The impact of eriophyoids on crops: recent issues on Aculus schlechtendali, Calepitrimerus vitis and Aculops lycopersici

The nature of the damage caused by eriophyoid mites and the assessment of yield losses still require detailed studies if appropriate control and risk mitigation strategies are to be planned. The economic importance of eriophyoid mites is increasing worldwide and a lot of species have reached a permanent pest status in certain crops, while others represent a quarantine threat for several countries. Due to their relevant role in Europe and elsewhere, three eriophyoid mites that have been frequently reported in recent research, are here considered as case studies: two of them (the apple rust mite, Aculus schlechtendali, and the grape rust mite, Calepitrimerus vitis) colonise temperate fruits, while one (the tomato russet mite, Aculops lycopersici) affects vegetables. The damage assessment related to the apple rust mite has been evaluated on different apple varieties with implications for pest control. Some factors affecting the spread and economic importance of the grape rust mite have been identified. The complexity and difficulty in controlling the tomato russet mite by chemicals enhances the interest in biological control agents. Considerations on interactions between eriophyoids and host plants (e.g. resistance, varietal susceptibility), on pest management regimes (e.g. impact of fungicides, resistance to acaricides, perspectives on biological control) are presented.     

Leaf domatia and foliar mite abundance in broadleaf deciduous forest of north Asia

Plant morphology may be shaped, in part, by the third trophic level. Leaf domatia, minute enclosures usually in vein axils on the leaf underside, may provide the basis for protective mutualism between plants and mites. Domatia are particularly frequent among species of trees, shrubs, and vines in the temperate broadleaf deciduous forests in north Asia where they may be important in determining the distribution and abundance of mites in the forest canopy. In lowland and montane broadleaf deciduous forests at Kwangn;akung and Chumbongsan in Korea, we found that approximately half of all woody species in all forest strata, including many dominant trees, have leaf domatia. Pooling across 24 plant species at the two sites, mites occupied a mode of 60% (range 20-100%) of domatia and used them for shelter, egg-laying, and development. On average, 70% of all active mites and 85% of mite eggs on leaves were found in domatia; over three-quarters of these were potentially beneficial to their hosts. Further, mite abundance and reproduction (expressed as the proportion of mites at the egg stage) were significantly greater on leaves of species with domatia than those without domatia in both forests. Effects of domatia on mite abundance were significant only for predaceous and fungivorous mite taxa; herbivore numbers did not differ significantly between leaves of species with and without domatia. Comparable patterns in broadleaf deciduous forest in North America and other biogeographic regions suggest that the effect of leaf domatia on foliar mite abundance is general. These results are consistent with several predictions of mutualism between plants and mites, and indicate that protective mutualisms may be frequent in the temperate zone.     

Host-plant specificity and specialization in eriophyoid mites and their importance for the use of eriophyoid mites as biocontrol agents of weeds

Eriophyoid mites, which are among the smallest plant feeders, are characterized by the intimate relationships they have with their hosts and the restricted range of plants upon which they can reproduce. The knowledge of their true host ranges and mechanisms causing host specificity is fundamental to understanding mite-host interactions, potential mite-host coevolution, and diversity of this group, as well as to apply effective control strategies or to use them as effective biological control agents. The aim of this paper is to review current knowledge on host specificity and specialization in eriophyoid mites, and to point out knowledge gaps and doubts. Using available data on described species and recorded hosts we showed that: (1) 80% of eriophyoids have been reported on only one host species, 95% on one host genus, and 99% on one host family; (2) Diptilomiopidae has the highest proportion of monophagous species and Phytoptidae has the fewest; (3) non-monophagous eriophyoids show the tendency to infest closely related hosts; 4) vagrant eriophyoids have a higher proportion of monophagous species than refuge-seeking and refuge-inducing species; (5) the proportions of monophagous species infesting annual and perennial hosts are similar; however, many species infesting annual hosts have wider host ranges than those infesting perennial hosts; (6) the proportions of species that are monophagous infesting evergreen and deciduous plants are similar; (7) non-monophagous eriophyoid species have wider geographic distribution than monophagous species. Field and laboratory host-specificity tests for several eriophyoid species and their importance for biological control of weeds are described. Testing the actual host range of a given eriophyoid species, searching for ecological data, genetic differentiation analysis, and recognizing factors and mechanisms that contribute to host specificity of eriophyoid mites are suggested as future directions for research.     

Eriophyoid mites (Acari: Eriophyoidea) on coniferous trees: is the occurrence of one species associated with the other?

