Big Buds Research Articles

Genomic and Pathogenic Characterization of Akanthomyces muscarius Isolated from Living Mite Infesting Hazelnut Big Buds.

The capability of entomopathogenic fungi to live as plant endophytes is well established. However, their presence in undiscovered environmental niches represents the beginning of a new challenging research journey. Recently, Akanthomyces muscarius (Ascomycota, Cordycipitaceae) (Petch) Spatafora, Kepler & B. Shrestha was isolated from hazelnut buds infested by the big bud mite pest Phytoptus avellanae Nalepa, which makes the buds swollen, reddish, and unable to further develop. Gall formation is known to be regulated by a consortium of microbes and mites, and to better understand the possible role of A. muscarius within the infested gall, its whole genome sequence was obtained using a hybrid approach of Illumina and Nanopore reads. The functional and comparative genomics analysis provided within this study may help answer questions related to the ecology and the entomopathogenicity of this fungus.

Global Status of Phytoplasma Diseases in Vegetable Crops.

The presence of phytoplasmas and their associated diseases is an emerging threat to vegetable production which leads to severe yield losses worldwide. Phytoplasmas are phloem-limited pleomorphic bacteria lacking the cell wall, mainly transmitted through leafhoppers but also by plant propagation materials and seeds. Phytoplasma diseases of vegetable crops are characterized by symptoms such as little leaves, phyllody, flower virescence, big buds, and witches’ brooms. Phytoplasmas enclosed in at least sixteen different ribosomal groups infecting vegetable crops have been reported thus far across the world. The aster yellows phytoplasma group (16SrI) is presently the prevalent, followed by the peanut witches’ broom (16SrII). Wide and overlapping crop and non-crop host ranges of phytoplasmas, polyphagous insect vectors, limited availability of resistance sources and unavailability of environmentally safe chemical control measures lead to an arduous effort in the management of these diseases. The most feasible control of vegetable phytoplasma diseases is a consequence of the development and implementation of integrated disease management programs. The availability of molecular tools for phytoplasma identification at the strain level greatly facilitated this kind of approach. It is moreover essential to understand the molecular basis of phytoplasma-vector interaction, epidemiology and other factors involved in disease development in order to reduce the disease outbreaks. Information on the knowledge about the most widespread phytoplasma diseases in vegetable crops is reviewed here in a comprehensive manner.

Florogenesis and Female Gametophyte Development in <i>Allium cepa</i> L. cv. Krishnapuram

Florogenesis is one of the most complicated and interesting processes in the nature. This process involves developmental, physiological and molecular events leading to transformation from vegetative to reproductive phase for optimal seed production and the continuation of species. The basic knowledge about flowering processes, male and female sexual systems support basic and applied research and breeding programs. Most of the onion varieties from India are short day varieties, more diverse than other exotic germplasm and useful as a source of new alleles for supporting breeding programs. The present investigation was focused to study for the first time florogenesis process by scanning electron study for the first time florogenesis process by scanning electron microscopy (SEM) and development of female gametophytes by light microscopy in order to acquire basic knowledge useful for optimizing in vitro process to produce gynogenic haploid to support and speed breeding program in short-day onion Allium cepa L. cv. Krishnapuram (KP) or Bangalore Rose. This study revealed that shoot primordium differentiated into inflorescence meristem in the month of December, while seeds were planted in the field in the September. The individual florets are preceded by a variying number of floral initials. The female gametophyte developed from chalazal side megaspore. The embryo sac development is a bisporic Allium type showing short-lived antipodals. The histological study suggests that the use of big or preanthesis flower buds with embryo sac for production of gynogenic haploids to support breeding program in onion cv. Krishnapuram (KP). However further studies are needed for confirmation of this observation.

Cryptic speciation within Phytoptus avellanae s.l. (Eriophyoidea: Phytoptidae) revealed by molecular data and observations on molting Tegonotus-like nymphs.

