外源水杨酸和茉莉酸诱导巨峰葡萄抗根瘤蚜

【目的】水杨酸和茉莉酸在植物诱导防御虫害反应中发挥着重要作用。本研究旨在探讨水杨酸和茉莉酸诱导葡萄对根瘤蚜的抗性。【方法】以盆栽巨峰为试材,在接种葡萄根瘤蚜Daktulosphaira vitifoliae的同时喷施水杨酸和茉莉酸,测定和评估了对根瘤蚜生长发育及产卵量的影响,以及对葡萄根系抗氧化相关酶［过氧化物酶(POD)和过氧化氢酶(CAT）］活性、丙二醛（MDA）含量、新梢生长量及光合速率的影响。【结果】水杨酸和茉莉酸诱导处理显著降低了根瘤蚜卵量及下代1,2龄若蚜总数,接种35 d后根瘤蚜的产卵量分别减少了41.35％和50.00％,1龄和2龄若蚜总数分别减少了42.31％和50.00％;根瘤蚜侵染后根系中POD和CAT活性均呈先升高后降低的趋势,且水杨酸和茉莉酸诱导处理在各测定时期均高于仅接种根瘤蚜处理;水杨酸和茉莉酸处理的根系中MDA含量在各测定时期均低于仅接种根瘤蚜处理;水杨酸和茉莉酸处理降低了根瘤蚜侵染对植株地上部生长及光合的抑制。接种处理后第30天,仅接种根瘤蚜处理的植株地上部生长量减少了48.11%,光合速率降低了58.77％,而水杨酸和茉莉酸处理后的新梢生长量分别减少了31.57％和25.71％,光合速率分别降低了32.89％和24.67％。【结论】叶片喷洒茉莉酸和水杨酸能够降低根瘤蚜种群密度,并提高葡萄根系活性氧清除能力和防御酶活性,缓解树势衰退。     

Biological studies of Oligonychus punicae (Acari: Tetranychidae) on grapevine cultivars

Life cycle, fecundity and longevity of the avocado brown mite, Oligonychus punicae (Hirst), were studied on six grapevine cultivars (Tucupita, Villanueva, Red Globe, Sirah, Sauvignon and Chenin Blanc), under laboratory conditions at 27 +/- 2 degrees C, 80 +/- 10% RH, and L12:D12 photoperiod. Mite-infested leaves were collected from vineyards, placed in paper bags and taken to the laboratory. A laboratory mite culture was established using the grape cultivar Criolla Negra as host plant. To elucidate potential effects on avocado brown mite parameters, we assessed levels of secondary metabolites, such as alkaloids, flavonoids, tannins and polyphenols, of leaves of the six grape cultivars, as well as the thickness of the adaxial cuticle-epidermis. The life cycle of O. punicae differed among cultivars with average values ranging between 8.2 days on Tucupita leaves and 9.1 days on Sirah. Relatively high fecundity was found on Tucupita leaves (2.8 eggs/female/day) during 11.4 oviposition days, while low fecundity values occurred on Sirah and Villanueva leaves, with 0.9 and 1.8 eggs/female/day during 7.9 and 6.7 days, respectively. Average longevity of O. punicae females ranged from 8.1 to 17.5 days on Sirah and Sauvignon leaves, respectively. Intrinsic rate of increase (r (m)) was highest on Sauvignon (0.292) and Tucupita (0.261), and lowest on Sirah (0.146) and Villanueva (0.135). Although significant differences in cuticle-epidermis thickness were detected among the six cultivars, it seemed not to affect mite parameters. Secondary metabolite content also varied between the cultivars. Generally, increasing flavonoid content coincided with decreasing reproductive parameters. The natural plant resistance observed in this study could be useful in the development of an integrated pest management program for mite pests in grape production.     

The influence of methyl jasmonate (JA-Me) and B-glucosidase on induction of resistance mechanisms of strawberry against two-spotted spider mite (Tetranychus urticae Koch.)

