The aetiology and development of damage in young fruit trees infested with fruit tree red spider mite, Panonychus ulmi (Koch)

Infestations of fruit tree red spider mite, Panonychus ulmi (Koch) altered the growth of young plants of plum and apple. At first, damage to the leaves from mite feeding did not affect their photosynthetic rates. The effects on other processes depended on the density of the infestation. Densities of 1–2 mites/cm² of leaf decreased the rate of shoot extension of Brompton plum, but about 0.5 mite/cm² increased it. Less dense infestations apparently caused no damage. The rate of growth of the leaf area of a plant relative to that of the mite population on it determined changes in the mite density, and therefore the effects of infestation. The growth of the root system was decreased before that of the shoots. Later, when some leaves were severely damaged photosynthesis was decreased. The onset and severity of this phase probably depended on the number of mites and days of feeding on individual leaves. The later-formed leaves were smaller, and sometimes fewer on infested plants. Some plants were infested with too low a density of mites to decrease shoot extension, but grew less in dry weight because of decreased photosynthesis later in the season. The initial effects are ascribed to an imbalance in the growth controlling substances caused by feeding. Radioactivity was detected in the growing regions of plants remote from mature leaves on which ¹⁴C-labelled mites were confined.     

Cross-resistance between flucycloxuron,clofentezine and hexythiazox in Panonychus ulmi (fruit tree red spider mite)

Between 1988 and 1992, 26 strains of Panonychus ulmi (fruit tree red spider mite) were collected from fields in which control failures had been observed with the acaricides clofentezine, hexythiazox or flucycloxuron.Strains were tested for susceptibility using a standardized laboratory method, to check whether control failure was due to (cross-) resistance. Classification of field populations was on the basis of their observed tolerance distribution as measured by estimates of the logLC₅₀ () and the inverse of the slope of the probit regression line () respectively. In the analyses we present classifications based on % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGGipm0dc9vqaqpepu0xbbG8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafqiVd0MbaK% aaaaa!369D!\[\hat \mu \] alone, and on % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGGipm0dc9vqaqpepu0xbbG8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafqiVd0MbaK% aaaaa!369D!\[\hat \mu \] and % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGGipm0dc9vqaqpepu0xbbG8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafq4WdmNbaK% aaaaa!36AA!\[\hat \sigma \].Regression analyses are used to predict the activity of the new compound flucycloxuron ((F)), in situations where activities of clofentezine ((C)) and/or hexythiazox ((H)) were known. There is strong evidence of cross-resistance between all three compounds. The best predictor of (F) is given by the multiple regression on (C) and (H) constrained to pass through the mean % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGGipm0dc9vqaqpepu0xbbG8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafqiVd0MbaK% aaaaa!369D!\[\hat \mu \] of the susceptible strain (R²=0.81). It can be also predicted from (C) alone (R²=0.738), or from (H) alone (R²=0.737). The squared correlation between (C) and (H) was R²=0.62.     

Hatching of the winter eggs of the fruit-tree red spider mite (Panonychus ulmi (Koch))

Observations on the hatching of winter eggs of Panonychus ulmi (Koch) from apple orchards in England over the 5 years 1962-6 are described. Differences of 2–3 weeks between orchards in the date at which 50% hatch was reached were quite common and this was out of step with petal fall in the majority of orchards. There was a continuous range between early and late hatching populations and a tendency for the populations to hatch in the same order every year. In 1966 populations on Cox's Orange Pippin hatched earlier than those on Worcester Pearmain but the difference was unlikely to be of practical importance. Neither recording accumulated day degrees for populations hatched out-of-doors nor hatching in an incubator after chilling was considered to give a sufficiently reliable forecast of 50% hatch but observations in 1966 suggested that this might be predicted from the total eggs hatched in an incubator expressed as a percentage of total healthy eggs.     

