Genetic diversity of apple‐ and crabapple‐infecting isolates of Venturia inaequalis in Pennsylvania,the United States,determined by microsatellite markers

Apple scab caused by Venturia inaequalis is the most destructive disease of apple worldwide. In this study, genetic diversity of 101 V. inaequalis isolates from cultivated apples and ornamental crabapples in Pennsylvania (PA, USA) was characterized using 14 microsatellite markers. A total of 157 alleles ranging from 5 (Vitg9/99) to 26 (Vica10/154) per locus were detected. Regardless of the host of origin, isolates were grouped into five clusters, which were largely supported by STRUCTURE and principal coordinate analysis. Cluster analyses based on genetic distances and population structure analysis suggest very small differentiation (PhiPT ranging from 0.016 to 0.103, depending on the population comparison) between apple and crabapple isolates of V. inaequalis. Pairwise comparisons among populations from different locations showed very low differentiation, and POPGENE analysis indicated frequent migration of alleles (Nm = 1.47). In pathogenicity tests using a detached leaf assay, isolates of V. inaequalis from crabapple caused characteristic scab symptoms on apple and were highly virulent. Results of the study indicate that scab lesions in crabapple trees in close vicinity to apple orchards could serve as reservoirs for spread of the pathogen. Movement of inoculum among locations and between hosts may be responsible for the limited population structure observed. Understanding the population structure of V. inaequalis isolates is significant for apple scab management as crabapples are often used as pollinizers and rootstock in apple orchards, and as ornamental trees.     

Environmental management and biological aspects of the two eriophyoid fig mites Aceria ficus (Cotte) and Rhyncaphytoptus ficifoliae Keifer in Egypt

Mites associated with abandoned fig trees in Egypt were observed during a 2-year study. This study included species diversity and seasonal fluctuations as well as some biological aspects of common eriophyoid species. Three phytophagous species consisted of the fig bud mite Aceria ficus (Cotte), the fig leaf mite Rhyncaphytoptus ficifoliae Keifer and the two-spotted spider mite Tetranychus urticae Koch, representing a basic trophic level, were fed upon by three of predacious mites (Pronematus ubiquitus (McGregor), Amblyselus swirskii Athias-Henriot, Agistemus exsertus Gonzalez). Population abundance of the injurious mites were affected by the prevailing climatic conditions, action of predators and leaf age. A control measure of one summer pesticide (abamectin) application throughout the year seemed to be the most successful management of harmful mites. Life table parameters showed that the population of A. ficus multiplied 28.52 times in a generation time of 17.90 days, while R. ficifoliae population increased 16.50 times in a generation time of 14.61 days. Field and laboratory studies indicated that the viviparity is a typical character in the reproduction of R. ficifoliae.     

Phoretic mites of three bark beetles (<Emphasis Type="Italic">Pityokteines</Emphasis> spp.) on Silver fir

The species composition and abundance of phoretic mites of the bark beetles Pityokteines curvidens, P. spinidens, and P. vorontzowi on Silver fir (Abies alba) were investigated in 2003 at two locations (Trakoscan and Litoric) in Croatia. Stem sections and branches from A. alba trees infested by Pityokteines ssp. were collected and incubated in rearing cages. Bark beetles emerging from the stem sections and branches were examined for photetic mites. A total of ten mite species were documented for the first time as associates of Pityokteines spp. on A. alba. These included Dendrolaelaps quadrisetus, Ereynetes scutulis, Histiostoma piceae, Paraleius leontonychus, Pleuronectocelaeno japonica, Proctolaelaps hystricoides, Schizostethus simulatrix, Tarsonemus minimax, Trichouropoda lamellose, and Uroobovella ipidis. T. minimax was the most frequent phoretic mite of all the three scolytines and U. ipidis was also common, whereas, the other mite species occurred less frequently. The species spectrum and relative abundance of mite associates were similar for all three Pityokteines species. Another species, Pleuronectocelaeno barbara was commonly found phoretic on P. curvidens, captured in pheromone traps in 2005 at the location Litoric. Furthermore, two previously collected mite specimens from Switzerland, phoretic on P. curvidens, were identified as Nanacarus sp. and Bonomia sp. The records from Croatia and Switzerland in the present study increase the number of known mite associates of Pityokteines spp. from one previously documented species to 14 species. None of the phoretic mites found in the survey in Croatia appear to have the potential to be used for biological control of Pityokteines spp., although the feeding habits are unknown for many species recorded.     

