Fine-scale genetic structure of grape phylloxera from the roots and leaves of Vitis

Patterns of variation at microsatellite loci suggest that root populations of the pest grape phylloxera (Daktulosphaira vitifoliae) are largely parthenogenetic in Australian vineyards. To investigate reproduction in leaf galling phylloxera and the association between these individuals and phylloxera on roots, we examined in detail genetic variation in phylloxera from a vineyard block. Some genotypes found on leaf galls within this block were not present on roots, whereas others spanned both zones. There was no evidence that genotypes on roots were the product of sexual reproduction in leaf galls. mtDNA variation was not associated with the location of the phylloxera clones. The spatial distribution of genotypes within a root population was further investigated by intensively sampling phylloxera from another vineyard block. Join-count spatial autocorrelation statistics were used to explore fine-scale spatial structure. Clones were nonrandomly distributed within the block and there was evidence that the distribution of clones followed rows. These findings suggest firstly that there is limited dispersal of root and leaf feeding phylloxera, and secondly that factors, other than vine host, are likely to be important and contribute to clonal structure within populations.     

Bleeding sap and old wood are the two main sources of contamination of merging organs of vine plants by Xylophilus ampelinus, the causal agent of bacterial necrosis

The spatial distribution of vine plants contaminated by Xylophilus ampelinus, the agent responsible for bacterial necrosis, was studied over a 5-year period within two vineyards in the Cognac area. Both vineyards were planted with Vitis vinifera cv. Ugni blanc but were different in age and agronomic location. The emission of X. ampelinus in contaminated bleeding sap was observed during vine sprouting. Contaminated bleeding sap is an important source of inoculum for external contamination due to the high susceptibility of young merging shoots to the pathogen. X. ampelinus emission by bleeding sap was not affected by the age of the plants or the location of the vineyards. However, its emission was irregular with time, and it varied between two fruit canes from individual plants and between plants as well as between years. Moreover, the two vineyards appeared to be entirely contaminated. Consequently, the behavior of the pathogen is not predictable. The distribution of the pathogen inside vine plant organs was analyzed through the four growing seasons. The old wood was contaminated throughout the year and constituted a stock inoculum for endophytic contamination of crude sap during the winter and the spring. Despite the fact that most of the young green shoots were contaminated in May, X.ampelinus was not found in green shoots in June and September, refuting the hypothesis of an epiphytic life of the pathogen under natural conditions. Although all plants were entirely contaminated in both vineyards, symptoms were rare and were observed on different plants each year.     

Bleeding Sap and Old Wood Are the Two Main Sources of Contamination of Merging Organs of Vine Plants by Xylophilus ampelinus, the Causal Agent of Bacterial Necrosis

The spatial distribution of vine plants contaminated by Xylophilus ampelinus, the agent responsible for bacterial necrosis, was studied over a 5-year period within two vineyards in the Cognac area. Both vineyards were planted with Vitis vinifera cv. Ugni blanc but were different in age and agronomic location. The emission of X. ampelinus in contaminated bleeding sap was observed during vine sprouting. Contaminated bleeding sap is an important source of inoculum for external contamination due to the high susceptibility of young merging shoots to the pathogen. X. ampelinus emission by bleeding sap was not affected by the age of the plants or the location of the vineyards. However, its emission was irregular with time, and it varied between two fruit canes from individual plants and between plants as well as between years. Moreover, the two vineyards appeared to be entirely contaminated. Consequently, the behavior of the pathogen is not predictable. The distribution of the pathogen inside vine plant organs was analyzed through the four growing seasons. The old wood was contaminated throughout the year and constituted a stock inoculum for endophytic contamination of crude sap during the winter and the spring. Despite the fact that most of the young green shoots were contaminated in May, X.ampelinus was not found in green shoots in June and September, refuting the hypothesis of an epiphytic life of the pathogen under natural conditions. Although all plants were entirely contaminated in both vineyards, symptoms were rare and were observed on different plants each year.     

