Relationships between pest density and associated leaf necrosis for an invasive leaf-mining weevil, Orchestes fagi L., on American beech (Fagus grandifolia Ehrh.)

Author(s):  
Sara Edwards ◽  
Garrett Brodersen ◽  
Cory Hughes ◽  
Keegan Moore ◽  
Benoit Morin ◽  
...  

Pest density-plant damage relationships are essential guides for decision-making in Integrated Pest Management. In this article, we established pest density-leaf damage relationships for the beech leaf-mining weevil,<i></i> Orchestes fagi <i></i>(L.) (formerly <i></i>Rhynchaenus fagi<i></i>, Coleoptera: Curculionidae) in its invasive range of Nova Scotia, Canada. Outbreaks of<i> O. fagi</i> cause tree-wide leaf necrosis in American beech (<i>Fagus grandifolia</i> Ehrh.), which can eventually result in tree mortality. In 2014 and 2016, we collected weekly samples in stands with American beech and assessed leaves for densities during different life stages (eggs, larvae, and pupae), population proxy measures (adult feeding damage, egg slits, and larval galleries), and percent necrosis. In general, feeding damage and leaf necrosis plateaued soon after end of budburst, but before larval mine expanded. This strongly suggested that leaf necrosis may be linked to damage caused by adults or mine initiation rather than that caused by larval mine expansion and gallery development. Density of <i>O. fagi</i> per leaf for life stages and population proxies all significantly explained ~ 42–81% of the variation in end-of season percent leaf necrosis. Results from this study provide a variety of relationships that could be used in both short- and long-term monitoring efforts for <i>O. fagi</i>.

2007 ◽  
Vol 56 (1-6) ◽  
pp. 163-169 ◽  
Author(s):  
M. Ramirez ◽  
J. Loo ◽  
M. J. Krasowski

Abstract Scions collected from diseased trees and from those without symptoms of beech bark disease (BBD) were cleft-grafted in 2003 and 2004 onto rootstock of unknown resistance to BBD. Grafting success varied among genotypes and year (30% in 2003 and 12% in 2004), and improved with increasing rootstock diameter. Successful grafts were used to test resistance to the beech scale insect, Cryptococcus fagisuga (the initiating agent of BBD) by introducing eggs onto the bark of scions and allowing time for the emergence of all developmental stages of the insects. Significantly fewer insects colonized scions collected from putatively resistant trees than those collected from diseased trees. In some cases, where egg placement overlapped a portion of the rootstock, insect colonies developed on the rootstock but not on the scion collected from resistant trees. Occasionally, scions from putatively resistant trees were colonized, whereas some of those from diseased trees were not. When scions from putatively resistant trees were heavily colonized, only adult insects were present and no eggs or other life stages of the insect were found. The findings indicate that the extent of resistance to the scale insect (hence to BBD) ranges from partial to total resistance.


2016 ◽  
Vol 149 (1) ◽  
pp. 129-137 ◽  
Author(s):  
Andrew Morrison ◽  
Jon Sweeney ◽  
Cory Hughes ◽  
Rob C. Johns

AbstractWe investigated the potential for human-mediated range expansion of an exotic beech leaf-mining weevil, Orchestes fagi (Linnaeus) (Coleoptera: Curculionidae: Curculioninae: Rhamphini) (formerly known as Rhynchaenus fagi) on timber or firewood, which for eight to nine months of the year may harbour adults in diapause. In both relatively low-density and high-density populations, adults were found on the base, middle, and upper boles of the primary host, American beech (Fagus grandifolia Ehrhart; Fagaceae), as well as red maple (Acer rubrum Linnaeus; Sapindaceae) and red spruce (Picea rubens Sargent; Pinaceae) in the vicinity. Comparatively few individuals were found on tree branches, or in the moss, duff, or soil collected beneath beech trees. Overwintering adults appeared to favour parts of trees with relatively high bark roughness. Our study suggests that, between the months of July through May, any woody stems near areas having O. fagi outbreaks are likely to harbour adults. Moreover, as all of the trees studied are common sources of timber or firewood, the harvest and transport of wood from these areas may facilitate outbreak spread; this may explain the multiple, distantly distributed populations of O. fagi that have been reported in eastern Nova Scotia, Canada in recent years.


1998 ◽  
Vol 76 (12) ◽  
pp. 2037-2041 ◽  
Author(s):  
Vladimir Vujanovic ◽  
Marc St-Arnaud ◽  
Peterjürgen Neumann ◽  
J André Fortin

Diarimella laurentidae, a new species occurring on dead bark and decorticated twigs of American beech (Fagus grandifolia Ehrh.), is reported from the Muir's Wood ecological reserve, located in the centre of the Haut-Saint-Laurent region in the province of Quebec. Diarimella laurentidae is characterized by stromatic, pulvinate, black, setose fructifications composed of a basal stroma of textura angularis, a brown peripheral wall of textura porrecta, conidiomatal setae of two types, and unicellular multisetulate conidia. Its relationships with described Diarimella species is discussed. This is the first report of a species of Diarimella from North America.Key words: Diarimella laurentidae, new fungus species, coelomycete, Fagus grandifolia.


