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Dispersal of eriophyoid mites is crucial for the successful colonization of new plants. Literature suggests that their long-distance dispersal is through aerial transfer. During dispersal, eriophyoids might be captured in vapor or fine drops of water (perhaps most likely in clouds) where they might be protected against water loss and desiccation, but where they would have no food and be exposed to low temperatures and oxygen concentrations. Considerable resistance of these mites to these stressful environmental conditions is expected and has only partly been confirmed experimentally. The aim of the bioassays conducted here was to assess the survival of five eriophyoid species off their host plants, with poor oxygen availability under two temperature regimes. The bioassays were carried out on live mites dipped into two media used as microenvironments: (1) vaseline oil (used also as control treatment), and (2) water solution of Tween 80 (0.2%) and cycloheximide (50 mg/l). The bioassays were performed at 5 ± 1 and 25 ± 1 °C. The survival of mites was assessed weekly (5 °C) or daily (25 °C) by counting live and active specimens. The following species were subjected to the bioassays: Aceria caulobia (a stem gall mite), Aceria ficus (a vagrant mite), Cecidophyopsis hendersoni (a vagrant mite), Colomerus vitis (protogyne/male population and deutogyne morphs; a leaf gall mite) and Phytoptus avellanae (a bud gall mite). The survival rate of the mites was higher at 5 °C than at 25 °C under both experimental conditions. At 5 °C, the survival of almost all species was higher in the water solution (up to 6-7 weeks) than in vaseline oil (3-5 weeks). Longer survival was found for A. caulobia and P. avellanae (gall-making species) than for C. hendersoni and A. ficus (vagrant species). As expected, the deutogynes of C. vitis survived longer than its protogynes. The current results suggest that individuals of some of the tested species are well suited for withstanding cold, starvation and low oxygen rates, which could be found at higher atmospheric layers, within the clouds, allowing them an effective long-distance dispersal.

Hazelnut is a traditional crop of Georgia, where hazelnut growing is enlarging and export is increasing. Samegrelo is the main hazelnut producing region of the country. Unfortunately, different species of insect and mite pests have been detected in the orchards of this region, which cause quality and yield reduction of this valuable crop. In this paper we present the results of a study carried out in five villages of Samegrelo region where we surveyed the incidence of important pests. The three main pests: ambrosia beetle (Xyleborus dispar), bud mite (Phytoptus avellanae) and hazel long-horned beetle (Oberea linearis) were surveyed. X. dispar was widespread and caused considerable damage to hazelnut orchards in all five villages, while P. avellanae and O. linearis were detected in only three of the surveyed orchards. The mean number of abnormal buds and shoots damaged by these pests was not significantly different among the investigated orchards. The locations, surveying details and amount of damage is presented.

The aim of this study was to identify the allelopatic effect of the components of a mixture of essential oils (EO) contained in the buds and leaves of hazel (Corylus L.) on herbivores. We examined the effect of these compounds on the choice of plants of two different hazel cultivars by Phytoptusavellanae Nal. (filbert big bud mite) and Myzocalliscoryli Goetze (filbert aphid), which are the most important pests of hazel in Poland and throughout the world. Our results show that plants of cv. ‘Mogulnus’ were more resistant than those of cv. ‘Barra’ to the feeding of mites and aphids in all study years. Using gas chromatography (GC) and GC/mass spectrometry methodology, we determined the qualitative and quantitative composition of EO in the buds and leaves of plants of these two hazel cultivars. The EO obtained from the analysed materials was a mixture of mono- and sesquiterpenes. The emission of volatile organic compounds from plants is known to repel or attract pests. The mixture of EO present in the hazel buds of cv. ‘Mogulus’, which is resistant to filbert big bud mite, was characterized by a high content of nerol, α-campholenol, methyl salicylate, spatulenol, β-caryophylene and δ-cadinene. In contrast, the leaves of this cultivar, colonized by filbert aphid but to a relatively small extent, contained greater quantities of nerol, α-campholenol, p-cymene, α-terpineol and germacrene D, than the leaves of cv. ‘Barra’, which is more accepted by aphids. However, the leaves of cv. ‘Barra’ were characterized by a considerably high content of menthol, limonene, isomenthone, methyl salicylate and L-menthone.

Confocal laser scanning microscopy (CLSM) methods are still rarely used by acarologists although they are very appropriate for studying minute arthropod pests, especially eriophyoid mites. In this paper, the female reproductive system of phytoptines, including the bud mite Phytoptus avellanae, the well-known pest of hazelnut, was studied using CLSM and resulted in new interpretations of the functioning anatomy of phytoptid genitalia. Comparison of cuticle-lined internal genitalia, based on novel CLSM-based 2D and 3D imaging, and multivariate analysis of morphometric measurements, show that two basic types of internal genitalia can be found within Phytoptinae: one type in phytoptines associated with monocotyledoneous hosts (especially Cyperaceae and Asparagaceae), and another one in those associated with various dicotyledoneous hosts. Phytoptines from monocots (genera Oziella and Acathrix and Phytoptus "caricis" sp. group) possess a spherical distal part of the spermathecal tube and a semitriangular transverse genital apodeme, whereas phytoptines from dicots (genus Phytoptus "avellenae" sp. group) possess an elongate distal part of the tube and a trapezoidal apodeme. These differences in the internal genitalic anatomy were used for modifying the diagnosis of phytoptine genera (Phytoptus, Oziella and Acathrix), and reorganizing the Phytoptinae, resulting in new synonymies: 11 species were transferred from genus Phytoptus "caricis" sp. group to the genus Oziella.

