Odour masking of tomato volatiles by coriander volatiles in host plant selection of Bemisia tabaci biotype B

The silverleaf whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is one of the most important pest insects in tomato crop systems worldwide. It has been previously demonstrated that intercropping tomato [Solanum lycopersicum L. Mill. (Solanaceae)] with coriander [Coriandrum sativum L. (Apiaceae)] reduces the incidence and severity of damage caused by B. tabaci. However, it is not yet known how coriander affects the insect′s behaviour. We evaluated the attractiveness of tomato constitutive volatiles to B. tabaci and what effect coriander constitutive volatiles have on the insect′s behaviour. To this end, we conducted three bioassays in a multiple‐choice four‐arm olfactometer (‘×’ type), measuring B. tabaci behaviour when offered tomato and coriander constitutive volatiles presented alone as well as together. We also evaluated the colonisation and establishment of B. tabaci in experimental plots with only single tomato plants and tomatoes intercropped with coriander in a greenhouse. Bemisia tabaci males and females recognised tomato constitutive volatiles as a positive stimulus (kairomonal effect), indicating that semiochemicals from this plant can play an important role in the insect’s host plant selection. Coriander constitutive volatiles reduced the attractiveness of tomato volatiles but no repellency to these volatiles was observed. Greater numbers of adults and nymphs of B. tabaci per plant were observed in tomato monoculture plots than in tomato intercropped with coriander. We suggest that coriander constitutive volatiles have an odour masking effect on tomato volatiles, thus interfering in the host plant selection of B. tabaci.     

不同寄主植物对B型烟粉虱发育适合度的影响

为探明寄主植物对B型烟粉虱Bemisia tabaci(Gennadius)种群发育适合度的影响,采用室内实验比较了B型烟粉虱在番茄、棉花、菜豆和辣椒上的生存曲线、发育进度和成虫性比等生物学指标。结果表明,B型烟粉虱种群在不同寄主植物上的生存曲线差异显著,由卵发育至成虫的存活率由高到低依次为:番茄=棉花>菜豆>辣椒。B型烟粉虱在辣椒、棉花、菜豆和番茄上50%成虫羽化期依次为25.5、23.0、22.8和22.5d,在辣椒上的发育进度显著慢于其他植物。在不同寄主植物上B型烟粉虱的雌成虫比例差异显著,由高到低依次为:辣椒(63.0%)>棉花(58.3%)>菜豆(52.0%)>番茄(49.7%)。在番茄上B型烟粉虱第二代的生存率显著高于第一代,发育速率较第一代加快,雌成虫比例(63.3%)也显著高于第一代(49.7%)。在棉花上,第一代和第二代间的生存曲线、发育进度和雌成虫比例则差异不显著。可见,不同寄主植物对B型烟粉虱的发育适合度不同,在番茄上的发育适合度则以第二代较第一代显著提高。此外,B型烟粉虱在不适寄主植物辣椒上的存活率较低,但后代雌成虫比例增加,推测B型烟粉虱可通过调整后代性比增加其在不适寄主植物上的种群。     

Detection of tomato leaf curl geminivirus in its vector Bemisia tabaci

Geminiviruses are single-stranded DNA plant infecting viruses that cause major losses in important crops in tropical and subtropical countries. Tomato leaf curl virus (TLCV) belonging to the genera Begomovirus, is a whitefly-transmitted geminivirus that causes a severe leaf curl disease in tomato (Lycopersicon esculentum). The importance of this disease has prompted a great need for a rapid identification of TLCV in its hosts and vector. Polymerase chain reaction (PCR) is the most sensitive approach to detect a minute amount of viral nucleic acid. It is the most ideal method to amplify geminiviruses as they replicate via a double-stranded, circular DNA form. In this study, geminivirus specific degenerated primers were employed to detect TLCV occurring in its vector whitefly Bemisia tabaci by PCR based approach. One primer pair, amplified TLCV DNA fragment of about 1.1 Kb representing partly replicase gene, intergenic region and partly coat protein gene was used. When a set of primer targeted to the core region of the coat protein gene of geminivirus was used, a PCR amplified fragment of about 0.5 Kb was obtained. This approach is highly useful for an early detection of TLCV occurring in very small amount in the vector B. tabaci. Its implications in geminivirus management strategies and their differentiation and being discussed.     