The goal of the research was to study the influence of methyl jasmonate (JA-Me) and beta-glucosidase treatments on fecundity and preference to infestation and oviposition of two-spotted spider mite feeding on strawberry. The experiments were conducted in laboratory conditions on leaves of Aga and Kent cultivars. Leaves were treated with: a. solution of 0.1% JA-Me in 0.05% Triton X-100 (by spraying); b. beta-glucosidase dissolved in 0.1 M citrate buffer at pH 6 (by petiole); c. 0.05% solution of the Triton X-100 (by spraying); d. 0.1 M citrate buffer at pH 6 (by petiole). In the no-choice test, application of JA-Me on leaves of strawberry caused reducing of number of eggs laid during three days of the experiment. In the choice test, which was carried out for determination of non-preference mechanism of resistance, there was a statistically significant lower number of mites on leaves treated with JA-Me compared to leaves treated with other compounds as well as to non-treated leaves after 24 hours from solutions application. Moreover, at the same experiment, females of two-spotted spider mite laid the least number of eggs on leaves treated with JA-Me. Analysis conducted using liquid chromatography method, revealed increase of the level of phenolic compounds like chlorogenic acid and rutin on leaves treated with JA-Me. Thus, it appears that JA-Me may be involved in antybiosis or non-preference mechanisms of resistance of strawberry to two-spotted spider mite.     

Attraction of Phytoseiulus persimilis (Acari: Phytoseiidae) towards volatiles from various Tetranychus urticae-infested plant species

Plants infested with the spider mite Tetranychus urticae Koch, may indirectly defend themselves by releasing volatiles that attract the predatory mite Phytoseiulus persimilis Athias-Henriot. Several plants from different plant families that varied in the level of spider mite acceptance were tested in an olfactometer. The predatory mites were significantly attracted to the spider mite-infested leaves of all test plant species. No differences in attractiveness of the infested plant leaves were found for predatory mites reared on spider mites on the different test plants or on lima bean. Thus, experience with the spider mite-induced plant volatiles did not affect the predatory mites. Jasmonic acid was applied to ginkgo leaves to induce a mimic of a spider mite-induced volatile blend, because the spider mites did not survive when incubated on ginkgo. The volatile blend induced in ginkgo by jasmonic acid was slightly attractive to predatory mites. Plants with a high degree of direct defence were thought to invest less in indirect defence than plants with a low degree of direct defence. However, plants that had a strong direct defence such as ginkgo and sweet pepper, did emit induced volatiles that attracted the predatory mite. This indicates that a combination of direct and indirect defence is to some extent compatible in plant species.     

Resistance of cultivated tomato to cell content-feeding herbivores is regulated by the octadecanoid-signaling pathway

The octadecanoid signaling pathway has been shown to play an important role in plant defense against various chewing insects and some pathogenic fungi. Here, we examined the interaction of a cell-content feeding arachnid herbivore, the two-spotted spider mite (Tetranychus urticae Koch), with cultivated tomato (Lycopersicon esculentum) and an isogenic mutant line (defenseless-1 [def-1]) that is deficient in the biosynthesis of the octadecanoid pathway-derived signal, jasmonic acid (JA). Spider mite feeding and fecundity on def-1 plants was significantly greater than on wild-type plants. Decreased resistance of def-1 plants was correlated with reduced JA accumulation and expression of defensive proteinase inhibitor (PI) genes, which were induced in mite-damaged wild-type leaves. Treatment of def-1 plants with methyl-JA restored resistance to spider mite feeding and reduced the fecundity of female mites. Plants expressing a 35S::prosystemin transgene that constitutively activates the octadecanoid pathway in a Def-1-dependent manner were highly resistant to attack by spider mites and western flower thrips (Frankliniella occidentalis), another cell-content feeder of economic importance. These findings indicate that activation of the octadecanoid signaling pathway promotes resistance of tomato to a broad spectrum of herbivores. The techniques of amplified fragment length polymorphism (AFLP) and bulk segregant analysis were used to map the Def-1 gene to a region on the long arm of chromosome 3 that is genetically separable from the map position of known JA biosynthetic genes. Tight linkage of Def-1 to a T-DNA insertion harboring the maize (Zea mays) Dissociation transposable element suggests a strategy for directed transposon tagging of the gene.     

