西花蓟马的鉴别及其与近缘种的区别

西花蓟马是我国2 0 0 3年在北京新发现的外来入侵害虫,因虫体很小鉴定困难。该文提供了西花蓟马详细的形态鉴别特征,同时给出了与西花蓟马相似的烟蓟马、花蓟马和佛罗里达花蓟马共4种花蓟马的鉴定检索表。     

The spread of the western flower thrips Frankliniella occidentalis (Pergande)

Abstract 1 Since the late 1970s, the western flower thrips has spread from its original distribution in western North America to become a major worldwide crop pest. 2 A wide range of data sources have been used to map the original distribution in the U.S.A. and Canada, and the progress of the spread in the U.S.A., Canada, Europe, northern Africa and Australia. 3 The possible reasons for the start of the spread are discussed. The most likely reason is that intensive insecticide use in horticulture in the 1970s and 1980s selected an insecticide resistant strain or strains. These then established in glasshouses across North America and spread from there to Europe, Asia, Africa and Australia. 4 The international spread of the western flower thrips occurred predominantly by the movement of horticultural material, such as cuttings, seedlings and potted plants. Within Europe, an outward spread from the original outbreak in the Netherlands is discernible. The speed of spread was 229 ± 20 km/year. 5 The spread has not been restricted to glasshouses. The western flower thrips has established outdoors in areas with milder winters; for example, across the southern U.S.A., southern Europe and Australia. It also overwinters in some regions with colder winters. 6 Polyphagous phytophagous thrips have many factors predisposing them to become worldwide crop pests, particularly in glasshouses. Some other species that might spread in a similar way to the western flower thrips are listed.     

Evaluation of the nematodes Steinernema feltiae and Thripinema nicklewoodi as biological control agents of western flower thrips Frankliniella occidentalis infesting chrysanthemum

In greenhouse studies, we evaluated a commercial formulation of the entomopathogenic nematode Steinernema feltiae and the inoculative release of the thrips-parasitic nematode Thripinema nicklewoodi against western flower thrips (WFT), Frankliniella occidentalis Pergande infesting potted chrysanthemums. Foliar sprays of S. feltiae applied at 1.25-2.5×10³ IJ mL^-1 and 1000 - 2000 L ha^-1 at 3-day intervals alone (targeting feeding stages) or in combination with soil applications (simultaneously treating non-feeding stages in the soil at the same rates) decreased but did not provide adequate control of thrips in flowering plants artificially infested with a dense population. Similar nematode treatments applied for four to five applications at 6-day intervals in two batches of initially clean chrysanthemums failed to prevent unacceptable damage to flowers and leaves from a dense natural infestation within the greenhouse. Although some IJ survived up to 48 h within flowers and flower buds, few nematode-infected thrips (larvae and adults) were recovered. In studies with T. nicklewoodi (which is not amenable for mass production), the inoculative releases of two parasitized hosts per plant enabled the nematode to become established within existing WFT populations under greenhouse conditions. However, relatively poor transmission and slow speed of kill (nematode primarily suppresses populations through host sterilization) prevented low level inoculations being effective over a single crop cycle. Further studies showed that transmission of T. nicklewoodi persisted for nine host generations, infected up to 83% of adult thrips and provided long-term suppression of discrete caged populations, but only after uneconomically high thrips densities had been reached.     

Dehydration yields distinct transcriptional shifts associated with glycogen metabolism and increases feeding in the western flower thrips,Frankliniella occidentalis

We examined water balance characteristics and the influence of desiccating conditions on the physiology and behavior of adult western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Western flower thrips are globally invasive and likely to contend with shifts in water availability across their expansive geographic range. Basic water balance characteristics, including water mass and dry mass, were established for adult males and females, revealing a distinct sexual dimorphism wherein females are larger, and males retain a larger percentage of their body mass as water. Males lose relative water mass more quickly and their survival times are shorter compared to females. RNA-seq analysis identified significant enrichment of a multitude of factors including carbohydrate transport and metabolism in dehydrated males and females. This was validated by altered glycogen levels, suggesting a rapid depletion in glycogen during dehydration. The probability of thrips feeding significantly increases when desiccation occurs, potentially to replenish water content and nutrient reserves. Our results establish the fundamental water balance characteristics of adult thrips and indicate that dehydration significantly influences the survivorship and feeding behavior of thrips; all of which being crucial factors that contribute to their capacity as vectors for plant pathogens.     

