假眼小绿叶蝉触角化感器的扫描电镜观察

扫描电镜观察结果表明,假眼小绿蝉触角上只有一种毛状感器,而且,感器数量和分布在雌雄两性个体间相似。     

Spatial and temporal distribution of Empoasca vitis within a vineyard

1 The intra‐plot spatial distribution of the green leafhopper Empoasca vitis (Goethe) (Cicadellidae, Empoascini) was assessed over three successive growing seasons in a Bordeaux vineyard. Weekly measurements of adult trappings and nymphal counts were performed in a 1.7‐ha plot on 130 sampling points. 2 Statistical and geostatistical analyses revealed inconsistent spatial distributions of adults and nymphs in spring, but consistent spatial distributions in summer, which were identical every year. 3 Similarities between spatial distributions of the mobile adults and the sedentary and aggregated nymphs strongly suggest that adults disperse inside the plot to areas preferred for egg deposition. 4 The similarity of summer populations among years suggests that this insects distribution is based on (perennial) differences in plot characteristics.     

烟碱对假眼小绿叶蝉和茶尺蠖的忌避(拒食)活性

【目的】尼古丁是茄科植物的重要生物碱,本文首次确定了硫酸烟碱对假眼小绿叶蝉Empoasca vitis G?the的驱避作用和田间防效,以及不同浓度硫酸烟碱对茶尺蠖Ectropis obliqua Prout的拒食作用。【方法】使用Y形嗅觉仪和T形观测室研究了假眼小绿叶蝉对硫酸烟碱的行为反应,使用叶碟法测试了硫酸烟碱对茶尺蠖的拒食作用。【结果】硫酸烟碱600倍稀释液和800倍稀释液处理茶梢分别对叶蝉若虫的寄主选择行为和雌成虫的产卵具有显著的驱避作用;田间喷施硫酸烟碱对假眼小绿叶蝉的防治效果较好。此外,硫酸烟碱对茶尺蠖幼虫具有拒食作用,并且拒食作用随着取食时间的延长而增强,取食8 d以后,死亡率显著高于对照。【结论】本研究结果为开发茶树害虫的植物源忌避(拒食)剂提供一定的科学参考。     

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.     

茶假眼小绿叶蝉对不同茶香精和寄主植物的趋性反应

利用"T"形室观察了茶假眼小绿叶蝉Empoasca vitis Gthe对4种茶香精和3种寄主植物的趋性反应。结果表明,假眼小绿叶蝉对不同茶香精粉和寄主植物的趋性反应不同。叶蝉对绿茶和乌龙茶A香精有明显的趋向反应,而对乌龙茶B香精即铁观音茶香精则有明显的忌避反应,对红茶香精则无反应。假眼小绿叶蝉对茶梢和青菜的趋性反应无显著差异,而对茶梢和大豆的趋性反应有差异,表现出更喜好趋向茶梢。     

假眼小绿叶蝉地理种群的线粒体DNA 16S rRNA基因序列分析及遗传分化研究

测定了12个不同地理种群的茶树害虫假眼小绿叶蝉Empoasca vitis(Gothe)和1个外群共103个个体的线粒体DNA 16S rRNA基因部分序列,比较其同源性,计算核苷酸组成,并构建单倍型进化关系图。结果表明:在获得的假眼小绿叶蝉536 bp的序列中A+T含量占76.8%,其中56个核苷酸位点存在变异;100个个体共检测出56种单倍型,单倍型多样性指数(H)为0.971,核苷酸多样性指数(Pi)0.006;12个种群间的平均基因流(Nm)为1.64。总群体的固定系数Fst为0.026;AMOVA分子方差分析结果表明假眼小绿叶蝉的遗传分化主要来自于种群内部(97.4%)。各地理种群的遗传距离与地理分布不具有直接对应的关系。根据构建的单倍型进化关系网,各地理种群的单倍型呈现一种混杂的分布格局,未显示出与地理分布的一致性。     

Isolation and characterization of polymorphic microsatellite loci in the green leafhopper Empoasca vitis Goethe (Homoptera)

Eight dinucleotide microsatellite loci were isolated and characterized within the green leafhopper Empoasca vitis (Goethe) using an enrichment cloning procedure. Primers were tested on 171 individuals collected in the southwest of France from the vine plants. The identified loci were polymorphic, with allelic diversity ranging from two to 18 alleles per locus. Observed heterozygosities were from 0.021 to 0.760. These microsatellite markers should prove to be a useful tool for estimating the population genetic structure, host-plant specialization and migration capacity of this insect.     

