Targeting hidden pests: acaricides against the coconut mite <Emphasis Type="Italic">Aceria guerreronis</Emphasis>

The control of hidden pest species with pesticides depends on the accurate timing of the application to reach the life stages during their only moment of vulnerability, which is when the pests (temporarily) leave their hiding places. A curious case involves the colonization of the coconut perianth, a bract-protected region of the fruit, by the coconut mite Aceria guerreronis. The coconut bracts apparently provide protection against the direct action of acaricides used against the coconut mite. Furthermore, some acaricides target mite eggs and/or immatures in addition to adults, leading to enhanced mortality and/or compromised progeny production, but only if reaching these stages. In this study, we developed methods for assessing the likely protection provided by the coconut bract against the acaricides used for managing the coconut mite. We also assessed the efficacy of the acaricides currently registered for use against this species. Our results support the notion that coconut bracts provide protection to the coconut mite against direct acaricide action. Some acaricides (abamectin and fenpyroximate) were effective only with the removal of the coconut bracts, whereas others (hexythiazox and spirodiclofen) were not effective even with bract removal. Coconut mites sheltered by bracts were protected against the acaricides over time, but the acaricides seemed to induce mite dispersion. In addition, the preventive application of some acaricides reduced the chances of the perianth colonization by the coconut mite. Among the acaricides used, two (hexythiazox and spirodiclofen) are registered as ovicides, but only one (spirodiclofen) acted on eggs, preventing hatching of approximately 40 % of the eggs. The acaricide impacts on coconut mite management are discussed.     

Acaricides in modern management of plant-feeding mites

This review focuses on biological profiles of contemporary acaricides, acaricide resistance, and other up-to-date issues related to acaricide use in management of plant-feeding mites. Over the last two decades a considerable number of synthetic acaricides emerged on the global market, most of which exert their effects acting on respiration targets. Among them, the most important are inhibitors of mitochondrial electron transport at complex I (METI-acaricides). Discovery of tetronic acid derivatives (spirodiclofen and spiromesifen) introduced a completely new mode of action: lipid synthesis inhibition. Acaricide resistance in spider mites has become a global phenomenon. The resistance is predominantly caused by a less sensitive target site (target site resistance) and enhanced detoxification (metabolic resistance). The major emphasis in current research on acaricide resistance mechanisms deals with elucidation of their molecular basis. Point mutations resulting in structural changes of target site and leading to its reduced sensitivity, have recently been associated with resistance in Tetranychus urticae Koch and other spider mites. The only sustainable, long-term perspective for acaricide use is their implementation in multitactic integrated pest management programs, in which acaricides are applied highly rationally and in interaction with other control tactics. Considering that the key recommendation for effective acaricide resistance management is reduction of the selection for resistance by alternations, sequences, rotations, and mixtures of compounds with different modes of action, the main challenge that acaricide use is facing is the need for new active substances with novel target sites. Besides implementation of advanced technologies for screening and design of new synthetic compounds, wider use of microbial and plant products with acaricidal activity could also contribute increased biochemical diversity of acaricides.     

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.

     

Determination of susceptibility and resistance of some greenhouse populations of Tetranychus urticae Koch to chlorpyrifos (Dursban 4) by the petri dish–Potter tower method

The level of susceptibility of the two-spotted spider mite, Tetranychus urticae Koch, populations collected from greenhouses in Antalya and Isparta regions of Turkey against chlorpyrifos was determined by a petri dish bioassay method. This study consisted of two stages. In the first stage, using a diagnostic dosage (0.026 ml chlorpyrifos in 100 ml distilled water) it was determined whether these populations are resistant or susceptible to chlorpyrifos. Then, different dosages of chlorpyrifos were applied to resistant populations to determine LC₅₀ and LC₉₀ values. Resistant ratios of populations were calculated by dividing the LC₅₀ values of resistant populations by that of a susceptible population of T. urticae strain GSS. The resistance ratio of T. urticae populations collected from greenhouses ranged from 8.00 to 1,774.00. Results show that while three of the populations gathered from the Isparta region, where greenhouse vegetable growing has been increasing since 2000, are susceptible, two of them are only partially resistant to chlorpyrifos. On the other hand, all the two-spotted spider mite populations collected from the Antalya region, the centre of greenhouse vegetable production for many years, were found to be highly resistant to chlorpyrifos.     