Seasonal pattern of oviposition by the North American grape berry moth (Lepidoptera: Tortricidae)

The seasonal patterns of oviposition by the North American grape berry moth, Paralobesia viteana (Clemens) (Lepidoptera: Tortricidae) were monitored in juice grape (Vitis labrusca) vineyards in southwest Michigan. Egg deposition was recorded throughout the growing season at two vineyards in 2006, and at four vineyards from 2007 to 2009. In each vineyard, a random sample of 100 grape clusters was visually inspected twice‐weekly and the number of newly laid eggs was counted. We found that oviposition was continuous but variable throughout the season. Egg deposition started in early June coinciding with early grape bloom, continued at low level until mid‐ to late July, intensified in August close to veraison, and ended in September often before harvest. There were no consistent periods without oviposition that would indicate distinct generations. To determine the contribution of moth immigration into the vineyard to the pattern of oviposition, six grape plants located at the edge of a vineyard next to woods were covered with field cages and stocked with infested fruit. Oviposition and berry infestation were followed weekly on covered and exposed plants. Although higher numbers of eggs and infested berries were found on fruit of exposed vines than enclosed vines, egg deposition and berry infestation followed the same pattern in both treatments. This result indicates that the seasonal pattern of egg deposition is not dependent on immigration of grape berry moth of wild grape origin. The pattern of oviposition by grape berry moth described here contributes to the difficulty of controlling this pest using conventional insecticides with short residual activity.     

叶幕PAR光能截留和分配对葡萄群体光合同化物源库关系的调控

 田间自然条件下在葡萄园群体水平上多年的研究证明：叶幕PAR光能截留率与葡萄群体净光合速率、叶幕和单叶PAR光能截留率与果实干物质总量占地上部生物量干重的百分比、与果实总糖产量占果实本身干物质总量的百分比、以及与果皮色素产量占果实本身干物质总量的千分比之间呈现显著或极显著的线性正相关关系。说明利用叶幕结构变异调节叶幕PAR光能截留和分配,可以对光合同化物源库关系和果实中物质代谢方向进行有效的调控。PAR光能截留率较高和分配合理的叶幕,不但通过较高的群体光合速率为产量和品质形成提供了丰富的同化物“源”,而且通过调节器官间“库”关系使同化物以较高的比例流向果实,同时使果实中物质代谢过程有利于合成构成品质的要素。     

Influences of blackberry margins on population dynamics of Drosophila suzukii and grape infestation in adjacent vineyards

Understanding the dynamics of pest insect populations in relation to the presence of non‐crop habitats and infestation levels of adjacent crops is essential to develop sustainable pest management strategies. The invasive pest species Drosophila suzukii (Diptera: Drosophilidae) is able to utilize a broad range of host plants. In viticulture, scientific risk assessment for D. suzukii has only recently started and studies assessing the effects of field margins containing wild host plants on D. suzukii population dynamics and on infestation risks in adjacent vineyards are lacking. Thus, in a one‐year field study, the role of different field margins on fly abundance and crop infestation in adjacent vineyards of Vitis vinifera, variety “Pinot Noir,” were investigated. Different monitoring methods were conducted to assess fly distribution, sex ratio and grape infestation in 14 vineyards adjacent to field margins containing either blackberry (BB) Rubus spp. or non‐host (NH) plants. Our results show that blackberries strongly enhanced D. suzukii abundance within field margin vegetation all year long, whereas fly abundance in vineyards adjacent to BB margins was just enhanced in some seasonal periods. Moreover, the influence of BB margins was limited by distance. However, high fly numbers in BB field margins did result in zero egg infestation of “Pinot Noir” berries. These results may have important implications for winegrowers to make efficient management decisions: regardless of high abundance of adult D. suzukii, only grape berry monitoring can assess the actual infestation risk and the potential need to take management action.     

