Laboratory evaluation of trap color and vinegar,yeast and fruit juice lure combinations for monitoring of Zaprionus indianus (Diptera: Drosophilidae)

Abstract

Zaprionus indianus Gupta (Diptera: Drosophilidae) is a successful invasive drosophilid that is currently impacting fig production in Mexico and Brazil. Very few studies have examined the improvement of trapping strategies for this pest. Here, we compared visual responses of Z. indianus to different colors and olfactory cues. Orange and brown colored traps were among the most attractive in choice and no-choice tests, with violet and white being the least attractive colors. Orange traps with brown circles around the access holes were more attractive than uniformly orange traps. Apple cider vinegar was significantly more attractive to adults than sugar cane vinegar or grape juice but was not significantly more attractive than white wine and red wine vinegars. Captures of Z. indianus in apple cider vinegar-baited traps were not improved by the addition of grape, pineapple or apple juices, or when compared against a sucrose solution or grape juice fermented with Saccharomyces cerevisiae, or grape juice fermented with Candida tropicalis. Pairwise comparisons of Z. indianus attraction to S. cerevisiae and C. tropicalis indicated a high dependence on the growth media used. Orange traps with brown circles baited with apple cider vinegar may prove useful for monitoring this pest under field conditions.     

A brief review of the status of fireblight in UK1

Fireblight (due to Erwinia amylovora) has continued to spread northwards and westwards in UK. In SW England, the disease has been particularly severe in perry pear orchards, causing the loss of many thousands of mature trees, and in cider apple orchards. Cider apple trees are not rapidly killed but crop losses have been severe in some years. The disease has become established in the NW midland counties of England and also in Wales. Outbreaks have occurred as far north as Lancashire just above the administrative line which separates the affected area from the disease-free (clear) area. Spread has occurred through infections in Crataegus hedges, especially along motorways, and also through movement of infected ornamental species. New legislation is envisaged which will redefine the clear area and increase the protection given.     

Epidemiology of a Neotropical rust (Puccinia psidii): periodical analysis of the temporal progress in a perennial host (Syzygium jambos)

The epidemiology of the Neotropical rust caused by Puccinia psidii in the Indian Myrtaceae Syzygium jambos (rose apple) was investigated in central Brazil. Disease severities recorded during a 12-month period were fitted by a Fourier curve with three cyclic components or harmonics. The first, second and third harmonics accounted for 49·6, 25·9, and 1·5% of total disease measured, respectively. A highly significant linear correlation was observed between the first harmonic and the accumulated number of days having at least 6 h wetness, or a minimum of 90% relative humidity, combined with temperatures that ranged from 18 to 20°C. No significant correlation was observed between the second and third harmonics and the weather variables evaluated. Rose apple trees showed a flush of growth with new susceptible host tissue during the evaluation period, with two major outbreaks of rust of variable intensity. Host growth was fitted by a Fourier curve with two significant harmonics. The first and second harmonics accounted for 37·5 and 22·1% of total host growth measured, respectively. A highly significant negative linear correlation was observed between the first harmonic and daily maximum and minimum temperatures, rainfall, and duration of the light period. Inoculum availability was not a limiting factor for disease progress since urediniospores were present during most of the period studied. A major peak in numbers of rust spores followed the main peak of disease severity. Thus, rust epidemics on rose apple in central Brazil were shown to depend on the duration of leaf wetness in the dark, and also on night-time temperatures during that same wetness period. This study is the first example of a periodical analysis of an epidemic in a perennial crop.     

The problem of Pitymys voles in orchards in central and southern Italy1

Voles of the genus Pitymys have in recent years caused serious damage in orchards (apple, citrus) in central and southern Italy. They gnaw the roots and base of the trunk of young and mature trees, killing them in a few days. The outbreaks can be related to certain recent changes in cultural practice, especially the introduction of overhead irrigation. Results are presented for control trials by trapping or by chlorophacinone baiting.     