Although Eriophyoidea is one of the most important phytophagous mite taxa owing to its negative impact on plants, reports on associations between occurrences of eriophyoid species are scarce. The aim of this paper is to test the hypothesis that the occurrence of one species is correlated with the occurrence of another in some predictive manner. Analyses are carried out for two popular coniferous trees in Poland, i.e., Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). Observations were made in four locations in Poland, from three age groups of trees, namely adult trees (thirty 15-cm shoot samples from each of ten trees), young trees (ten 15-cm shoot samples from each of ten trees) and seedlings (100 whole-seedling samples). The associations were estimated by Yule’s V index. Among four eriophyoid species observed on Scots pine, and the same number of species on Norway spruce, in general no association pattern was observed. It means that their occurrence is independent. The most likely explanation for the absence of co-occurrence is the abundance of microhabitats on coniferous trees for eriophyoid mites, combined with the low mite density on these plant hosts.     

中山市小榄镇城区绿地植物调查与评价

本文对小榄镇城区绿地植物种类进行了调查与研究.调查发现,小榄镇植物种类丰富,有105科433种.其中,公园绿地和苗圃区植物种类最多,街头与街道附属绿地植物种类较单调:乔木与灌木应用较多,藤本植物应用较少:乔木花卉于公园中应用较多;人工造林的林相、林型单一.旧城区绿地严重缺乏;部分工厂、学校对绿化不重视.研究提出,合理选择绿化树种,将木兰科植物作为乡土类的重点,紫葳科、木棉科和豆科作为外来树种引进的重点;对贺榄山现存桉树、相思疏残林进行林相改造,选择樟科、壳斗科、山茶科等作为骨干树种分期、分批进行混植.最后,筛选出适合各种类型绿地应用的绿化树种.     

Impact and management of the eriophyoid mite Trisetacus juniperinus on the evergreen cypress Cupressus sempervirens

Abstract 1 In the Mediterranean region, the eriophyoid mite Trisetacus juniperinus causes considerable damage to the evergreen cypress, Cupressus sempervirens L., particularly in nurseries and young stands, disturbing the apical growth of the tree. 2 The impact of mites on survival and apical growth of two commercial clones of cypress (Agrimed and Bolgheri), as well as the results of differently timed pesticide applications to suppress mite population on newly grafted trees, were evaluated. 3 Mites easily infested clonal scions from rootstocks that were previously infested in the nursery, inducing tip deformation and disturbance of the growth. Apical growth was significantly lower in infested than in control trees 2 years following the graft. 4 Deformed apical buds were left early by mites, which dispersed in the crown and may have incurred high mortality. This is interpreted as a defensive reaction of the cypress to the mite attack, which involves costs resulting in reduced apical growth in both clones. However, mites partly overcame tree defences in the Bolgheri clone. 5 Healthy rootstock and graft material should be used to limit damage and maintain plant growth because natural infestations rarely occur. In case of attack, a pesticide should be applied as soon as possible because precocious mite infestation has a log‐lasting effect on tree growth, with considerable economic damage.     

广州地区夏季观赏植物资源及园林应用调查研究

为了解广州地区夏季观赏植物资源及园林应用情况,采用实地调查和资料收集的方法,开展了广州地区公园、园林苗圃、高校、城市街道、城市绿地和华南植物园等夏季观赏植物资源的调查和编目,记载了广州地区夏季观赏植物约81科289种,分析和讨论了观赏特性及园林应用,提出了广州地区夏季观赏植物资源合理开发与保护的建议和意见,为更好地发掘广州夏季观赏植物资源和促进夏季观赏植物的园林建设提供依据。     

钱江源国家公园森林物种组成和群落结构

全面了解以国家公园为主体的自然保护地体系木本植物物种组成,特别是珍稀濒危物种,分析其区系特征及不同植被类型群落结构现状,对国家公园物种保护和不同植被类型恢复具有重要指导意义。基于对钱江源国家公园全域的木本植物调查,详细分析了不同胸径大小级森林植被类型的物种组成、区系特征、种-个体曲线分析和结构特征。调查涵盖313个木本物种,温带分布的科多于热带分布的科(22/35),热带分布的属略少于温带分布的属(28/31);中国特有属7个,特有种101个,中国珍稀保护物种10个,世界自然保护联盟(IUCN)红色名录的近危、易危和濒危物种17个。在同等取样水平下,物种多样性在常绿阔叶林最高,天然针叶林次之,杉木林最低;全域所有个体及各林型的径级分布总体呈现明显的倒"J"形,群落总体上更新良好。研究发现钱江源国家公园物种丰富,但由于包含较多次生林等植被类型,整体温带多于热带区系成分,亟待采取措施恢复至典型中亚热带常绿阔叶林植被;研究对钱江源国家公园木本植物物种的多样性及其更新情况等科学和保护实践急需解决的基本问题做出了回答,也为未来钱江源国家公园生物多样性保护和恢复提供了科学依据。     

