Long-term impact of a leaf miner outbreak on the performance of quaking aspen

2013 ◽  
Vol 43 (6) ◽  
pp. 563-569 ◽  
Author(s):  
Diane Wagner ◽  
Patricia Doak

The aspen leaf miner, Phyllocnistis populiella Cham., has caused widespread and severe damage to aspen in the boreal forests of western North America for over a decade. We suppressed P. populiella on individual small aspen ramets using insecticide at two sites near Fairbanks, Alaska, annually for 7 years and compared plant performance with controls. Insecticide treatment successfully reduced leaf damage by P. populiella during most years and had little effect on herbivory by externally feeding invertebrates. By the end of the study, control ramets had suffered a reduction in height and girth relative to treated ramets and to the original, pretreatment size. Control ramets produced smaller leaves during some years and, after 7 years, produced fewer total shoots and leaves than ramets sprayed with insecticide. Treatment did not affect mortality, but at the warmer of the two sites, ramets sustaining ambient levels of leaf mining were significantly more likely to die back to basal sprouts than those treated with insecticide. We conclude that a decade of P. populiella outbreak has caused strongly negative effects on aspen development and the production of aboveground tissues.

2007 ◽  
Vol 85 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Patricia Doak ◽  
Diane Wagner ◽  
Adam Watson

Extrafloral nectaries (EFNs) are secretory glands most commonly linked to defensive mutualisms. Both a plant’s need for defense and the strength of defense provided by mutualists will vary with plant condition and local insect community. Thus, the benefit of EFNs may vary spatially and temporally. However, little attention has been paid to natural variation in the presence and abundance of EFNs within and among individuals of the same species. Quaking aspen, Populus tremuloides Michx., bear EFNs on a subset of their leaves. Here, we describe patterns of EFN expression on shoots within ramets, among ramets, and among putative clones in interior Alaska. We also examine the relationship between EFN presence and herbivory by both the very abundant aspen leaf miner, Phyllocnistis populiella Chambers, and less common chewing herbivores. The proportion of leaves bearing EFNs varied from 33% to 87% among distinct aspen stands. Within stands, short (1–2 m height) ramets had higher EFN frequency than their taller (>4 m) neighbors. Patterns of herbivory also differed between short and tall ramets. Compared with leaves without EFNs, those with EFNs suffered less mining damage on short ramets but slightly higher damage on tall ramets. Tall ramets suffered more chewing damage than short ramets, but this damage was unrelated to the presence of EFNs. Our results suggest that variable EFN expression may be explained by variation in the benefits of EFNs. Leaves with EFNs on short ramets benefit through reduction in leaf mining, but this benefit does not extend to tall ramets or other forms of herbivory.


2021 ◽  
Author(s):  
Nina Sajna ◽  
Tjaša Štruc ◽  
Maarten de Groot

Abstract Insect herbivores, whose larval stages live and feed inside a plant leaf, are expected to have an impact on the leaf beyond the actual tissue damage. They might influence leaf photosynthesis. Here, we provide a brief insight by studying a simple model relationship between the spring geophyte ramsons Allium ursinum with short-lived green leaves and its oligophagous, leaf-mining hoverfly Cheilosia fasciata. We expected that the effect of leaf miners on short-lived leaves could interfere with resource allocation for the next season. Measurements of leaf greenness and chlorophyll fluorescence were performed to evaluate the stress impact of leaf miner damage upon photosynthesis during the short vegetative season of ramsons. Results showed that the onset of leaf senescence occurred earlier in infested leaves, which was also indicated by lower maximum efficiency of photochemistry compared to non-infested leaves. There was no evidence that infested leaves were able to compensate for the damage by increasing the rate of photosynthesis. Given the short lifespan of leaves and the earlier onset of senescence in infested leaves, we discuss two differential hypotheses: negative effects for the plant if the larvae have already left the mine, and negative effects for the leaf miner if the larvae are still developing inside the leaf.


2005 ◽  
Vol 13 (2) ◽  
pp. 21-50 ◽  
Author(s):  
Martin Lavoie ◽  
David Paré ◽  
Nicole Fenton ◽  
Arthur Groot ◽  
Kim Taylor

The Clay Belt region of Quebec and Ontario supports a large forest resource and an important forest industry. In this region, the majority of the harvested volume allotted to forest companies is in forested peatlands and boreal forests prone to paludification. Paludification is the accumulation of organic matter over time, and is generally believed to be caused by increasing soil moisture and Sphagnum colonization. Paludification is influenced by external and internal factors; it reduces soil temperature, decomposition rates, microbial activity, and nutrient availability. As a result, paludification may lead to lower site productivity with time after disturbance. Therefore, in harvested stands with a thick organic matter layer, low soil disturbance (as opposed to fire) and water table rise may create favourable conditions for paludification that may ultimately be detrimental to timber production. Past experiences suggest several solutions to prevent or control the negative effects of paludification. Drainage and fertilization applied together are generally good techniques to control paludification and to improve tree productivity. On the other hand, we suggest that site preparation as well as prescribed burning, preceded or not by drainage, are avenues of research that deserve to be explored because they hold the potential to control or even reverse paludification, especially where peat accumulation is caused by natural succession or where lateral peat expansion has occurred. Key words: paludification, forested peatland, productivity, wildfire, careful logging, soil disturbance.