Grape phylloxera (Daktulosphaira vitifoliae) – a review of potential detection and alternative management options

The management options for grape phylloxera, Daktulosphaira vitifoliae, a monophagous insect pest of Vitis species are reviewed. Although in a worldwide context, grape phylloxera is managed predominantly by the use of resistant rootstocks developed through conventional breeding of hybrid crosses of American Vitis species, this management aspect is largely excluded from the review so that emerging technologies in the field of detection, quarantine and alternative management are discussed. In some viticulture regions of the world, where grape phylloxera's geographic distribution is limited (e.g. Australia), the pest is managed through a combination of surveillance, detection and quarantine. Although some alternative management options for grape phylloxera exist they have received relatively limited research attention because of the relative success of resistant rootstocks. The resilience of resistant rootstocks as the primary management option could also be challenged in the future by host‐plant interactions with diverse grape phylloxera clonal lineages and by potential impacts of climate change on both grapevine and grape phylloxera distribution. A range of control options exist which could be integrated into an improved management system for grape phylloxera. Priority areas for future evaluation and further development include early detection techniques, investigation into the use of biological control agents and development of an integrated approach to grapevine phylloxera management.     

Pest response in packed table grapes to low temperature storage combined with slow-release sulfur dioxide pads in basic and large-scale tests

The effect of low temperature storage combined with slow release sulfur dioxide pads was determined in basic laboratory and large-scale commercial tests on western flower thrips, Frankliniella occidentalis Pergande; grape mealybug, Pseudococcus maritimus (Ehrhorn); Pacific spider mite, Tetranychus pacificus McGregor; twospotted spider mite, Tetranychus urticae Koch; and omnivorous leafroller, Platynota stultana Walshingham. Temperatures within the foam containers among the packed clusters decreased from ambient to 2 degrees C within approximately 1 d and ranged from 0.4 to 1.7 degrees C in all tests. Sulfur dioxide concentrations in the foam containers ranged between 0.2 and 1.6 ppm during the 1- to 6-wk storage period in basic tests and 0.5-1.1 ppm during the 1- to 8-wk storage period in the large-scale test. Western flower thrips was completely controlled by a > or =1-wk exposure. Grape mealybug mortality was > or =93% after 2-5 wk exposures and 100% after a 6-wk exposure in basic tests. Pacific spider mite and twospotted spider mite mortality was 98.0 and 99.6%, respectively, after a 6-wk exposure. Mortality of grape mealybug and twospotted spider mite increased significantly at > or =3-wk exposures and Pacific spider mite mortality increased significantly at > or =4-wk exposures. Mortality of the spider mites in general was directly related to the duration of exposure. An 8-wk exposure to low temperature storage combined with slow release sulfur dioxide pads in the large-scale test resulted in 100% mortality of western flower thrips, twospotted spider mite, and omnivorous leafroller. The treatment resulted in <8% survival of grape mealybug and <1% survival of Pacific spider mite in the large-scale test. The combination treatment offers an economical method to attain quarantine control of certain insects and mites.     