2015 ◽  
Vol 45 (6) ◽  
pp. 632-638 ◽  
Author(s):  
Kim Bannon ◽  
Sylvain Delagrange ◽  
Nicolas Bélanger ◽  
Christian Messier

Studies have reported divergent results on the effect of soil fertility and canopy opening on understory density and growth of sugar maple (AS; Acer saccharum Marsh.) and American beech (FG; Fagus grandifolia Ehrh.). The main objective of this study was to evaluate the effect of a gradient of canopy opening and soil fertility on the density and growth of AS and FG saplings in southwestern Quebec, Canada. We investigated 56 stands containing both AS and FG that were subjected to different disturbance history types (DHTs) (UF, unmanaged forest; PC, partial cut; and CC, clearcut) on various soil types. AS and FG absolute and relative sapling density varied greatly among the 56 stands; however, no significant effects of DHT, soil nutrient availability, or their interaction were found. Both species responded positively in terms of radial growth to canopy openings, with FG growth being slightly better than AS growth in PC stands compared with other canopy treatments. Contrary to our hypothesis, AS did not show significantly higher growth than FG following clear-cutting. These results do not support the idea that AS abundance and growth could be promoted by increasing the intensity of the canopy opening during harvest, at least on the generally acidic and base-poor soils that were investigated.


2009 ◽  
Vol 39 (12) ◽  
pp. 2273-2282 ◽  
Author(s):  
Louis Duchesne ◽  
Rock Ouimet

Recently, sugar maple ( Acer saccharum Marsh.) decline in northeastern North America has been regarded as a major factor structuring hardwood forests by favouring American beech ( Fagus grandifolia Ehrh.) in the understory of maple-dominated stands. To determine whether soil fertility differences associated with sugar maple decline may have promoted the expansion of American beech, we explored the relationships between the soil base status and the sapling and tree strata density and composition, using data from 426 permanent sample plots distributed throughout Quebec. Our results indicate that American beech is currently expanding in the sugar maple range of Quebec. The abundance and proportion of American beech in the sapling stratum are mainly associated with the proportion of American beech in the tree stratum, the relative basal area of dead sugar maple trees, and the base status of soils. In accordance with the many studies reporting on the high sensitivity of sugar maple to the acid–base status of soils and the decline of the sugar maple population, this study supports the hypothesis that soil base cation depletion, caused in part by atmospheric acid deposition, is among the main factors involved in the present-day expansion of American beech over a large area in Quebec.


2007 ◽  
Vol 24 (1) ◽  
pp. 14-21 ◽  
Author(s):  
Jodi A. Forrester ◽  
Kimberly K. Bohn

Abstract Forest management in northern hardwoods benefits from the use of site preparation treatments when the amount of American beech (Fagus grandifolia Ehrh.) and fern species in the understory interferes with regeneration of more desirable species, e.g., sugar maple (Acer saccharum Marshall). We assessed the cover and diversity of herbaceous and woody species in the ground layer of three Adirondack northern hardwood stands before and 3 years after a mechanical site preparation that removed all trees less than 14 cm with a brush saw. The treatment significantly increased the cover of all species cumulatively, with herbaceous, shrub, and arborescent species increasing significantly more in treated plots than in untreated plots. Sugar maple cover increased more in treated plots than in untreated plots, although American beech did as well. Species richness increased significantly more in treated plots than in untreated plots, but differences in diversity and evenness were not significantly different because of treatment after 3 years. Multivariate analysis indicated only minor changes in the plant community composition. Results show that mechanical site preparation techniques are a viable option for promoting abundance and maintaining diversity of the ground-layer vegetation in northern hardwood forests.


2020 ◽  
Vol 25 (12) ◽  
pp. 2286-2299
Author(s):  
Xia Chen ◽  
Li Sun ◽  
Yu-ping Zhang ◽  
Yan-xuan Zhang ◽  
Jian-zhen Lin

To identify the searching ability of avermectin-resistant and susceptible strains of Neoseiulus cucumeris (Oudemans), the responses of the two strains to stimuli from Tetranychus urticae Koch on sweet potato leaves were examined in the laboratory. The results showed that avermectin-resistant and susceptible adult N. cucumeris females responded to different stages and intact webs (spider mite, egg, feces, and leaf damage) of T. urticae, but not to the destroyed webs and feces of and feeding damage by T. urticae. Moreover, no significant differences were observed in the responses of the avermectin-resistant and susceptible strains of N. cucumeris. Both strains of N. cucumeris were often observed inside the intact webs of T. urticae. These results show that the avermectin-resistant and susceptible strains of N. cucumeris have the ability to search actively for T. urticae on sweet potato leaves. This behavior clearly increases the searching efficiency of N. cucumeris and may help its use in the biocontrol of T. urticae.


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