Effects of ground cover (straw and compost) on the abundance of natural enemies and soil macro invertebrates in vineyards

1 Herbicides are commonly applied under grapevines in Australia to remove weeds and thereby to avoid water loss through transpiration. 2 Interest in sustainability promotes a reduction in chemical inputs, including herbicides, leading to trials with surface mulches to suppress weeds. 3 Surface mulches may also influence the abundance of a range of invertebrates. Potentially, an increase in natural enemies will contribute to pest control and encourage a reduction in pesticide application. 4 We used three trapping methods and direct soil sampling to assess invertebrates at ground level, in the canopy and in the soil to determine the influence of mulch on natural enemies, potential pests and soil macroinvertebrates, including earthworms. 5 Collections sorted to family demonstrated that the addition of straw or compost mulches increased natural enemies collected with pitfall traps and soil organisms. However, there was no clear indication of the overall superiority of either mulch. 6 Abundance of ground beetles, parasitoid Hymenoptera and spiders collected with pitfall traps were increased by the addition of mulches. In the canopy, predatory and parasitic Diptera and predatory Hemiptera increased after mulching. 7 Earthworms collected by hand sorting soil increased with straw mulching. 8 No influence on pests was detected. Although Lepidoptera and Sigmurethra, collected in pitfall traps, increased with straw mulching, neither included pest species. 9 The results are discussed with reference to the potential economic impact of mulches.     

假眼小绿叶蝉卵的寄生蜂种类及种群动态

通过田间采梢、室内镜下查卵和饲养观察,初步获得假眼小绿叶蝉Empoasca vitis Gthe卵寄生蜂2种,分别隶属于三棒缨小蜂属Stethynium sp.和裂骨缨小蜂属Schizophragma sp.,其中三棒缨小蜂属Stethyniumsp.是优势种。2种缨小蜂的寄生动态调查结果显示,除8月和12月寄生率较低外,其它月份的自然寄生率都在30%以上,特别是10~11月寄生率最高达65%,对小绿叶蝉的虫口数量具有重要控制作用,值得进一步研究和保护利用。     

假眼小绿叶蝉微卫星位点的生物信息学分析

【目的】为开发假眼小绿叶蝉Empoasca vitis分子标记,采用高通量测序技术对假眼小绿叶蝉DNA进行了测序与分析。【方法】本研究基于Illumina Hi Seq测序技术,构建了PE文库(~400bp),对获得的测序数据利用生物信息学分析手段完成全基因组扫描,并进一步使用MISA分析鉴定基因组序列中出现的微卫星序列(SSR)。针对微卫星序列共设计10对引物,并使用3步法进行引物多态性筛选。【结果】共计检测Scaffold数量为183 194条,其中包含SSR的Scaffold共计1 545条,共计筛选出1 569个SSR位点。在假眼小绿叶蝉的微卫星中,共包括87种重复基元类型,二核苷酸与三核苷酸重复序列为主要重复类型,分别占SSRs总数的70.26%和27.84%;二核苷酸重复基元CA/TG和三核苷酸重复基元AAT/ATT是优势重复基元,分别占SSRs总数的33.96%和5.86%。在设计的10对引物中,5对具有多态性,在8个假眼小绿叶蝉个体中共发现16个等位基因。【结论】结果说明假眼小绿叶蝉SSR位点在多态性方面具有极大的可开发性,具有多态性的SSR位点可对假眼小绿叶蝉种群间的分化,种群间的扩散机理和途径及影响因素等问题提供分子视角。     