Eriophyoid big bud mites are key pests of hazelnuts throughout the world although little is known of the identity and impact of the species on New Zealand hazelnut crops The objective of this study was to determine the efficacy of and optimum timing for sulphur application to control these mites A field experiment tested the application of sulphur (112 g ai/tree) at 3 62 and 88 accumulated mite emergence from overwintering big buds The greatest reduction in emerging mite numbers was achieved with an application at 62 emergence The importance of determining peak mite emergence the appearance of hazelnut buds and weather conditions to optimise the time to apply control measures are discussed

The hazelnut (Corylus avellana L.) agroecosystem includes several groups of harmful and beneficial organisms. This paper lists the mite species that have been recorded on hazelnut in Turkey, based on the collections of the authors as well as bibliographical sources, and gives the distribution and economic importance of each species. Forty-five mite species belonging to 20 families were found. The most common and important pest was Phytoptus avellanae Nal., present as both .gall. and .vagrant. forms. Cecidophyopsis vermiformis (Nal.) was also common in hazelnut orchards but has less economic impact than P. avellanae. Tetranycopsis horridus (Can. &Fanz.) was also important, but only on a local scale. Minor pests, widespread but not important, included Aculus comatus (Nal.), Tegonotus depressus Nal., Coptophylla lamimani (Keifer), Anthocoptes loricatus Nal., Eotetranychus coryli (Reck) and Tetranychus sp. The beneficial mite fauna was also rich, including 23 species of predatory mites, the most common of which was Kampimodromus aberrans (Oud.). Additionally, Czenspinskia transversostriata (Oud.) and Tarsonemus stammeri Schaarschmidt are reported for the first time in Turkey.

The big bud mite (Phytoptus avellanae Nal.), one of the most important pests of hazelnut (Corylus spp., Corylaceae), has two forms - a gall form and a vagrant form. The gall form lives inside big buds. It has a simple life cycle and a single nymphal type. The vagrant form lives on vegetative and generative organs and inside the big buds. It has a different and rather complex life cycle and two nymphal types. In this study the gall and vagrant forms of P. avellanae were examined biologically and morphologically. Biological studies were performed at 20 ± 1°C and 70% R.H. in the laboratory and mites were reared on leaf discs and the duration of the different stages was determined. The gall form did not survive on the leaf disc after the first instar nymphal stage, whereas the vagrant form survived on the leaf disc. The latter had two nymphal types, one with the normal two nymphal stages, but the other with three nymphal stages. This condition is unknown in any other eriophyoid. Morphological compari...

Eriophyoid big bud mites are key pests of hazelnut throughout the world, but they are difficult to control with chemicals or other methods because they are protected inside the bud. The most effective time for control is during the relatively short emergence period which is difficult for growers to predict. The key objectives of this study were to monitor mite emergence from big buds in spring, determine the phenology of mites in relation to tree phenology and weather, and identify the optimum timing for control measures. Mite emergence was found to occur between early and late spring in Canterbury, New Zealand. Mite emergence and movement occurred when daily maximum temperatures were15 degrees C and when mean temperatures were9 degrees C, with mite emergence increasing with temperature. The developmental status of new buds during mite emergence was a crucial factor in the infestation of new buds. An accumulated heat sum model (DD), starting at Julian date 152 and using a lower threshold temperature of 6 degrees C, predicted the onset of emergence on two cultivars and at two sites at approximately 172 DD. A regression model based on leaf number, bud length, bud width, DD and Julian date provided a more satisfactory prediction of percent accumulated mite emergence. It is recommended both peak mite emergence and the developmental status of hazelnut buds be used to optimise the time to apply control measures. The optimum time to apply a control was predicted to be before buds measure 0.5 x 0.5 mm (width x length), are enclosed within the axil, and have a rounded tip, or, when 50% accumulated mite emergence has occurred, whichever occurs first.

SUMMARY The interaction of environmental and genetic variation in hazelnut (Corylus avellana) shoot development and the behaviour, survival, and colonisation of eriophyid bud mites (Phytoptus avellanae and Cecidophyopsis vermiformis) were studied. The distribution of galled buds on shoots indicated that mites colonised only those buds formed during the mite migration period. The point of entry is probably the growing shoot tip. Once within this structure, as the shoot develops the mites have access to a succession of newly-formed, bud primordia that are unprotected by bud scales. The relative accessibility of the apical meristem and bud primordia may affect host susceptibility.