Belowground microbial symbiont enhances plant susceptibility to a spider mite through change in soybean leaf quality

To examine how rhizobia affect the chemical and nutrient status in leaves of soybean (Glycine max L.), and how rhizobia change plant susceptibility to a generalist spider mite (Tetranycus urticae), we cultivated root-nodulating soybeans (R+) and their non-nodulating mutant (R−) in a common garden. We experimentally fertilized the plants with nitrogen to examine effects of rhizobia on the plant traits and plant susceptibility to spider mites at different nitrogen levels. R+ plants produced more leaves containing greater nitrogen and less total phenolics than R− plants. Spider mites fed on R+ leaves produced more eggs than those fed on R− leaves. The positive effect of rhizobia on spider mite fecundity could be due to an increase in foliar N content and/or to a decrease in concentration of phenolics. Although root nodule mass did not differ among different nitrogen levels, ureide-N, an indicator of nitrogen provided by rhizobia, in xylem sap decreased at moderate and high soil nitrogen levels. Therefore, we expected that rhizobia effects on egg production of the spider mite would decrease in high soil nitrogen conditions. However, the effect of rhizobia was still maintained even at high soil nitrogen levels. Thus, soil nitrogen and rhizobia may independently affect the reproductive performance of the spider mite.     

烟草水浸提液对葡萄根瘤蚜侵染危害的控制效应

【目的】检疫害虫葡萄根瘤蚜Daktulosphaira vitifoliae已经在我国多个地区葡萄园发现为害, 直接影响葡萄生长; 前期实验发现烟草水浸提液可有效控制离体根上根瘤蚜的存活率, 本研究进一步开展盆栽验证, 探讨烟草水浸提液对葡萄根瘤蚜侵染的控制效应及葡萄植株生长抑制的缓解作用。【方法】以两年生温室盆栽‘巨峰’自根苗为实验材料, 接种根瘤蚜虫卵35 d后进行烟草水浸提液处理, 处理后测定供试植株的根结数、生长量、根系活力、叶片光合速率及叶绿素荧光等指标。【结果】20 mg/mL和50 mg/mL的烟草水浸提液对根瘤蚜均有一定程度的抑制作用, 施药21 d后, 葡萄根部的新增根结数分别比侵染对照下降了42.9%和52.8%。烟草水浸提液处理还在一定程度上缓解了根瘤蚜侵染对植株的光合能力和荧光的抑制作用。20 mg/mL和50 mg/mL烟草水浸提液处理的株高分别比侵染对照提高了57.1%和7.7%; 根瘤蚜侵染降低了土壤中真菌、细菌和放线菌的数量, 烟草水浸提液处理进一步降低了真菌和放线菌的数量, 降低了由微生物带来的次生侵染几率。【结论】烟草水浸提液对葡萄根瘤蚜的侵染具有控制效果, 并可对葡萄根瘤蚜侵染已造成的寄主危害有一定的缓解作用。     

Effects of fungicide residues on the survival, fecundity, and predation of the mites Tetranychus urticae (Acari: Tetranychidae) and Galendromus occidentalis (Acari: Phytoseiidae)

Representative fungicides from three or four families used for management of powdery mildew and other diseases in tree fruits were evaluated for their effects on a common spider mite and predator mite species, respectively. A modified Munger cell technique was effective in measuring the response of phytophagous and predaceous mites to fungicide residues on detached leaves in the laboratory. Demethylation-inhibiting (DMI) (imidazole [triflumazole] and triazole [myclobutanil]) and strobilurin (trifloxystrobin) fungicides were not toxic to female Tetranychus urticae Koch and Galendromus occidentalis (Nesbitt), and no sublethal effects were found on fecundity and predation rate after 3-5-d exposure to residues. Benomyl, a benzimidazole fungicide, increased adult mortality and reduced fecundity for both mite species; however, it did not alter the predation rate of G. occidentalis females on T. urticae eggs and larvae. Female G. occidentalis that survived the lethal effects of benomyl and the comparison acaricide pyridaben were unimpaired in predation. Our results for benomyl substantiate those of earlier studies and provide evidence for nontoxic effects of DMI and strobilurin fungicides on mites. We propose that DMI and strobilurin fungicides are a good fit for integrated mite management programs due to conservation of phytoseiid predatory mites.     

