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, Orchestes fagi L. (formerly Rhynchaenus fagi, Coleoptera: Curculionidae), in its invasive range of Nova Scotia, Canada. Outbreaks of O. fagi cause tree-wide leaf necrosis in American beech (Fagus grandifolia 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 the end of budburst, but before the larval mine expanded. This strongly suggested that leaf necrosis may be linked to damage caused by adults or by mine initiation rather than that caused by larval mine expansion and gallery development. The density of O. fagi 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 O. fagi.
The beech leaf-mining weevil (Orchestes fagi L. (Coleoptera: Curculionidae)) is widespread in its native Europe and has recently been introduced to North America. Its leaf-mining larvae feed ...exclusively on beech (Fagus L. (Fagaceae)) species. They form a linear mine from the oviposition site on the midrib to the leaf margin and cause extensive wilting and browning of leaves. No other leafminers occurring in North America cause similar damage to beech. Adults also feed on expanding beech leaves in spring, causing scattered "shot" holes. In Europe, the beech leaf-mining weevil does not cause mortality in the Palearctic species European beech (Fagus sylvatica L.), despite occasional outbreaks in European beech forests that cause defoliation, lower fruit production, and retard growth. In North America, the first adult specimens of beech leaf-mining weevil were collected in 2012 in Nova Scotia, Canada, in Halifax, Lunenburg, and Cape Breton counties, where they were associated with American beech (Fagus grandifolia Ehrh).
Purpose
The woolly beech aphid thrives on European beech leaves, which has complex direct and indirect impacts on above- and belowground processes. A mechanistic understanding of insect-mediated ...changes in organic carbon (OC) availability for microbial life and its implications for element cycling is still lacking. This study aims at disentangling aphid-induced effects on phyllosphere and rhizosphere bacterial communities, as well as investigating feedbacks to OC transfer from the canopy to the mineral soil.
Methods
Following 2.5 months of infestation, we tracked the fate of OC (
13
CO
2
pulse-labelling) in several compartments of beech sapling – soil mesocosms over 5 days. In ecosystem solutions, water extracts and soil/plant compartments we determined OC and N and solid δ
13
C. Bacterial community structure (16S rRNA gene targeted amplicon sequencing and quantitative PCR) and metabolite profiles (LC-qTOF-MS) were analysed.
Results
We found significantly higher aphid-mediated inputs of OC within throughfall. Honeydew-derived C on infested leaves was inconsequential for total phyllosphere bacterial abundances, but verifiably affected the community structure. In all soil compartments, cold-water extractable OC pools declined significantly by frequent inputs of readily available OC. This pattern might relate to reductions in rhizodepositions and altered microbial processing by accelerated soil C-mineralization. As a result, the abundance of metabolites changed significantly in different ecosystem solutions.
Conclusions
Our findings attest that insect infestations induce distinct direct and indirect effects on plant-insect-microbiome interactions leading to marked alterations in C dynamics. This integrated approach improves our understanding on microbial dynamics and biogeochemistry and evaluates the role of insects for ecosystem processes.
Leafminers are a taxonomically diverse group of endophagous insects. A number of them are pests in forestry, horticulture and agriculture, and some of them have become important invasive species. ...Here, we discuss the characteristics of invasive leafminers of woody plants. We first present 12 cases of invasive leaf-mining species belonging to four different insect orders. For each of them, we briefly describe their invasion, including pathways of introduction, their impact and management methods and their ecology. We then discuss various aspects of these invasions. Leafminers are introduced to new continents and spread through various pathways such as horticultural trade and accidental transport of adults and pre-imaginal stages in containers and vehicles. They may also spread long distances with air currents. A few species have serious economic impacts as orchard pests, such as the citrus leafminer,
Phyllocnistis citrella
, or as pests of ornamental plants, such as the horse-chestnut leafminer,
Cameraria ohridella
. The ecological impact of these species should be better studied, especially those killing native trees, such as the birch leaf-mining weevil,
Orchestes fagi
, in Canada. Compared to other insect groups, invasive leafminers are usually recruited by a range of native parasitoids, which may or may not succeed in controlling the invasive species. Biological control by introduction of parasitoids from the native range has often been successful to control invasive leafminers. The review ends by short discussions on taxonomic issues and on the use of leafminers as models to study invasion ecology.