福建主要茶树品种理化特性与假眼小绿叶蝉种群数量的相关性分析

比较分析了福建4个主要茶树品种(福云6号、铁观音、毛蟹、黄棪)的理化特性与假眼小绿叶蝉种群数量之间的相关关系,结果显示,假眼小绿叶蝉的种群数量与茶树品种叶片的物理结构———叶片总厚度、上表皮、上表皮角质层、下表皮、海绵组织厚度之间的相关性不显著,而与叶片下表皮角质层和栅栏组织厚度之间存在显著负相关。在生化指标方面,假眼小绿叶蝉的种群数量与茶树叶片中茶多酚、水溶性糖、可溶性蛋白、儿茶素含量之间的相关性不显著;与咖啡碱的含量有一定负相关,相关关系接近显著水平;而与游离氨基酸含量呈显著正相关。     

Influences of seasonal flooding on macroinvertebrate abundance in wetland habitats

SUMMARY. 1. We studied the effects of seasonal flooding on macro-invertebrate abundance by manipulating water regime and detrital level within three contiguous experimental marshes in Manitoba, Canada, over 2 years. One area was seasonally flooded (standing water present through midsummer) with emergent vegetation left undisturbed throughout the study, one was semipermanently flooded (standing water present through the ice-free season) with the vegetation left undisturbed, and one was seasonally flooded with the vegetation harvested at the end of the first summer.
2. Abundances of frequent macroinvertebrate taxa were compared between the seasonally flooded-undisturbed treatment area and each of the other areas.
3. Densities of total invertebrates and of the dominant taxa (Cladocera, Ostracoda and Culicidae) were reduced dramatically by a year of semipermanent flooding, despite high levels of paniculate organic food resources and low populations of predators. Densities were not reduced by lowering the availability of detritus under seasonally flooded conditions.
4. Taxa unaffected by water regime included Dytiscidae, Corixidae, Chironomidae, Ceratopogonidae and Ephydridae.
5. Semi-permanent flooding may have eliminated environmental cues necessary for oviposition, embryonic development and hatch among dominant taxa. High invertebrate densities in temporary waters may be more dependent upon life history traits of resident fauna than upon habitat features such as food availability or predation pressure.     

Larval development of Empoasca vitis and Edwardsiana rosae (Homoptera: Cicadellidae) at different temperatures on grapevine leaves

The grape leafhopper Empoasca vitis (Homoptera: Cicadellidae) is regarded as a major insect pest in many European grapevine growing areas, with an increasing importance realized in recent years maybe as a result of climatic change. Both larvae and adults feed on the phloem vessels of the leaves, causing characteristic symptoms also referred to as hopperburn. Phenology of adult leafhoppers was monitored in one vineyard in three successive years and indicated that immigration of a few hibernated E. vitis individuals into vineyards might take place already quite early in the year depending on winter temperatures and starts to progress in substantial numbers right at grapevine bud burst. In addition, these monitoring studies have shown that there are several other leafhopper species occurring on grapevine plants besides E. vitis, such as the rose leafhopper Edwardsiana rosae (Homoptera: Cicadellidae). Here, we report on the development of larval instars of both leafhopper species, E. vitis and E. rosae on grapevine leaves under different temperature regimes in the laboratory. Shortest larval developmental time was observed at night temperatures of 13–15°C and day temperatures of 23–25°C, which was in agreement with predicted optimal temperatures for both species. At the temperature regime of 20°C night and 30°C day temperature, either no egg hatch was observed or early development of first‐instar larvae was not successful for both species. These results suggest that warm (18°C) nights and moderately warm (28°C) days are representing the upper thermal threshold for development of both E. vitis and E. rosae embryonic stages on grapevine leaves, questioning current assumptions of an increasing importance of E. vitis as a grapevine pest under future climate change.     

Organic farming promotes bee abundance in vineyards in Italy but not in South Africa

Although grapevine is a crop that produces fruit without insect pollination, vineyards may provide resources for bees and other pollinators. Flower resources such as pollen and nectar are provided by the vine plants as well as other flowering plants including cover crops grown between the vine rows. Little is known about how management and landscape context affects bee communities in pollinator-independent crop systems such as grapevine. This study investigates the effect of organic versus conventional management on bee species richness and abundance in vineyards in Italy and South Africa both having a Mediterranean climate. In each country, six pairs of organic and conventional vineyards were studied in simplified and complex agricultural landscapes. A total of 433 bee individuals from 25 species and 1049 individuals from 15 species were recovered in pan traps from Italy and South Africa respectively. Bee abundance showed region specific response to the effects of vineyard management. Flowering plants and proportion of uncultivated land mediated differences in bee abundance. Higher flowering plant species richness and flower density were found in organic vineyards compared to conventional vineyards in South Africa but these flowering plant indices were not significantly different between the two vineyard management types in Italy. This emphasizes the necessity for local and region specific studies for informing conservation, as even in the same crop system with a similar climate, the effects of farm management differed between countries.     

