Leafminer Cameraria Ohridella Research Articles

Description of Intra-Annual Changes in Cambial Activity and Differentiation of Secondary Conductive Tissues of Aesculus hippocastanum Trees Affected by the Leaf Miner Cameraria ohridella

Aesculus hippocastanum trees are commonly infested by the leaf miner Cameraria ohridella, whose larval activity causes the destruction of the leaf parenchyma and induces defoliation. Pest attacks result in, e.g., production of smaller fruits and tree re-flowering in autumn. Concerning pest influence on stem structure only scarce information of narrower annual growth rings of wood has been published. Therefore, we determined the effect of the presence of the leaf miner infestation on intra-annual cambial activity and on differentiation of conductive tissues. These data were compared with phenological phases and pest activity. Pest feeding resulted in changes in onset, cessation and duration of cambial divisions, and differentiation of secondary xylem. The duration of cambial activity was about a month shorter in heavily infested trees and was connected with premature tree defoliation. Affected trees were characterised by a reduction in cambial divisions and earlier cessation of wood differentiation resulting in narrower wood rings. Furthermore, the infested trees exhibited altered wood structure, with more vessels of smaller diameters, however these changes did not affect its theoretical hydraulic conductivity. Interestingly, pest attack did not influence secondary phloem differentiation. The probable influence of long-term infestation on tree growth and condition was discussed.

Seasonal Changes and the Interaction between the Horse Chestnut Leaf Miner Cameraria ohridella and Horse Chestnut Leaf Blotch Disease Caused by Guignardia aesculi

The horse chestnut leaf miner Cameraria ohridella (Lepidoptera: Gracillariidae) is an invasive pest of horse chestnut Aesculus hippocastanum (Sapindales: Sapindaceae) and has spread through Europe since 1985. Horse chestnut leaf blotch is a fungal disease caused by Guignardia aesculi (Botryosphaeriales: Botryosphaeriaceae) 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 using digital image analysis of sampled leaves. A simple phenomenological model describing the expected dynamics of the two species was developed. The study revealed that the damage caused by both the pests and the fungus varied significantly among sampling sites within the city. The overall leaf damage exceeded 50% in no-raking sites in August. The mathematical model indicates that infestation by C. ohridella is more affected by G. aesculi than vice versa. Guignardia aesculi is thus the superior competitor of the two species. Our findings highlight the delicate interplay between insect pests and fungal pathogens and the spatiotemporal dynamics influencing them, calling for more research in this understudied area.

The influence of horse-chestnut grafting on characteristics of resistance to chestnut leaf miner Cameraria ohridella Deschka & Dimić

The influence of horse-chestnut grafting on characteristics of resistance to chestnut leaf miner Cameraria ohridella Deschka & Dimic

Массовое повреждение листьев конского каштана (Aesculus hippocastanum) охридским минером (Cameraria ohridella) на территории Пензы в 2019 году

Массовое повреждение листьев конского каштана (Aesculus hippocastanum) охридским минером (Cameraria ohridella) на территории Пензы в 2019 году

Improvement of the method for detecting and monitoring the dynamics of the number of chestnut leafminer (Cameraria ohridella Deschka & Dimic) in stands of horse chestnut using color traps

The possibility of using colored glue traps for detecting and monitoring the dynamics of the number of the chestnut leafminer Cameraria ohridella was studied. The efficiency of the trap is determined depending on the color.

Chemical composition of horse-chestnut (Aesculus) leaves and their susceptibility to chestnut leaf miner Cameraria ohridella Deschka & Dimi\u0107

For over 20 years, trees of Aesculus spp. have been attacked by the larvae of Cameraria ohridella, which causes damage to the leaves. It has been observed that members of the genus Aesculus are characterized by diverse susceptibility to C. ohridella. Four specimens of the Aesculus genus which differ in susceptibility to this leaf miner—Aesculus turbinata (susceptible), Aesculus × neglecta (resistant) and two specimens of Aesculus hippocastanum (relatively susceptible and relatively resistant)—were examined. The levels of substances which may function as attractants (chloroplast pigments, anthocyanins), deterrents or repellents (flavonols, phenols), or a source of nutrients (free α-amino acids and carbohydrates) were determined in leaves of these four trees during two growing seasons. The results showed that the more pest-susceptible A. turbinata had, in both growing seasons, significantly higher levels of leaf carbohydrates and anthocyanins than the resistant Ae. × neglecta. Thus, anthocyanins and carbohydrates may be the traits which affect oviposition preference and favor the feeding of C. ohridella in the susceptible Ae. turbinata. The relatively susceptible specimen of Ae. hippocastanum contained slightly higher carbohydrate and anthocyanin levels than the relatively resistant one, but only in one growing season. Therefore, it does not explain the causes of their different susceptibility to the pest. The concentration of phenolics in the susceptible Ae. turbinata tree and the relatively susceptible Ae. hippocastanum individual was higher than in the resistant Ae. × neglecta and relatively resistant Ae. hippocastanum, respectively. This may suggest that leaf phenolic composition, but not overall concentration, is responsible for different susceptibility of examined trees of Aesculus spp. to the horse-chestnut leaf miner. The present results also demonstrate that the determined chemical compounds do not constitute a complete description of the biochemical relationships between C. ohridella and the examined horse-chestnut trees.