Development of an enrichment medium to detect Dekkera/Brettanomyces bruxellensis, a spoilage wine yeast, on the surface of grape berries

Brettanomyces bruxellensis spoilage is a serious problem for the wine industry. Mainly, by producing 4-ethylphenol and 4-ethylguaiacol, it confers off-odors to the wine and changes its aromatic quality. The presence of B. bruxellensis cells on the berry was speculated but it had never been clearly demonstrated. On grape berries, the microbial ecosystem is highly diverse and the population of B. bruxellensis can be very small. The aim of our study was to reveal and confirm the presence of B. bruxellensis on the surface of grape berries. We developed an enrichment medium for B. bruxellensis in order to overcome the detection limit of the molecular methods (species-specific PCR, ITS-RFLP PCR, PCR-DGGE). This medium, named EBB medium, made it possible to detect B. bruxellensis after 10 days of culture. For the first time, the presence of B. bruxellensis has been clearly established in several vineyards and at different stages of the grape development after the veraison. This work led to the conclusion that the grape berry is the primary source of B. bruxellensis. Grape growers and winemakers should take these results into account when deciding on the treatment to apply in the vineyards and the must. With the information provided here, B. bruxellensis prevention could start in the vineyard.     

Spatial Pattern of Phomopsis Cane and Leaf Spot Symptoms in Commercial Vineyards in Ohio

Spatial patterns of incidence of Phomopsis cane and leaf spot were examined using 57 data sets obtained from a statewide survey of grape vineyards in Ohio from 2002–2004. To characterize small‐scale patterns at the vine scale or below, discrete‐distributional analyses were used to quantify the heterogeneity of disease incidence within vineyards. The number of diseased leaves and internodes (out of 15) per sampling unit was better fitted by the beta‐binomial than the binomial distribution in 67% and 91% of the cases, respectively. The index of aggregation was significantly >1 for 78% and 98% of the cases for diseased leaves and internodes, respectively. These results indicated aggregation of this disease at an individual vine scale (or lower). Conversely, there was little evidence of aggregation at scales larger than a vine (e.g. disease foci extending beyond individual vines) for most vineyards based on Spatial Analysis by Distance IndicEs (SADIE). SADIE analysis suggested a random pattern of the count of diseased leaves and internodes in the majority (>86%) of the cases. Based on SADIE, there was significant (P ≤ 0.05) evidence of association between leaf and internode disease counts per vineyard in 75% of cases, indicating that the dispersal of inoculum from the previously infected wood tissues (canes) affected both leaf and internode in the same manner. In contrast, association of disease counts from one year to the next was only significant in approximately 15% of the cases, indicating the difficulty in predicting the level of disease in a section of a vineyard based on the previous year’s observations alone.     

Ecology and economic impact of two plant bugs (Hemiptera: Miridae) in commercial vineyards

The current study investigated the seasonal phenology, spatial distribution, feeding damage and economic impact of two plant bugs, Lygocoris inconspicuous Knight and Taedia scrupeus Say, in commercial vineyards. For both plant bugs, densities of nymphs were higher on vines located near the edge of woodlots rather than in the interior of vineyards, which may be attributed to the presence of wild vines and other alternate host-plants in wooded areas. Nymphs of both species fed on apical leaves and developing fruit clusters of vine shoots, initiating development after swelling of buds in the spring and reaching the adult stage when vines were in bloom. Confining high densities of L. inconspicuous (10 nymphs) on individual shoots early in the season resulted in significant reduction of the number of fruit clusters per shoot, even when feeding was restricted to short (7 d) duration; the average weight of fruit clusters, in contrast, was not affected to a large extent by feeding activity of nymphs. An experiment evaluating the impact of low density of L. inconspicuous (0-0.3 nymphs per shoot) indicated a marginally significant negative relationship between density of nymphs and average weight of fruit clusters. Control measures may be economically justified when population density exceeds a combined threshold of one nymph of either L. inconspicuous or T. scrupeus per 10 shoots of vines.     