线虫诱导番茄抗性对烟粉虱发育及存活的影响

有害生物为害植物后可以诱导后者产生防御抗性,进而对同株植物上其它生物产生一定的负面影响。本文以蔬菜生产中的两大重要有害生物——南方根结线Meloidogyne incognita和烟粉虱Bemisia tabaci为研究对象,在实验室内, 利用不同浓度（200头/株、500头/株、1000头/株）的南方根结线虫侵染番茄,分别在侵染后的第3、7、11 d接种烟粉虱,研究南方根结线虫为害番茄后诱导的植物抗性对叶部害虫烟粉虱生长发育及存活等特性的影响。结果表明,受三种浓度的南方根结线虫危害3 d、7 d和11 d后的番茄植株上,与对照植株上相比烟粉虱卵至成虫的发育明显延长;当500头/株和1000头/株浓度南方根结线虫危害3 d 和7 d 后,该番茄植株上烟粉虱的发育历期与对照相比差异达到显著水平,而在南方根结线虫危害11 d的番茄上,尽管烟粉虱发育历期也随接种南方根结线虫浓度的增加而延长,但处理组与对照组之间的发育历期均无显著差异。在南方根结线虫危害3 d、7 d后的番茄上接种烟粉虱,后者卵-成虫的存活率较对照组番茄上明显下降,且差异达到显著水平,而南方根结线虫不同为害时间、不同为害浓度的处理之间对烟粉虱存活率的影响差异并不显著。研究表明,当南方根结线虫与烟粉虱分别在根部和叶部为害同一株植物时,前者通过植物对后者的影响是负面的,二者之间的互作关系应属于拮抗类型。     

Elevated ozone induces jasmonic acid defense of tomato plants and reduces midgut proteinase activity in Helicoverpa armigera

As a consequence of membrane lipid peroxidation, foliar defense compounds are changed by elevated ozone (O₃), which in turn affects the palatability and performance of insect herbivores. The induced defense of two tomato [Solanum esculentum L. (Solanaceae)] genotypes, namely jasmonic acid (JA) pathway‐deficient mutant spr2 and its wild‐type control, was studied in response to cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae), as well as the digestive adaptation of these insects under elevated O₃ in open‐top field chambers. Our data indicated that elevated O₃ increased foliar JA and salicylic acid (SA) levels simultaneously and up‐regulated proteinase inhibitors (PIs) and lipoxidase activities in wild‐type plants, regardless of H. armigera infestation. In contrast, only the O₃+H. armigera treatment increased free SA levels in spr2 plants, but did not affect JA level or PI activities. Additionally, the lower activity of midgut digestive enzymes, including active alkaline trypsin‐like enzyme and chymotrypsin‐like enzyme, was observed in the midgut of cotton bollworms after they consumed wild‐type plants treated for 2 h with elevated O₃. With temporary increases at 8 h, all four digestive enzymes of interest in the insect midgut dropped when they were fed with wild‐type plants under elevated O₃ treatment. Increases in atmospheric O₃ are thought to increase JA signaling and consequently reduce the activities of midgut digestive enzymes in H. armigera, therefore enhancing plant resistance against insect herbivores.     

抗生素利福平对Q烟粉虱防御基因表达水平的影响

通过饲喂昆虫,抗生素广泛应用于昆虫共生菌功能研究中。为了探讨抗生素对烟粉虱功能基因的直接影响,研究了通过喂食含利福平棉花叶片后烟粉虱体内乙醇脱氢酶adh-class III,knottin抗菌肽,四次跨膜蛋白tetraspanin-3,丝氨酸蛋白酶抑制剂serpin和TCP1-delta基因等5个防御基因表达量变化,结果表明50.0μg/m L利福平处理,烟粉虱adh-class III、knottin、tetraspanin-3基因表达量显著高于对照(P0.05),而serpin和TCP1-delta基因表达量没有显著差异(P0.05)。100.0μg/m L利福平处理,5个防御基因表达量均显著高于对照(P0.05)。抗生素利福平影响烟粉虱防御基因表达且与其浓度相关。本研究结果对于利用抗生素揭示昆虫共生菌功能研究具有重要参考价值。     

Observations on the trapping of the whitefly Bemisia tabaci by glandular hairs on tomato leaves

Observations were made on the role of glandular leaf hairs of four tomato cultivars in trapping cotton whitefly, Bemisia tabaci, adults. Dead, trapped whitefly occurred in similar numbers on both the upper and lower surfaces of leaves even though glandular hairs were denser on the former. Females constituted 58% of untrapped but 86% of trapped adults, many becoming trapped during oviposition which occurred mainly on the lower surfaces. Of the four cultivars studied, Strain B trapped more whitefly than Ace, Marglobe or Moneymaker.     