Combined transcript and metabolite analysis reveals genes involved in spider mite induced volatile formation in cucumber plants

Many plants have an indirect defense against herbivores by emitting volatiles that attract carnivorous enemies of the herbivores. In cucumber (Cucumis sativus) the production of carnivore attractants can be induced by herbivory or jasmonic acid spraying. From the leaves of cucumber plants with and without spider mite infestation, two subtractive cDNA libraries were made that were enriched in cDNA fragments up- or down-regulated by spider mite infestation. A total of 713 randomly selected clones from these libraries were used to make a cDNA microarray. Subsequently, cucumber plants were sprayed with jasmonic acid, mechanically damaged, infested with spider mites, or left untreated (control). Leaf samples were taken at a range of different time points, and induced volatile compounds and mRNA (from the same leaves) were collected. cDNAs prepared from the mRNA were hybridized to the clones on the microarray. The resulting gene expression profiles were analyzed in combination with volatile production data in order to gain insight in the possible involvement of the studied genes in the synthesis of those volatiles. The clones on the microarray and the induced cucumber volatiles could be grouped into a number of clusters in which specific biosynthetic genes clustered with the product of that pathway. For example, lipoxygenase cDNA clones clustered with the volatile (Z)-3-hexenyl acetate and the volatile sesquiterpene (E,E)- alpha-farnesene clustered with an up-regulated sesquiterpene synthase fragment. This fragment was used to screen a cDNA library which resulted in the cloning of the cucumber (E,E)-alpha-farnesene and (E)-beta-caryophyllene synthases. The use of combined global gene expression analysis and metabolite analysis for the discovery of genes involved in specific biosynthetic processes is discussed.     

An ecosystem analysis of spider mite outbreaks: physiological stimulation or natural enemy suppression

A simulation model was used to assess the role of several mechanisms proposed to be responsible for spider mite outbreaks on cotton that are typically observed following applications of insecticides. Simulation results were compared to an outbreak that occurred after two pyrethroid applications on cotton in a controlled experiment in the San Joaquin Valley of California. In the model, physiological effects were simulated by increasing spider mite fecundity and decreasing developmental duration, whereas loss of natural enemies was simulated by increasing spider mite age-specific survival. At the levels simulated, survival had the greatest impact on maximum spider mite density, degree days (^oD) to maximum density, and cumulative spider mite-^oD, whereas fecundity had the least, and developmental duration had an intermediate effect. There were substantial two-way interactions among all three life history parameters, with age-specific survival having the most influence. Survival had the greatest effect on spider mite population dynamics when in combination with short developmental duration. The influence of developmental duration on maximum spider mite density was greater than comparable percentage changes in fecundity, an effect that was more pronounced at high than at low survival. Changing fecundity, developmental duration, or age-specific survival individually did not result in a spider mite outbreak of the magnitude observed in the field. However, changing these three parameters simultaneously, resulted in a simulated maximum density of 8,000/m², which represents a 12-fold increase over the untreated control, and closely mimicked the previously observed field outbreak. It is proposed that spider mite outbreaks on cotton following insecticide applications are not solely the result of physiological stimulation, but are rather due to several life history parameters being affected simultaneously, with natural enemy-mediated survival having the greatest individual impact. Implications of chemically-induced phenomena affecting spider mite management on cotton are discussed. A copy of the crop and herbivore simulation models can be obtained by sending an IBM compatible disk to L. T. Wilson.     

(A)sexual reproduction – a review of life cycles of grape phylloxera, Daktulosphaira vitifoliae

Since its emergence as a pest of grapevine about 150 years ago, studies on the life cycle and mode of reproduction of grape phylloxera ( Daktulosphaira vitifoliae Fitch) (Homoptera: Phylloxeridae) have been of considerable scientific interest and importance for applied viticulture. The life cycle of grape phylloxera, as described in the mid to late nineteenth century, is still subject to discussion and confusion. In this article, we aim to provide for the first time an overview of the reported life cycle strategies of grape phylloxera by summarizing documented observations, the results of controlled field and laboratory assays, and the results of molecular genetic analyses. Thus, we present a detailed morphological comparison of grape phylloxera morphs and provide clarification of these by suggesting a simplified nomenclature as well as revising errors found in the published literature. Moreover, recent molecular markers studies, which further enhance our understanding of the impact of sexual recombination on grape phylloxera, are described and discussed.     

