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1.
1 The emerald ash borer Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is a serious exotic pest of ash trees (Fraxinus spp.) in North America, and is responsible for the deaths of millions of trees in Ontario and Michigan. One of the greatest challenges facing the successful management of the pest is the ability to accurately detect its presence in a tree. 2 Observations were made on A. planipennis larval feeding galleries found within 65 young, green‐ash trees cut from plantations in Essex County, Ontario, Canada. The within‐tree distributions of feeding galleries were described in relation to height‐above‐ground, stem diameter, bark thickness and stem aspect. 3 Galleries were not distributed randomly or evenly; minimum boundaries of stem diameter and bark thickness and a maximum boundary of height‐above‐ground were detected. Indications of maximum boundaries for stem diameter and bark thickness were also observed. Galleries were found most often on the south‐west side of the tree. 4 Using the technique of upper boundary regression, we were able to identify significant quadratic relationships between A. planipennis gallery density and stem diameter and bark thickness, as well as a significant negative linear relationship between gallery density and height‐above‐ground. 5 Agrilus planipennis gallery density in newly‐infested trees was lower than in previously‐infested trees, and was observed to peak at smaller stem diameters and bark thicknesses than in previously‐infested trees. 6 Survey teams would increase their probability of detecting new A. planipennis infestations by initiating searches for exit holes and feeding galleries in trunk sections and branches of approximately 7 cm in diameter.  相似文献   

2.
  • 1 Emerald ash borer Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is an invasive forest insect pest threatening more than 8 billion ash (Fraxinus spp.) trees in North America. Development of effective survey methods and strategies to slow the spread of A. planipennis requires an understanding of dispersal, particularly in recently established satellite populations.
  • 2 We assessed the dispersal of A. planipennis beetles over a single generation at two sites by intensively sampling ash trees at known distances from infested ash logs, the point source of the infestations. Larval density was recorded from more than 100 trees at each site.
  • 3 Density of A. planipennis larvae by distance for one site was fit to the Ricker function, inverse power function, and the negative exponential function using a maximum likelihood approach. The prediction of the best model, a negative exponential function, was compared with the results from both sites.
  • 4 The present study demonstrates that larval densities rapidly declined with distance, and that most larvae (88.9 and 90.3%) were on trees within 100 m of the emergence point of the adults at each site. The larval distribution pattern observed at both sites was adequately described by the negative exponential function.
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3.
Development of effective trapping tools for forest pests and evaluating the key components of these tools is necessary to locate early‐stage infestations and develop management responses to them. Agrilus planipennis Fairmaire (emerald ash borer) is an introduced pest of ash (Fraxinus spp. L.) in North America. The effectiveness of different trap and lure combinations were tested in areas with low and high density populations of A. planipennis. At low density sites, purple prism traps outperformed green traps and girdled ash trap trees in capture rates (adults per day) and rates of detection of A. planipennis. Also, manuka oil lures, used as a standard lure in a national survey programme, captured higher rates of A. planipennis than did previous standards of girdled ash trap trees. There was no logistic relationship between the detection of A. planipennis on a trap and the diameter of the ash tree from which the trap was suspended, possibly because of the use of artificial lures with these traps. There was also no difference in the mean number of A. lanipennis captured per day between ash species and between vigour rating of ash associated with the traps. However, traps placed in open grown and dominant trees captured more beetles than traps placed in lower canopy class trees. At sites defined as low and high density, there was no difference in the larval density per cm3 of phloem. This suggests that exposure time to A. planipennis has been shorter at those low density sites. By exploiting the trap and tree characteristics that improve A. planipennis capture rates and detection efficacy, there can be future improvement in management of this pest. If detection can occur before infested ash trees exhibit signs and symptoms, there may be a potential for reducing the mortality of ash within stands.  相似文献   

4.
Management programs for invasive species are often developed at a regional or national level, but physical intervention generally takes place over relatively small areas occupied by newly founded, isolated populations. The ability to predict how local habitat variation affects the expansion of such newly founded populations is essential for efficiently targeting resources to slow the spread of an invasive species. We assembled a coupled map lattice model that simulates the local spread of newly founded colonies of the emerald ash borer (Agrilus planipennis Fairmaire), a devastating forest insect pest of ash (Fraxinus spp.) trees. Using this model, we investigated the spread of A. planipennis in environments with different Fraxinus spp. distributions, and explored the consequences of ovipositional foraging behavior on the local spread of A. planipennis. Simulations indicate that increased larval density, resulting from lower host tree density or higher initial population sizes, can increase the spread rate during the first few years after colonization by increasing a density-dependent developmental rate and via host resource depletion. Both the radial spread rate and population size were greatly influenced by ovipositional foraging behavior. Two known behaviors of ovipositing A. planipennis females, attraction towards areas with high ash tree density and attraction to stressed trees, had opposing effects on spread. Results from this model illustrate the significant influence of resource distribution and foraging behavior on localized spread, and the importance of these factors when formulating strategies to monitor and manage invasive pests.  相似文献   