Versuche über die Empfindlichkeit vonTrichogramma (Hymenoptera,Chalcidoidea) gegenüber Fungiziden

Zusammenfassung Die Wirkung von 12 im Obstbau gebräuchlichen Fungiziden in praxisüblichen Anwendungskonzentrationen aufTrichogramma-Imagines wurde in Laborversuchen geprüft.Alle berücksichtigten Mehltau-Bekämpfungsmittel, Binapacryl, Dinocap, Triamphos und Chinomethionat, erwiesen sich als mehr oder weniger toxisch, desgleichen die Schorf-Bekämpfungsmittel Mancozeb, Dichlofluanid, Metiram und TMTD. Für die Schorf-Bekämpfungsmittel Captan, Dithianon, Dodin und Zineb wurde unter den Versuchsbedingungen keine Giftwirkung nachgewiesen.Die Angaben der Literatur über die Wirkung der genannten Fungizide aufTrichogramma und andere Chalcidoidea werden diskutiert.

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Summary The effects uponTrichogramma adults of 12 fungicides which are commonly in use in orchards, in normal concentrations were examined by laboratory trials.The mildew fungicides, binapacryl, dinocap, triamphos, and oxythioquinox proved to be toxic as well as the apple scab fungicides mancozeb (= coordination product of zinc ion and [ethylenebis(dithiocarbamato)] manganese), dichlofluanid, metiram (= zinc-activated polyethylene thiuram disulfide), and thiram. Under the conditions of the experiments, there was no evidence of a toxic effect exerted by the apple scab fungicides captan, dithianon, dodine, and zineb.The available data from literature on the effects of the fungicides mentioned uponTrichogramma and other chalcidoids are discussed.

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Durchgeführt mit Unterstützung der Deutschen Forschungsgemeinschaft.

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Dem Direktor des Instituts, Herrn Professor Dr. J. M. Franz, danke ich für sein reges Interesse an den Versuchen und die mir jederzeit gewährte Unterstützung.     

Side effects of some fungicides on phytoseiid mites (Acari, Phytoseiidae) in north-Italian vineyards

The effects of fungicides containing mancozeb or copper oxychloride, as principal active ingredients, on phytoseiid mites were investigated in a vineyard comprising four varieties (Prosecco, Cabernet Franc, Pinot gris and Merlot) and located in north-eastern Italy. Phytoseiid colonisation was different among the four varieties: Amblyseius andersoni and Kampimodromus aberrans were dominant on Pinot gris and Merlot, respectively, while Typhlodromus pyri was more common than the above species on Prosecco and Cabernet Franc. Applications of mancozeb fungicides significantly affected K. aberrans populations. Concerning T. pyri, a significant effect was observed on Cabernet but not on Prosecco. The effects of mancozeb fungicides on A. andersoni were less clear. The response of phytoseiids to fungicides containing mancozeb appeared to be mediated by the variety. Therefore, the choice of one or two varieties as a standard reference for field tests is recommended. These results also suggest that the side effects of fungicides on predatory mites should be studied on different phytoseiid species and, possibly, on susceptible and resistant strains in order to gain useful insights.     

Zum Massenwechsel der SpinnmilbeTetranychus cinnabarinus (Boisd.) und der RaubmilbeAmblyseius gossypii (Elbadry) auf Baumwolle

Population dynamics of Tetranychus cinnabarinus (Boisd.) and Amblyseius gossypii (Elbadry) (Acari) on cotton plants Population dynamics of spider mites and predators on cotton plants were influenced by the date of cotton plantation. The plantation of cotton in October–November led to earlier and higher infestation of cotton leaves with spider mites than that of cotton planted in March. Similar magnitude of predatory mite infestation was observed in the cotton planted either October–November or in March. However, another lower peak of predatory mite population was recorded during May in the cotton planted in October–November. Spider mite populationl decreased gradually when predatory mite population increased rapidly on cotton leaves during August regardless to the date of cotton plantation. Chemical control of tetranychid mites on cotton plants should be applied by the first week of July to encounter population outbreaks which arise by the end of July and during August.     

A review of the major biological approaches to control the worldwide pest Tetranychus urticae (Acari: Tetranychidae) with special reference to natural pesticides

The two-spotted spider mite, Tetranychus urticae Koch, is a phytophagous pest that can cause significant yield losses in many agricultural crops, including fruits, cotton, vegetables, and ornamentals. To date, 3877 host species have been reported around the world in both outdoor crops and greenhouses. In this paper, we present the common methods to control this pest including chemical and biological practices. While synthetic acaricides have been widely used to manage T. urticae, in recent years, interest in pesticides derived from plants has increased considerably as a result of environmental concerns and pest population resistance to conventional pesticides. Some botanical pesticides can be easily produced, are relatively efficient against pests, and with few exceptions, their mammalian toxicity and persistence in the environment is low. Thus, the use of plant extracts appears to be a promising alternative strategy for pest management. The present paper reviews studies on the biocidal activities of plant extracts, including essential oils, against T. urticae, a plant-feeding mite found worldwide and a serious agricultural and home garden pest.     