Optimization of dietary RNA interference delivery to western flower thrips Frankliniella occidentalis and onion thrips Thrips tabaci

In insect reverse genetics, dietary delivery of interfering RNAs is a practical approach in nonmodel species, such as thrips, whose small size, and feeding behavior restricts the use of other delivery methods. In a laboratory context, an unsuitable diet could confound the interpretation of an RNA interference (RNAi) phenotype, however well-formulated artificial diets can minimize experimental variability, reduce the need for insect handling, and can further be used for roles, such as delivering double-strand RNA (dsRNA)-expressing recombinant bacteria. In this study, artificial diets for oral delivery of dsRNA were developed for two important pest thrips species, western flower thrips (Frankliniella occidentalis) and onion thrips (Thrips tabaci), with the goal of (a) stimulating feeding behavior, (b) supporting optimal growth rates of dsRNA-expressing symbiotic bacteria, and (c) nutritionally supporting the thrips for sufficient periods to observe RNAi phenotypes. The efficacy of artificial diets for ingesting “naked” dsRNA or dsRNA-expressing symbionts and dsRNA delivery via host plant uptake was evaluated. Compared with previously published diet formulations, new combinations based on tryptone, yeast, and soy were superior for enhancing feeding and longevity. However, simply adding “naked” dsRNA to an artificial diet was an unreliable form of RNAi delivery in our hands due to dsRNA degradation. Delivery via host plants was more successful, and the new diet formulation was suitable for symbiont-mediated dsRNA delivery, which we believe is the most convenient approach for large-scale knockdown experiments. This study, therefore, provides alternative methodologies for thrips rearing, dietary RNAi delivery, and insights into the challenges of performing dietary RNAi in nonmodel insects.     

Effects of manipulating spray-application parameters on efficacy of the entomopathogenic fungus Beauveria bassiana against western flower thrips,Frankliniella occidentalis,infesting greenhouse impatiens crops

The effects of various spray application parameters on the efficacy of a clay-based wettable powder formulation of Beauveria bassiana strain GHA conidia against western flower thrips, Frankliniella occidentalis, were evaluated in a series of greenhouse tests. With the aim of optimizing spray application methods to maximize biopesticide efficacy, a series of independent experiments was conducted that varied four spray parameters: application interval, rate, volume, and spray-program timing. Impatiens crops infested with western flower thrips were treated with (1) multiple sprays at the rate of 5×10¹³ conidia in 935 L aqueous carrier ha^?1 applied at 3-, 5-, and 7-day intervals, (2) weekly sprays at rates of 5×10¹³, 1×10¹⁴, and 2.0×10¹⁴ conidia in 935 L carrier ha^?1, (3) weekly sprays at a rate of 2.0×10¹⁴ conidia in volumes of 935, 1870, and 3740 L water ha^?1, and (4) multiple sprays at the rate of 2.0×10¹⁴ conidia in 3740 L carrier ha^?1 applied at 5-day intervals in spray programs initiated before versus after the onset of flowering. Pollen-bearing impatiens flowers were sampled twice weekly to estimate thrips population density, and adult female and second-instar thrips were collected 24 h post application for determination of acquired dose (conidia/insect). Numbers of conidia inoculated onto thrips increased with increasing spray frequency and volume. Dose was unexpectedly not directly correlated with application rate when volume was held constant, suggesting that thrips avoided concentrated spray residues. Statistically significant thrips population reductions relative to controls were achieved only when three to four sprays were applied at the highest label rate in the highest volume at < 7-day intervals. Applications against thrips infesting young, preflowering impatiens crops were not consistently more effective than applications in older crops. The most effective treatment programs reduced pest populations by 30–40% compared to untreated controls; this slowed, but did not stop, the growth of pest populations. Results indicate that use of fungi for thrips management will require integration with other control agents.     