Limited asymptomatic colonization of apple tree shoots by Neonectria ditissima following infection of leaf scars and pruning wounds

European apple canker, caused by Neonectria ditissima, is an important disease of apple (Malus domestica). The fungus may reside in the tree without causing symptoms for up to a few years, thus making canker control difficult. Asymptomatic infections established in the nursery can result in severe canker outbreaks in newly established apple orchards. It has been suggested that N. ditissima might colonize the tree beyond the infection point during the asymptomatic stage. We investigated whether N. ditissima can colonize the internal tissues of apple shoots, both prior to and after visual symptoms. Apple trees were artificially inoculated via pruning wounds and leaf scars; then the pathogen was tracked at the inoculation point and beyond with isolation or real-time quantitative PCR (qPCR). Before visual symptoms, N. ditissima could be detected in the infected pruning cut or leaf scar, but not at a distance of 10–15 mm from the entry point, or greater. Conversely, after symptom expression, the pathogen could be detected in the symptomless tissue at 10–15 mm from a canker lesion. This study demonstrated that the asymptomatic infection by N. ditissima can be detected using qPCR and that the pathogen does not grow systemically much beyond the initial entry point inside the plant before visual canker symptoms appear.     

Extended longevity of Erwinia amylovora vectored by honeybees under in vitro conditions and its capacity for dissemination

Fire blight outbreaks in Korea were first reported in 2015. Regular outbreaks have occurred since, indicating a continuous cycle of the fire blight pathogen in Korea. We determined the role of Apis mellifera (honeybee) as a vector of Erwinia amylovora by verifying the following: (a) E. amylovora longevity in/on honeybees; (b) the most common body parts that carry the bacteria; (c) the rate of bacterial spread to healthy host organs; and (d) the relationship between dispersal of viable but nonculturable (VBNC) and virulent bacterial cells. E. amylovora survived for 15 days on the exterior of honeybee bodies and was most abundant on the abdomen in comparison to other areas such as the labellum, wings, and hind legs. In the digestive system of honeybees, E. amylovora survived for 7 days, and bacteria were found in faeces for 3 days after exposure. The bacteria are likely to be VBNC on honeybees. Honeybees that were contaminated with bacteria transferred E. amylovora to healthy immature apple fruit, shoots, and flowers for 10 days after exposure. E. amylovora was also transferred from inoculated plant parts to uncontaminated honeybees. In addition, bacteria moved from inoculated plant tissues to unexposed honeybees and then from these honeybees to healthy plant tissues. Therefore, E. amylovora can survive in/on honeybees for extended amounts of time, which contradicts previous reports. The bacteria moved to host tissues via honeybees, suggesting that honeybees are the vectors of E. amylovora and play a role in the development of new outbreaks of fire blight disease in the central regions of Korea.     

不同食料对苹果蠹蛾生长发育和繁殖的影响

在室内研究了红玉苹果、红元帅苹果、张掖2号苹果、沙果、苹果梨、早酥梨、杏对苹果蠹蛾［Cydia pomonella (L.)］生长发育和繁殖的影响。结果表明,不同食料对苹果蠹蛾幼虫和蛹的发育历期、存活率、蛹重、雌成虫寿命、雌成虫产卵量等有显著影响。幼虫取食沙果、早酥梨、红玉苹果最有利于其生长发育和繁殖;取食红元帅苹果和张掖2号苹果的影响居中;而取食杏和苹果梨对其生长发育和繁殖表现出明显的不利性,主要表现为幼虫死亡率增加,幼虫期延长,蛹期延长,蛹重减轻,雌成虫寿命缩短,单雌产卵量降低。     

Molecular Identification of a Sexual Interloper: The Pear Pathogen, Venturia pirina, has Sex on Apple

ABSTRACT Venturia pirina (the pear scab pathogen) and V. inaequalis (the apple scab pathogen) were detected as ascospores discharged from apple leaf litter in New Zealand (spring 1998). Pseudothecia of both species were located on dead apple leaves; however, only those of V. inaequalis were associated with scab lesions. V. pirina was identified by rDNA sequence analyses, because morphological characters could not distinguish this fungus from V. asperata (a rare saprophyte on apple) and other Venturia spp. pathogenic on rosaceous fruit trees. Species-specific polymerase chain reaction primers designed to the 18S end of the internal transcribed spacer 1 region differentiated Venturia fruit tree pathogens reliably. V. pirina field isolates were pathogenic on pear, but only weak saprophytes on apple. In rare instances, when appressoria of V. pirina appeared to penetrate the cuticle of apple leaves, epidermal cells responded with a localized hypersensitive response (HR). To our knowledge, this is the first report of induction of HR-like events by V. pirina on its nonhost, apple, and also the first record of sexual reproduction of V. pirina on apple. It is assumed that V. pirina pseudothecia formed from saprophytic lesions in senescing apple leaves when active defense mechanisms such as HR were no longer induced.     

