Spatial and temporal increase of eastern filbert blight in European hazelnut orchards in the pacific northwest

ABSTRACT Since its first detection in southwest Washington state 30 years ago, eastern filbert blight, caused by Anisogramma anomala, has spread slowly southward ( approximately 2 km/year) into the Willamette Valley of Oregon, an important hazelnut production region. Experiments were conducted to measure gradients of disease spread, rates of disease increase as affected by distance from an inoculum source and variation in host plant resistance, and dispersal of ascospores of A. anomala from diseased orchards. In each of 3 years, 1-year-old hazelnut trees placed from 0 to 150 m north of diseased orchards were infected uniformly and slopes of disease gradients were not significantly different from zero. In 1 year when trees also were placed south of an orchard, the disease gradient was significant (P < 0.05), with disease incidence high at the edge of the orchard and few trees infected at 10 m south of the orchard. Disease gradients were shallower and the magnitude of the area under the disease progress curve (AUDPC) greater in 0.1-ha mini-orchards of highly susceptible cv. Ennis than in mini-orchards of moderately susceptible cvs. Barcelona or Casina. Lower AUDPC values were observed in mini-orchards of Barcelona interplanted with a moderately resistant pollenizer Hall's Giant compared with the highly susceptible pollenizer Daviana. Fungicides applied biweekly starting at bud break reduced AUDPC values in Ennis mini-orchards to values observed in Barcelona and Casina mini-orchards. Data from aspirated spore samplers placed on towers adjacent to severely diseased hazelnut orchards indicated that spores of A. anomala dispersed horizontally and vertically away from the canopy during periods of extended branch wetness and, thus, show potential to be transported long distances in wind currents. Weather patterns in the Pacific Northwest may account for the relatively slow, southward spread of eastern filbert blight within Oregon's Willamette Valley. Of 196 precipitation events greater than 10 h in duration recorded from 1974 to 1995, conditions most favorable for ascospores discharge, periods with wind from the north were rare, representing <6% of total hours.     

Effects of Single-Drop Impactions and Natural and Simulated Rains on the Dispersal of Botryosphaeria dothidea Conidia

ABSTRACT Laboratory and field experiments were conducted to study the dispersal of Botryosphaeria dothidea conidia using single-drop impactions and natural and simulated precipitations. For laboratory studies, 200 single drops were released from a height of 1 m on infected pistachio nuts. On pieces of photographic film, 50% of the droplets were collected within 20 mm (average droplet travel distance) of the target area, and the droplets ranged from 0.041 to 3.19 mm in diameter, with an average of 0.3 mm. Each droplet carried an average of 23 B. dothidea conidia. In 3 years of field experiments, rainwater was collected in funnels connected to bottles positioned at different heights inside the tree canopy and at different distances away from the edge of tree canopy in three commercial pistachio orchards in San Joaquin, Yolo, and Glenn counties in California. Numbers of conidia in rainwater varied among and within sampling seasons by sampling dates and orchards. Up to 67,000 conidia/ml were obtained in rainwater samples collected from an orchard in Yolo County. Rainwater from orchards in Yolo and Glenn counties contained a consistently higher number of conidia than rainwater collected from the orchard in San Joaquin County. Variation in numbers of conidia also existed among heights where bottles were located. There were significantly more conidia in rainwater collected inside than outside tree canopies. Inside tree canopies, bottles located at 100 and 150 cm above ground collected more B. dothidea conidia than those placed at 50 and 200 cm. Conidia were collected as far as 1 m from the tree canopy edge. Based on data from the Glenn County orchard, a linear relationship between number of conidia (Y) and rainfall amount (X) in millimeters was determined as Y = 240X - 3,867, with r(2) = 0.91, which meant that a minimum of 16.1 mm of rain was needed to disperse conidia of B. dothidea. The power law model best described the dispersal gradients of B. dothidea propagules in the 1999-2000 and 2001-02 sampling seasons, with r(2) values of >/=0.73, whereas the exponential law model fit best for the 2000-01 data, with r(2) values of >/=0.81. In a rain simulation experiment, the intensity of the rain generated by a nozzle at 138 kPa of pressure inside the tree canopy was approximately five times higher than rain recorded outside the tree canopy. Rain removed up to 65% of conidia from infected fruit. These results confirmed that B. dothidea is a splash-dispersed pathogen with relatively short distances of spore dispersal within pistachio orchards. Only pycnidia are present in pistachio orchards; therefore, the results also indicate that inoculum of B. dothidea should be entirely splashed dispersed.     