Distribution of eriophyoid mites (Acari: Eriophyoidea) on coniferous trees

The aim of the paper was to determine the infestation parameters and species composition of eriophyoid mites for different parts of Norway spruce and Scots pine as well as for different age groups of the trees. The observations on the occurrence of the mites were conducted in 2004 and 2005 in 4 locations distributed in various regions of Poland, accounting for 11 environments (location x year). Three plant age groups were studied: (1) adult trees: 40–60 years old, additionally divided into three levels: top, middle and bottom; (2) young trees: 6–10 years old; and (3) seedlings: 2–3 years old. The same number of species (five) occurred on each coniferous tree, but only one, the rarest, was common on both tree species. Out of 500 samples for each species, mites were found on 279 pine (55.8%) and 252 spruce samples (50.2%). No tendency for the mites to choose any particular level on Scots pine and Norway spruce was observed. In addition, no tendency for the mites to choose trees from any of the age groups was observed for both Scots pine and Norway spruce, in the latter case the result obtained also for mite species subdivided into vagrant and refuge-seeking ones. Final conclusions were that in case of adult trees samples can be taken from the bottom part of a tree; however, sampling from young trees growing among adult trees may be seen as the most efficient sampling method.     

Behavioural studies on eriophyoid mites: an overview

Eriophyoid mites are excellent candidates for ethological research using the approaches of behavioural ecology and sociobiology. These tiny haplodiploid mites are highly specialized plant parasites, producing galls, forming nests, inhabiting refuges or living freely on plants. They reproduce via spermatophores deposited on a substrate and without pairing, which is a fascinating, though still poorly understood, mode of reproduction widespread in some groups of arthropods. Eriophyoid males can be involved in external sperm competition. In some species they also guard pre-emergent females and deposit spermatophores beside them. Although slow-walking, the minute eriophyoid mites can disperse for long distances on air currents or specific animal carriers. After landing on a plant they can distinguish between suitable and unsuitable hosts. Biological observations on a deuterogynous species indicate that parasociality could occur among eriophyoid mites. Many eriophyoids are of economic importance. Knowledge of their behaviour may promote understanding their ecology, may resolve problems in their phylogeny and may help developing methods for their control. In this paper, attention is directed to dispersal modes of eriophyoid mites, their feeding and host acceptance, spermatophore deposition and mating, defence against predators, and social behaviour.     

Plant-related factors influence the effectiveness of Neoseiulus fallacis (Acari: Phytoseiidae), a biological control agent of spider mites on landscape ornamental plants

The predatory mite Neoseiulus fallacis (Garman) was evaluated as a biological control agent of herbivorous mites on outdoor-grown ornamental landscape plants. To elucidate factors that may affect predator efficiency, replicated tests were conducted on 30 ornamental plant cultivars that varied in relationship to their generalized morphology (e.g., conifers, shade trees, evergreen shrubs, deciduous shrubs, and herbaceous perennials), production method (potted or field grown), canopy density, and the prey species present on each. Plant morphological grouping and foliar density appeared to be the most influential factors in predicting successful biological control. Among plant morphological groups, N. fallacis was most effective on shrubs and herbaceous perennials and less effective on conifers and shade trees. N. fallacis was equally effective at controlling spider mites on containerized (potted) and field grown plants, and there was no difference in control of mites on plants with Tetranychus spp. versus those with Oligonychus or Schizotetranychus spp. Moderate to unsuccessful control of spider mites by N. fallacis occurred mostly on tall, vertical plants with sparse canopies. Acceptable spider mite control occurred in four large-scale releases of N. fallacis into production plantings of Abies procera, Thuja occidentalis 'Emerald', Malus rootstock, and Viburnum plicatum 'Newport'. These data suggest that N. fallacis can be an effective biological control agent of multiple spider mite species in a range of low-growing and selected higher growing ornamental plants.     

Three new species of eriophyoid mites (Acari,Eriophyoidea) associated with Lauraceae in China

In this paper, three new species of eriophyoid mites in the family Eriophyidae associated with Phoebe hunanensis Hand.–Mazz. (Lauraceae), namely Gammaphytoptus striatilobus sp. n., Phyllocoptes setalsolenidion sp. n., and Dechela phoebe sp. n. are described and illustrated. All are vagrants causing no apparent damage to the same host plants.     