六种新烟碱类杀虫剂残留在苹果实验室模拟加工中的变化

为明确苹果中残留的烯啶虫胺、噻虫嗪、吡虫啉、噻虫胺、呋虫胺和啶虫脒6种新烟碱类药剂在不同加工过程中的变化情况,采用高效液相色谱法研究了6种药剂在苹果实验室罐头、果酱、果酒和果醋模拟加工过程中的残留量变化。结果表明:在苹果罐头加工过程中,6种药剂在罐头中残留量与初始浓度相比均显著降低,其中吡虫啉和噻虫胺在罐头中的加工因子较高,均为0.8,啶虫脒在罐头中的加工因子最低,为0.1。罐头汁中烯啶虫胺的加工因子最高,为0.5,其次为啶虫脒和噻虫嗪,均为0.4。在果酱加工过程中,烯啶虫胺、噻虫嗪、吡虫啉、噻虫胺、呋虫胺和啶虫脒的加工因子分别为0.8、0.9、0.9、1.0、0.9和0.9。在果酒中除吡虫啉的加工因子为0.1外,其余药剂加工因子均小于0.1。在果醋中除噻虫胺有少量残留(0.05 mg/kg)外,其余药剂均低于检出限。6种新烟碱类药剂在苹果实验室模拟加工过程中,加工因子均小于1,残留降低。     

Fireblight in Poland

Fireblight ( Erwinia amylovom ) was first detected in Poland in 1966 and then occurred irregularly, in isolated foci mainly along the northern coast of the country, until 1975. During this period, radical measures were taken for localization and elimination of the disease. Since 1976, the disease has become established in numerous areas across northern Poland, and since 1985 has spread towards the centre of the country. Pear, apple and wild hawthorn are affected. In recent years, damage in affected areas has been only at a moderate level. A Ministerial Decree makes fireblight control compulsory. Inspections are carried out throughout the country and any outbreaks must be notified. Complete elimination of infected and adjacent host plants is recommended in areas of low incidence. In heavily affected areas, it is recommended to prune away all infected parts. Severe restrictions apply to nurseries. General preventive measures are also recommended.     

A dynamic model simulating infection of apple leaves by Venturia inaequalis

A new dynamic model of the infection of apple leaves by Venturia inaequalis is described. The model begins with the release of spores by rain and incorporates the effect of light on the discharge of ascospores from pseudothecia. The model then simulates infection through the sub-processes of germination, appressorium formation and penetration, separately for ascospores and conidia landed concurrently on wet leaves. The rate of the infection process is determined using different equations for ascospores and conidia. Spore mortality when leaves dry is determined by the stage of infection and RH in the dry period. The infection process is driven by surface wetness, temperature and RH. The progress of each infection period is measured as infection efficiency (IE), namely the percentage of landed spores which have penetrated and thereby infected leaves. The final IE quantifies the favourability of weather in each infection period. In orchard tests in each of three years, the new model detected crucial infection periods in spring and early summer which accounted for outbreaks of leaf scab. These periods were not detected by a static model based on Mills'criteria. The models performed similarly in detecting infection periods later in summer.     

Symptoms and molecular characterization of apple dimple fruit viroid isolates from apples in Japan

Apple dimple fruit viroid was detected from an apple tree (‘Jonagold’) bearing apples with mild dapple apple symptom. The isolates in Japan were distinct from those in apples in Italy and China and in fig in Italy. Graft-inoculation experiments showed that the symptoms were variable depending on the cultivar, and the symptom on ‘Starking Delicious’ was virtually similar to those reported in Italy. Symptoms induced by apple dimple fruit viroid were similar in part to those by apple fruit crinkle viroid or apple scar skin viroid, indicating that they cannot be discriminated by symptoms on any specific variety.     

气相色谱-氮磷检测法检测喹啉铜在苹果中的残留及消解动态

为探明喹啉铜在苹果中的安全性,制定喹啉铜在苹果上的安全使用标准,研究了山东烟台、河北石家庄和安徽宿州3个试验点喹啉铜在苹果中的残留消解动态和最终残留量。样品前处理过程中,以乙二胺四乙酸(EDTA)作为竞争配体,将喹啉铜转化为8-羟基喹啉,采用气相色谱-氮磷检测器(GC-FTD)检测。结果表明:在0.0605、1.0和2.0 mg/kg 3个添加水平下,喹啉铜的平均添加回收率为80%~98%,相对标准偏差(RSD)为1.0%~2.3%,在苹果中的定量限为0.0605 mg/kg;喹啉铜在苹果中的消解过程符合一级反应动力学方程,消解速度较快,半衰期为4.4~7.4 d,其在苹果中的残留量随着时间延长而递减。参照我国制定的苹果中喹啉铜限量标准2.0 mg/kg (临时限量),按照本试验剂量和次数施用喹啉铜21 d后,所采收的苹果是安全的。     