Vergleichende Untersuchungen zur Wirkung einer mechanischen (Wasserberieselung) und einer chemischen Bekämpfungsmaßnahme gegen Erdnußspinnmilben in Ägypten

Comparative studies on the influence of sprinkler irrigation and chemical control on Tetranychid mites infesting peanut The application of water to peanut plants using sprinkler irrigation systems showed a depressing effect on mite densities. Since the upper surface of the leaves are appreciably wetted, few numbers ofT arabicus (Attiah) andT. cucurbitacearum (Sayed) inhabit only the lower leaves surface. Data showed that spider mite populations on sprinkled plot were lower than those on acaricide treated plot and control plot.     

Enzyme variation among some southwest Turkey populations of the two-spotted spider mite, Tetranychus urticae Koch

Ten different two-spotted spider mite (Tetranychus urticae Koch) populations were collected from greenhouses in two geographically different regions of Turkey, Antalya and Isparta. Individual spider mites were homogenized in microplates using multi-homogenizer, and the genetic variations in the esterase of these populations were studied by nondenaturing polyacrylamide gel electrophoresis. The results showed that esterase enzymes were polymorphic in all populations in both regions. However more intrapopulation and interpopulation variations were observed in the population from Antalya region.     

中国古老月季品种‘秋水芙蓉’在月季抗性育种中的应用

本研究采用中国古老月季花品种‘秋水芙蓉’与中国原产的野生蔷薇屑植物杂交的方法,来培育具有较高抗性的月季新品种群,共计13个组合,授粉花424朵,获远缘杂交种108株,最终有30株在北京地区连续2a露地越冬后存活.文中对杂种的形态、抗寒性、抗病性进行了描述与分析,并对‘秋水芙蓉’×报春刺玫的杂种进行了初步的遗传分析,提出‘秋水芙蓉’在今后的月季育种中有一定的应用价值,可以期望通过它培育出崭新的中国月季新品种。     

Susceptibility of female populations of <Emphasis Type="Italic">Panonychus ulmi</Emphasis> (Koch) (Acari: Tetranychidae) to some acaricides in apple orchards

The levels of susceptibility of adult female European red mite, Panonychus ulmi (Koch) populations collected from apple orchards in Bursa region of Turkey, to acaricides, dicofol, bromopropylate and fenpyroximate belong to two different groups and an acaricide–insecticide, amitraz, were determined by a petri leaf disk-Potter spray tower method. When compared with the susceptible population, resistance ratios, as indicated by LC₅₀ values, ranged from 2.2 to 11.9, 0.8 to 3.6, 1.0 to 22.5 and 0.9 to 7.9, while LC₉₀ values varied from 1.6 to 9.8, 1.0 to 5.4, 1.0 to 47.4, 1.4 to 36.6, respectively, for amitraz, dicofol, bromopropylate and fenpyroximate. An examination of bioassay responses showed that susceptibility was lower for fenpyroximate and bromopropylate than for the other two compounds in the order of amitraz < dicofol. In conclusion, P. ulmi susceptibility to tested compounds varied widely from location to location.     

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.     

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.     