Differential effects of flagellins from Pseudomonas syringae pv. tabaci,tomato and glycinea on plant defense response

To investigate the factor that determines incompatible interactions between Pseudomonas syringae pv. tabaci and non-host plants, an elicitor of hypersensitive reaction (HR) was partially purified from the supernatant of a nutrient-poor medium of bacterial culture by DEAE column chromatography. The major protein in the elicitor-active fractions was identified as a flagellin which is a component of flagellar filaments. The flagellins purified from P. syringae pv. tomato and glycinea, incompatible pathogens of tobacco plants, induced fragmentation of chromosomal DNA and oxidative burst accompanied by programmed cell death in tobacco (Nicotiana tabacum) Bright Yellow (BY-2) cells, but the flagellin from pv. tabaci, a compatible pathogen, did not. However, the amino acid sequences of flagellins deduced from fliC genes showed a high homology among these P. syringae pathovars. In particular, the amino acid sequences of pv. tabaci and glycinea are completely identical. However, both recombinant flagellins produced in Escherichia coli possess HR-inducing activity in BY-2 cells. These results indicate that the post-translational modification of flagellins has an important role for HR-inducing ability in tobacco cells. Furthermore, we discuss the cause of a different elicitor activity among flagellins on tobacco cells and the role of flagellins in the determining specificity.     

不同邻作作物对番茄田间烟粉虱种群动态的影响

为明确不同邻作模式下番茄田间烟粉虱的种群动态与空间分布格局,于云南省昆明市选取与西葫芦、黄瓜、玫瑰等作物邻作的番茄田及单作番茄田为研究样地,通过五点取样法进行调查,采用四分位法对不同作物邻作的番茄田间烟粉虱种群动态进行分析.结果表明:在烟粉虱的主要发生期,番茄单作田间烟粉虱种群数量最高,雌成虫达26.69头?叶-1,雄...     

不同番茄品种挥发物对B型烟粉虱寄主选择行为的影响

采用顶空固相微萃取和气相色谱-质谱法鉴定了6个番茄品种(浙杂809、浙杂203、合作903、凯特一号、黄椭圆和金妃)植株挥发物的成分,并利用Y型嗅觉仪测定了烟粉虱对不同番茄品种植株及其挥发物的嗅觉反应.结果表明:从6个番茄品种中共鉴定出13种化合物,其主要成分为萜类化合物,品种间挥发物的组成成分和各成分所占比例存在差异.(+)-3-蒈烯和β-石竹烯对B型烟粉虱的驱避性较其他萜类强.烟粉虱对含萜类挥发物种类多、比例高的品种(如浙杂809和浙杂203)选择性较弱,而对含萜类挥发物种类少、比例低的品种(如黄椭圆和金妃)选择性较强.     

Wolbachia infections of the whitefly Bemisia tabaci

We report the first systematic survey for the presence of Wolbachia endosymbionts in aphids and whiteflies, particularly different populations and biotypes of Bemisia tabaci. Additional agriculturally important species included were predator species, leafhoppers, and lepidopterans. We used a polymerase chain reaction (PCR)-based detection assay with ribosomal 16S rDNA and Wolbachia cell surface protein (wsp) gene primers. Wolbachia were detected in a number of whitefly populations and species, whitefly predators, and one leafhopper species; however, none of the aphid species tested were found infected. Single, double, and triple infections were detected in some of the B. tabaci populations. PCR and phylogenetic analysis of wsp gene sequences indicated that all Wolbachia strains found belong to group B. Topologies of the optimal tree derived by maximum likelihood (ML) and a ML tree in which Wolbachia sequences from B. tabaci are constrained to be monophyletic are significantly different. Our results indicate that there have been at least four independent Wolbachia infection events in B. tabaci. The importance of the presence of Wolbachia infections in B. tabaci is discussed.     

