Methods used for sample storage, specimen clearing, slide mounting, species illustration and morphometric description in alpha-taxonomic studies are essential for the Eriophyoidea. Eriophyoid mites are very tiny and delicate, for which truly permanent specimen slides currently cannot be prepared, resulting in eventual loss of material, including type specimens. Often, published descriptions and drawings have not achieved the required level of quality, and thus many relevant taxonomic details have been permanently lost or neglected. These shortcomings can make certain identifications impossible and cause significant confusion. Consequently, there is a considerable need for accurate and uniform descriptive and illustrative data for the Eriophyoidea. Based on their expertise on this topic, the authors provide guidelines and advices, assisted also by illustrations, of the main critical aspects in managing eriophyoid mites in order to supplement and improve techniques for handling and preparation of specimens, and for improving their taxonomic study. The effects of the short- and long-term preservation methods (i.e., fresh, dried and liquid preservative choices) on digesting the internal tissues of the mites are discussed. Clearing and mounting procedures are analyzed, and special tips are suggested for handling mites and designing tools needed during these steps. Methods for recovering specimens from unsuitable slides (i.e., undercleared and overcleared specimens) are proposed and described. Techniques and tricks to produce descriptive line drawings of good quality are highlighted, and the content to include in plates is stressed. Finally, detailed instructions for standardization of measurements are given.

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Eriophyid mites have been considered to have a high potential for use as classical biological control agents of weeds. We reviewed known examples of the use of eriophyid mites to control weedy plants to learn how effective they have been. In the past 13 years, since Rosenthal's 1996 review, 13 species have undergone some degree of pre-release evaluation (Aceria genistae, A. lantanae, Aceria sp. [boneseed leaf buckle mite (BLBM)], A. salsolae, A. sobhiani, A. solstitialis, A. tamaricis, A. thalgi, A. thessalonicae, Cecidophyes rouhollahi, Floracarus perrepae, Leipothrix dipsacivagus and L. knautiae), but only four (A. genistae, Aceria sp. [BLBM], C. rouhollahi and F. perrepae) have been authorized for introduction. Prior to this, three species (Aceria chondrillae, A. malherbae and Aculus hyperici) were introduced and have become established. Although these three species impact the fitness of their host plant, it is not clear how much they have contributed to reduction of the population of the target weed. In some cases, natural enemies, resistant plant genotypes, and adverse abiotic conditions have reduced the ability of eriophyid mites to control target weed populations. Some eriophyid mites that are highly coevolved with their host plant may be poor prospects for biological control because of host plant resistance or tolerance of the plant to the mite. Susceptibility of eriophyids to predators and pathogens may also prevent them from achieving population densities necessary to reduce host plant populations. Short generation time, high intrinsic rate of increase and high mobility by aerial dispersal imply that eriophyids should have rapid rates of evolution. This raises concerns that eriophyids may be more likely to lose efficacy over time due to coevolution with the target weed or that they may be more likely to adapt to nontarget host plants compared to insects, which have a longer generation time and slower population growth rate. Critical areas for future research include life history, foraging and dispersal behavior, mechanisms controlling host plant specificity, and evolutionary stability of eriophyid mites. This knowledge is critical for designing and interpreting laboratory and field experiments to measure host plant specificity and potential impact on target and nontarget plants, which must be known before they can be approved for release. One of the more successful examples of an eriophyid mite controlling an invasive alien weed is Phyllocoptes fructiphilus, whose impact is primarily due to transmission of a virus pathogenic to the target, Rosa multiflora. Neither the mite nor the virus originated from the target weed, which suggests that using "novel enemies" may sometimes be an effective strategy for using eriophyid mites.

Eriophyoid mites (Acari Eriophyoidea) are phytophagous arthropods forming intimate relationships with their host plants. These mites are associated with annual and perennial plants including ferns, and are highly specialized with a dominant monophagy. They can be classified in different ecological classes, i.e., vagrant, gall-making and refuge-seeking species. Many of them are major pests and some of them are vectors of plant pathogens. This paper critically reviews the knowledge on eriophyoids of agricultural importance with emphasis on sources for host plant resistance to these mites. The role of species belonging to the family Eriophyidae as vectors of plant viruses is discussed. Eriophyoid-host plant interactions, the susceptibility within selected crops and main host plant tolerance/resistance mechanisms are discussed. Fundamental concepts, subjects, and problems emerged in this review are pointed out and studies are suggested to clarify some controversial points.

More than one hundred species of Eriophyoidea have been recorded hitherto from Turkey. Within the last decade, a large plant survey was carried out in order to investigate the eriophyoid fauna present in Turkey, with particular emphasis on species affecting weeds and ornamental plants. In addition, the Turkish literature has been examined for previous records of eriophyoid mites. New species, Paraphytoptus intybi n. sp. on common cichory, Cichorium intybus (Compositae) and Phytoptus albae n. sp. on white poplar, Populus alba (Salicaceae), are described and illustrated herein. In addition, a further 31 species were found to be new records for the eriophyoid fauna of Turkey with Aceria calaceris, Phyllocoptes didelphis and Vasates immigrans being new reports for the Palaearctic region. All known eriophyoid species records from Turkey appearing in papers published up until March 2013 are listed in this catalogue along with remarks and information on their current distribution in Turkey and taxonomic status.