Biological control study onTylenchulus semipenetrans (Cobb) (Nematodes) by certain soil mesofauna

Pot experiments were carried out to explore the role of macrochilid mites,Macrocheles muscaedomesticae (Scop.), and staphylinid beetles,Philonthus longicornis Steph. and collembola,Onychiurus sp. singly and in combination onTylenchulus semipenetrans (Cobb) on sour orange at 29±5°C 74±5% R. H. in green house. All tested soil mesofauna significantly reduced the population of the nematode. The highest predation rate was achieved by the predator mite,M. muscaedomesticae (Scop.) singly, followed by the combination of soil mite plus collembola. The numbers of soil mesofauna recovered from soil at the end of the experiment were significantly higher in treatments of nematode plus one of each of soil mesofauna than monoinoculation of each.     

Compatibility of foliage-dwelling predatory mites and mycoinsecticides,and their combined efficacy against western flower thrips <Emphasis Type="Italic">Frankliniella occidentalis</Emphasis>

Foliage-dwelling predatory mites and foliar applications of mycoinsecticides are commonly used in biological control programs for Western flower thrips. A laboratory study was designed to examine the compatibility of two foliage-dwelling predatory mites with two commercially available mycoinsecticides, followed by a greenhouse study to assess their combined efficacy against Western flower thrips, with a view to their concurrent use in an integrated strategy. The following commercially available biocontrol agents were evaluated: the predatory mites, Neoseiulus cucumeris (Oudemans) and Amblyseius swirskii (Athias-Henriot); and entomopathogenic fungi, Metarhizium anisopliae (Metschnikoff) Sorokin (now classified as Metarhizium brunneum) strain F52 and Beauveria bassiana (Balsamo) GHA strain. Mortality caused by the mycoinsecticides ranged from 0 to 15.98% in the laboratory studies. In the greenhouse, the relative efficacy of predatory mite slow-release breeding sachets, Met52 EC spray, and a combined application was determined. Under high pest pressure, Met52 EC-alone was not as effective as N. cucumeris-alone or the combination treatment over 8 weeks. Neoseiulus cucumeris-alone provided better control of thrips than Met52 EC, but in a mixed infestation of thrips and two-spotted spider mites, the combination treatment worked best overall; the spider mites were effectively suppressed by Met52 EC. Under low pest pressure in the experiment with A. swirskii, use of Met52 EC or A. swirskii sachets effectively suppressed thrips population growth; moreover, the combination treatment completely eliminated both thrips and spider mites.     

Distribution of Aeolothrips intermedius Bagnall (Thysanoptera: Aeolothripidae) and its potential prey Thysanoptera species on different cultivated host plants

The results of the monitoring of Thysanoptera species on cultivated plants in Slovenia (2000–2001), Croatia (1994–1996), and Serbia and Montenegro (1988–2003) are presented in this study. The aim of the investigation was to study the host plant distribution of the predator Aeolothrips intermedius Bagnall and its potential prey. Banded thrips were found on 30 different host plant species belonging to 16 botanical families, always in mixed populations with phytophagous or facultative phytophagous insects (including 18 Thysanoptera species). On the vegetative parts of the cultivated plants, banded thrips were found less numerous in spite of the massive population of some harmful thrips species. This indicates highly important role of pollen as alternative food for Aeolothrips intermedius.     

泰山古松柏叶螨类景观防治指标的确定及化学防治

为了保证良好的景观效果，根据叶螨发生程度和叶片受害程度，确定古松、柏上叶螨类防治指标为20头/20cm枝段。并选取常用的六种杀虫杀螨剂对古松和古柏上的叶螨进行化学防治，其中以灭虫灵、立打螨等效果最为显著。     

Varroa mites,viruses and bacteria incidences in Kenyan domesticated honeybee colonies