Spatial variability in the level of infestation of the leaves of horse chestnut by the horse chestnut leaf miner, Cameraria ohridella (Lepidoptera: Gracillariidae) and in the number of adult moths and parasitoids emerging from leaf litter in an urban environment

The horse chestnut leaf miner Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae) was first recorded in Europe near lake Ohrid in the former Yugoslav Republic of Macedonia in 1985 since when it has spread throughout the whole of Europe. The reasons for its spread are well documented. The aim of this study was to assess the population density of the first generation of C. ohridella at eight sites in the urban area of Ceske Budějovice, Czech Republic in two consecutive years. The density was estimated visually in terms of the damage done to horse chestnut leaves by C. ohridella larvae at each site during the vegetative season. The results revealed high variability in the mean percentage of the leaf area damaged ranging from 1.43% to 31.00% and from 0.26% to 23.40% in 2012 and 2013, respectively. The effect of site, year and interaction between these two factors were statistically highly significant. Spatial analysis revealed no autocorrelation in damage among sites indicating that the distribution of C. ohridella is random and not affected by the level of infestation at neighbouring sites. In autumn, samples of leaves were collected and the mortality of diapausing pupae of C. ohridella determined. It ranged from 12.50% to 25.82% and from 10.31% to 22.35% in 2012 and 2013, respectively. There was no significant effect of site and year and their interaction on pupal mortality. The leaf samples were then weighed and put into photo-eclectors, which were placed outdoors. Numbers of adults of C. ohridella and hymenopteran parasitoids that emerged in spring were recorded daily. There were statistically significant associations of the total number of adults that emerged from samples in spring with both site and year as well as their interaction. The number of moths that emerged was positively correlated with the damage done by the first generation of C. ohridella the previous year. Similarly, the total number of parasitoids that emerged was correlated with the number of moths that emerged. The implications of these findings for the optimization of C. ohridella control are discussed.

Evaluating methods to quantify spatial variation in the velocity of biological invasions

Invading species rarely spread homogeneously through a landscape and invasion patterns typically display irregular frontal boundaries as the invasion progresses through space. Those irregular patterns are generally produced by local environmental factors that may slow or accelerate movement of the frontal boundary. While there is an abundant literature on species distribution modelling methods that quantify local suitability for species establishment, comparatively few studies have examined methods for measuring the local velocity of invasions that can then be statistically analysed in relation to spatially variable environmental factors. Previous studies have used simulations to compare different methods for estimating the overall rate of spread of an invasion. We adopted a similar approach of simulating invasions that resemble two real case‐studies, both in terms of their spatial resolution (i.e. considering the size of one cell as one km) and their spatial extent (> 600 000 km²). Simulations were sampled to compare how different methods used to measure local spread rate, namely the neighbouring, nearest distance and Delaunay methods, perform for spatio‐temporal comparisons. We varied the assessment using three levels of complexity of the spatio‐temporal pattern of invasion, three sample sizes (500, 1000 and 2000 points), three different spatial sampling patterns (stratified, random, aggregated), three interpolation methods (generalized linear model, kriging, thin plate spline regression) and two spatio‐temporal modelling structures (trend surface analysis and boundary displacement), resulting in a total of 486 different scenarios. The thin plate spline regression interpolation method, in combination with trend surface analysis, was found to provide the most robust local spread rate quantification as it was able to reliably accommodate different sampling conditions and invasion patterns. This best approach was successfully applied to two case‐studies, the invasion of France by the horse‐chestnut leafminerCameraria ohridellaand by the bluetongue virus, generally in agreement with previously published values of spread rates. Potential avenues for further research are discussed.