Engineered multidomain cysteine protease inhibitors yield resistance against western flower thrips (Frankliniella occidentalis) in greenhouse trials

Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), cause very large economic damage on a variety of field and greenhouse crops. In this study, plant resistance against thrips was introduced into transgenic potato plants through the expression of novel, custom-made, multidomain protease inhibitors. Representative classes of inhibitors of cysteine and aspartic proteases [kininogen domain 3 (K), stefin A (A), cystatin C (C), potato cystatin (P) and equistatin (EIM)] were fused into reading frames consisting of four (K-A-C-P) to five (EIM-K-A-C-P) proteins, and were shown to fold into functional inhibitors in the yeast Pichia pastoris. The multidomain proteins were expressed in potato and found to be more resistant to degradation by plant proteases than the individual domains. In a time span of 14-16 days, transgenic potato plants expressing EIMKACP and KACP at a similar concentration reduced the number of larvae and adults to less than 20% of the control. Leaf damage on protected plants was minimal. Engineered multidomain cysteine protease inhibitors thus provide a novel way of controlling western flower thrips in greenhouse and field crops, and open up possibilities for novel insect resistance applications in transgenic crops.     

西花蓟马的抗药性及其治理策略

西花蓟马Frankliniella occidentalis（Pergande）是世界性的园艺作物上的重要害虫,几乎对每种类型的杀虫剂均产生了抗药性,包括有机磷、氨基甲酸酯、拟除虫菊酯类杀虫剂和多杀菌素等。本文对国外西花蓟马的抗药性发展现状和抗性机制进行了总结,并提出了抗性治理策略,即科学合理使用杀虫剂,结合栽培防治、物理防治、生物防治和寄主植物抗性等方式降低杀虫剂对西花蓟马的选择压,从而达到抗性治理的目的。     

Specific cysteine protease inhibitors act as deterrents of western flower thrips, Frankliniella occidentalis (Pergande), in transgenic potato

In this study, the effects of the accumulation of cysteine protease inhibitors on the food preferences of adult female western flower thrips, Frankliniella occidentalis (Pergande), were investigated. Representative members of the cystatin and thyropin gene families (stefin A, cystatin C, kininogen domain 3 and equistatin) were expressed in potato (Solanum tuberosum) cv. Impala, Kondor and Line V plants. In choice assays, a strong time- and concentration-dependent deterrence from plants expressing stefin A and equistatin was observed. Cystatin C and kininogen domain 3 were not found to be active. All tested inhibitors were equally or more active than stefin A at inhibiting the proteolytic activity of thrips, but, in contrast with stefin A, they were all expressed in potato as partially degraded proteins. The resistance of cysteine protease inhibitors against degradation in planta by endogenous plant proteases may therefore be relevant in explaining the observed differences in the deterrence of thrips. The results demonstrate that, when given a choice, western flower thrips will select plants with low levels of certain cysteine protease inhibitors. The novel implications of the defensive role of plant cysteine protease inhibitors as both deterrents and antimetabolic proteins are discussed.     

Behavioural and chemical evidence of a male‐produced aggregation pheromone in the flower thrips Frankliniella intonsa

The response of adult flower thrips Frankliniella intonsa (Trybom) (Thysanoptera: Thripidae) to conspecifics is investigated in Y‐tube olfactometer bioassays. The results show that both males and females are attracted to the odours of adult males, which indicates a male‐produced aggregation pheromone in this species. Gas chromatography‐mass spectroscopy analyses of headspace volatiles collected on solid‐phase microextraction fibres show that two major components and six minor components are present in volatiles from males but not in females. Further gas chromatography‐mass spectroscopy analyses reveal that the two major components in head‐space volatiles produced by F. intonsa males are the same compounds that are reported in volatiles of Frankliniella occidentalis males: (R)‐lavandulyl acetate and neryl (S)‐2‐methylbutanoate. However, the quantity of these two compounds in the volatiles differs between the species.     