Influence of temperature on hatching of winter eggs of fruit-tree red spider mite, Panonychus ulmi (Koch)

The effects of the duration and degree of chilling, and the temperature of incubation, on hatching of winter eggs of Panonychus ulmi (Koch) were investigated. For chilling, 0°C and 5°C were more effective than — 5° and 9°, and the limits for the reaction were close to — 10° and 15°. As the chilling period was increased from 60 to 200 days, the percentage hatch on incubation at 21° increased, and the mean incubation time and its variance decreased. Before the maximum effect of chilling was achieved, percentage hatch on incubation at 9° and 15° was higher than at 21°; 27° was lethal to most winter eggs though not to summer eggs. After chilling, the later stages of diapause development could occur at temperatures from 0° to 21°₎ i.e. above and below the threshold temperature for morphogenesis, 6–7° in both winter and summer eggs. Diapause development cannot, therefore, be a unitary process. The significance of the results is discussed in relation to forecasting the time of hatch in the field, and to the phenological aspects of hatching in the spring.     

Resistance to organophosphates, and the genetic background, in fruit tree red spider mite, Panonychus ulmi, from English apple orchards

Assays on adult females and eggs of Panonychus ulmi , on leaf discs of Myrobalan plum, were used to characterise and establish homogenous organophosphateresistant (OR) and susceptible strains. Reciprocal crosses of these strains, and assays on adult mites and eggs of the parent, F₁ and F₂ generations confirmed that resistance was controlled by a single major gene, the expression of which was dominant in the response to parathion, and incompletely dominant to vamidothion, dimethoate and demeton-S-methyl. Reproductive incompatibility, between strains, as in Tetranychus urticae , was not found.
Bioassays on larvae hatched from winter eggs, collected from several orchards in Kent, Essex and Somerset, were used to evaluate the spectrum of cross-resistance to a range of 20 organophosphates (OPs). Together with assays on adult females, these tests showed 10- to 100-fold resistance to most of the OPs used for several years including those noted above, but less than 10-fold to azinphos compounds and to several recently-introduced OPs, e. g. dialifos, triazophos, dioxathion. The resistance spectrum in strain OR and five field strains was similar, but some had higher levels to parathion and demeton-S-methyl, and others to dioxathion after 3–4 years' exposure. Resistance levels to individual OPs may be enhanced by specific selection. Strains resistant to OPs showed only 2- to 5-fold resistance to two carbamates, and were fully susceptible to dicofol.     

Simulation of the interactions of predatoryTyphlodromus mites with the European red mite,Panonychus ulmi (Koch)

Interactions of Typhlodromus mites and their prey, the European red mite, in orchard settings were examined through computer simulation. In particular, the consequences of very slow dispersal by the predators, compared with the weather-dependent higher rates of prey dispersal, were elucidated. In simulations of the interactions of the predator and its prey, both dispersal and temperature strongly affected the available supply of juvenile prey, and thus could determine whether the predators on an individual tree survived or perished.     

Resistance to binapacryl and tetradifon, and the genetic background, in fruit tree red spider mite, Panonychus ulmi, from English apple orchards

Assays on eggs of Panonychus ulmi held on leaf discs of Myrobalan plum were used to characterise strains (1) multi-resistant to organophosphates (OPs) and binapacryl (strain BR), (2) multi-resistant to OPs and tetradifon (strain TR), and (3) susceptible to OPs, binapacryl and tetradifon (strain EM). By crosses of EM females and BR males, and of EM females and TR males, and by repeated backcrossing with EM males under selection pressure of the acaricides concerned, two strains were produced in which the specific genes for resistance to binapacryl and tetradifon were isolated in the genome of the EM strain. Reciprocal crosses of the resulting backcrossed strains with EM, assays on the F₁ eggs and the F₂ haploid eggs, confirmed the presence of single major genes for resistance to binapacryl and tetradifon, and the absence of maternal effects. The expression of gene BR was incompletely dominant in response to binapacryl, whilst gene TR was effectively dominant in response to tetradifon. Eggs of the field-derived strain BR showed c. 50× resistance to binapacryl, 8–19 × to dinobuton, but only c. 2× to dinocap and dinoseb. The backcrossed strain was less resistant (26 ×) to binapacryl implying that resistance in strain BR was augmented by the effects of minor genes. Resistance to tetradifon (150–200 × on eggs) involved cross-resistance to tetrasul (23 ×) and to chlorfensulphide (27×); resistance in the field-derived strain appeared to depend on the major gene alone. Resistance mechanisms were highly specific in their effects, so that there was no cross-resistance to unrelated acaricides, including amitraz, dicofol, cyhexatin, formetanate, chlordimeform, and quinomethionate. Fecundity of strain BR was 44% less than that of EM; laboratory and field evidence suggest that multi-resistant mites tend to be less fit than susceptible mites. The practical implications are discussed.     