Direct and Unbiased Information Recovery from Liquid Chromatography–Mass Spectrometry Raw Data for Phenotype-Differentiating Metabolites Based on Screening Window Coefficient of Ion Currents

A reworking of a data mining strategy, in which statistical treatment of raw data from liquid chromatography-mass spectrometry (LC-MS) precedes recognition of chromatographic peaks, is presented. In this algorithm the tR-m/z plane of LC-MS data is divided into equal-sized segments of twelve seconds by one m/z unit each, and the total ion currents in corresponding segments as specified by the tR-m/z pair from multiple LC-MS runs are evaluated to generate mean ion currents (μ) and standard deviations (σ). The μ's and σ's of the segments, derived from contrasting classes of LC-MS data set (e.g., resistant-susceptible, case-control, etc.), are used to calculate the Z-factor (screening window coefficient) which is in turn used to rank the segments. Chromatographic peaks are recognized only where the ion currents are shown to differentiate the classes. The result-reporting format enables detection of positive as well as negative correlations between ion intensities and biological traits under study and thus points to the presence of potentially phenotype-discriminating metabolites. Examples of data analyses are presented, in which ions that may distinguish resistant and susceptible species of Aesculus to the leaf-miner Cameraria ohridella were detected.

Parasitoids and parasitism rates of the horse chestnut leaf miner Cameraria ohridella Deschka and Dimić [Lepidoptera: Gracillariidae] across four sites in south-west London

The horse chestnut leaf miner Cameraria ohridella was discovered in the Balkans in 1986 and appeared in the UK in 2002. The aim of this study was to quantify and describe the parasitism rates and parasitoids of the moth in urban and rural stands of Aesculus hippocastanum in the UK and to compare the results with those from European studies. A maximum parasitism rate of 6.67% was obtained, and a significant difference in parasitism rate between urban and rural stands was noted. Two species Minotetrastichus frontalis and Pnigalio agraules alone were responsible for 37% of total parasitism. However, the results show no ideal candidate for use in the biological control of C. ohridella within the native UK parasitoids.

Did the parasitoid Pnigalio mediterraneus (Hymenoptera: Eulophidae) track the invasion of the horse chestnut leafminer?

How communities of natural enemies, such as parasitoids, adapt to the range expansion of their hosts or the arrival of a novel invasive host is an important question in invasion biology. Do parasitoids track the expansion of their hosts from their shared native range? Do they locally adapt both behaviorally and physiologically to the arrival of a novel species by shifting hosts? Few studies have addressed those questions, yet they are important to develop efficient methods to manage invasive species. Here we focus on Pnigalio mediterraneus Ferriere and Delucchi (Hymenoptera: Eulophidae), an important parasitoid of two major agricultural and ornamental pests, the olive fruit fly Bactrocera oleae Rossi (Diptera: Tephritidae) and the horse chestnut leafminer Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae). C. ohridella recently invaded Europe starting from the Southern Balkans, whereas B. oleae has been associated since the Quaternary with wild olives in the Mediterranean, where it largely spread after the domestication of cultivated olives. We used two markers, the ribosomal spacer ITS2 and the mitochondrial gene COI. Although the ITS2 dataset provided little variation and no phylogeographic signal, analysis of mtDNA of 188 individuals of P. mediterraneus from 54 European localities allowed us to identify 53 haplotypes. Both nucleotide and haplotype diversity were higher for Mediterranean samples, and from samples reared from B. oleae. The statistical parsimony network identified one haplotype as the most frequent, ancestral and mainly associated with C. ohridella. Our findings suggest that P. mediterraneus locally host switched to C. ohridella from other hosts in the Balkans and later tracked the horse chestnut leafminer invasion over Europe. Therefore both host-tracking and ecological sorting could explain the current distribution of P. mediterraneus haplotypes.

Population genetic characteristics of horse chestnut in Serbia

The general population genetic characteristics of cultivated horse chestnut trees excelling in growth, phenotype characteristics, type of inflorescence, productivity and resistance to the leafminer Cameraria ohridella Deschka and Dimic were analyzed in Serbia. The analyzed population genetic parameters point to fundamental differences in the genetic structure among the cultivated populations in Serbia. The study shows the variability in all properties among the populations and inter-individual variability within the populations. The variability and differential characteristics were assessed using statistical parameters, taking into account the satisfactory reflection of the hereditary potential. The assessed differences in the vitality and evolution potential of different populations can determine the methods of horse chestnut gene pool collection, reconstruction and improvement.

