognized North American Biological Species (NABS) of Armillaria in future biological, ecological and taxonomic studies.     

Emulating natural disturbance regimes as a basis for forest management: A North American view

It is widely accepted that for many North American forest ecosystems, changes in species composition and structure are associated with departures from natural disturbance regimes (e.g., fire exclusion). It also widely accepted that restoration of species composition and structure, similar to those which existed under natural disturbance regimes, will in turn restore and maintain: (1) ecosystem resilience to a broad range of environmental challenges; (2) important elements of ecosystem function; and (3) disturbance-adapted species assemblages and thus conservation of biodiversity. Much of the research relevant to emulating natural disturbance regimes (ENDR) in North America has focused on natural fire regimes, particularly those characterized by frequent/low-severity fires. Increasingly, attention is being focused on natural disturbance regimes other than fire and on interactions between different disturbance types. However, the greatest challenges to implementation of ENDR are socioeconomic rather than ecological. There is, for example, limited social acceptance of management based on high-severity natural disturbance regimes. And while there is much broader acceptance of ENDR based on frequent/low-severity disturbance regimes, there is nevertheless strong disagreement concerning how ENDR is to be implemented.     

Mounding site preparation: A review of European and North American experience

Mounding site preparation in the northern boreal and temperate regions is reviewed under the following headings: Terminology, History, Kinds of mounds, Effects of mounding, and Mound making.     

Biomass production for biofuels using agroforestry: potential for the North Central Region of the United States

As demand for energy increases in the United States, alternative energy sources are being sought both domestically and abroad. Biofuels have been promoted as a major source of alternative energy, but sustainable supply of biomass still remains a major challenge. Agroforestry offers a potential way to integrate perennial woody bioenergy crops with traditional agricultural crops to satisfy energy demands without sacrificing food production in the North Central Region of the United States. We suggest shelterbelts, alley cropping and working riparian buffer strips as ideal candidates for biomass production in agroforestry settings in this region. In addition to satisfying domestic energy demands, these systems could also potentially increase water quality, sequester carbon, improve aesthetics, and provide critical wildlife habitat. However, obstacles to implementing agroforestry systems for biomass production, such as a competitive price structure and stable markets, must be overcome before large-scale adoption by landowners.     

Disturbance severity and canopy position control the radial growth response of maple trees (<Emphasis Type="Italic">Acer</Emphasis> spp.) in forests of northwest Ohio impacted by emerald ash borer (<Emphasis Type="Italic">Agrilus planipennis</Emphasis>)

Key message

Radial growth of silver and red maples was investigated across three forests in northwest Ohio following the outbreak of the invasive emerald ash borer. The growth response of maples was driven by an advancement in canopy class and disturbance severity.

Context

Forest disturbances resulting in species-specific diffuse mortality cause shifts in aboveground and belowground competition. This competition may differentially affect non-impacted trees, depending on crown class, disturbance severity, and species-specific responses.

Aims

The purpose of this study is to elucidate the primary drivers of silver and red maple (Acer saccharinum and A. rubrum) growth following emerald ash borer (EAB, Agrilus planipennis)-induced ash tree (Fraxinus spp.) mortality in riparian forests of northwest Ohio.

Methods

Using dendroecological approaches, we analyzed the pattern of radial growth in red and silver maples in conjunction with the EAB outbreak.

Results

This study revealed growth rates of maples increased 72% following EAB arrival and trees advancing in crown class grew 41% faster than those not advancing. The growth response varied by initial crown class, with trees in the intermediate class responding most dramatically. Furthermore, the positive correlation between relative basal area of ash and the radial growth response of maples indicates the important role of disturbance severity in post-disturbance dynamics.

Conclusion

These findings suggest that, although advancement in crown class may allow predictions of “winners” in forest succession post-disturbance, even trees not changing crown class benefit from decreased competition. Results from this study provide a detailed account of radial growth responses in maples following EAB-induced ash mortality and lend insight into the future canopy composition of ash-dominated riparian forests.

     

Efficacy of fungicides on Hymenoscyphus fraxineus and their potential for control of ash dieback in forest nurseries

Twenty‐six commercial formulations of fungicides at six concentrations were evaluated in vitro for their efficacy on mycelial growth of Hymenoscyphus fraxineus (anamorph Chalara fraxinea). The results are presented as EC₅₀, EC₉₀ and minimal inhibitory concentration values; the comparisons with the recommended application concentrations showed that 10 of the 26 fungicides were highly effective in their ability to inhibit the mycelial growth of the pathogen. The eight most effective fungicides identified based on multiple comparisons analysis were azoxystrobin, bitertanol, captan (in two‐component preparation with trifloxystrobin), difenoconazole, kresoxim‐methyl, spiroxamine (in multicomponent preparation with tebuconazole and triadimenol), tebuconazole and trifloxystrobin. Azoxystrobin, difenoconazole, kresoxim‐methyl, mancozeb, myclobutanil, pyrimethanil, tebuconazole and trifloxystrobin were selected to verify their effectiveness in in planta tests. During two field tests in nurseries, it was found out that tebuconazole (triazole), trifloxystrobin and kresoxim‐methyl (strobilurins) and mancozeb (dithiocarbamate) were significantly effective against H. fraxineus. The best results were gained with tebuconazole, when mean percentage of diseased saplings was 16.3%, whereas in the control, it was 63.6%. The combination and alternation of fungicides from the triazole, strobilurine and dithiocarbamate chemical groups should be an effective tool for protecting ash saplings in forest nurseries. Moreover, exact timing of the treatment reflecting rainfall and development of first symptoms in the foliage will be also important.     