Age-stage,two-sex life table of European red spider mite,Panonychus ulmi (Koch) (Prostigmata: Tetranychidae) on mulberry varieties

To understand the influence of four mulberry varieties on the development and reproduction of the European red spider mite, Panonychus ulmi (Koch) (Prostigmata: Tetranychidae), age-stage two-sex life tables of P. ulmi on Goshoerami, KNG, Chinese white and Rokokuyaso varieties were constructed under ambient laboratory conditions during summer season of the year with an average temperature of 26.22 ± 2.23 °C, relative humidity of 70 ± 5% and photoperiod of 14:10 h (L: D). Panonychus ulmi developed comparatively better on KNG and Goshoerami varieties than the other two varieties, as indicated by high fecundity (45.05 ± 1.89 and 41.23 ± 1.66 eggs female^?1, respectively) and intrinsic rate of increase (0.165 ± 0.01 and 0.168 ± 0.03 day^?1, respectively). Lowest intrinsic rate of increase (r) was observed on Chinese white and Rokokuyaso (0.055 ± 0.03 and 0.057 ± 0.10 day^?1, respectively). Total development time of immature females was shortest on KNG than on the other varieties. Immature survival was significantly higher on KNG and Goshoerami varieties (76.76 ± 7.59 and 72.96 ± 8.21%, respectively) and was lower on Chinese white and Rokokuyaso (46.76 ± 9.00 and 43.32 ± 8.71%, respectively). Based on all the above parameters, KNG and Goshoerami were found as most suitable varieties for P. ulmi than Chinese white and Rokokuyaso.     

Variation in the intensity of diapause in winter eggs of fruit tree red spider mite, Panonychus ultni

Winter eggs of Panonychus ulmi from six orchards in Kent showed a range of 3 weeks in the dates of 50 % hatch at field temperatures. From the effects of the duration and temperature of chilling, and the temperature of incubation, it was concluded that samples varied in their chilling requirement, and not in threshold temperatures for development. Diapause was terminated most effectively by chilling initially at o ^oC (for late-hatching strains) or 5 followed by 9 for the last month or two. Heritable variation in diapause intensity is discussed in relation to heat sums and the forecasting of hatch, and to phenology.     

Integrated control of apple pests in New Zealand 6. Incidence of European red mite,Panonychus ulmi (Koch), and its predators

Mite relationships were investigated in an orchard near Nelson from 1962 to 1974 in conjunction with a long‐term experiment into integrated control of apple pests. From 42% to 57% of the total winter eggs of Panonychus ulmi hatched over a period of 48–53 days from the last week of September until mid November. The main hatch—from 10% to 90%—took 19–20 days. Five generations occurred in each season, from October to March, although some females laid winter eggs from mid January if leaf condition became poor. Insect predators found were Stethorus bifidus, Sejanus albisignata, Arthrocnodax sp., and Xylapothrips sp. The mite Typhlodromus pyri (Phytoseiidae), the most important predator, had up to 5 generations from October to March; some females ceased to feed or oviposit from mid February onwards, and took on the characteristics of the overwintering diapause phase. With the integrated programme based on ryania, a favourable balance of P. ulmi and T. pyri was established after an initial outbreak of P. ulmi in the 1st or 2nd season, and was maintained until 1970–71, when P. ulmi outbreaks occurred on several cultivars in a season marked by hot, dry conditions in November and December. Natural control was restored the next year except on cy. Delicious, where P. ulmi remained in greater numbers for several years. With a complete commercial spray programme from 1962 to 1967 P. ulmi became resistant to all acaricides used; with the regular azinphos‐methyl programme and no acaricides in 1967–68 a population of T. pyri resistant to this insecticide emerged. The approximately × 10 resistance level did not increase appreciably, so the azinphos‐methyl dosage was reduced from 0.05% to 0.025% to allow greater survival. Several hot, dry summers followed, and commercial control of P. ulmi by T. pyri did not occur until 1973–74. A programme of low‐dosage carbaryl allowed T. pyri and S. albisignata to establish in fair numbers, but control of P. ulmi was not achieved. Experiments with mineral oils and cyhexatin have shown them to have some potential for inclusion against P. ulmi in future integrated programmes.     