The toxicity of selected acaricides against five stored product mites under laboratory assay

In laboratory tests, the toxicity of acaricides targeted against house dust mites was tested on five species of stored product mites (Acarus siro, Aleuroglyphus ovatus, Carpoglyphus lactis, Lepidoglyphus destructor, and Tyroborus lini). The formulations of benzyl-benzoate, benzyl-benzoate/permethrin/pyriproxyfen, and neem were diluted in water and applied to filter paper in an unventilated chamber. The mortality of mites was observed after 24 h of exposure to acaricide-impregnated filter paper. All of the tested acaricides were toxic to all of the mite species. There were significant differences in mortality among the species and the acaricides. Benzyl-benzoate/permethrin/pyriproxyfen was the most effective, followed by benzyl-benzoate and neem. L. destructor (LD₅₀ 0.01–0.11 μg) was the most sensitive mite species, followed by A. siro (LD₅₀ 0.04–0.12 μg), T. lini (LD₅₀ 2–21 μg), A. ovatus (LD₅₀ 3–18 μg), and C. lactis (LD₅₀ 4–64 μg). Based on the highly toxic effects of the tested acaricides against the stored product mites, the acaricides should be considered as a potential tool in the control of stored product mites, although next screening is necessary.     

基于mtDNA-COI基因序列的针叶小爪螨种群遗传结构影响因素分析

寄主植物、地理距离、农药胁迫、生境片段化等是影响种群遗传结构和进化的重要因素(Harrison etal.,1996;Hutchinson et al.,1999;Knutsen et al.,2000;罗育发等,2006;褚栋等,2008)。许多有关昆虫与植物间关系的研究发现植食性昆虫具有通过缩小或扩大其寄主范围或转移到新寄主上的进化潜力(Via,1990),这种现象可能使种群间产生完全的     

Fogging can control<Emphasis Type="Italic"> Tetranychus urticae</Emphasis> on greenhouse cucumbers

The effect of a fogging system on interactions between Tetranychus urticae and Phytoseiulus persimilis was studied in two cucumber greenhouses in northern Italy. The greenhouses were divided into two compartments, one (referred to as fog area) was humidified using a fogging system and the other was not humidified (no fog area). Four cultivars were investigated: Akito and Frontera during 2000, Dinero and Jazzer during 2001. Tetranychus urticae was released on a number of plants in both compartments. The release of P. persimilis was planned in both compartments at definite T. urticae thresholds. Phytoseiid releases failed, and the colonization by other predators was scarce.Thus, the effect of the fogging system was evaluated only on T. urticae populations. During the first experimental year, spider mite populations reached low densities in the fog area of both cultivars. Higher densities were found in the no fog area, especially in late June and early July. One year later, spider mites were more abundant in the no fog area of the Dinero cultivar. On the Jazzer cultivar, where most plants were infected by powdery mildew, spider mites were less abundant and differences between the two areas were less marked. Since relative humidity values exceeding 90% (considered as effective on T. urticae) were recorded during the night when the fogging system was not active, we suggest that contact with misty water was the main factor responsible for the reduction of T. urticae populations in the fog area.     

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.     

Influence of host plant species on the development and reproduction of hawthorn spider mites

A leaf disc bioassay was employed to investigate the influence of host species of deciduous fruit trees, like apple, peach, plum, cherry and apricot, on the development and reproduction of the hawthorn spider mite Tetranychus viennensis Zacher in the laboratory under conditions of 25±1°C, 60±10% RH and a photoperiod of 16 h: 8 h light: dark. This was done by determining the duration of each life stage of the mites, the intrinsic rate of population increase (r _m ), mean generation time (T) and net reproductive rate (R ₀) of the spider mites on each of the host plant species. Differences in life table parameters of the spider mite among host plants were analyzed with the jack-knife method. The results indicated that plum might be the best suitable plant for the spider mite among the plants tested due to shorter developmental period and higher intrinsic rate of increase, whereas cherry and apricot were least suitable due to their long developmental duration and low intrinsic rates of increase. When the spider mites were transferred from apple to other fruit trees, negative effects on developmental duration, fecundity and life table parameters were found in the first generation, but the effects faded out in succeeding generations. When transferred onto plum and peach, the spider mite adapted to the new hosts in the second generation; however, on cherry and apricot, it adapted in the third generation. __________ Translated from Acta Ecologica Sinica, 2005, 27(7) [译自: 生态学报, 2005, 27(7)]     

