Introduced forest pests have become one of the major threats to forests, and biological control is one of the few environmentally acceptable management practices. Assessing the impacts of a ...biocontrol program includes evaluating the establishment of biocontrol agents, the control of target pest, the impact on the affected organism, and the indirect impacts that the biocontrol agent may have on the whole community. We assessed the recovery of forest vegetation following the mortality of ash trees caused by the invasive emerald ash borer (EAB) pest in forest stands where biocontrol agents were released or not. We used a multilevel framework to evaluate potential indirect effects of the biocontrol agents on native forest seedlings. Our results showed a higher number of ash saplings where increasing numbers of the dominant EAB biocontrol agent were released, while the number of invasive and weedy saplings was negatively associated with the number of ash saplings, and the density of native seedlings was negatively associated with invasive and weedy saplings. The protection of ash saplings by the biocontrol agent may help native recruitment during forest transition by supporting the growth of native hardwood seedlings over invasive and weedy species. These results show that research on the efficacy of EAB biocontrol should include all ash size classes and the community dynamics of co-occurring species.
Green leaf volatiles (GLVs) function as host attractants, pheromone synergists, or sexual kairomones for a number of coleopteran folivores. Hence, we focused on host GLVs to determine if they were ...attractive to adults of the emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae), which feeds on ash (Fraxinus) foliage. Eight GLVs were identified by chromatography-electroantennogram (GC) and GC-mass spectrometry in foliar headspace volatiles collected in traps containing Super-Q from white ash, Fraxinus americana, and green ash, Fraxinus pennsylvanica, trees. GLVs in the aeration extracts elicited antennal responses from both male and female adults in gas chromatography-electroantennogram detection bioassays. Male antennae were more responsive than female antennae and showed the strongest response to (Z)-3-hexenol. Six field experiments were conducted in Canada and the USA from 2004 to 2006 to evaluate the attractiveness of candidate GLVs, in various lure combinations and dosages. Field experiments demonstrated that lures containing (Z)-3-hexenol were the most effective in increasing trap catch when placed on purple traps in open areas or along the edges of woodlots containing ash. Lures with (Z)-3-hexenol were more attractive to males than females, and dosage may be a factor determining its effectiveness.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Detection of newly established populations of Agrilus planipennis Fairmaire, the most destructive forest insect to invade the United States, remains challenging. Regulatory agencies currently rely on ...artificial traps, consisting of baited three-sided panels suspended in the canopy of ash (Fraxinus spp.) trees. Detection trees represent another survey option. Ash trees are girdled in spring to attract ovipositing A. planipennis females then debarked in fall to assess larval presence and density. From 2008–2010, systematic grids of detection trees and artificial traps were established across a 390-km2 area for the SLow Ash Mortality pilot project. We compared probabilities of detection associated with detection trees and artificial traps along varying A. planipennis density proxies estimated as distance-weighted averages of larval counts (detection trees) or adult captures (traps) within 800 m of each detection tree or trap. Detection trees were consistently more likely to be positive, that is, detect A. planipennis, than traps in all three years, even when traps were placed in canopies of detection trees. Probability of detection with a single detection tree was >50% when density proxies for the area were <5 larvae per detection tree, while the probability of detection with an artificial trap placed in the same area was <35%, even when density proxies exceeded 25 larvae per detection tree. At very low densities of <5 larvae per detection tree, using three detection trees would increase detection probabilities to 90%, while five artificial traps would increase the detection probability only to 40%.