Sweet trees, sour circumstances: the long search for sustainability in the North American maple products industry

Maple sugar and maple syrup have long been important non-timber forest products in North America. We examined the historical and the scientific literature to determine the long-term sustainability of the industry in an economic, an ecological, and a cultural context. During the 18th and 19th centuries, maple sugar was an inexpensive substitute for cane sugar and a cash crop that fit into the work schedule of the northern farmer. Maple syrup replaced maple sugar as the mainstay of the industry at the end of the 19th century as increasingly cheaper cane sugar and other sweeteners undercut the sugar market. Active government intervention and support have made Quebec the major bulk supplier of maple syrup today. Quebec alone produces approximately 80% of the world’s supply of maple products. A series of good sap years and production in excess of demand, however, has recently reduced the price of bulk syrup and the profit of producers in Quebec. Producers in the United States have focused on the more lucrative and price stable retail syrup market.

Farming practices in the late 18th and early 19th centuries tended to clear away sugar maple on the more fertile, level sites and preserve sugar maple as a source of fuel wood, sugar and syrup on the less accessible, marginal sites. The crude tapping procedures employed at the same time often killed the trees. Widespread grazing in the 20th century and more recently diameter-limit cutting of even-aged stands have hindered the regeneration of the sugarbush. An emphasis on monocultures and global warming currently threatens the sustainability of the sugarbush. On the whole, however, the maple products industry has probably increased sugar maple’s representation in the forest. From a cultural standpoint, the industry represents a positive work experience that unites families, connects one to the land, and provides a sense of continuity with the past.     

Smart increment borer: a portable device for automated sampling of tree-ring cores

Manual sampling of large number of cores is an arduous task, especially when core diameter is large. We developed an automated tree-ring sampling device, the “smart increment borer”, to increase the sample throughput and minimize the need for muscular exertion. The lightweight, portable device employs a battery-powered electric wrench and the complete system to drive the boring operation weighs less than 10 kg. It is capable of taking both 5- and 12-mm diameter cores of more than 80-cm length. Compared to equipment used in previously published articles, this device enables more rapid sampling and demonstrates a superior torque output/total weight ratio. The device is also capable of facilitating the starting operation of a 12-mm increment borer. It facilitates a variety of effective sampling solutions for dendrochronology/climatology and wood anatomy/quality research.     

The North American long-term soil productivity experiment: Findings from the first decade of research

First decade findings on the impacts of organic matter removal and soil compaction are reported for the 26 oldest installations in the nation-wide network of long-term soil productivity sites. Complete removal of surface organic matter led to declines in soil C concentration to 20 cm depth and to reduced nutrient availability. The effect is attributed mainly to the loss of the forest floor. Soil C storage seemed undiminished, but could be explained by bulk density changes following disturbance and to decomposition inputs of organic C from roots remaining from the harvested forest. Biomass removal during harvesting had no influence on forest growth through 10 years. Soil compaction effects depended upon initial bulk density. Soils with densities greater than 1.4 Mg m⁻³ resisted compaction. Density recovery was slow, particularly on soils with frigid temperature regimes. Forest productivity response to soil compaction depended both on soil texture and the degree of understory competition. Production declined on compacted clay soils, increased on sands, and generally was unaffected if an understory was absent.     

Host specificity of Asian parasitoids for potential classical biological control of <Emphasis Type="Italic">Drosophila suzukii</Emphasis>

The Asian spotted wing drosophila, Drosophila suzukii, has recently become a serious pest of soft fruits in Europe. Classical biological control through the introduction of larval parasitoids from its native range in Asia is presently being considered. However, host specificity of potential biological control agents has to be determined to avoid releasing species that may have unintended non-target impacts. Larvae of six different European non-target fly species and the target D. suzukii were exposed either on diet or blueberries to three Asian larval parasitoids, Asobara japonica, Leptopilina japonica, and Ganaspis cf. brasiliensis, and one European species, Leptopilina heterotoma. Asobara japonica showed the lowest specificity, attacking and developing in all Drosophilidae. Leptopilina japonica successfully parasitized two non-target Drosophilidae, D. melanogaster and D. subobscura, with one singly progeny emerging from D. immigrans. Ganaspis cf. brasiliensis had the highest level of specificity but variations occurred between two geographical populations tested. A Japanese population was strictly specific to D. suzukii, whereas another population from China parasitized D. suzukii, D. melanogaster and sporadically D. subobscura. The European L. heterotoma successfully developed in D. melanogaster, D. subobscura and occasionally in D. immigrans, but nearly all eggs and larvae in D. suzukii were encapsulated. These results show that Ganaspis cf. brasiliensis is the species with the highest potential for biological control, but more studies are needed on its taxonomic status and the existence of biotypes or cryptic species varying in their specificity before field releases can be conducted in Europe.     

Agroforestry: a profitable land use. An overview of the 12th North American Agroforestry Conference

This special issue features papers contributed by presenters at the 12th North American Agroforestry Conference held June 4–9, 2011 in Athens, Georgia, USA. The conference brought together agroforestry researchers, educators, practitioners, and students to highlight agroforestry research, implementation, policy, education, and entrepreneurial opportunities across North America. Eight papers cover topics ranging from adoption of silvopastoral systems across eco-regions and countries; economics of pine straw production; and timber and alley crop production in the Southeastern U.S.; reduction of sublimation of snow with shelterbelts in Canada, carbon offset incentives for agroforestry practices; consumer and market dynamics for chestnut and elderberry specialty crops; and web-based graduate degree and certificate programs in agroforestry.