Comparison of two methods of monitoring thrips populations in a greenhouse rose crop

The thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is among the most important pests of greenhouse crops in Europe and causes considerable damage to commercial rose crops. The usage of pesticides is associated with major problems, and thus the interest of implementing integrated pest management (IPM) for rose crops is increasing. One essential component of IPM is field monitoring/scouting. Growers use information gathered from scouting to select and schedule appropriate control tactics. Thrips populations were surveyed in 2005 and 2006 in a greenhouse planted with roses, Rosa x Hybrida in Southern of France. From April to August, thrips were counted using yellow sticky traps (YST), knock-down techniques [i.e., tapping flower heads (FT)] and actual counts of entire plants. Thrips abundance recorded using YST correlated well with abundance levels determined through FT or actual counts (whole plant). Our results demonstrate that it is accurate to estimate thrips populations using YST in rose crops in greenhouse. Because YST takes at least twice less time than other monitoring methods, it could be used as a valid and easy monitoring technique in further development of IPM programs on roses. The possibility of setting a damage threshold using the data from the YST in the greenhouse is discussed.     

Greenhouse trials for the control of aphids on cut-roses with the chalcidAphelinus abdominalis Dalm. (Aphelinidae,Hymen.)

For the control of the aphid speciesMacrosiphum euphorbiae, an important aphid species on greenhouse cut roses in Austria, with the parasitoidAphelinus abdominalis, trials were carried out in the rose varieties Frisco, Kardinal and Vivaldi at a commercial producer on a greenhouse area of 630 to 700m². Both the inundative release of 9,6A. abdominalis/m² in total and the release of 2,2A. abdominalis/m² in total, within an open rearing system were investigated and the percentage of infested rose shoots in combination with the degree of infestation were evaluated. The results showed that an effective reduction of present or newly developing aphid populations was possible for several weeks under the conditions of a commercial greenhouse production. The amount of insecticides used against aphids decreased by up to 75% in comparison to greenhouses were only chemical pest control was carried out. The suitability of the different introduction methods ofA. abdominalis for the control of aphids on greenhouse cut roses is discussed.     

Nebenwirkungen von Insektiziden auf die Erdbeerspinnmilbe,Tetranychus turkestani (Ugar. & Nik.) (Acarina,Tetranychidae) und ihre natürlichen Feinde

Zusammenfassung Die Massenvermehrung der Erdbeerspinnmilbe,Tetranychus turkestani auf Baumwolle im Iraq nach Anwendung von Insektiziden gegen Baumwollschädlinge hängt offensichtlich von 2 Faktoren ab: einer Vernichtung der natürlichen Feinde (Raubilben und-thripse) sowie einer Verlängerung der Lebensdauer und Steigerung der Eizahl der Spinnmilbe. Beide letzteren Erscheinungen dürften auf einem dirkten Einfluß der insektiziden Wirkstoffe auf den Metabolismus der Milbe beruhen.

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Side effects of insecticides on the Strawberry Spider mite, Tetranychus turkestani (Ugar. & Nik.) (Acarina, Tetranychidae) and its natural enemies

Outbreaks observed in populations of the spider miteTetranychus turkestani on cotton in Iraq after treating with insecticides apparently depended on two main factors: destruction of the natural enemies of insects especially, and increasing of longevity and fecundity in the mite populations. The latter is probably connected with a direct influence of the chemicals used on the metabolism of the mite.