Effect of sun-exposure of the horse chestnut (Aesculus hippocastanum L.) on the occurrence and number of parasitoids of the horse chestnut leafminer (Cameraria ohridella Deschka & Dimic) in central Poland in 2004- 2006

The research on parasitoids of the horse chestnut leafminer (Cameraria ohridella Deschka & Dymic, 1986) of the order Hymenoptera was conducted in the years 2004– 2006 in six locations in central Poland. The complex of parasitoids was composed of 14 species. Minotetrastrichus frontalis (Nees) and Pnigalio agraules (Walker), (Hymenoptera: Eulophidae) were the dominant species in all locations. It was noted that sun-exposure of the horse chestnut (Aesculus hippocastanum L.) had a significant effect on abundance of parasitoids attacking the horse chestnut leafminer and their percentage share over the study period. The greatest number of parasitoids was found in the trees which were most exposed to sunray penetration, thus the warmest.

State of horse-chestnut, Aesculus hippocastanum L., in Lithuania: diseases and pest damages

Commonly used ornamental tree Aesculus hippocastanum has been successfully used for planting for a long time in Lithuania. Data of the state of A. hippocastanum were assessed in 55 cities and settlements of the country during 1992–2009. The changing state of A. hippocastanum was recorded to begin to deteriorate in 1995–1997 when the species was affected by fungi diseases caused by Guignardia aesculi, Erysiphe flexuos and Schizophyllum commune. Horse-chestnut leafminer Cameraria ohridella has been the most harmful pest over all territory of Lithuania since 2005–2007. Effectiveness of natural predators and different means for C. ohridella control as well as for spread of fungal diseases were analyzed and discussed. Keywords: environment, Aesculus hippocastanum, diseases, pests

Aesculus pavia foliar saponins: defensive role against the leafminer Cameraria ohridella

Recently, the leafminer Cameraria ohridella Deschka & Dimic has caused heavy damage to the white-flowering horse chestnut in Europe. Among the Aesculus genus, A. pavia L. HBT genotype, characterised by red flowers, showed an atypical resistance towards this pest. Its leaves, shaken in water, originated a dense foam, indicating the presence of saponins, unlike the common horse chestnut tree. The aim was to isolate and identify these leaf saponins and test their possible defensive role against C. ohridella. Spectroscopic analyses showed that A. pavia HBT genotype leaves contained a mixture of saponins, four of which were based on the same structure as commercial escin saponins, the typical saponin mixture produced by A. hippocastanum and accumulated only within bark and fruit tissues. The mixture showed a repellent effect on C. ohridella moth. The number of mines detected on the leaves of A. hippocastanum plants treated with A. pavia HBT saponins through watering and stem brushing was significantly lower than the control, and in many cases no mines were ever observed. The results showed that the exogenous saponins were translocated from roots/stem to the leaf tissues, and their accumulation seemed to ensure an appreciable degree of protection against the leafminer.

Temporal and spatial variations in the parasitoid complex of the horse chestnut leafminer during its invasion of Europe

The enemy release hypothesis posits that the initial success of invasive species depends on the scarcity and poor adaptation of native natural enemies such as predators and parasitoids. As for parasitoids, invading hosts are first attacked at low rates by a species-poor complex of mainly generalist species. Over the years, however, parasitoid richness may increase either because the invading host continuously encounters new parasitoid species during its spread (geographic spread-hypothesis) or because local parasitoids need different periods of time to adapt to the novel host (adjustment-hypothesis). Both scenarios should result in a continuous increase of parasitoid richness over time. In this study, we reconstructed the development of the hymenopteran parasitoid complex of the invasive leafminer Cameraria ohridella (Lepidoptera, Gracillariidae). Our results show that the overall parasitism rate increases as a function of host residence time as well as geographic and climatic factors, altogether reflecting the historic spread of C. ohridella. The same variables also explain the individual parasitism rates of several species in the parasitoid complex, but fail to explain the abundance of others. Evidence supporting the “geographic spread-hypothesis” was found in the parasitism pattern of Cirrospilus talitzkii (Hymenoptera, Eulophidae), while that of Pediobius saulius, another eulophid, indicated an increase of parasitism rates by behavioral, phenological or biological adjustments. Compared to fully integrated host-parasitoid associations, however, parasitism rates of C. ohridella are still very low. In addition, the parasitoid complex lacks specialists, provided that the species determined are valid and not complexes of cryptic (and presumably more specialized) species. Probably, the adjustment of specialist parasitoids requires more than a few decades, particularly to invaders which establish in ecological niches free of native hosts, thus eliminating any possibility of recruitment of pre-adapted parasitoids.