低温胁迫对西花蓟马抗氧化酶活性的影响

西花蓟马Frankliniella occidentalis(Pergande)是一种重要入侵害虫。温度是影响西花蓟马生长发育和繁殖的一个重要非生物因子,西花蓟马对温度的耐受性决定了它的越冬存活率和地理分布。本文研究了4种抗氧化酶在低温胁迫下的活力变化。结果表明,4种抗氧化酶对低温胁迫具有不同的响应模式。低温处理能显著提高SOD的活力,对POD的活力则具有明显的抑制作用;然而,CAT和GST的活力在低温胁迫处理表现为先降低,随后逐渐提高的趋势。本研究结果表明4种抗氧化酶在西花蓟马应对低温胁迫中具有重要作用。     

Cadmium hyperaccumulation protects Thlaspi caerulescens from leaf feeding damage by thrips (Frankliniella occidentalis)

Metal hyperaccumulation has been proposed as a plant defensive strategy. Here, we investigated whether cadmium (Cd) hyperaccumulation protected Thlaspi caerulescens from leaf feeding damage by thrips (Frankliniella occidentalis). Two ecotypes differing in Cd accumulation, Ganges (high) and Prayon (low), were grown in compost amended with 0-1000 mg Cd kg(-1) in two experiments under glasshouse conditions. F2 and F3 plants from the Prayon x Ganges crosses were grown with 5 mg Cd kg(-1). Plants were naturally colonized by thrips and the leaf feeding damage index (LFDI) was assessed. The LFDI decreased significantly with increasing Cd in both ecotypes, and correlated with shoot Cd concentration in a log-linear fashion. Prayon was more attractive to thrips than Ganges, but the ecotypic difference in the LFDI was largely accounted for by the shoot Cd concentration. In the F2 and F3 plants, the LFDI correlated significantly and negatively with shoot Cd, but not with shoot zinc (Zn) or sulphur (S) concentrations. We conclude that Cd hyperaccumulation deters thrips from feeding on T. caerulescens leaves, which may offer an adaptive benefit to the plant.     

Susceptibility of western flower thrips, Frankliniella occidentalis (Pergande) to fumigation with methyl bromide

All life stages of the western flower thrips (Frankliniella occidentalis Pergande) were tested for their response to the fumigant methyl bromide and dose response curves were established. Pseudo-pupae were the most tolerant stage with a calculated LD99 of 53.1 mg litre“¹ h at 15^oC with a gas concentration of 13.5 mg litre”¹, but no survivors were found in any test above a concentration time product of 40 mg litre“¹ h. Standard 4 h fumigations achieving a CTP of 54 mg litre”¹ h that are used to control other pests are therefore likely to give very high levels of control of western flower thrips.     

Biological control of the western flower thrips,Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), in glasshouse sweet peppers with Orius spp. (Hemiptera: Anthocoridae). A comparative study between O. niger (Wolff) and O. insidiosus (Say)

In a comparative study for biocontrol of the western flower thrips (WFT) in commercial sweet peppers Orius spp. effectively controlled WFT. The introduced native Orius niger had replaced the introduced imported Orius insidiosus by the end of the growing season.     

北京地区西花蓟马田间种群的抗药性监测

采用叶管药膜法在室内测定了2009—2010年北京海淀地区和昌平地区西花蓟马Frankliniella occidentalis(Pergande)田间种群对12种杀虫剂敏感性的年度变化。结果表明,北京昌平和海淀地区的西花蓟马对多数的药剂仍处于敏感状态,但对氯氟氰菊酯已产生近40倍的抗性,昌平种群对多杀菌素具有产生低水平抗性的趋势(抗性倍数为4倍)。推荐药剂包括多杀菌素、阿维菌素、甲氨基阿维菌素苯甲酸盐(甲维盐)、毒死蜱和溴虫腈,应注意与其它药剂的轮换使用,灭多威对西花蓟马的毒力水平最低,不推荐使用。     