供氮水平对番茄苗期Q型烟粉虱成虫种群动态的影响

烟粉虱(Bemisia tabaci)是重要的农业害虫。在栽培管理中,为了减少化学农药的施用,对该害虫采取生态防控措施日益得到重视。以Q型烟粉虱为研究对象,根据温室大棚内9次烟粉虱成虫种群数量调查和番茄苗期5项农艺指标测量,结合主成分分析、线性逐步回归分析及Pearson相关性分析,从"氮素-番茄-Q型烟粉虱"互作角度开展生态防控措施研究,旨在探明番茄苗期的烟粉虱成虫种群发生数量与氮素水平关系。结果表明:3个氮水平(高氮1134 mg·L^-1,标准氮945 mg·L^-1,低氮756 mg·L^-1)下的5个番茄指标(株高、茎粗、叶面积、叶绿素相对含量、叶片全氮含量)最大值基本呈现高氮>标准氮>低氮的规律;调查的9次烟粉虱虫口数量在最大峰值时的高低排序为高氮>标准氮>低氮。主成分分析表明,3种氮素水平下叶绿素相对含量是影响烟粉虱成虫虫口数量的主要因子。线性回归与相关性分析表明,3种氮素水平下的叶片全氮含量、叶绿素相对含量与虫口种群数量相关性较高。氮营养是影响植物和烟粉虱的关键因素之一,高氮水平下番茄长...     

Effects of antibiotics on fitness of the B biotype and a non-B biotype of the whitefly Bemisia tabaci

The whitefly, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae), harbors primary and secondary endosymbionts. Previous research showed that the invasive B biotype and an indigenous non‐B biotype (named non‐B ZHJ‐1 population) of B. tabaci from Zhejiang, China, harbored different endosymbionts. To investigate the function of these endosymbionts in the two biotypes of B. tabaci, we fed adult whiteflies with three antibiotics, tetracycline, ampicillin trihydrate, and rifampicin, and evaluated the fitness of their offspring on cotton plants. These three antibiotics did not remove the primary endosymbiont Portiera aleyrodidarum but were capable of eliminating the secondary endosymbionts. In the B biotype, treatments of adults with tetracycline or ampicillin trihydrate accelerated development and increased the survival of their offspring, while treatment of adults with rifampicin significantly retarded the development of their offspring but did not affect their survival. In the non‐B ZHJ‐1 population, treatments of adults with tetracycline or ampicillin trihydrate also accelerated the development of their offspring but did not significantly affect their survival, while treatment of adults with rifampicin significantly retarded development and reduced the survival of their offspring. These results suggest that removal of some secondary endosymbionts and/or reduction of the primary endosymbiont from B. tabaci may produce both favorable and unfavorable effects on the fitness of the host insects.     

Release rate for a pre-plant application of Nesidiocoris tenuis for Bemisia tabaci control in tomato

Nesidiocoris tenuis Reuter (Het.: Miridae) is widely used as a biological control agent of whiteflies and other pests in greenhouse-grown tomatoes. It is typically released augmentatively some weeks after transplanting and needs several weeks to establish. Releasing N. tenuis prior to transplanting could accelerate its establishment. However, timing for releases could affect biological control and require changes in release rates of the predator. Because N. tenuis is also phytophagous it must be released at a rate which provides the best equilibrium between adequate biological control of Bemisia tabaci Genn. and acceptable injury to the crop. The objective of this study was therefore to evaluate different release rates for releasing N. tenuis prior to transplanting for maximizing control capacity and minimizing injury to crop. The study was carried out in two subsequent trials in which different release rates were evaluated under a worst case scenario of rapid immigration of the pest into a tomato greenhouse. In the first experiment (winter experiment), four treatments were compared: (1) B. tabaci (0 N. tenuis/plant), (2) B. tabaci?+?0.5?N. tenuis/plant, (3) B. tabaci?+?1?N. tenuis/plant and (4) B. tabaci?+?2?N. tenuis/plant. In the second experiment (summer experiment), the treatments were: (1) B. tabaci (0 N. tenuis/plant), (2) B. tabaci?+?0.5?N. tenuis/plant and (3) B. tabaci?+?1?N. tenuis/plant. All the evaluated rates significantly reduced the population of whitefly and gave adequate control of the pest. However, only 0.5?N. tenuis/plant did not increase crop damage compared to the treatment with no N. tenuis.     

ToCV单独侵染和TYLCV&ToCV复合侵染番茄植株上烟粉虱寄主适应性及寄主植物营养成分含量和防御反应变化

[目的]本研究以番茄褪绿病毒(tomato chlorosis virus,ToCV)和番茄黄化曲叶病毒(tomato yellow leaf curl virus,TYLCV)为主体,旨在明确ToCV单独侵染及TYLCV&ToCV复合侵染对烟粉虱Bemisia tabaci MED隐种寄主适应性的影响,并从寄主植物营...     