葡萄生态系统中自然微生物群落多样性及其代谢酶系统的研究现状

自然微生物是影响葡萄生理生长和葡萄酒质量的重要因素,广泛存在于葡萄和葡萄酒的生态系统中。其中,微生物的种类、数量和生长分布取决于气候、土壤、生长时期和发酵过程控制等多种因素。自然状态下,葡萄微生态系统的物种组成和代谢作用直接影响葡萄藤的健康和葡萄酒的发酵质量,并产生特定的葡萄酒风土特征。因此,本文对现有研究的葡萄园土壤、果实和葡萄酒自然发酵过程中的真菌和细菌的群落多样性和动态变化,及其代谢酶类对葡萄酒质量特性的影响进行了综述,以期通过对微生物群落的生理代谢和生态作用的全面认识,探究葡萄微生态的互作机理和代谢功能,促使微生物群落向葡萄和葡萄酒有益的方向发展,从而达到葡萄生态系统可持续、高质量发展的目的。     

Carbaryl resistance in populations of grape berry moth (Lepidoptera: Tortricidae) in New York and Pennsylvania

We collected grape berry moth, Endopiza viteana (Clemens) (from cultivated and wild Vitis along Lake Erie in Pennsylvania and New York), and measured carbaryl susceptibility in first instars. A model of susceptibility was based on the concentration-mortality curve of laboratory-maintained colonies originating from wild Vitis with no prior history of carbaryl exposure, and a noncommercial vineyard with modest previous exposure to carbaryl. We estimated LC50 and LC90 for susceptible grape berry moth larvae at 45.4 and 2319 microg/ml, respectively. Bioassays on field-collected larvae from commercial vineyards in both states, where grape growers were abiding by current pest management guidelines for carbaryl use, revealed carbaryl resistance ratios from 7 to 71 at the LC50 level. With the loss or restriction of alternative chemical control tactics in the Food Quality Protection Act era, resistance management programs for grape berry moth should be immediately developed and implemented to regain the efficacy of this once effective insecticide and other related chemical compounds.     

Regulated deficit irrigation and density of Erythroneura spp. (Hemiptera: Cicadellidae) on grape

This study looked at regulated deficit irrigation (RDI) on leafhoppers in the genus Erythroneura (Erythroneura elegantula Osborn, or western grape leafhopper, and Erythroneura variabilis Beamer) (Hemiptera: Cicadellidae), which are serious pests of cultivated grape (Vitis vinifera L.) in California. RDI is an irrigation strategy that reduces irrigation during a critical point in the phenology of a cultivated perennial crop, to improve vegetative balance and crop quality. Erythroneura spp. are known to respond negatively to vine water stress, and the second generation ofleafhoppers begins during a potential RDI initiation period, between berry set and veraison (beginning of fruit maturation). In experiments at commercial wine grape vineyards, I imposed deficits of between 25 and 50% of crop full evapotranspiration (ET(c)) between berry set and veraison, with control treatments based on the growers' standard irrigations (typically between 0.8 and 1.0 ET(c)), and then we counted leafhopper nymphs weekly, and leafhopper eggs after the second generation. Results show a consistent reduction of second generation nymphal density with this type of RDI, with average density approximately 50% lower under deficit treatments in all three studies. Deficit irrigation reduced second generation egg density by 54% at one site and by 29.9% at another. These results confirm previous studies regarding the sensitivity of Erythroneura spp. to grapevine water stress, and, in addition, they show that a season-wide irrigation deficit is not necessary for reduction in leafhopper density. Results suggest that lower oviposition at least partly explains the lower nymphal density in the deficit treatments.     