Developmental success and reproductive incompatibility among populations of the European red mite,Panonychus ulmi (Acari: Tetranychidae)

Developmental success on 47 species of plant and reproductive compatibility were studied for four strains of the European red mite,Panonychus ulmi (Koch), collected from dwarf bamboo, elm and apple trees. The host range was variable in those strains and there was no plant species on which all four strains were able to reach maturity.Intra-populational crosses in the dwarf-bamboo strain and the two apple strains of mites, as well as crosses between the two apple strains, gave both female and male progeny. Inter-populational crosses between the dwarf-bamboo and apple strains produced only male progeny, as in the case where females of each strain were kept virgin, indicating that these two were reproductively incompatible and had an arrhenotokous reproductive system. When females of the elm strain were crossed with males of the elm, dwarf-bamboo or apple strain, no males were produced, as in the case for virgin females of the elm strain which had a thelytokous reproductive system. It is thus concluded that the strains derived from different host species were reproductively incompatible with one another.     

Dispersal of the glasshouse red spider mite Tetranychus urticae Koch (Acarina, Tetranychidae)

Under glass Tetranychus urticae Koch spreads by (a) migration of teneral females to oviposition sites (b) migration of mites from heavily infested plants by falling without the usual silken parachutes normally used by Tetranychid mites and (c) movement over the soil surface in accordance with the plane of polarized light.It is postulated that the effect of this combination of dispersal mechanisms is to restrict mite populations to one portion of a glasshouse from season to season with relatively slow lateral spread from these centres during each growing season.

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Zusammenfassung Bewegung auf der Wirtspflanze ist auf negativ geotaktisches Wandern der jungen Weibchen beschränkt, während Abwanderung nur stattfindet, wenn die Wirtspflanze so sehr zu Schaden gekommen ist, daß an den obersten Teilen der Pflanze keine frischen Blätter mehr vorhanden sind.Experimente haben gezeigt, daß — ungleich anderen Tetranychiden — Milben dieser Art nicht an seidenen Fallschirmen in der Luft treiben können, sondern zwangsläufig von seidenen Fäden zu Boden fallen, die sie als pendelnde Taue an stark befallenen Pflanzen bilden. Am Boden reagieren die Milben auf die Ebene des polarisierten Lichtes.Es wird daraus geschlossen, daß in Gurkenhäusern die Ausbreitung von den Überwinterungs-plätzen oder stark befallenen Pflanzen aus seitwärts nur in beschränktem Ausmaße erfolgt, so daß die Kolonien von Jahr zu Jahr in den gleichen Teilen des Gewächshauses auftreten.

     

丁氟螨酯对二斑叶螨生长发育的影响

[目的]丁氟螨酯是一种新型酰基乙腈类非内吸性杀螨剂,对害螨的各个螨态都有很高活性,具有较高的应用价值.本文评价了丁氟螨酯对二斑叶螨生长发育的影响,以期为合理用药和二斑叶螨的综合防治提供理论依据.[方法]采用浸叶法测定丁氟螨酯对二斑叶螨成螨与卵的致死中浓度、雌成螨产卵量、各螨态存活率以及各发育历期的影响.[结果]经丁氟螨...     