Ethyl formate as a postharvest fumigant for selected pests of table grapes

Ethyl formate (EF) in combination with CO2 was tested for control of arthropods commonly infesting California table grapes. In addition, table grape tolerance to EF exposure was evaluated. LC99 estimates were developed for target pests by using a range of EF concentrations (0.04-4.7% EF). Response to treatments varied greatly between species, as well as life stages within species. Western flower thrips, Frankliniella occidentalis (Pergande), and adult and crawler stages of grape mealybug, Pseudococcus maritimus (Ehrhorn), were most susceptible to EF treatments. Least susceptible were grape mealybug eggs; Pacific spider mite, Tetranychus pacificus McGregor; and omnivorous leafroller, Platynota stultana Walsingham. The LC99 for target pests fell within the range of EF concentrations tolerated by table grapes with the exception of 1-, 3-, and 5-d-old omnivorous leafroller pupae.     

Accumulation of amino acids and phenolic compounds in biochemical plant responses to feeding of two different herbivorous arthropod pests

The study aimed at comparing the changes in the content of free amino acids, phenolic compounds and the activity of PAL and TAL caused by two piercing-sucking arthropods: the grape mealybug (Pseudococcus maritimus Ehrh.) and the two-spotted spider mite (Tetranychus urticae Koch) in the leaves of orchid and strawberry, respectively. The obtained results show that the amino acid content and the ratio of amino acids to phenolic compounds increased in both plant species infested by the mealybug and the mite. However, such response was weakly dependent on changes in activity of the analysed enzymes. The pest feeding affected accumulation of the phenolic compounds, since the induction of the PAL activity in mealybug-infested orchid leaves during the first 5 h of the experiment preceded the increase in phenolic compounds during the first week of insect feeding. Instead, the increased activity of TAL was accompanied by elevated levels of phenolic compounds in the leaves of strawberry infested by mites. Mechanisms of biochemical plant responses induced by infestation of the studied herbivorous arthropods are discussed.     

The impact of insecticides applied in apple orchards on the predatory mite Kampimodromus aberrans (Acari: Phytoseiidae)

Kampimodromus aberrans is an effective predatory mite in fruit orchards. The side-effects of insecticides on this species have been little studied. Field and laboratory experiments were conducted to evaluate the effects of insecticides on K. aberrans. Field experiments showed the detrimental effects of etofenprox, tau-fluvalinate and spinosad on predatory mites. Spider mite (Panonychus ulmi) populations reached higher densities on plots treated with etofenprox and tau-fluvalinate than in the other treatments. Single or multiple applications of neonicotinoids caused no detrimental effects on predatory mites. In the laboratory, spinosad and tau-fluvalinate caused 100 % mortality. Etofenprox caused a significant mortality and reduced fecundity. The remaining insecticides did not affect female survival except for imidacloprid. Thiamethoxam, clothianidin, thiacloprid, chlorpyrifos, lufenuron and methoxyfenozide were associated with a significant reduction in fecundity. No effect on fecundity was found for indoxacarb or acetamiprid. Escape rate of K. aberrans in laboratory was relatively high for etofenprox and spinosad, and to a lesser extent thiacloprid. The use of etofenprox, tau-fluvalinate and spinosad was detrimental for K. aberrans and the first two insecticides induced spider mite population increases. The remaining insecticides caused no negative effects on predatory mites in field trials. Some of them (reduced fecundity and repellence) should be considered with caution in integrated pest management programs.     