Varroa mite (Varroa destructor Anderson and Trueman) is a major global threat to the western honey bee (Apis mellifera L.). The ectoparasite has been implicated in the spread of honeybee viruses. Beekeeping plays a major role in transmission of the mite. The study aimed at assessing levels of Varroa infestation, bee viruses and bacteria incidences in domesticated honeybee colonies. Samples of adult honey bees, bee brood and Varroa mites were collected from Baringo, Narok, Kwale, Magarini, Voi, Ijara, Busia and Siaya in Kenya. Ten hives in each site were inspected for the presence of Varroa mites on adult bees using the icing sugar technique and forceps in sealed brood cells. The number of mites observed were recorded per site. Ribonucleic acid was extracted from the mites, brood and adult bees and a polymerase chain reaction was performed to detect the black queen cell virus. Pooled RNA samples of brood and adult bees were used in next generation sequencing on a 454 GS FLX platform to detect bee viruses and bacteria. Varroa mites were reported in all the study sites at varying levels. The black queen cell virus and three iflaviruses, European foul brood and its secondary causative agent Enterococcus faecalis were reported. The Kenyan honeybee population is threatened by bee pests and pathogens. There is a need for constant monitoring of bee pests and diseases in honeybee colonies in the country for early detection and to provide data on the status of bee health. All stakeholders in the beekeeping value chain should be enlightened on their role in pest and disease transmission.     

Begünstigung von Erdnuß-Spinnmilben durch Anbau von Erdnüssen in Obst-Plantagen sowie Ergebnisse von Bekämpfungsversuchen

Favouring Tetranychid mites by intercropping peanut plants on citrus plants and results of chemical control measures The mite populations ofT. cucurbitacearum (Sayed) andT. arabicus (Attiah) reached noxious levels on the peanut plants intercropped on orange trees, during July and August, when the increasing in temperature was accompanied with increasing in humidity. It seems that intercropping the peanut plants on fruit trees and cultural practices may affect as well peanut plant condition as the mortality of mites and consequently increase mite infestation.Regarding, the control experiments, it had been found that 5 acaricides used were very effective in decreasing Tetranychid populations on peanut plants.     

Identification of the antifungal compound,trans-cinnamic acid,produced by Photorhabdus luminescens,a potential biopesticide against pecan scab

Pecan scab (caused by Fusicladium effusum) limits the productivity of pecan in the southeastern USA. Alternatives to conventional fungicides should be biorational, of low environmental risk with a lower risk of fungicide resistance. Research showed that metabolites from the nematode symbiont Photorhabdus luminescens suppress pecan scab, but the bioactive molecules had not been identified. Extracts from P. luminescens were investigated using a bioactivity-directed fractionation approach to identify the constituent(s) responsible for the activity. High throughput antifungal bioautography assays against Colletotrichum gloeosporioides, C. fragariae, and C. acutatum were used to guide the fractionation. One of the metabolites was purified and identified as trans-cinnamic acid (TCA) using silica gel chromatography followed by semi-preparative high-performance liquid chromatography. In vitro tests confirmed toxicity of TCA to C. gloeosporioides, C. fragariae, and C. acutatum at 10 and 100 μg mL^?1 using fungal bioautography inhibition screening plates. The antimycotic activity of TCA was tested in vitro against F. effusum. Zone of inhibition tests, and tests with TCA incorporated into agar showed TCA toxicity to F. effusum at concentration 148–200+ μg mL^?1. Further tests incorporating TCA into liquid media demonstrated that TCA arrested all growth of F. effusum at a concentration even as low as 64 μg mL^?1. Naturally occurring antimicrobial products might offer an alternative to disease control in crops, helping in minimizing the risk of fungicide resistance, while also minimizing any negative impact on the environment. Additional research is warranted to determine the potential to use TCA as a suppressive agent for pecan scab and other diseases.     

New PCR–RFLP diagnostics methodology for detecting <Emphasis Type="Italic">Varroa destructor</Emphasis> resistant to synthetic pyrethroids

A significant share of the current seasonal losses of honey bee colonies can be attributed to the ectoparasitic mite Varroa destructor. Its direct feeding behaviour and virus vectoring decimate the colony until collapse if there is no effective control management in place. The synthetic pyrethroids such as tau-fluvalinate and flumethrin were intensively used to control the mite until multiple cases of resistance were reported since the early 1990s. Previous studies have shown that there are three different mutations at amino acid position 925 (L925V, I and M) of the V. destructor voltage-gated sodium channel associated with the resistance to these compounds. Here, we report the development of a new PCR–RFLP methodology to discriminate between susceptible and pyrethroid-resistant Varroa destructor mites. This is a DNA-based assay that proved to be as accurate and robust as the previously reported TaqMan^®-based high-throughput genotyping assays but significantly cheaper and more accessible to low-resourced laboratories. It is also easier to identify resistant mites using the new assay. The beekeeping community will surely welcome this new technology since there are very few effective acaricides to deal with the mite. They are aware that pyrethroids can be very effective in absence of resistance so having the possibility to use them as alternative to other compounds as part of an integrated management strategy would be of great help for long-term controlling of the parasite.     