Tree growth equations are an important and common tool used to effectively assess the yield and determine management practices in forest plantations. Increasingly, they are being developed for urban ...forests, providing tools to assist urban forest managers with species selection, placement, and estimation of management costs and ecosystem services. This study describes the development of allometric equations for Fraxinus americana and F. pennsylvanica growing in Oakville, Canada. With data collected from 103 ash trees, five allometric models were tested to develop equations estimating diameter-at-breast-height (dbh), tree height, crown width and crown height, using age and dbh as explanatory variables. Mean annual growth rates are presented to demonstrate species growth performance and were not significantly different over the first 40 years of growth for the two species. Of all the tested random coefficient models for both species, the cubic with weight 1/x provided the best fit for estimating dbh from age. The best models for other parameters were the loglog for crown height from dbh, the quadratic for crown diameter from dbh, and the linear for tree height from dbh for F. americana. Model types showed more consistency for F. pennsylvanica with linear providing the best fit for crown diameter, crown height and tree height from dbh. The number of model types suggests the difficulty of fitting any single model to the vast array of conditions affecting plant growth in urban areas where management practices and environment can significantly influence tree size and growth. These models may be used to estimate the growth of ash tree populations in Oakville and communities with similar climate, soil, planting, and management environments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The cosmopolitan genus Fraxinus comprises about 40 species occupying several habitats in the Northern Hemisphere. With some species hybridizing and sharing genetic variants, questions remain on the ...species assignment of germplasm within the genus Fraxinus despite numerous species-specific assessments. A multidisciplinary approach was employed to provide a definitive insight into the genetics of an endangered Fraxinus “manna ash” collection, located in a rich plant biodiversity hotspot of the Madonie Mountains (Sicily). Although the collection size was small, genetic diversity, assessed by chloroplast (cpSSR) and nuclear (nSSR) microsatellites (SSR—Simple Sequence Repeats), allowed identifying three different chloroplast haplotypes, with one (H5) dominant, and several polymorphic loci, able to discriminate most of the local accessions studied. Molecular data were linked to cytofluorimetric and phenotypic evaluations and, contrary to popular belief that manna ash is Fraxinus ornus L., the germplasm currently used for manna production belongs to Fraxinus angustifolia Vahl. Interestingly, joint analysis of our genetic panel with a large European dataset of Fraxinus spp. suggested the presence of a possible glacial refuge in Sicily, confirming its importance as biodiversity source. Our results will be helpful for the design of long-term conservation programs for genetic resources, such as in situ and ex situ conservation, seed collection and tree reintroduction.
The papers included in this Special Issue address a variety of important aspects of plant biodiversity and genetic resources, including definitions, descriptions, and illustrations of different ...components and their value for food and nutrition security, breeding, and environmental services. Furthermore, comprehensive information is provided regarding conservation approaches and techniques for plant genetic resources, policy aspects, and results of biological, genetic, morphological, economic, social, and breeding-related research activities. The complexity and vulnerability of (plant) biodiversity and its inherent genetic resources, as an integral part of the contextual ecosystem and the human web of life, are clearly demonstrated in this Special Issue, and for several encountered problems and constraints, possible approaches or solutions are presented to overcome these.
Determining the deposition and field persistence of mycoinsecticides is essential in the development of effective and economical application strategies, including specifically the timing and ...frequency of spray applications. In this study we used three methods to evaluate the persistence of
Beauveria bassiana strain GHA applied for control of the emerald ash borer (EAB),
Agrilus planipennis, an invasive pest attacking ash trees,
Fraxinus spp., in North America. Fungal inocula present on ash bark and leaves, collected at ⩽1, 7 and 14
days after spraying, were quantified by use of molecular (real-time PCR assay) and culture-based methods (semi-selective wheat germ dodine agar). We also assayed fungus-sprayed leaves and bark against adult beetles to determine whether the level of inocula persisting in the field was sufficient to affect beetle survival. Our data quantified deposition of
B. bassiana and documented fungal persistence. We observed significant decline in recovery of colony-forming units of
B. bassiana within 1
week of application. The decline was more pronounced on leaves than on bark, and was also evident in loss of virulence of treated substrates to adult EAB with increasing time after application. However, sufficient inocula persisted on bark and leaves for 7--14
days to cause 40--57% and 17--38% mortality, respectively, making pre-emergent sprays a practical means to target adults during emergence, pre-oviposition feeding, or oviposition.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The objectives of this review paper are to provide an overview of issues related to forest health and forest entomology, explain existing methods for forest insect pest detection, and provide ...background information on a case study of emerald ash borer. Early detection of potentially invasive insect species is a key aspect of preventing these species from causing damage. Invasion management efforts are typically more feasible and efficient if they are applied as early as possible. Two proposed approaches for detection are highlighted and include dendroentomology and near infrared spectroscopy (NIR). Dendroentomology utilizes tree ring principles to identify the years of outbreak and the dynamics of past insect herbivory on trees. NIR has been successfully used for assessing various forest health concerns (primarily hyperspectral imaging) and decay in trees. Emerald ash borer (EAB) (Agrilus planipennis), is a non-native beetle responsible for widespread mortality of several North American ash species (Fraxinus sp.). Current non-destructive methods for early detection of EAB in specific trees are limited, which restricts the effectiveness of management efforts. Ongoing research efforts are focused on developing methods for early detection of emerald ash borer.
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