烟粉虱(Bemisia tabaci)的寄主选择性

通过田间系统调查、实验室嗅觉测定、笼内和培养皿内自由扩散观察,对烟粉虱的寄主选择性进行了研究.结果表明,在田间,烟粉虱对不同的寄主植物存在明显的寄主选择性,其中对茄子、花椰菜、黄瓜等植物具有较强的嗜性,而对蕹菜、芹菜、苋菜等植物的嗜性较差;烟粉虱对同一植物的不同品种也有明显的选择性.烟粉虱对寄主植物颜色有明显的选择性,选择结果与烟粉虱对这些寄主的嗜性趋势基本一致.烟粉虱对单株寄主植物的嗅觉反应不敏感,但对植物叶片的乙醇抽提物有明显的嗅觉反应,并表现出较强的寄主选择性.在养虫笼内,烟粉虱从虫源皿向寄主植物自由扩散的过程中,在不同寄主植物和同一植物的不同品种上着落的成虫数量不同,并且在一定的时间范围内,着落在寄主叶片上的虫量还会不断的发生变化.     

Lack of fitness costs associated with acetamiprid resistance in Bemisia tabaci (Hemiptera: Aleyrodidae)

Sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is a devastating pest that can cause severe damage to a range of crops by direct feeding and by plant virus transmission. Because of indiscriminate use of insecticides, this whitefly has developed resistance to several insecticides, including neonicotinoids. Our objectives were to determine fitness components affected by acetamiprid resistance in B. tabaci. Assay results showed that selection with acetamiprid had removed heterozygotes from the field population because the survival rate of the resistant population was significantly greater than that of the field population at a very high dose. Comparison of various life traits between the acetamiprid-selected (Aceta-SEL) population and three other populations showed that the numbers of eggs laid by acetamiprid Aceta-SEL population were significantly lower compared with that of other populations but that the proportions of eggs hatched were significantly higher. However, the time taken by nymphal stages of the Aceta-SEL population to develop was significantly higher than that of the susceptible populations. The intrinsic rate of increase, net reproductive rate, mean generation time, and doubling time of Aceta-SEL was significantly higher than Lab-PK and UNSEL populations, but the growth index was similar for all populations. The growth index and high intrinsic value of Aceta-SEL population suggest that the resistance allele may not have detrimental impact. The lack of fitness costs in B. tabaci could promote the rapid development of resistance to acetamiprid and other neonicotinoids. This resistance could threaten the sustainability of whitefly management program on genetically engineered cotton (Gossypium hirsutum L.) where neonicotinoids are being sprayed to manage sucking pests in the field.     

B型烟粉虱对不同茄子品种的选择及适生性分析

【目的】研究烟粉虱Bemisia tabaci(Gennadius)对同种寄主不同品种的选择性及适生性,可为该寄主抗性品种的选育和烟粉虱的综合治理提供理论依据。【方法】在温度(29±2)℃、湿度80%±5%的自然光照温室内,进行B型烟粉虱对不同茄子品种的选择性以及这些品种对其生长发育、繁殖、存活和生命表参数的影响实验。【结果】B型烟粉虱对茄子不同品种的选择及适生性具有一定的差异,在14个茄子品种或材料中,B型烟粉虱对黑马紫长茄的选择性最强,对龙茄1号的选择性最弱;B型烟粉虱从卵发育到成虫的存活率在辽茄3号上最低,在龙茄1号上最高;世代发育历期在辽茄3号上最短,在徐州长茄上最长。此外,B型烟粉虱在苏崎茄、扬茄1号和紫圆茄上的种群趋势指数(I)分别为68.7215、37.4675、25.6245,表明B型烟粉虱对这3个品种的适生性为苏崎茄>扬茄1号>紫圆茄。     

Influence of plant combinations on population characteristics of Bemisia tabaci biotypes B and Q

In recent years, the dominant biotype of Bemisia tabaci (Gennadius) has shifted from biotype B to Q in many locations of China. Our field monitoring showed that B. tabaci biotype Q could be found on pepper Capsicum frutescens L. while biotype B could not be found on the plant. To study the role of the host plant in the displacement of biotype B by Q, the adult mortality, female fecundity, and adult emergence of both biotypes B and Q on different host combinations were studied using a model system involving pepper and eggplant. The results showed that pepper is not a preferred host for either biotype B or Q adults in comparison with eggplant. The negative impact of pepper to biotype B is, however, much greater than that to biotype Q. Because both the survival rates of the adult whitefly and the average number of emerged adults per female of biotype Q on pepper are higher than that of biotype B, biotype Q showed higher fitness in comparison with biotype B. Our results suggest that the existence and differential impact of a nonpreferred host might affect the population fitness and therefore could play a role in the displacement of biotype B in some regions.