This paper discusses three problems concerning the Woodland Grayling, Hipparchia fagi Scopoli, 1763, with respect to the identity and application of the junior name Papilio hermione Linnaeus, 1764. ...In 1977, the late Otakar Kudrna designated a specimen of the Rock Grayling, Hipparchia alcyone Denis & Schiffermüller, 1775, to become the lectotype of Papilio hermione - as a result of which hermione supplanted alcyone as the senior epithet for this species. Because P. hermione is the nominal type species of Hipparchia Fabricius, 1807, Kudrna's action rendered this a genus based on a misidentified species. Third, while a majority of lepidopterists have ignored Kudrna's action and continue to apply the name H. alcyone to the Rock Grayling, and still regard P. hermione as a junior subjective synonym of H. fagi, the formal nomenclature for the Rock Grayling has become unstable because a large minority have nonetheless accepted Kudrna's lectotype designation and all that follows from it. It is demonstrated here that no syntypes of Papilio hermione (or Papilio fagi) have survived; consequently, Kudrna's lectotype designation for P. hermione is invalid. By designation of a single specimen of the Woodland Grayling as neotype for both P. fagi and P. hermione, the two names are rendered objectively synonymous, thereby restoring stability to the species name for the Rock Grayling (as Hipparchia alcyone), and to the application of Papilio hermione (= Hipparchia fagi) as nominal type species of the generic name Hipparchia.
Mass outbreaks of herbivore insects perturb the functional properties of forests, by substantially altering water and nutrient cycling of infested trees. Less clear is how low to moderate herbivory ...affects the vertical flow of nutrients from trees to the soil. We report on the effects of low to moderate infestation levels of the woolly beech aphid (Phyllaphis fagi L.) on the nutrient dynamics and hydrology of European beech (Fagus sylvatica L.). We traced the vertical dynamics of macro and micronutrients via throughfall (TF), stemflow (SF) and Oa litter leachates from potted saplings underneath infested and uninfested control trees. The low infestation levels were insufficient to significantly alter TF and litter leachate composition, although, on average, the release of K and DOC and the immobilization of N (NH₄–N) in TF solution were more pronounced under aphid infestation. SF chemistry was significantly altered by aphid activity exhibiting intensified fluxes of K (+159 %), Mg (+82 %), Mn (+93 %), S (+86 %), SO₄–S (+62 %), DOS (+137 %), DOC (+51 %) and DON (+62 %), compared to control trees. SF is likely enriched by low and mid-level aphid activity due to its increased residence time in the canopy. It has interaction with large areas of aboveground vegetative surface area representing a cumulative flux of solutes and particulates from both foliar and woody surfaces from above-lying portions of the canopy. Accordingly, SF might be a useful indicator to evaluate the impact of sap- and leaf-feeding herbivores on forest ecosystems.
Bukva predstavlja jednu od najvažnijih vrsta drveća u Bosni i Hercegovini. Stoga, potrebno je praćenje zdravstvenog stanja bukovih sastojina i poduzimanje svih neophodnih preventivnih i represivnih ...mjera kako bi se zdravstveno stanje ovih sastojina unaprijedilo. U okviru istraživanja analiziran je utjecaj bukove skočipipe na površinu oštećenja listova na stabalcima bukve od imaga i ličinke u ovisnosti od lokacije i položaja stabalaca bukve u sastojini (svjetlo/sjena). Lokacije istraživanja su se nalazile unutar kulture smreke, visokih šuma bukve i mješovitih šuma bukve i jele sa smrekom. Bukova skočipipa predstavlja jednog od glavnih defolijatora koji se javljaju na stablima bukve. Uzorak istraživanja čine 15 stabalaca bukve, po 5 stabalaca na tri lokacije. Na svakoj lokaciji odabrana su 3 stabalca čija krošnja je bila na svjetlu i dva stabalca čija krošnja je bila u sjeni (ukupno 9 stabalaca na svjetlu i 6 stabalaca u zasjeni). Na svakom stablu pregledavana su i mjerena oštećenja od imaga i ličinke bukove skočipipe. Ustanovljeno je da prosječna površina oštećenja lista bukve od imaga je varirala od 2-4%, a ličinke od 4-8%. Statističkim analizama je utvrđeno postojanje statistički značajnih razlika u površini oštećenja lista bukve od ličinke u ovisnosti od položaja stabalaca bukve u sastojini.
The impact of beech weevil on the damaged area of beech trees from adult and larvae was analyzed, depending on the location and position of trees of beech in stand (sun/shadow). The research localities were located within the forest plantation of spruce, natural beech forests and mixed beech, fir and spruce forests. Beech weevil represents one of the main defoliators appearing on beech trees. The research sample consists of 15 beech trees, 5 trees per location, on three locations. On each location, were selected 3 trees with the crown in the sun and 2 trees with the crown in the shade (a total of 9 trees in the sun and 6 trees in the shade). On each tree were measured damages from the adult and larvae of beech weevil. It has been found that the average damaged area on beech leaf varied for adult from 2-4%, and larvae 4-8%. Statistical analysis showed a statistically significant differences in damaged areas of beech leaf from larvae, depending on the position of beech trees in the stand.
Venturiales Shen, M.; Zhang, J.Q.; Zhao, L.L. ...