Observations on the seasonal abundance ofIcerya purchasi onAcacia baileyana in Adelaide,South Australia

Population estimates of the cottony-cushion scale,Icerya purchasi Maskell were obtained from 2Acacia baileyana F. von Mueller trees in Adelaide, South Australia. Most scales were located within 50 cm of the tip of the twig (sample unit), some adults being found on thick woody branches (5 to 10 cm Ø) and on the tree trunk (>50 cm Ø). Scales were present throughout the year, mostly in very low numbers, and completed 2 annual generations i.e. from April to October and from November to April. This was confirmed by data on the duration of development from a field experiment with 12 sets of monthly cohorts.     

Acantharian abundance and symbiont productivity at the VERTEX seasonal station

The abundances of acantharians and the carbon fixation ratesof their symbiotic algae were measured over an 18 month periodat the VERTEX seasonal station, 1400 km west of Monterey, CA.Abundances varied up to 4 1 acantharians l^–1, with thehighest values in the upper euphotic zone. Integrated abundancesvaried seasonally by a factor of two and were highest (<170000 acantharians m^–2) in the summer and fall The biomassof acantharians (estimated from cell volume) ranged from 6.8to 56.7 mg C m^–2 and did not exhibit a seasonal pattern.The mean number of symbiotic algae per acantharian averaged14 7 and varied between 11 and 23 on different cruises. Approximatelyhalf of the acantharians at this station had symbiotic algae.Carbon fixation rates of the acantharian symbionts were highestnear the surface (maximum rate of 26.7 ng C acantharian^–1day^–1) and declined exponentially with depth. In the upper20 m, symbiont carbon fixation in acantharians was >4% ofthe total primary production and between 6 and 35% of the primaryproduction by plankton larger than 100 µm Exports of acanthariansfrom the euphotic zone by the sinking of intact cells were atleast 2–6% of the standing stock per day and would representup to 9% of the total sinking organic carbon flux. These ratesof carbon exports are comparable to the rate of carbon fixationby the symbionts in the acantharian population     

Seasonal abundance of Draeculacephala minerva and other Xylella fastidiosa vectors in California almond orchards and vineyards

Almond leaf scorch (ALS) disease is caused by the bacterium Xylella fastidiosa and transmitted by xylem-feeding insects. Reports of increased incidence of ALS-diseased trees in California prompted surveys in three almond [Prunus dulcis (Mill.) D. A. Webb]-growing regions, from June 2003 to September 2005, to determine insect vector species composition and abundance. For comparison, sampling in and near vineyards in the San Joaquin Valley, California, also was completed. Sampling in or near almond orchards collected >42,000 Cicadomorpha of which 4.8% were xylem feeders, including 1912 grass sharpshooter, Draeculacephala minerva Ball; five Xyphon fulgida Nottingham; and a single spittlebug, Philaenus spumarius L. The most abundant vector was D. minerva. Season-long sampling indicated that D. minerva was a year-round resident in and/or near almonds in the Sacramento Valley, but not in the San Joaquin Valley. Similarly, D. minerca was rare in vineyards in the San Joaquin Valley, but was abundant in irrigated pastures near vineyards. D. minerva was most frequently collected along orchard margins, and peak densities were observed in summer, the period of time when bacterial titers are reported to increase in infected trees. Screening of D. minerva for presence of X.fastidiosa found that 1.1% of insects collected near almond orchards and 4.5% of insects collected from pastures tested positive. The X. fastidiosa subspecies and genotype detected in insects collected from orchards matched those collected from ALS-diseased almond trees in the same orchard. Of the few X. fulgida and P. spumarius collected, none tested positive for X. fastidiosa. Results are discussed with respect to X. fastidiosa vector control and detection methods.