Deposits of the mildew fungicide binapacryl on the leaves of apple trees of differing sizes after mist blower spraying

Trials in 1975 and 1976 showed that deposit levels of the fungicide binapacryl, on the leaves of bush trees of Cox's Orange Pippin (Cox) after mist blower spraying, varied inversely with tree spread. Deposit levels were measured on young mildew-susceptible leaves from a well-sprayed zone around the periphery of the tree canopy at a height of 1.5 m. Low deposit levels in large, dense trees were associated with poor mildew control. Leaves from the smallest trees had deposit levels considerably greater than those found for larger trees (in another nearby orchard) which had adequate mildew control. Fungicide deposit levels on leaves from up to five different zones of trees of three different sizes (the largest trees were of the variety Bramley's Seedling) were measured in 1977. The smallest trees had significantly higher deposit levels than the larger trees in the lower centre and lower outside zones of the trees, whereas both orchards of Cox had the same (commercially acceptable) level of mildew infection at the end of the season. Leaves from zones less accessible to spray had lowerdeposit levels than those nearer the sprayer.     

橡胶盔蚧寄生蜂的种群结构与空间分布研究

通过普查与定点调查的方法,研究了橡胶盔蚧寄生蜂的种群结构和橡胶盔蚧及其寄生蜂的空间分布。结果表明,橡胶盔蚧天敌寄生蜂达10种,其中优势种2种,常见种4种,稀有种4种。优势种优雅岐脉跳小蜂和蜡蚧褐腰啮小蜂分别占整个种群数量的64.32%和11.76%。橡胶盔蚧寄生蜂在橡胶树不同方位上的分布不同。在层次上,寄生蜂在上层的平均寄生率要比下层高;在方位上,寄生蜂在南面的平均寄生率最高,而在北面的平均寄生率最低。通过Taylor幂法和Iwao的回归分析对橡胶盔蚧及其寄生蜂的空间分布型进行研究,得出结果一致,即橡胶盔蚧及其寄生蜂种群在橡胶树上的空间分布型均为聚集分布,且种群密度越高分布越聚集。     

寄生荔枝蒂蛀虫卵的斑螟分索赤眼蜂过寄生驯化培育

针对寄生荔枝蒂蛀虫卵的斑螟分索赤眼蜂Trichogrammatoidea hypsipylae Nagaraja不能正常羽化出蜂问题,室内以米蛾Corcyra cephalonia（stainton）卵为寄主,分别以1：3、1：5、1：10（对照）的蜂卵比接蜂培养,经过35代过寄生连代繁殖驯化,其36代（F36）成蜂个体大小显著小于对照组。与对照组相比,成蜂体长、体宽分别减小28．89％、16．08％（1：3处理）和27．43％、20．56％（1：5处理）。经蜂卵1：3、1：5接蜂连代繁殖驯化后的F36斑螟分索赤眼蜂对荔枝蒂蛀虫卵的寄生率分别为44％和55％,与对照差异不显著,但能顺利从荔枝蒂蛀虫卵内羽化出蜂,羽化率分别为31．8％、25．5％,对照则无羽化出蜂。表明通过过寄生驯化培育可以改变斑螟分索赤眼蜂的个体大小,并有望使其在荔枝园内建立稳定种群,达到持续控制荔枝蒂蛀虫的目的。     