Agroecological management of a soil‐dwelling orthopteran pest in vineyards

The efficacy of different combinations of undervine and inter‐row treatments for managing a soil‐dwelling orthopteran pest, weta (Hemiandrus sp.), in vineyards was investigated over 2 seasons. This insect damages vine buds, thus reducing subsequent grape yield. The undervine treatments comprised pea straw mulch, mussel shells, tick beans [Vicia faba Linn. var minor (Fab)], plastic sleeves on vine trunks (treated control) and control (no intervention), while inter‐rows contained either the existing vegetation or tick beans. Treatments were arranged in a randomized complete block design with 10 replicates. Data were collected on weta densities, damage to beans and components of yield. The latter were numbers of bud laid down per vine, shoots per bud, clusters per shoot, grape bunches per vine, bunch weight and yield. The undervine treatments significantly affected all variables except the number of shoots per bud. In contrast, none of the variables was significantly affected by the inter‐row treatments or their interaction with undervine treatments, apart from weta density. At the end of the experiment, weta density in the shell treatment was about 58% lower than in the control. As a result, there was about 39% significant yield increase in that treatment compared to the control. Although the undervine beans and sleeves treatments increased yield, there were no reductions in weta density. With undervine beans, the insect fed on the bean plants instead of vine buds. Thus, yield in that treatment was approximately 28% higher than in the control. These results demonstrate that simple agroecological management approaches can reduce above‐ground damage by soil‐dwelling insects.     

Isolation and characterization of Bacillus subtilis KS1 for the biocontrol of grapevine fungal diseases

Bacillus subtilis KS1 was isolated from grape berry skin as a biological control agent against grapevine fungal diseases. KS1 was identified as a new strain of B. subtilis according to morphological, biochemical, and genetic analyses. In vitro bioassay demonstrated that KS1 suppressed the growth of Botrytis cinerea (the casual agent of grape grey mold) and Colletotrichum gloeosporioides (the casual agent of grape ripe rot). The biocontrol activity of KS1 against grapevine fungal diseases in vineyards was evaluated over a 3-year span (from 2007 to 2009). Downy mildew, caused by Plasmopara viticola, was reduced on berry skins and leaves by treatment with KS1. The KS1 genome possesses ituD and lpa-14 genes, both of which play a role in iturin A production followed by iturin A production in the culture. In contrast, mutants lacking both genes lost the antagonistic activity against B. cinerea and C. gloeosporioides and the activity in iturin A production, suggesting that the antagonistic activity of KS1 against grapevine fungal pathogens may depend on iturin A production. As KS1 showed tolerance to various chemical pesticides, chemical pesticides could be applied before and/or after KS1 treatment in vineyards. Due to its potential as a biological control agent against grape downy mildew, KS1 is expected to contribute to the further improvement of integrated pest management systems and to potentially reduce the amount of chemical fungicides applied in vineyards.     

Effect of adjacent steppe-like habitats on spider diversity in vine plants

Spiders are important natural enemies of pests in many agroecosystems. Spiders’ diversity and abundance—and therefore their biological control potential—often increases with the presence of non-crop habitats adjacent to the agroecosystem and/or the abundance of such habitats in the landscape. This research aims to determine whether spider communities dwelling on vine plant trunks are richer and more abundant in terraced vineyards than in plain vineyards. We found that spiders’ abundance and species richness were significantly greater during part of the season in the plain than the terraced types of vineyards. The abundance of spiders on the vine plants in the terraced vineyards decreased gradually from the field margins to the centre while no such pattern was observed in the plain vineyards. Subsequent experiments will be needed in order to elucidate the role of the individual mechanisms and parameters that underpin our findings. For example, the air flow (direction and intensity), the presence of the predators, heterogeneity and the presence of shrubs on the slopes of terraces should be studied further. Particularly, because our findings contradict the general assumption that terraced vineyards should host richer spider communities.     