江苏省珍稀濒危保护植物资源及其园林应用前景

珍稀濒危保护植物是人类重要的植物资源之一,江苏地处暖温带和亚热带的过渡地带,自然条件优越,植物种类多样,蕴含着丰富的珍稀濒危保护植物。文章调查整理出78种江苏省珍稀濒危保护植物,隶属40科65属,其中本省自然分布的有21种,从其他省份引种栽培的有57种。为了能促进江苏省珍稀濒危保护植物在园林绿化中的应用,分别从江苏省珍稀濒危保护植物的概况、观赏价值、园林应用现状以及在园林中的应用前景等方面进行论述,以期为绿化工作者提供参考。     

Adventive eriophyoid mites: a global review of their impact, pathways, prevention and challenges

Eriophyoids have high potential as adventive mite species (AMS) because their small size make them difficult to detect, and can be easily distributed in world trade. Economic, social and environmental impact from adventive eriophyoid mites has been significant. Considerable attention has been given to adventive insect species while adventive mites have received little attention and little information is available for eriophyoids. This paper summarizes information on adventive eriophyoid mites, their impact, and the history of some important invasions. The status of adventive species of eriophyoids introduced as biological control agents of weeds is presented. A list of eriophyoid mites reported as invasive species worldwide is given. Pathways of concern and biosecurity actions to reduce the risk of eriophyoid mites are discussed. The need to raise public awareness of the risk and importance of these tiny organisms as AMS is emphasized. Scientific and technical challenges to deal with adventive eriophyoids are discussed.     

Two species of eriophyoid mites (Acari, Prostigmata) in wheat cultivation (Triticum aestivum L.) and associated grass community in Wielkopolska, Poland

Abstract: Quantitative characteristics of the occurrence of eriophyoid mites on wheat and associated grasses were studied. Three groups of hosts: cultivated wheat ( Triticum aestivum ), quackgrass ( Agropyron repens ) in cultivation, and quackgrass in balks were analysed. Two species of eriophyoid mites were recorded: Aceria tosichella Keifer and Abacarus hystrix (Nalepa). A. hystrix appeared more frequent [present in 65.0% of all collected samples; (95% confidence interval: 50–80)] and abundant [mean number of individuals per sample: 207.3 (94.4–351.5)] than A. tosichella (17.5%; (7.5–3.0), 13.8 (0.9–32.8), respectively). Significant differences in numbers among studied mite species populations on different host plants have been found. It is concluded that wheat is the marginal host for these two eriophyoids when compared to quackgrass.     

Plant–eriophyoid mite interactions: cellular biochemistry and metabolic responses induced in mite-injured plants. Part I

This review is a comprehensive study of recent advances related to cytological, biochemical and physiological changes induced in plants in response to eriophyoid mite attack. It has been shown that responses of host plants to eriophyoids are variable. Most of the variability is due to individual eriophyoid mite–plant interactions. Usually, the direction and intensity of changes in eriophyoid-infested plant organs depend on mite genotype, density, or the feeding period, and are strongly differentiated relative to host plant species, cultivar, age and location. Although the mechanisms of changes elicited by eriophyoid mites within plants are not fully understood, in many cases the qualitative and quantitative biochemical status of mite-infested plants are known to affect the performance of consecutive herbivorous arthropods. In future, elucidation of the pathways from eriophyoid mite damage to plant gene activation will be necessary to clarify plant responses and to explain variation in plant tissue damage at the feeding and adjacent sites.     

Spatial Scales of Pollen and Seed-Mediated Gene Flow in Tropical Rain Forest Trees

Gene flow via seed and pollen is a primary determinant of genetic and species diversity in plant communities at different spatial scales. This paper reviews studies of gene flow and population genetic structure in tropical rain forest trees and places them in ecological and biogeographic context. Although much pollination is among nearest neighbors, an increasing number of genetic studies report pollination ranging from 0.5–14 km for canopy tree species, resulting in extensive breeding areas in disturbed and undisturbed rain forest. Direct genetic measures of seed dispersal are still rare; however, studies of fine scale spatial genetic structure (SGS) indicate that the bulk of effective seed dispersal occurs at local scales, and we found no difference in SGS (Sp statistic) between temperate (N?=?24 species) and tropical forest trees (N?=?15). Our analysis did find significantly higher genetic differentiation in tropical trees (F _ST?=?0.177; N?=?42) than in temperate forest trees (F _ST?=?0.116; N?=?82). This may be due to the fact that tropical trees experience low but significant rates of self-fertilization and bi-parental inbreeding, whereas half of the temperate tree species in our survey are wind pollinated and are more strictly allogamous. Genetic drift may also be more pronounced in tropical trees due to the low population densities of most species.