The host plant-mediated impact of simulated acid rain on the development and reproduction of Tetranychus cinnabarinus (Acari, Tetranychidae)

Abstract:  The host plant-mediated impact of simulated acid rain (pH 3.0, 3.5, 4.0, 5.6, and 6.8) on the behaviour, development, and reproduction of carmine spider mite, Tetranychus cinnabarinus (Boisduvals), were evaluated at 25°C in a series of laboratory trials. The results indicated that the adults of carmine spider mite prefer to aggregate on pH 4.0 acid rain-treated eggplant leaves. The developmental times of nymph, larva and the pre-oviposition period of the mite on kidney bean leaves were significantly affected by acid rain treatments. The developmental times for the immature stages ranged from 11.4 days on pH 4.0 acid rain-treated leaves to 12.7 days on other acid rain-treated leaves. The survival of immatures varied from 85.14% on pH 4.0 acid rain-treated leaves to 78.83% on deionized water-treated leaves (pH 6.8). The mites feeding on acid rain-treated leaves (pH 3.0–5.6) had significantly greater reproductivity and longevity than those feeding on deionized water-treated leaves. The average greatest reproductivity (74.6 eggs per female) and longest female longevity (8.9 days) were recorded on pH 4.0 acid rain-treated leaves. Accordingly, the intrinsic rate of increase ( r _m ) for the mite on pH 4.0 acid rain-treated leaves was the highest. Jackknife estimates of r _m varied from 0.201 on pH 4.0 acid rain-treated leaves to 0.158 on pH 5.6 acid rain-treated leaves. The results implied that the population growth of the mite were enhanced by application of acid rain (pH 3.0–5.6) on host plants.     

Changes in grape phylloxera abundance in ungrafted vineyards

To examine seasonal changes in the abundance of grape phylloxera Daktulosphaira vitifoliae (Fitch), several sampling methods were tested at vineyards in Victoria, Australia. At a recently infested site, changes detected by root assessment, trunk trapping, and emergence trapping were closely correlated, although the largest numbers of grape phylloxera were obtained using traps that collected phylloxera emerging from soil. This trapping technique was further used to investigate changes in grape phylloxera numbers across three different sites from southeastern Australia as well as in three consecutive seasons at the same vineyard. Grape phylloxera numbers decreased as vines deteriorated; a single peak of emergence occurred in every summer. Size and timing of emergence peaks varied between sites and also between vine blocks within a site. The number of grape phylloxera trapped was correlated with degree-days. Monitoring soil temperature may provide a way of timing control options against grape phylloxera and a way of identifying peak periods when phylloxera detection surveys should be completed or when grape phylloxera are at the highest risk of spreading among vineyards.     

Toxicity of neem (Azadirachta indica A. Juss) formulations for twospotted spider mite and Euseius alatus de leon and Phytoseiulus macropilis (Banks) (Acari: Phytoseiidae)

The toxicity of selected commercial formulations of neem on Tetranychus urticae Koch (Acari: Tetranychidae) and two predatory mites Euseius alatus De Leon and Phytoseiulus macropilis (Banks) was studied. Topical toxicity was tested with the commercial formulations (Natuneem, Neemseto and Callneem) and extract of neem's seeds at concentration 1%, compared to the standard acaricide abamectin at concentration of 0.3 ml/L and the control treatment (distilled water). Based on the best performance against T. urticae through topical contact, the formulation Neemseto was selected to be evaluated using different concentrations against eggs, and residual and repellent effects on adults of the mites. Egg treatment consisted of dipping eggs into Neemseto dilutions and control treatment for five seconds. In addition, residual and repellent effects of Neemseto for adult mites consisted of using leaf discs dipped into the dilutions for five seconds. The toxicity of Neemseto on eggs and adults was greater for T. urticae compared to the toxicity observed for the predatory mites. Neemseto was repellent for T. urticae and E. alatus when tested at the concentrations of 0.25, 0.50 and 1.0%, and did not affect P. macropilis. Neemseto using all concentrations, while for the predatory mites significant reduction of mite fecundity was only observed at the largest concentrations reduced the fecundity of T. urticae significantly. So Neemseto, among tested neem formulations, performed better against the twospotted spider mite and exhibited relatively low impact against the predatory mites studied.