Botany ◽  
2018 ◽  
Vol 96 (8) ◽  
pp. 491-497 ◽  
Author(s):  
Diane Wagner ◽  
Patricia Doak

The genus Salix L. tends to be tolerant of herbivory, but severe outbreaks of herbivorous insects may compromise growth. First documented in Alaska in 1991, the willow leaf blotch miner, Micrurapteryx salicifoliella, is now responsible for frequent and widespread foliar damage to Salix in interior Alaska. We experimentally tested the effect of leaf mining on the performance of four susceptible Salix species across two years of outbreak, and placed the results in the context of a broader survey of leaf mining damage. Across the four species, reduction of leaf mining damage increased average stem elongation, numbers of leaves per shoot, and leaf area. Leaf mining damage was negatively related to leaf water content; a consequence of the leaf miner’s habit of breaching the cuticle on the underside of leaves. Growth deficits due to leaf mining are likely caused by both the loss of leaf tissue to leaf miner feeding and subsequent leaf desiccation. The results are notable in the context of a general decline in productivity in interior Alaska over the past few decades and because the leaf miner impacts Salix species also used by vertebrate browsers of cultural and economic importance, such as moose.


2012 ◽  
Vol 42 (1) ◽  
pp. 123-133 ◽  
Author(s):  
Guylaine Bois ◽  
Louis Imbeau ◽  
Marc J. Mazerolle

As short-term effects of partial cuts generally decrease available cover for snowshoe hare ( Lepus americanus Erxleben), most studies have shown negative effects of such treatments on this keystone species in boreal ecosystems. This study aims to determine the long-term impact of commercial thinning on snowshoe hare habitat, and we hypothesized that habitat quality, as well as habitat use, recovers with time since treatment. We selected stands aged 50–90 years dominated by black spruce ( Picea mariana (Mill.) Britton, Sterns & Poggenb.) in Abitibi (Quebec). We used models of habitat parameters to explain the abundance of snowshoe hare tracks and pellets in 20 commercially thinned stands treated between 1989 and 1999 and 12 control stands. Lateral cover was the dominant parameter influencing snowshoe hare habitat use. On average, commercially thinned stands had a lower lateral cover than controls (–18%). We also found that snowshoe hare use of commercially thinned stands increases with time since treatment. However, 11–18 years are needed before commercially thinned stands return to the same level of lateral cover and snowshoe hare signs as control stands. Commercial thinning is generally followed by harvesting all merchantable stems 15 years after treatment. Thus, we suggest that commercial thinning as currently practiced should be avoided if the objective is to maintain quality habitat for snowshoe hare and its associated predators.


2000 ◽  
Vol 16 (3) ◽  
pp. 447-464 ◽  
Author(s):  
Pilar Angulo-sandoval ◽  
T. Mitchell Aide

Variation in herbivory is often associated with plant density and light environment. The effect of these variables was studied on leaf production and herbivory of Manilkara bidentata in Puerto Rico. The major herbivore of M. bidentata is the leaf miner Acrocercops sp. To determine the effect of plant density, twenty-four 20-m × 20-m plots were established and the densities of saplings, juveniles and adults were determined. Leaf production, herbivory and growth were measured on saplings. Plant density was determined in eight 20-m × 20-m plots surrounding the focal plots. The effect of light was determined by comparing leaf phenology, leaf quality and herbivory in vertical and horizontal profiles. Sapling density in 60-m × 60-m plots was associated with herbivory. In the vertical profile, leaf production was continuous only for the canopy: herbivory increased from the canopy (1.3%) towards the understorey (35.6%). In the horizontal profile leaf production was related to light. Saplings in low light environments had narrow peaks in leaf production compared with saplings in high light environments. Differences in leaf phenology did not result in differences in herbivory possibly because of variation in herbivory among leaves. Although many saplings lost more than 80% of new leaf area, there was no detectable effect on growth. High levels of intra-specific variation in herbivory suggest that to better understand plant/herbivore interactions it is necessary to consider all size classes in a population. It is also important to document these pattern across different spatial scales.