Transformation of soil microbial community structure and rhizoctonia-suppressive potential in response to apple roots

ABSTRACT Changes in the composition of soil microbial communities and relative disease-suppressive ability of resident microflora in response to apple cultivation were assessed in orchard soils from a site possessing trees established for 1 to 5 years. The fungal community from roots of apple seedlings grown in noncultivated orchard soil was dominated by isolates from genera commonly considered saprophytic. Plant-pathogenic fungi in the genera Phytophthora, Pythium, and Rhizoctonia constituted an increasing proportion of the fungal community isolated from seedling roots with increasing orchard block age. Bacillus megaterium and Burkholderia cepacia dominated the bacterial communities recovered from noncultivated soil and the rhizosphere of apple seedlings grown in orchard soil, respectively. Populations of the two bacteria in their respective habitats declined dramatically with increasing orchard block age. Lesion nematode populations did not differ among soil and root samples from orchard blocks of different ages. Similar changes in microbial communities were observed in response to planting noncultivated orchard soil to five successive cycles of 'Gala' apple seedlings. Pasteurization of soil had no effect on apple growth in noncultivated soil but significantly enhanced apple growth in third-year orchard block soil. Seedlings grown in pasteurized soil from the third-year orchard block were equal in size to those grown in noncultivated soil, demonstrating that suppression of plant growth resulted from changes in the composition of the soil microbial community. Rhizoctonia solani anastomosis group 5 (AG 5) had no effect on growth of apple trees in noncultivated soil but significantly reduced the growth of apple trees in soil from third-year orchard soil. Changes in the ability of the resident soil microflora to suppress R. solani AG 5 were associated with reductions in the relative populations of Burkholderia cepacia and Pseudomonas putida in the rhizosphere of apple.     

苹果与炭疽菌互作研究进展

近年来,由炭疽菌引起的苹果炭疽病已成为阻碍苹果产业健康发展的重要病害之一。苹果与炭疽菌的互作研究有助于苹果炭疽病的科学防治和抗病育种。笔者从苹果炭疽病病菌的致病机制、苹果种质资源对炭疽菌的抗性表现和苹果对炭疽菌的抗病机制等方面对苹果与炭疽菌的互作研究进行系统综述,并对炭疽菌的致病机理和苹果抗病基因等研究前景进行了展望。     

Effects of residues of fenvalerate and permethrin on the feeding behaviour of Tetranychus urticae (Koch)

The effects of synthetic pyrethroids on the feeding behaviour of the two-spotted spider mite Tetranychus urticae (Koch) were studied using a modified leaf disc technique. Four different concentrations of the pyrethroids fenvalerate and permethrin and of the organophosphorous insecticide phosmet were sprayed on to Henderson lima bean plants in the laboratory. A water spray was used as a control. Leaf discs were taken from each treatment, including the control, at 2h, 1, 2, 4, 7, 11 and 14 days after treatment. One mite was placed on each disc, allowed to acclimatise and then observed for 1 h. Experiments were conducted under laboratory light at 25 (±1.5)°C and 30 (±2)% r.h. Mites on untreated and phosmet-treated discs spent an average 70–95% of the time feeding; mite behaviour appeared to be unaffected by phosmet. In contrast, mites often spent only 5–40% of the time feeding on discs treated with fenvalerate or with the higher rates of permethrin. In response to pyrethroid residues mites exhibited hyperactivity, longer search periods and reduced feeding, reduced oviposition and a preference for areas with lower residues. These changes in mite behaviour may partially explain mite outbreaks in the field on apple trees following treatment with pyrethroids.     

Characterization of <Emphasis Type="Italic">Phaeoacremonium</Emphasis> isolates associated with Petri disease of table grape in Northeastern Brazil,with description of <Emphasis Type="Italic">Phaeoacremonium nordesticola</Emphasis> sp. nov.