Hazelnut big bud mite, Phytoptus avellanae Nalepa, is one of the most harmful pests of Corylus spp. (Corylaceae) worldwide. Herein, we show that this species represents a complex of two cryptic species: one that lives and reproduces in buds causing their enlargement ('big buds') and drying, whereas the other is a vagrant living on leaves, under bud scales and in catkins, based on phylogenetic analyzes of mitochondrial cytochrome c oxidase subunit I (COI) DNA and the nuclear D2 region of 28S rDNA sequences. A molecular assessment based on mtCOI DNA and nuclear D2 28S rDNA revealed consistent differences of 16.8 and 3.5% between the two species, respectively. Molecular analysis also revealed that atypical flattened nymphs (Tegonotus-like nymphs sensu Keifer in Mites Injurious to Economic Plants, University of California Press, Berkeley, pp 327-562, 1975) with differently annulated opisthosoma, which appear in the life cycle of P. avellanae s.l., belong to the 'vagrant' lineage, i.e. vagrant cryptic species. Light microscopy images of Tegonotus-like nymphs molting into males and females are presented for the first time. Our results suggest that the name P. avellanae comprise two species. Big bud mite should keep the name P. avellanae, and the vagrant cryptic species should be re-named after a proper morphological description is made.

Timing of sulphur spray application for control of hazelnut big bud mites (<i>Phytoptus avellanae</i> and <i>Cecidophyopsis vermiformis</i>)

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

Forecasting emergence and movement of overwintering hazelnut big bud mites from big buds

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 were >15 degrees C and when mean temperatures were >9 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.

Ecology and Control of Eriophyid Mites Injurious to Fruit Trees in Japan

Studies on the damage, biology, natural enemies and management of the economically important eriophyid mites: persimmon bud mite, Aceria diospyri, ficus mottle mite, Aceria ficus, peach silver mite, Aculus fockeui, and pink citrus mite, Aculops pelekassi in Japan are reviewed. A. diospyri and A. pelekassi mainly cause damage to the fruits of host plants. The rust symptom on persimmon fruits by A. diospyri differs among varieties. A. ficus causes economic loss in fig with leaf mosaic, leaf malformation, fruit mosaic, and fruit drop. A. fockeui injures peach leaves, reduces the sugar content of the fruit, and the damaged trees have lower vigor due to post-harvest defoliation. These mites overwinter in buds of host plants as adults. Overwintered mites begin to reproduce on the leaves after late May or mid-April. Fruit infesting mites, A. diospyri and A. pelekassi, migrate to and infest fruits after June. Since the density of overwintered A. ficus is high in large dormant fig buds, cutting of the big buds is effective to reduce mite damage in the next season. Several acaricides, insecticides and fungicides are effective against the eriophyid mites. A. pelekassi populations with dithiocarbamate-fungicide resistance were confirmed in the early 1990's and outbreaks of the mite sometimes cause severe damage to citrus fruits. It was found that some phytoseiids, a tydeid and a stigmaeid feed on these eriophyids. Phytoseiidae mites play an important role in the control of A. diospyri, A. ficus and A. fockeui populations in low densities. A marked resurgence in A. fockeui populations occurs after synthetic pyrethroids are sprayed, because they have no effect on A. fockeui but are harmful to the predators, such as phytoseiid mites.

Some biological and morphological differences between gall and vagrant forms of Phytoptus avellanae Nal. (Acari: Phytoptidae)

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 comparisons showed that the gall and vagrant forms were significantly different from each other in size, shape and color.

Torulopsis in gynecology

Torulopsis glabrata, a pathogenic yeast, causes a vulvovaginal mycosis in about 10% of all cases, whereas mostly candida albicans is identified. Yeasts of the genus Torulopsis seem to occur especially on healthy women, whereas in cases of the well-known risk factors the growth of Candida albicans is advanced. Torulopsidosis of the vagina commonly takes a mild course. The diagnosis is ensured only in cooperation with special laboratories. However, microscopic traps are absence of pseudomycelia and relatively small buds which contrast with the big buds of candida albicans. Although the clinical course is usually less heavy than in cases of candidosis, a six- to ten-day treatment with local imidazole or Polyene antimycotics is necessary to avoid recurrences. The fact that yeasts of the genus Torulopsis form no pseudomycelia is perhaps an explanation for the mostly mild course of illness on the one hand and for the weak response to cellwall-synthesis blocking antimycotics on the other hand.