温度对西花蓟马(Frankliniella occidentalis)生长发育和存活率的影响

在15、20、25℃和30℃,RH75％的条件下,分析了温度与西花蓟马发育速率的关系,并测定了西花蓟马的发育起点温度、有效积温和存活率。结果表明：在15～30℃范围内,西花蓟马各虫期的发育速率随温度的升高而加快;用直接最优法对发育起点温度和有效积温进行估算,求得西花蓟马的卵、若虫、预蛹和伪蛹及世代发育起点温度分别为5．70、7．04、4．49、6．84℃和6．23℃;世代的有效积温为219．73d&#183;℃。西花蓟马的世代存活率在25℃时最高,为40．12％;30℃时西花蓟马的存活率最低,为17．80％。     

西花蓟马对多杀菌素的抗性汰选和遗传方式

在室内进行了西花蓟马Frankliniella occidentalis(Pergande)种群对多杀菌素的抗性筛选和抗性遗传方式分析。经过2年多的汰选,抗性水平相比较初始种群提高了30倍,与同时测定的敏感品系相比抗性达到80.8倍。抗性遗传方式分析结果表明,正、反交后代显性度分别为0.51和0.43,二者差异不显著,说明西花蓟马对多杀菌素的抗性为常染色体、不完全显性遗传;剂量对数死亡机率值曲线分析结果显示回交后代在死亡率50%处,自交后代在死亡率25%和75%处未出现明显平坡,回交和自交后代实测值卡方检验进一步证实抗性为多基因控制。     

Life history of western flower thrips, Frankliniella occidentalis (Thysan., Thripae), on five different vegetable leaves

Biological characteristics of western flower thrips, Frankliniella occidentalis (Pergande) (Thysan., Thripae), were investigated on excised leaves of five vegetables: cabbage (Brassica oleracea L. var. Jingfeng 1), cucumber (Cucumis sativus L. var. Zhongnong 8), capsicum (Capsicum annuum L. var. Zhongjiao 5), kidney bean (Phaseolus vulgaris L. var. Gonggeizhe) and tomato (Lycopersicon esculentum M. var. zhongza 9). The developmental time from egg to adult on the cucumber, cabbage, bean, capsicum and tomato leaf was 9.22 ± 0.13, 10.19 ± 0.08, 10.42 ± 0.06, 12.15 ± 0.07 and 12.91 ± 0.04 days, respectively. Survivorship of immatures on cucumber, cabbage and tomato was high (75–80%) but low on capsicum (50%). The total number of first instars produced was highest on cabbage (76.62 ± 11.79), while the daily first instar production was highest on cucumber (6.12 ± 1.81), whereas the total and daily first instar production rates were lowest on capsicum (7.67 ± 3.35 and 1.89 ± 0.91). F. occidentalis had the highest intrinsic rate of increase (r_m) on cucumber (0.208), followed by cabbage (0.184), bean (0.164), tomato (0.100) and capsicum (0.017). The results indicate that cucumber was the most suitable host plant for F. occidentalis, whereas capsicum was the least suitable.     

外来入侵害虫——西花蓟马在山东省不同地区主要花卉上的分布

【背景】外来入侵害虫西花蓟马于2003年首次在北京郊区被发现,并逐渐扩散蔓延,目前已在我国局部地区暴发成灾。【方法】于2008～2009年通过定点调查的方法对山东省115个地区258个样点的主要花卉上的蓟马种类进行了分析。【结果】山东省主要花卉上发生的蓟马有11种,包括花蓟马、黄胸蓟马、黄蓟马、西花蓟马、棕榈蓟马、烟蓟马、禾花蓟马、横纹蓟马、腹小头蓟马、黑白纹蓟马、油加律带蓟马等,其优势种为花蓟马。外来入侵害虫西花蓟马在山东省18个地区的花卉上被发现。其中,荣成市区发生最重,占蓟马采集总量的51.86%;德州市区和青岛市区发生次之,分别占蓟马采集总量的34.21%和33.88%;其他地区西花蓟马发生量占采集总量的1.39%～18.75%。【结论与意义】西花蓟马已在山东省定殖并广泛分布,相关部门应做好西花蓟马的预防与控制工作。