利用松毛虫赤眼蜂防治苹果小卷叶蛾的研究

1984—1988年在果园开展了利用松毛虫赤眼蜂防治苹果小巷叶蛾的试验示范,放蜂面积7万余亩,卵块和卵粒寄生率分别达92.41和87.29％,虫果率仅2—3％,效果好于化学防治。果园放蜂以每亩设8—12个点,放蜂4次,总蜂最12万头,效果较好。P~(32)标记证明,赤眼蜂的扩散距高,在6小时内有61.96％的蜂分布在5米范围内,而24小时后则比较均匀地分布到30米的范围。     

松毛虫赤眼蜂雄峰寄主栖息地定向行为的研究

在实验室中,调查了松毛虫赤眼蜂雄蜂寄主栖息地定向行为与一些因子的关系.嗅觉试验表明,马尾松毛虫雌蛾翅膀的气味对雄蜂寄主栖息地定向行为无直接关系.来自寄主植物马尾松针(186mg)的气味能刺激雄蜂加强在气味区的搜索活动,但仅有松针气味尚不能明显地将雄蜂滞留在气味区内。同种雌蜂(N=20头)的气味对雄蜂虽有明显的引诱作用,但对雄蜂的滞留亦无明显的影响,当松针(186mg)加上雌蜂(N=20头)时,气味区滞留的雄蜂头数即明显增加,由此可见,奇主植物和雌蜂气味的共同作用是雄蜂寄主栖息地定向中的关键因子。     

豆科植物繁殖烟蚜及扩繁烟蚜茧蜂的潜力

为探究豆科植物作为繁育烟蚜和扩繁烟蚜茧蜂寄主植物的潜力,本研究测试了烟蚜在豌豆、蚕豆、大豆和绿豆4种豆科植物上的发育历期和繁殖力,随后比较了豆科植物和烟草繁育的烟蚜茧蜂以及蚕豆烟蚜茧蜂回接烟草所获得的子代蜂在羽化率、体型、成虫寿命和寄生力等重要生物学特性上的差异。结果表明：与豌豆和蚕豆相比,大豆与绿豆上蚜虫发育历期更短;大豆与绿豆单头烟蚜总产蚜量为22.3头和25.2头,显著高于豌豆和蚕豆的21头和18.2头;不同植物上蚜虫扩繁速度有显著差异,绿豆不适合作为扩繁烟蚜和烟蚜茧蜂的寄主植物;豌豆与大豆上僵蚜羽化率为67.5%和78.33%,显著低于其他植物;各植物上子代蜂性比无显著差异;烟草繁育的子代蜂成虫寿命（6.89 d）和后足胫节长（雌蜂573.5 μm,雄蜂493.5 μm）均显著高于豆科植物;不同寄主植物繁育烟蚜茧蜂的寄生力由大到小为烟草,蚕豆,豌豆,大豆;回接组烟蚜茧蜂各项指标均不低于烟草组。综合考虑扩繁周期、时间、空间利用率及经济成本等因素,蚕豆有望成为烟蚜茧蜂规模化扩繁的寄主植物。     

苹果园天敌昆虫群落的空间分布研究

天敌昆虫在苹果树树冠的空间分布有一定的差异。天敌昆虫在苹果树树冠东、南、西、北四个方位以及内、外部等的水平位置上的数量分布无明显的差异；在苹果树树冠上、中、下部的垂直水平上的分布差异大，树冠中、下部明显多于上部。     

囊泡病毒和类囊泡病毒及其与寄生蜂之间的关系

囊泡病毒(ascoviruses)和类囊泡病毒(ascovirus-like viruses)通过寄生蜂para-sitoid wasp的产卵行为而散布于鳞翅目Lepidoptera幼虫体内,它与寄生蜂的关系多种多样。大部分的囊泡病毒和类囊泡病毒都是致病性的,由雌蜂携带传播。一些囊泡病毒和类囊泡病毒则是互利共生生物,其基因稳定地存在于寄生蜂的细胞核中,世代间垂直传播,通过抑制鳞翅目幼虫的防御机制来促进幼蜂的成功发育。囊泡病毒DpAV4则根据所处的寄生体系可以是致病性病毒、互利型或共生非致病性病毒。各种生物学特性显示囊泡病毒与寄生蜂之间的关系取决于寄生蜂控制病毒复制的调节因子,囊泡病毒与寄生蜂的关系类型依赖于它们之间关系得以进化的种类系统。     

Cold Hardiness Assessment in Seven Commercial Fig Cultivars (<Emphasis Type="Italic">Ficus Carica</Emphasis> L.)