Possibilities of protection of the horse-chestnut Aesculus hippocastanum L. against the horse chestnut leaf-miner Cameraria ohridella Deschka et Dimic

Możliwości ochrony kasztanowca zwyczajnegoAesculus hippocastanumL. przed szrotówkiem kasztanowcowiaczkiemCameraria ohridellaDeschka et Dimic

Serological marking of Pnigalio agraules (Hymenoptera: Eulophidae) for field dispersal studies

The parasitoid wasp Pnigalio agraules (Wlk.) is a key natural enemy of the horsechestnut leafminer Cameraria ohridella Deschka and Dimic (Lepidoptera: Gracillariidae). As a basis for mark-release-recapture studies, aimed at investigating the dispersal of this parasitoid in the field, adults of P. agraules were marked using a vertebrate-specific immunoglobulin (IgG). The marker was later detected by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The IgG was either applied externally by spraying or internally by feeding an IgG-enriched diet. Different concentrations of the marker were used and the influence of abiotic (climatic conditions, time elapsed between marking and marker examination) and biotic factors (sex and age of the parasitoids) on the detection of the immunomarker was tested. External marking by spraying led to more homogeneous labelling than feeding the marker. Parasitoids labelled with 0.25 mg rabbit IgG per ten individuals contained enough immunomarker to be easily distinguished from unmarked ones. Neither the climatic conditions nor the sex or age of the insects had an influence on the detection of the marker. The IgG remained well detectable during the entire lifespan of the parasitoids, which was not negatively affected by the marking procedure. Serological marking can be used to investigate the dispersal behaviour of beneficial insects within mark-release-recapture studies.

Sequential Sampling Plan for Cameraria ohridella (Lepidoptera: Gracillariidae) on Horse Chestnut Tree

A fixed precision sequential sampling plan for estimating the density of the horse chestnut, Aesculus hippocastanum L., leafminer Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae) was developed. Data were collected from 2002 to 2004 in Turin, northwestern Italy, with the aim of developing a sampling strategy for estimating populations of C. ohridella mines. Taylor’s power law was used as a regression model. Sampling parameters were estimated from 216 data sets, and an additional 110 independent data sets were used to validate the fixed precision sequential sampling plan with resampling software. Covariance analysis indicated that there were not significant differences in the coefficient of Taylor’s power law between heights of the foliage, months, and years. Dispersion patterns of C. ohridella were determined to be aggregated. The parameters of the Taylor’s power law were used to calculate minimum sample sizes and sampling stop lines for different precision levels. Considering a mean density value of five mines per leaf, an average sample number of only 49 leaves was necessary to achieve a desired precision level of 0.25. As the precision level was increased to 0.10, the average sample size increased to 303 leaves. The sequential sampling plan should provide an effective management of C. ohridella in the urban areas, minimizing sampling time and cost, and at the same should be an effective tool to reduce insecticide applications and prevent the esthetic damage.

Sequential Sampling Plan for <I>Cameraria ohridella</I> (Lepidoptera: Gracillariidae) on Horse Chestnut Tree

A fixed precision sequential sampling plan for estimating the density of the horse chestnut, Aesculus hippocastanum L., leafminer Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae) was developed. Data were collected from 2002 to 2004 in Turin, northwestern Italy, with the aim of developing a sampling strategy for estimating populations of C. ohridella mines. Taylor's power law was used as a regression model. Sampling parameters were estimated from 216 data sets, and an additional 110 independent data sets were used to validate the fixed precision sequential sampling plan with resampling software. Covariance analysis indicated that there were not significant differences in the coefficient of Taylor's power law between heights of the foliage, months, and years. Dispersion patterns of C. ohridella were determined to be aggregated. The parameters of the Taylor's power law were used to calculate minimum sample sizes and sampling stop lines for different precision levels. Considering a mean density value of five mines per leaf, an average sample number of only 49 leaves was necessary to achieve a desired precision level of 0.25. As the precision level was increased to 0.10, the average sample size increased to 303 leaves. The sequential sampling plan should provide an effective management of C. ohridella in the urban areas, minimizing sampling time and cost, and at the same should be an effective tool to reduce insecticide applications and prevent the esthetic damage.