Effect of the nematicide carbofuran on the population development of the citrus parasitic nematodeTylenchulus semipenetrans and predacious soil mites in citrus orchard under organic manure regime of fertilization

Effect of the nematicide carbofuran on the population development of the citrus parasitic nematodeTylenchulus semipenetrans and predacious soil mites in citrus orchard under organic manure regime of fertilization. In an Egyptian citrus orchard under farmyard manure regime of fertilization an experiment was conducted for three successive seasons (1993–1995) to investigate the potency of the nematicide carbofuran against the population of the citrus parasitic nematodeTylenchulus semipenetrans Cobb. and any side-effects on predacious soil mites. An initial reduction inT. semipenetrans populations was observed after application, although a remarkable increase in the population occurred afterwards. In contrast, the average number of predators decreased, particularly in 1995. In organic plots without nematicide, predators increased to great numbers andT. semipenetrans caused negligible injury. In the fertilizer-free treatment, theT. semipenetrans population was low although that of predacious mites was high. The study indicated that carbofuran treatments reduced the population of predacious soil mites and in their absence the population of the parasitic nematode,T. semipenetrans was likely to increase.     

Cannibalism and interspecific predation of the phytoseiid mite,<Emphasis Type="Italic"> Amblyseius swirskii</Emphasis>

A laboratory study revealed that females of the phytoseiid mite, Amblyseius swirskii Athias-Henriot, fed on protonymphs of their own species or of other predatory mites i.e. Agistemus exsertus Gonzales and Euseius scutalis Athias-Henriot exhibited a marked decline in their fecundity and a shortening in their longevity. Moreover, the rate of predation was also reduced. When A. swirskii females were fed on nymphs of the two-spotted spider mite Tetranychus urticae Koch after having been fed previously on protonymphs of either A. swirskii or A. exsertus increases in the rates of oviposition and consumption were observed, although these rates were lower than those of conspecific females reared continuously on the two-spotted spider mite only.     

House dust mites and their sensitivity to wood oils and volatiles

Allergic diseases such as bronchial asthma, perennial rhinitis, and atopic dermatitis caused by the house dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae, which are dominant species in homes, have recently become serious health problems. Reducing the number of and exposure to mites and mite allergens are the most important factors in preventing allergic diseases. Recently, the effects of essential oils of plants on house dust mites have received much attention with a view to producing natural mite-killing agents. Essential oils and their components of wood and their leaves have also received much attention. In this article, we summarize the biology of house dust mites, mite allergens, and their concentration in homes, and discuss the control of house dust mites by using plant and wood extractives, especially in relation to the influence of essential oils and volatiles from wood on house dust mites.     

Reproductive response and development of three soil predaceous mites utilizing the acarid miteTyrophagus casei Oud. as an alternate diet

The reproductive potential and development of the three soil predaceous mitesHypoaspis miles (Berlese),Laclaspis zaheri Shereef & Soliman andLasioseius africanus Hafez & Nasr were tested using the acarid mite,Tyrophagus casei Oudemans as an alternate prey. Laboratory studies revealed thatT. casei proved to be a promising diet for the reproduction ofH. miles, while the reproductive response of the other two predaceous mites to such prey was poor although their larvae developed to the adult stage when fed on it.     

Resistance to amitraz in the parasitic honey bee mite Varroa destructor is associated with mutations in the β-adrenergic-like octopamine receptor

Varroa destructor is considered a major reason for high loss rate of Western honey bee (Apis mellifera) colonies. To prevent colony losses caused by V. destructor, it is necessary to actively manage the mite population. Beekeepers, particularly commercial beekeepers, have few alternative treatments other than synthetic acaricides to control the parasite, resulting in intensive treatment regimens that led to the evolution of resistance in mite populations. To investigate the mechanism of the resistance to amitraz detected in V. destructor mites from French and U.S. apiaries, we identified and characterized octopamine and tyramine receptors (the known targets of amitraz) in this species. The comparison of sequences obtained from mites collected from different apiaries with different treatment regimens, showed that the amino acid substitutions N87S or Y215H in the OctβR were associated with treatment failures reported in French or U.S. apiaries, respectively. Based on our findings, we have developed and tested two high throughput diagnostic assays based on TaqMan technology able to accurately detect mites carrying the mutations in this receptor. This valuable information may be of help for beekeepers when selecting the most suitable acaricide to manage V. destructor.