Freezing injury is one of the most restrictive dynamics issues that commercial fig producers are fronting. This study was aimed to compare cold hardiness among seven commercial fig cultivars at three different developmental stages. We investigated the association between freezing tolerance and soluble carbohydrate and proline fluctuations during acclimation in the one-year-old fig shoots. Using both electrolyte leakage measurement and tetrazolium stain test LT₅₀ values were calculated, which differentiate freezing tolerance among the studied cultivars. The results showed significant differences among the cultivars at three evaluation stages of dormancy. The average of cold winter resistance in studied cultivars in November, January, and March, were ?16.89, ?20.23, and ?21.35?°C, respectively. LT₅₀ electrolyte leakage, cold hardiness index, significantly varied among the fig cultivars. In November to January, ‘Atabaki’ and ‘Kashki’ cultivars showed the maximum of ?0.11?°C/per day, and the minimum of ?0.01?°C/per day of adaptation rate, respectively. Soluble carbohydrate (sugars) concentrations of shoot samples increased during cold acclimation from November (49?mg/g dry weight (DW)) to January (130?mg/g DW) and then decreased in March (93?mg/g DW). Proline content varied significantly among the cultivars in November and January. High correlations were observed between LT₅₀ values and the soluble carbohydrates content compared with proline. Soluble sugars content might be a better indication of cold hardiness than proline content in fig trees. ‘Atabaki’ cultivar showed a very good resistance to winter freezing in comparison to others cultivars, although it seems to be very sensitive to fall freezing. The outcome of this study can be considered for sustainable production and breeding programs in common figs.     

芝麻花对稻螟赤眼蜂寄生和扩散能力的影响

芝麻是一种适合于稻田生态系统的蜜源植物,但其对稻田优势赤眼蜂稻螟赤眼蜂的作用未有系统的研究。本文在室内和大田的条件下考察了芝麻花对稻螟赤眼蜂寄生力和扩散能力的影响。室内结果表明,芝麻花可以显著的提高稻螟赤眼蜂对米蛾卵的寄生力。同时芝麻花显著影响了稻螟赤眼蜂的初始扩散能力,初始起飞蜂比例从71.4%下降至50.5%,但总的扩散蜂比例从91.9%增加至95.4%。田间结果显示田埂种植芝麻花可以提高稻螟赤眼蜂的寄生能力约30%,且更多的蜂扩散至距田埂20~25 m的距离。总之,芝麻花可显著的提高稻螟赤眼蜂寄生和扩散能力。     

低温贮藏对丽蚜小蜂生长发育和扩散的影响

丽蚜小蜂Encarsia formosa作为烟粉虱Bemisia tabaci和温室白粉虱Trialeurodes vaporariorum的重要寄生性天敌,目前已实现了规模化繁育,广泛应用于设施蔬菜粉虱类害虫的防控。该寄生蜂在大面积释放前往往要进行数量储备,因此低温贮藏是实现其规模化生产和应用的重要环节。本文在明确丽蚜小蜂蛹期最适贮藏发育阶段的基础上,研究了不同低温贮藏方式对丽蚜小蜂生长发育和适合度的影响,并在温室条件下明确了低温贮藏对其扩散和寄生的影响。结果表明,丽蚜小蜂的蛹在4℃和8℃下低温贮藏仍可继续发育,解剖低温贮藏后未羽化的丽蚜小蜂发现其死亡主要发生在蛹的发育初期和后期,蛹的发育中期死亡比例最低;贮藏前经历适度的低温诱导（12℃/7 d）可以显著提高丽蚜小蜂的羽化率、寄生量和成虫寿命（P<0.05）;温室条件下未经低温贮藏的丽蚜小蜂主要在1～4 m范围内扩散,而低温贮藏后羽化的丽蚜小蜂主要在1～2 m范围内扩散;适度的低温诱导（12℃/7 d）同样可以明显提高丽蚜小蜂在温室条件下的寄生率（P<0.05）。研究结果对于更好地发挥丽蚜小蜂在生物防治中的控害作用具有重要的应用意义。     