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Mit 4 Tabellen     

The abundance of <Emphasis Type="Italic">Orius niger</Emphasis> (Wolf.) and <Emphasis Type="Italic">O. minutus</Emphasis> (L.) in potato fields and their life table parameters when fed on two prey species

Two-spotted spider mite (TSSM) and onion thrips are serious pests of potatoes in the Ardabil region (Iran). In the present study, anthocorid species were identified in potato fields of this region during 2006 and 2007. The results of the abundance study indicate that Orius niger (Wolff) and O. minutus (Linnaeus) are major predators of these pests in potato fields. The life table parameters of these predators were compared when they were fed 2nd instar larvae of onion thrips or female TSSM on potato leaves. In these experiments, O. niger had a lower nymphal mortality, longer oviposition period, higher net reproductive rate (R ₀), and higher intrinsic rate of natural increase (r _m ) when fed thrips instead of mites. O. minutus feeding on mites compare to thrips had a lower nymphal mortality, longer oviposition period, higher net reproductive rate, and higher intrinsic rate of natural increase. Based on these results, it can be concluded that these predators could be useful as biological agents in potato fields.     

Biologie und Bekämpfung der SpinnmilbeTetranychus telarius L. auf Aubergine (Eierfrüchten)

Zusammenfassung 1. Die Spinnmilbenpopulation war von Anfang Oktober bis Anfang Ende Januar gering. Während dieser Zeit haben sie das Wachstum und Produktion der Pflanzen nicht sonderlich beeinflußt. Danach stieg ihre Zahl schlagartig und rief Schaden unter den Aubergine-Pflanzen hervor.2. Wir halten die Temperatur für den Hauptfaktor für den Anstieg und Abfall der Spinnmilbenpopulation. Niederschläge haben geringen Einfluß.3. Die Spinnmilben werden bereits bei Temperaturen von 13,4–15°C aktiv. Die Aktivität nimmt mit dem Temperaturanstieg zu und die Milbenzahl erreicht einen Gipfel bei etwa 21°C. Weiter ansteigende Temperatur bewirkt einen Abfall der Anzahl.4. Im Sommer werden keine Spinnmilben gefunden.5. Bei leichtem Befall werden die Spinnmilben an den unteren Blatteilen gefunden, bei schwerem Befall aber auch an der oberen Blattoberfläche.6. Kelthane und Tedion sind die besten Bekämpfungsmittel gegen die Spinnmilbe.7. Organische Phosphorverbindungen ermöglichen einen Anstieg der Spinnmilbenpopulation, wahrscheinlich durch das Abtöten ihrer natürlichen Feinde, und die Milben werden resistent gegen ihre Wirkung.

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Conclusion 1. Spider mite populations were very small at the beginning of October and until the end of January. During that time they had no harmful effect on plant growth and production. After that date their numbers increased strikingly and caused damage to the eggplants.2. We consider temperature as the major factor influencing the increase and decrease in spider mite populations. Precipitation has little effect.3. Spider mites become active and reproduce already at mean temperatures of 13,4–15°C. The activity increases with the increase in temperature and the numbers reached the peak at mean temperature of 21°C. Further increase in temperature caused the decrease in numbers.4. Spider mites are not found in summer.5. Spider mite is found on the lower surface of the leaf when infestation is light, but also on the upper surface when infestation is severe.6. Kelthane and Tedion give the best control of the spider mite.7. The organo-phosphorous compounds allow increase of spider mite populations, probably by killing its natural enemies, and the mites developing resistance against their effect.

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Der Schreiber möchte Seiner Excellenz, dem Minister für Landwirtschaft, für sein besonderes Interesse und seine Ermutigung Dank sagen; ebenso dem herrn Direktor der wissenschaftlichen Abteilung für das Bereitstellen aller während der Untersuchungen benötigten Einrichtungen. Besonderer Dank gebührt Herrn A. Arafat für das Sammeln der Daten.Dank möchte ich auch dem Superintendenten der Fara'a Versuchs-Station sagen, welcher mir das Material, Geräte und Labor zur Verfügung stellte, und allen Mitarbeitern, die niemals ihre Hilfe versagten, wenn sie darum gebeten wurden.