Studies in mycology,
06/2020, Volume:
96, Issue:
1
Journal Article
Peer reviewed
Open access
Members of Venturiales (Dothideomycetes) are widely distributed, and comprise saprobes, as well as plant, human and animal pathogens. In spite of their economic importance, the general lack of ...cultures and DNA data has resulted in taxa being poorly resolved. In the present study five loci, ITS, LSU rDNA, tef1, tub2 and rpb2 are used for analysing 115 venturialean taxa representing 30 genera in three families in the current classification of Venturiales. Based on the multigene phylogenetic analysis, morphological and ecological characteristics, one new family, Cylindrosympodiaceae, and eight new genera are described, namely Bellamyces, Fagicola, Fraxinicola, Fuscohilum,Neofusicladium, Parafusicladium, Pinaceicola and Sterila. In addition, 12 species are described as new to science, and 41 new combinations are proposed. The taxonomic status of 153 species have been re-evaluated with 20 species excluded from Venturiales. Based on this revision of Venturiales, morphological characteristics such as conidial arrangement (solitary or in chains) or conidiogenesis (blastic-solitary, sympodial or annellidic), proved to be significant at generic level. Venturia as currently defined represents a generic complex. Furthermore, plant pathogens appear more terminal in phylogenetic analyses within Venturiaceae and Sympoventuriaceae, suggesting that the ancestral state of Venturiales is most likely saprobic.
The beech leaf-mining weevil, Orchestes fagi (L.), is native to Europe where it commonly attacks European beech. The weevil was discovered infesting American beech in Halifax and Cape Breton Island, ...Nova Scotia, Canada in 2012, but anecdotal reports of defoliated beech in the Halifax area as early as 2006 suggest it established 5–10 years prior to its discovery. Our objectives were to estimate the impact of O. fagi on American beech in forested sites and urban areas, as well as its economic impact on owners of residential properties with mature American beech. In 2014, we established fifteen plots in forested sites containing a total of 260 American beech at Sandy Lake, Oakfield, and Mount Uniacke (n = 5 plots per site), where weevil infestation levels were moderate, low, and nil, respectively. At the same time we recorded the degree of cankering by beech bark disease on the main stems of each tree. Plots were visited annually to record tree mortality (2014–2019) and percentage of leaves with larval mines or adult feeding (2016–2019). Between 2016 and 2019, the percentage of leaves mined by weevil larvae increased from 6 to 59% at Mount Uniacke and from 48 to 83% at Oakfield. During the same period, cumulative beech mortality increased from 35 to 48% at Mount Uniacke and from 10 to 70% at Oakfield. At Sandy Lake in 2016, 88% of the beech trees had died and there were too few living beech to collect a leaf sample in our plots so estimates of weevil damage (87% of leaves with mines) were obtained from life table plots in the same area. Tree mortality was associated with severity of cankering by beech bark disease only at Mount Uniacke, the site with the fewest years of defoliation by the leaf-mining weevil. We also surveyed residents of Halifax in 2016 and 2018 to determine the rate of beech mortality and costs of tree removal in urban residential areas in the same region (within 40 km) of the forest areas. Relative to the forested sites at Sandy lake and Oakfield, mortality rates were lower in urban areas (32% in 2016, 44% in 2018), even though signs of weevil defoliation had been apparent to residents as early as 2011–2012. Direct costs ($CAN) to property owners who hired arborists to remove dead beech trees averaged $1934 ($300–$6600) per resident in 2018. Options for mitigating the impact of O. fagi on American beech are briefly discussed.
We investigated auditory signals and morphology of the stridulatory apparatus of the European beech leaf‐mining weevil, Orchestes fagi L. (Coleoptera: Curculionidae), an invasive herbivore now ...established in Nova Scotia, Canada, to determine their potential for enhancing survey tools to monitor the spread of the species in Canada. We recorded and described sounds produced by adult O. fagi, analyzed the morphology of the stridulatory mechanism for intersexual differences and asymmetry, and examined behavioral responses elicited in conspecifics by playback of stridulation recordings. Adult O. fagi produced sounds under three conditions: male in distress, female in distress, and male in the presence of female. Female distress chirps lasted significantly longer than male distress chirps and male chirps in the presence of females, but peak frequencies and mean number of chirps per s did not differ significantly among the three groups. Morphology of the stridulation structures in male and female O. fagi was compared using scanning electron microscopy. Orchestes fagi have an elytro‐tergal file‐ and scraper‐type sound production apparatus, through which sound is produced upon anterior motion of the abdomen. Female O. fagi have a ‘pars stridens’ that is longer and has more ridges than males. Width and number of ridges per length of pars stridens did not differ between the sexes. Evidence of asymmetry was found in male pars stridens, with the right side being longer than the left. Playback of recorded sounds to adult weevils suggests female O. fagi were repelled by sounds produced by distressed males.
We investigated auditory signals and morphology of the stridulatory apparatus of adult Orchestes fagi (Coleoptera: Curculionidae), an invasive herbivore in Nova Scotia, Canada. We described sounds, and the stridulatory mechanism, and examined behavioral responses by playback of stridulation recordings. Females have a pars stridens that is longer and has more ridges than males, evidence of asymmetry was found in male pars stridens (the right side being longer), and playback of recorded sounds suggests females were repelled by distressed males.
PDF