Mutualism between a phytopathogenic fungus (Botrytis cinerea) and a vineyard pest (Lobesia botrana). Positive effects on insect development and oviposition behaviour

In vineyards, larvae of the grape berry moth (Lobesia botrana) favour the development of the grey mould fungus Botrytis cinerea. To study the possibility of a mutualistic relationship between these organisms, we investigated the effects of the fungus on the development and oviposition behaviour of the insect. Larvae were reared on whole plants infected or uninfected with the fungus, or on an artificial diet containing either infected grape berries or the mycelium. The presence of the fungus consistently led to a reduction in the duration of insect development (4–6 d) and mortality (20–67 %). The fecundity increased from 12 to 76 %. Moreover, the fact that the females laid eggs preferentially on fungus-infected grape berries confirms the mutualistic association between these organisms. The fungus alone contributed to the positive effects. We showed the existence of a mutualistic relationship between the two organisms which are both damaging to vineyards.     

The Vineyard Yeast Microbiome,a Mixed Model Microbial Map

Vineyards harbour a wide variety of microorganisms that play a pivotal role in pre- and post-harvest grape quality and will contribute significantly to the final aromatic properties of wine. The aim of the current study was to investigate the spatial distribution of microbial communities within and between individual vineyard management units. For the first time in such a study, we applied the Theory of Sampling (TOS) to sample gapes from adjacent and well established commercial vineyards within the same terroir unit and from several sampling points within each individual vineyard. Cultivation-based and molecular data sets were generated to capture the spatial heterogeneity in microbial populations within and between vineyards and analysed with novel mixed-model networks, which combine sample correlations and microbial community distribution probabilities. The data demonstrate that farming systems have a significant impact on fungal diversity but more importantly that there is significant species heterogeneity between samples in the same vineyard. Cultivation-based methods confirmed that while the same oxidative yeast species dominated in all vineyards, the least treated vineyard displayed significantly higher species richness, including many yeasts with biocontrol potential. The cultivatable yeast population was not fully representative of the more complex populations seen with molecular methods, and only the molecular data allowed discrimination amongst farming practices with multivariate and network analysis methods. Importantly, yeast species distribution is subject to significant intra-vineyard spatial fluctuations and the frequently reported heterogeneity of tank samples of grapes harvested from single vineyards at the same stage of ripeness might therefore, at least in part, be due to the differing microbiota in different sections of the vineyard.     

Population ecology of the gall-forming aphid,Aploneura lentisci (Pass.) in Israel

1. Aploneura lentisci (Passerini ) (Homoptera, Aphididae) forms kidney-shaped galls on the leaflets of its primary host, Pistacia lentiscus (Anacardiaceae). Observations on its population dynamics and ecology werecarried out in 1980–1985.
2. The galls are formed annually on newly-growing shoots of the same year. Each gall is founded by a single nymph and contains its parthenogenetic offspring. The infestation period (late March-early April) is short relative to the period of appearance of new shoots. The distribution of galls on the shoots is non-random (“clumped”). Early shoots emerging near pruning cuts, when the rest of the buds are still dormant, are often very heavily infested.
3. Clone size within galls increases from 1 in April to several hundred in September (at least 2 parthenogenetic generations). Alates of the last generation leave the galls gradually as they form. By the following March, previous-year galls contain no live aphids.
4. Population density of galls varied greatly among years. Possible causes of this variation are discussed.

     

Mathematical analysis of a model for a plant-herbivore system

The apple twig borer (Amphicerus bicaudatus) is an insect pest of the grape vine, causing considerable damage to the grape vine in early spring. A simple difference equation model is formulated and analysed for this plant-herbivore system based on two control strategies, cane removal and pesticide application. The system has two equilibria, one where the pest is present and one where the pest is absent. Regions are found in parameter space for global stability of the equilibria and in the absence of global stability it is shown that there exist periodic or quasiperiodic solutions.     

Comparative development and reproduction of Planococcus ficus and Planococcus citri (Hemiptera: Pseudococcidae) on grapevine under field conditions

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