Biology,revised taxonomy and impact on host plants of<Emphasis Type="Italic">Ophelimus maskelli</Emphasis>, an invasive gall inducer on<Emphasis Type="Italic">Eucalyptus</Emphasis> spp. in the Mediterranean Area

Ophelimus maskelli (Ashmead) (Hymenoptera: Eulophidae), an invasive species in the Mediterranean area that occurs naturally onEucalyptus camaldulensis at Wagga Wagga in New South Wales, was studied in Israel on the same host plant. The most distinctive characteristic ofO. maskelli as compared with other congeners is the presence of only a single seta on the submarginal vein.O. maskelli shows a clear tendency to oviposit in developed, immature leaves, and it prefers to oviposit on an area of the leaf blade near the petiole. The female lays an average of 109 eggs when maintained on water alone. The egglaying distribution tended towards aggregation, and the same tendency has also been observed within and among trees. The wasp prefers to attack the lower canopy. The gall diameter ranged from 1.2 to 0.9 mm, and gall density from 11.5 to 36.0 galls cm⁻², respectively. The typical color of the gall appeared as soon as third instar larva developed. Galls on shaded leaves remained green or greenish-yellow, whereas those that were exposed to the sun were reddish.O. maskelli produces three generations per year in Israel. High flight occurs among the spring generations, starting in early March. The wasps were attracted to green sticky plates much more than to the other tested colors. Heavy galling byO. maskelli results in premature shedding of the leaves, soon after the emergence of the wasps. Among the 84 eucalyptus species tested, the following 14 species were found to be suitable hosts:E. botryoides, E. bridgesiana, E. camaldulensis, E. cinerea, E. globulus, E. gunii, E. nicholii, E. pulverulenta, E. robusta, E. rudis, E. saligna, E. tereticornis andE. viminalis. This study focused on morphological and development characters that can clearly distinguishO. maskelli fromOphelimus eucalypti Gahan, and on examining the effect of crossing between eucalyptus species on the development possibilities of the wasps. Also considered were the effect of the food on adult survival, the competition between the eulophid gall makerLeptocybe invasa Fisher & LaSalle andO. maskelli, the heavy damage inflicted on eucalyptus, and the health problems and nuisance to people caused by the wasp near heavily infested trees during the mass emergence of adults. http://www.phytoparasitica.org posting Dec. 5, 2006.     

利用黄粉虫蛹人工繁殖白蛾周氏啮小蜂的研究

以黄粉虫Tenebrio molitor L.蛹作为白蛾周氏啮小蜂Chouioia cunea Yang的人工寄主,在（28±0.5）℃条件下观察其发育历期,以不同蜂蛹比例进行接种,观察小蜂的寄生情况。结果表明,黄粉虫蛹能够满足白蛾周氏啮小蜂发育的营养需求,发育历期为17.2～22.9d,虽然成功寄生率只有75%左右,但基本可以满足常年大规模繁蜂的需要。不同接蜂比例对寄生率、出蜂蛹率和出蜂量有显著影响,蜂蛹比在2∶1以上较好。白蛾周氏啮小蜂在冷冻致死的黄粉虫蛹上也有产卵行为,但蛹内卵和幼虫量很少,它们在死亡寄主体内存活不超过72h。     

赤眼蜂寄生行为研究(Ⅰ)——过寄生与子代分配

寄生蜂的过寄生现象是经常发生的。Ullyett(1949)认为,一种有效的昆虫寄生蜂,往往以蜂卵在寄主上的分布这种方式来使其达到最高存活率。Smith(1916)指出,由于蜂卵在寄主上的分布不同,形成了过寄生。关于过寄生对寄生蜂种群繁殖率的影响,国     