2019 ◽  
Vol 27 (3) ◽  
pp. 238-243 ◽  
Author(s):  
L. V. Shupranova ◽  
K. K. Holoborodko ◽  
O. V. Seliutina ◽  
O. Y. Pakhomov

In the last two decades, the horse chestnut (Aesculus hippocastanum L.), introduced into the steppe zone of Ukraine, has been severely affected by the horse chestnut leaf miner Camereraria ohridella Deschka & Dimič, 1986, which results in damage to the assimilating organs, premature leaf defoliation and, as a consequence, a significant reduction in the reserve substances required for normal life of the plant. In recent studies, the main focus has been placed on the study of the pest’s effects on the non-enzymatic antioxidant protection system of the representatives of the genus Aesculus, while the enzymatic system of horse chestnut protection from the active forms of oxygen under stress is still poorly understood. The purpose of this study was to evaluate the reaction of catalase and two peroxidases of A. hippocastanum leaves, which differ in the level of damage by C. ohridella. The intensity of damage to A. hippocastanum leaves by the horse chestnut leaf miner in the park zones and botanical gardens of Dnipro city was determined, the activity and isoenzyme composition of benzidine-peroxidase, activity of guaiacol-peroxidase and catalase were measured. The lowest average benzidine-peroxidase activity was found in the group of trees with low level of leaf blight and the highest activity – in the group with high level. The opposite dependence was shown by catalase, the activity of which significantly decreases with increasing level of damage inflicted by the phytophage on the chestnut’s assimilating organs. Based on the determination of the variation coefficients, it has been shown that benzidine-peroxidase activity has a higher level of variability than that of catalase and guaiacol-peroxidase. It is established that under the influence of the leaf miner, activity of guaiacol-peroxidase was significantly higher by 87.1% and 75.6%, respectively, for medium and high levels of damage caused to the leaf by this phytophage as compared to that for low levels of damage. The increased level of leaf damage caused by the phytophage is reflected in the change in the isozyme profile of benzidine-peroxidase. The high activity of benzidine-peroxidase in the leaves of A. hippocastanum is due to the presence of several molecular forms that exhibit maximum activity in the narrow pH range (4.15–4.69). Quantitative redistribution of activity between the different molecular forms of benzidine peroxidase can be considered as the main regularity of changes in the expression of benzidine-peroxidase caused by different levels of leaf damage. The results showed that only one benzidine-peroxidase isoform with an isoelectric point of 4.15 shows a significant increase in activity (on average by 2.1 times) in A. hippocastanum leaves with medium and high levels of damage by C. ohridella. Significant reduction in activity is reported for dominant isoperoxidase with an isoelectric point of 4.25 revealing medium pest damage, and for high damage only a decreasing tendency is shown. The data obtained show that horse chestnut trees can specifically respond to mechanical damage by C. ohridella to leaves due to the changes in the activity of individual molecular forms of peroxidase. Further studies of oxidative metabolism are needed to understand the formation of resistance of representatives of the Aesculus genus to damage caused by this moth species based on a wider range of redox enzymes.


Author(s):  
Michal Kopačka ◽  
Gösta Nachman ◽  
Rostislav Zemek

The horse chestnut leaf miner Cameraria ohridella (Lepidoptera: Gracillariidae) is an invasive pest of horse chestnut and has spread through Europe since 1985. The horse chestnut leaf blotch Guignardia aesculi (Botryosphaeriales: Botryosphaeriaceae) is a fungal disease that also seriously damages horse chestnut trees in Europe. The interaction between the leaf miner and the fungus has not yet been sufficiently described. Therefore, the aim of the present study was to assess leaf damage inflicted to horse chestnut by both C. ohridella and G. aesculi during the vegetation season and to model their interaction. The damage to leaf area was measured monthly from May to September 2013 in České Budějovice, the Czech Republic. A simple phenomenological model describing the expected dynamics of the two species was developed. The study revealed a significant effect of sampling site and sampling period on the damage caused by both the pest and the fungus. The mathematical model indicates that infestation by C. ohridella is more affected by G. aesculi than vice versa. The possible mechanisms affecting the relationship between G. aesculi and C. ohridella are discussed.


2020 ◽  
Author(s):  
Zhijie Zhang ◽  
Yanjie Liu ◽  
Ling Yuan ◽  
Ewald Weber ◽  
Mark van Kleunen

AbstractAllelopathy (i.e. chemical interactions between plants) is known to affect individual performance, community structure and plant invasions. Yet, a quantitative synthesis is lacking. We performed a meta-analysis of 385 studies that measured allelopathic effects of one species (allelopathy plant) on another species or itself (test plant). Overall, allelopathy reduced plant performance by 25%, but the variation in allelopathy was high. Type of method affected allelopathic effect. Compared to leachates, allelopathy was more negative when residues of allelopathy plants were applied, and less negative when soil conditioned by allelopathy plants was applied. The negative effects of allelopathy diminished with study duration, and increased with concentrations of leachates or residues. Although allelopathy was not significantly related to life span, life form and domestication of the interacting plants, it became more negative with increasing phylogenetic distance. Moreover, native plants suffered more negative effects from leachates of naturalized alien plants than of other native plants. Our synthesis reveals that allelopathy could contribute to success of alien plants. The negative relationship between phylogenetic distance and allelopathy indicates that allelopathy might drive coexistence of close-related species (i.e. convergence) or dominance of single species.


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