5.
Low impact alternatives to synthetic insecticides for the control of apple sawfly (Hoplocampa testudinea Klug) are scarce encumbering pest management in organic apple orchards. We investigated the soil persistence and field efficacy of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (BotaniGard) against apple sawfly under common organic orchard practices. We also assessed the efficacy of B. bassiana GHA and Metarhizium brunneum Petch (indigenous strain) against sawfly in the laboratory. Larvae treated with either fungus in the laboratory died faster than control larvae and displayed 49.4%–68.4% mycosis. In the field, B. bassiana density remained high in the week after application, during larval descent to the soil. Fungal density decreased to 25% at 49 d after application and to 0.4% after 55 weeks. Molecular markers revealed that the majority of fungal isolates recovered comprised the applied B. bassiana strain GHA. Larvae pupating in soil cages in the orchard for 49 d displayed 17% mycosis. The high efficacy under laboratory conditions was not seen in the field. B. bassiana application resulted in densities above the upper natural background level during the growing season, but reversion to background levels occurred within a year. It remains to be investigated whether this has a detrimental effect on nontarget organisms. Additional work is needed to bridge the knowledge gap between laboratory and field efficacy in orchards.  相似文献   

6.
Effective methods are needed to protect ash trees (Fraxinus spp.) from emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive buprestid that has killed millions of North American ash (Fraxinus spp.) trees. We randomly assigned 175 ash trees (11.5-48.1 cm in diameter) in 25 blocks located in three study sites in Michigan to one of seven insecticide treatments in May 2007. Treatments included 1) trunk-injected emamectin benzoate; 2) trunk-injected imidacloprid; 3) basal trunk spray of dinotefuran with or 4) without Pentra-Bark, an agricultural surfactant; 5) basal trunk spray of imidacloprid with or 6) without Pentra-Bark; or (7) control. Foliar insecticide residues (enzyme-linked immunosorbent assay) and toxicity of leaves to adult A. planipennis (4-d bioassays) were quantified at 3-4-wk intervals posttreatment. Seven blocks of trees were felled and sampled in fall 2007 to quantify A. planipennis larval density. Half of the remaining blocks were retreated in spring 2008. Bioassays and residue analyses were repeated in summer 2008, and then all trees were sampled to assess larval density in winter. Foliage from emamectin benzoate-treated trees was highly toxic to adult A. planipennis, and larval density was < 1% of that in comparable control trees, even two seasons posttreatment. Larval densities in trees treated with trunk-injected imidacloprid in 2007 + 2008 were similar to control trees. Dinotefuran and imidacloprid were effectively translocated within trees treated with the noninvasive basal trunk sprays; the surfactant did not appreciably enhance A. planipennis control. In 2008, larval densities were 57-68% lower in trees treated with dinotefuran or imidacloprid trunk sprays in 2007 + 2008 than on controls, but densities in trees treated only in 2007 were similar to controls. Highly effective control provided by emamectin benzoate for > or = 2 yr may reduce costs or logistical issues associated with treatment.  相似文献   

7.
The emerald ash borer (Agrilus planipennis) is a destructive invasive beetle that has caused mortality of millions of Fraxinus spp. trees in North America. The extended interval between insect establishment, detection and management has allowed this pest to spread over large parts of North America. Artificial purple canopy traps are currently used in national detection surveys for this beetle. The effectiveness of purple canopy traps at low‐to‐moderate A. planipennis population densities in relation to road proximity was evaluated in 2013 and 2014. Transects of traps were established at set distances from roads in northern Michigan near an isolated A. planipennis infestation. It was hypothesized that trap effectiveness is influenced by road proximity, and that traps placed closer to roads were more likely to detect A. planipennis. A significant relationship was established between the mean number of A. planipennis captured on traps and road proximity (nearness), while no significant relationship was observed between detection success and road proximity. These findings suggest establishing traps further from roads (which can be less economically efficient) provides no greater likelihood of detection than establishing traps on or near the road edge. Basal area of non‐ash and ash species, beetle population density, vigour rating, ash tree species and sampling duration were shown to significantly influence the number of A. planipennis captured on traps.  相似文献   