采用果园喷雾施药机械施药时农药有效沉积率的计算方法

针对传统农药沉积率测算方法无法精确反映果园中农药实际利用率的问题,提出一种结合果树冠层特征与叶面沉积量直接测算农药药液在果树靶标上有效沉积率的方法,以期建立一种适用于不同栽种模式的果园通用农药沉积率计算方法。首先采用传统方法计算采用风送式自走喷雾机喷雾后农药在乔化稀植型果园的地面流失率,将其结果与采用果树冠层特征与叶面沉积量相结合的方法计算的有效沉积率进行比较,再通过计算采用风送式自走喷雾机喷雾后农药在矮砧密植型果园的有效沉积率以及采用担架柱塞泵式喷雾机和植保无人飞机喷雾后农药的有效沉积率,验证本研究所提出的将果树冠层特征与叶面沉积量相结合计算农药有效沉积率方法的准确性及适用性。结果表明:基于叶面沉积量结合果树冠层特征方法计算得到的农药有效沉积率与采用传统方法计算得到的农药地面流失率结果基本一致,均能体现施药机械的农药利用率,但比较而言,本研究所提出的方法在果园植保机械喷雾施药有效利用率的影响因素方面考虑更全面,兼顾了叶面沉积量和果树冠层结构的影响,且对于不同栽种模式下的果园更具适应性。将果树冠层特征与叶面沉积量相结合进行果园农药有效沉积率的计算,可以更加真实地反映出果园农药的实际利用情况,同时通过将果树冠层结构量化为叶面积指数、冠层阴影面积等指标,可以为不同栽种模式下的果园选择适宜的植保机械,结合地面流失率的测量,计算出果园农药的飘移量,从而通过调整喷雾角度、雾滴大小、喷雾流量等参数,实现对植保机械的优化,达到精准施药的目的。     

Attraction and antennal response of the common wasp,Vespula vulgaris (L.), to selected synthetic chemicals in New Zealand beech forests

BACKGROUND: The common wasp, Vespula vulgaris (L.), and the German wasp, Vespula germanica (F.), are significant problems in New Zealand beech forests (Nothofagus spp.), adversely affecting native birds and invertebrate biodiversity. This work was undertaken to develop synthetic attractants for these species to enable more efficient monitoring and management. RESULTS: Seven known wasp attractants (acetic acid, butyl butyrate, isobutanol, heptyl butyrate, octyl butyrate and 2,4‐hexadienyl butyrate) were field tested, and only heptyl butyrate and octyl butyrate attracted significantly higher numbers of wasps than a non‐baited trap. Accordingly, a series of straight‐chain esters from methyl to decyl butyrate were prepared and field tested for attraction of social wasps. Peak biological activity occurred with hexyl butyrate, heptyl butyrate, octyl butyrate and nonyl butyrate. Polyethylene bags emitting approximately 18.4–22.6 mg day^?1 of heptyl butyrate were more attractive than polyethylene bags emitting approximately 14.7–16.8 mg day^?1 of heptyl butyrate in the field. Electroantennogram (EAG) studies indicated that queens and workers of V. vulgaris had olfactory receptor neurons responding to various aliphatic butyrates. CONCLUSION: These results are the first to be reported on the EAG response and the attraction of social wasps to synthetic chemicals in New Zealand beech forests and will enable monitoring of social wasp activity in beech forests. Copyright © 2009 Society of Chemical Industry     

云南柠檬园橘臀纹粉蚧的发生及防治初探

对德宏柠檬产区柠檬园树体冠层和土壤耕作层橘臀纹粉蚧的发生情况及防治措施进行了研究,结果表明：橘臀纹粉蚧每年7至10月在柠檬树地上冠层部分形成一个为害期,4月和6月在地下耕作层根部形成两个为害高峰,于橘臀纹粉蚧低龄期采用10%吡虫啉可湿性粉剂2000倍液进行灌根,防治效果最好。