Demography of the twospotted spider mite,Tetranychus urticae Koch

Summary A simple life table model was constructed for Tetranychus urticae in which daily survivorship of eggs and motil stages, fecundity, and development time was altered to assess the impact of each parameter on the intrinsic rate of increase. r. Interpretation of the trade-offs focused on management considerations.A second aspect of the study concerned age and stage structure in mite populations including the time path of convergence to a stable age distribution and the effect of changes in birth and death rates on the age profile. The stable stage distributions of 7 tetranychid mite species were computed using 25 separate life tables. In spite of the wide range of r-values induced by different experimental conditions, all of the stage distributions were quite similar averaging roughly 66% eggs, 26% immatures, and 8% adults. Several population studies were cited which reported stage distributions of growing mite populations. The empirical evidence suggested that natural mite populations are often quite near this stable distribution.A practical problem involving the extent to which hormoligosis (insecticide stimulation) affects mite population growth rate was addressed using the life table model and laboratory data from controlled studies. The findings suggested that mite populations treated with insecticide may attain a 1.4- to a 4.2-fold difference in population size relative to an untreated population after 2 generations and over a 1,300-fold potential difference after 10 generations.     

Changes in the Growth-regulator Content of Plum Infested with Fruit Tree Red Spider Mite, Panonychus ulmi (Koch)

Extracts and diffusates were collected from the extending regionof Brompton plum shoots shortly after a reduced rate of extensionwas detected in those infested with fruit tree red spider mites.Bioassays showed greater amounts of gibberellin-like substancesand smaller amounts of auxin-like substances, with the exceptionof IAA, in the mite-infested material. Although the extendinginternodes of infested plants contained significantly less IAAthan the controls, there were similar amounts of IAA in theexpanding leaves of infested and control plants.     

Clofentezine and fenbutatin oxide resistance in the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) from deciduous fruit tree orchards in Western Australia

The resistance status of Tetranychus urticae Koch to the miticides clofentezine and fenbutatin oxide was investigated in deciduous fruit tree orchards in Western Australia. Mites were collected from 30 orchards across three fruit growing regions and subjected to discriminating–dose assays. There was a significant relationship between clofentezine (=;0.64) and fenbutatin oxide (V=;0.44) use and the proportion of resistant mites in each sample. Improved clofentezine models were obtained when the Perth Hills region (V=;0.90) was modelled separately from Donnybrook and Manjimup (V=;0.80). Clofentezine could be expected to fail in the latter regions after four sprays and in the former region after only one spray. The relatively low pest status of T. urticae in Western Australia did not delay the clofentezine resistance. For any given number of spray applications the response of T. urticae to fenbutatin oxide was more variable than it was to clofentezine.     

Effects of elevated CO2 and water stress on population growth of the two-spotted spider mite,Tetranychus urticae Koch (Acari: Tetranychidae), on sweet pepper under environmentally controlled conditions

Weather events such as drought and elevated atmospheric CO₂ are likely to interact with plants in numerous ways with diverse mechanisms. As a consequence of changes in quality of plants, the performance parameters and population dynamics of herbivores are expected to be influenced. In this study, a split-plot design was used to evaluate the interaction of elevated CO₂ and irrigation regime on population growth of the two-spotted spider mite, Tetranychus urticae Koch (Tetranychidae: Tetranychini), feeding on sweet pepper, Capsicum annum L. (Solanaceae), in environmentally controlled chambers. Results showed that exposure to elevated CO₂ significantly increased the C/N ratio in sweet pepper plants. Except in case of the adult stage, elevated CO₂ did not significantly increase the population density of other developmental stages or the overall population of T. urticae. However, water stress by itself and in combination with elevated CO₂ had significant effects on per capita population growth rate (r) and population density of mites. Maximum growth rate and population density of mites were observed at a combination of elevated CO₂ and intermediate water stress. Further studies, especially in field conditions, investigating the impact of elevated CO₂ and water stress on population size and growth of herbivores in other plant species may contribute to a greater understanding of the implications of global climate change on future crop productivity.     

苹果全爪螨实验种群的密度效应研究

研究了苹果全爪螨实验种群的密度效应。实验结果表明：二斑叶螨卵期不存在密度效应;幼、若螨期间存在密度效应,幼、若螨密度与其成活率明显相关,幼、若螨初始密度的增加导致死亡率增加,并且当代性比向偏雌性方向发展,而子代性比向偏雄性方向发展;不同幼、若螨密度和成螨密度对成螨产卵量均有极显著差异。苹果叶片上螨口密度大于2．5～3．5头／cm^2时,扩散量明显增加。