8.
  1. Indigenous artisans in the Great Lakes region rely on the ring‐porous property of black ash Fraxinus nigra Marshall (Oleaceae), which allows annual layers of xylem to be easily separated to make baskets that are important economic resources and vessels of culture.
  2. The emerald ash borer Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is threatening North America's ash resource, including black ash and this centuries‐old art form, resulting in grave concern about the availability of black ash trees for basketmaking and about movement of black ash (along with A. planipennis) from areas where it is cut to lands where it is pounded and split to make baskets.
  3. We evaluated the traditional practice of storing black ash logs submerged in water as a possible method for killing within‐tree life stages of A. planipennis at the same time as preserving the wood's value for basketmaking.
  4. Black ash trees infested with overwintering A. planipennis larvae were felled and cut into 60‐cm bolts in 2010 and in 2011. These were submerged in a river for different lengths of time and, after treatment, placed into rearing tubes to determine survival and adult emergence, or dissected within 24 h to determine larval mortality, and then pounded and peeled into splints to assess colour and pliability.
  5. In 2010, all A. planipennis larvae had died and no adults emerged from logs submerged in spring for 10 weeks or longer, whereas some larvae survived and adults emerged from logs submerged for up to 9 weeks.
  6. In 2011, submergence for 18 weeks during winter or 14 weeks in spring resulted in complete mortality of A. planipennis larvae and no emergence of adults at the same time as still preserving wood quality for basketmaking.
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9.
  1. In its native range in Asia, emerald ash borer (EAB; Agrilus planipennis Fairmaire) is a secondary colonizer of its coevolved hosts, including Manchurian ash (Fraxinus mandschurica Ruprecht). However, why larval performance is enhanced on stressed trees remains to be determined.
  2. We examined the mechanisms that may reduce the resistance of stressed Manchurian ashes. Trees in a common garden were girdled or left untreated as controls and both treatments were inoculated with EAB eggs. Larvae and bark tissue were harvested after feeding and larval performance so that the defensive mechanisms and nutritional quality of bark tissue could be assessed.
  3. Larval survival and mass was twice as high on girdled trees, although girdling had no effect on bark phenolics. The activity of two enzymes involved in wound repair and lignification (peroxidase and cinnamic alcohol dehydrogenase) was increased by girdling in bark tissue. Starch and total protein levels declined in girdled stems, although sugar content was unchanged. Total disulphide levels, a measure of protein oxidative damage, were increased by girdling, although no difference in lipid oxidative damage in ash phloem tissue was detected.
  4. Girdling ash increased larval performance even though it elevated some wound repair mechanisms and decreased some indices of plant nutritional quality. Other tree responses to girdling also were poor predictors of larval performance. It appears that mechanisms of stress‐induced variation in resistance of Manchurian ash to EAB differ from those that may explain interspecific variation in resistance.
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10.
  1. A recent invader to North America, emerald ash borer Agrilus planipennis Fairmaire (Buprestidae), is expanding its western range into new habitats. We examined how site factors affect the emergence and damage caused by this beetle on the western edge of its contiguous population in eastern Wisconsin, U.S.A. We characterized forest structure and quantified signs and symptoms of A. planipennis from 2010 to 2013.
  2. We evaluated the potential for establishment of three host‐specific parasitic Hymenoptera, released as biological control agents of A. planipennis. During June to September 2011, we conducted releases of 1500 Oobius agrili Zhang and Huang (Encyrtidae), 1900 Spathius agrili Yang (Braconidae) and 2700 Tetrastichus planipennisi Yang (Eulophidae) at the same location.
  3. Signs and symptoms of A. planipennis increased in abundance during the present study. Emergence of A. planipennis was greater in larger diameter trees and in subplots with more ash trees. More epicormic shoots were on the upper halves of trees in subplots with a higher percentage of ash. Fraxinus nigra exhibited a higher incidence of ruptured bark than Fraxinus pennsylvanica.
  4. In January 2013, we felled four infested ash trees and censused insect emergence from the entire trees. We recovered 441 A. planipennis, 41 T. planipennisi and no other released parasitoids.
  5. These results suggest that, of these three parasitoids, T. planipennisi has the highest likelihood of contributing to biological control in Wisconsin, although ash mortality will proceed rapidly and likely supersede the effects of the parasitoids. The best opportunity for introduced parasitoids to benefit Wisconsin may arise in post‐outbreak, recovering forests.
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