Severe outbreaks of Alternaria leaf blotch and fruit spot were recently observed in cv. Pink Lady apples in northern Israel, especially on fruit. Such severe outbreaks have not been reported from other countries. Symptoms involved cracks and rot around the calyx and external rot of the fruit body. Up to 80 % of the fruit in some orchards were affected by the disease. Microscopic examinations, fulfillment of Koch’s postulates and molecular (genetic) analyses confirmed the causal agent as Alternaria alternata f. sp. mali. The incidence of Alternaria increased as the degree of calyx cracking increased, or if fruit were both cracked and rotted. Injecting spore suspensions into the fruit produced typical rot symptoms. Injection assays of detached fruit of eight apple cultivars showed that cvs. Pink Lady and Golden Delicious were susceptible whereas cv. Jonathan was resistant. Pink Lady and Golden Delicious produced more fruit rot as the inoculum concentration increased. Rot in all three cultivars was moderate close to the skin but more severe close to the seed locule. Aqueous extracts taken from Jonathan fruit peel inhibited germ tube elongation of A. alternata f. sp. mali in vitro. This is the first report on heavy infection of Pink Lady fruit in Israel caused by A. alternata f. sp. mali.     

Biological control of apple crown gall by nonpathogenic Rhizobium vitis strain VAR03-1

A nonpathogenic strain of Rhizobium vitis, VAR03-1, was tested as a biological control agent for crown gall of apple. When apple tree roots were soaked in a cell suspension of antagonists before planting in the field, treatment with VAR03-1 significantly reduced the number of plants with tumors and the disease severity. The inhibitory effects of treatment with VAR03-1 and the nonpathogenic R. rhizogenes strain K84, which is commercially used as a biological control agent throughout the world, on apple crown gall were almost identical. VAR03-1 was bacteriocinogenic, producing a halo of inhibition against two species of tumorigenic Rhizobium isolated from galled apple trees. Moreover, VAR03-1 established populations on roots of apple tree rootstock and persisted on roots for 437?days. This is the first report that the nonpathogenic R. vitis VAR03-1 effectively controls crown gall of apple.     

Crab apple blossoms as a model for research on biological control of fire blight

ABSTRACT Nonseasonal availability of pomaceous flowers could improve laboratory detection and prefield testing of biocontrol agents for fire blight of pear and apple. Crab apple was selected as a model because of its high flower productivity on 1-year-old wood, high susceptibility to fire blight, and availability from nurseries. Cultivars Manchurian and Snowdrift were manipulated to bloom once by transferring dormant nursery trees from a cold room to a greenhouse and a second time by defoliating trees and applying 1% cytokinin and 0.1% gibberellins to the buds with a brush. Different sets of trees were induced at different times to bloom, so that flowers were produced 12 months in the year. When known bacterial antagonists (Erwinia herbicola strain C9-1 and Pseudomonas fluorescens strain A506) were applied alone or in combination to the stigmas of detached crab apple blossoms prior to inoculation with the pathogen (E. amylovora strain Ea153), population interactions over time were comparable to those reported in previous studies involving pear or apple. In a subsequent series of experiments, the relative effects of 12 bacterial strains on stigmatic populations of strain Ea153 were similar for detached blossoms of crab apple in the laboratory, blossoms of intact crab apple trees in the greenhouse, and blossoms of pear and apple in the field. Additionally, when stigmas of detached crab apple blossoms were inoculated with antagonists (strains C9-1 and A506) and the pathogen, and later subjected to a 24-h wetting period, bacterial populations in the flower hypanthium increased and disease was suppressed. These studies indicate that crab apple blossoms can serve as a suitable model for year-round evaluation and study of biocontrol agents for fire blight.     

Role of Cylindrosporium-type conidia of Mycosphaerella pomi (Pass.) Lindau: cause of Brooks fruit spot of apple, as an infection source in apple orchards

Ascospores of Mycosphaerella pomi, the pathogen of Brooks fruit spot of apple, were produced in pseudothecia on previously infected and overwintered apple leaves from late April through early August in Aomori Prefecture, Japan. In June 2003, the ascospores were germinating and producing Cylindrosporium-type conidia on apple fruit and leaf surfaces in an orchard. After ascospores were sprayed on apple leaves, Cylindrosporium-type conidia developed on the leaf surfaces. Such Cylindrosporium-type conidia caused typical symptoms of Brooks fruit spot on apple trees after inoculations. These results suggested that the Cylindrosporium-type conidia also serve as an infection source, in addition to the ascospores, for Brooks fruit spot in apple orchards.