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Wheat bulb fly, Delia coarctata, is an important pest of winter wheat in the UK, causing significant damage of up to 4 t/ha. Accepted population thresholds for D. coarctata are 250 eggs/m2 for crops sown up to the end of October and 100 eggs/m2 for crops sown from November. Fields with populations of D. coarctata that exceed the thresholds are at higher risk of experiencing economically damaging infestations. In the UK, recent withdrawal of insecticides means that only a seed treatment (Signal 300 ES) is available for chemical control of D. coarctata; however, this is only effective for late-sown crops and accurate estimations of annual population levels are required to ensure a seed treatment is applied if needed. As a result of the lack of postdrilling control strategies, the management of D. coarctata is becoming reliant on nonchemical methods of control. Control strategies that are effective in managing similar stem-boring pests of wheat include sowing earlier and using higher seed rates to produce crops with greater pest tolerance. In this study, we develop two predictive models that can be used for integrated D. coarctata management. The first is an updated pest level prediction model that predicts D. coarctata populations from meteorological parameters with a predictive accuracy of 70%, a significant improvement on previous prediction models. Our second model predicts the maximum number of shoots for a winter wheat crop that would be expected at the terminal spikelet development stage. This shoot number model uses information about the thermal time from plant emergence to terminal spikelet, leaf phyllochron length, plant population and sowing date to predict the degree of tolerance a crop will have against D. coarctata. The shoot number model was calibrated against data collected from five field experiments and tested against data from four experiments. Model testing demonstrated that the shoot number model has a predictive accuracy of 65.7%. The foundation for a future decision support system using these models for the sustainable management of D. coarcata risk is described. It should be noted that these models represent a stepping-stone towards a decision support system and that further model validation over a wider geographic range is required.  相似文献   

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The objective of this study was to assess the parity, presence of blood in the stomach, and the gonotrophic discordance of females of Aedes aegypti and Aedes albopictus captured in two areas of the city of São Paulo. The captures were undertaken monthly, by aspiration, in the period from January, 2015 to August, 2017. All the females of the two species had their midguts and ovaries dissected to determine the presence of blood and the parity/stage of maturation. With regard to parity, 27% and 34% of the females of Ae. aegypti and Ae. albopictus, respectively, were parous or were in advanced stages of the development of their ovaries (33% and 27%, respectively). The larger part of the females of Ae. aegypti and Ae. albopictus contained blood in their stomachs (77% and 60%, respectively), beyond which 36% and 27% of the females of Ae. aegypti and Ae. albopictus, respectively, were in gonotrophic discordance. Our results indicate favorable conditions in the study areas because of the presence of parous females. Moreover, this frequent and multiple contact of Ae. aegypti and Ae. albopictus females with vertebrate hosts, such as humans, increases the possibility of transmitting the viruses they may be carrying.  相似文献   

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为调查甘肃省部分地区蚊虫及蚊媒病毒的种类及分布,本课题组2014年在甘肃省酒泉市和陇南市地区共采集蚊虫4 412只.酒泉市共采集蚊虫2属3种2 833只,其中背点伊蚊(Aedes dorsalis)2 665只(94.1%)、刺扰伊蚊(Aedes vexans)150只(5.3%)、淡色库蚊(Culex pipiens pallens)18只(0.6%);陇南市共采集2属2种1 579只蚊虫,其中淡色库蚊1 451只(91.9%)、中华按蚊(Anopheles sinensis)128只(8.1%).经实验室常规处理后,将蚊虫标本分为96批,接种于C6/36、BHK和Vero细胞,进行病毒分离和多种病毒基因特异性扩增检测.结果显示,96批蚊虫标本在3种细胞中均未出现细胞病变效应(cytopathic effect,CPE),在18批蚊虫标本研磨液中检测到辽宁病毒(Liaoning virus,LNV)基因阳性.病毒核苷酸序列的遗传进化分析显示,在甘肃省检测到的辽宁病毒与此前在我国新疆维吾尔自治区发现的辽宁病毒亲缘关系最近.  相似文献   

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An inexpensive culture medium based on sunflower seed extract (SSE) for production of Leptolegnia chapmanii was developed. Vegetative growth on solid and liquid SSE was compared with two culture media used routinely (peptone, yeast and glucose (PYG) and Emerson YPss). Results indicate that the oomycete is able to grow on SSE medium, producing more zoospores at a faster rate as well as inducing higher mortality rates in Aedes aegypti larvae.  相似文献   

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作物抗性品种、布局、耕作制度以及栽培管理等农业措施可以有效地调节害虫的种群数量,合理和综合运用这些措施,可以实现害虫生态调控的目的,从而为农作物的无公害生产提供新的植保技术。本文从农业措施在害虫控制中的直接作用、对天敌昆虫的影响等方面进行了综述,同时对利用农业措施控制害虫的几个问题进行了探讨,以期为合理利用和正确评价农业措施控制害虫提供参考。  相似文献   

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Studying interactions of multiple pesticides applied simultaneously in a mixture is a common task in phytopathology. Statistical methods are employed to test whether the treatment components influence each other's efficacy in a promotive or inhibitory way (synergistic or antagonistic interaction) or rather act independent of one another (additivity). The trouble is that widely used procedures based on chi‐square tests are often seriously flawed, either because people apply them in a preposterous way or because the method simply does not fit the problem at hand. Browsing recent volumes of entomological journals, we found that numerous researchers have (in all likelihood unwittingly) analysed their data as if they had had a sample size of 100 or, equally bad, a sample size of one! We show how to avoid such poor practices and further argue that chi‐square testing is, even if applied correctly (meaning that no technical errors are made), a limited purpose tool for assessing treatment interactions.  相似文献   

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Because correct identification of insects is crucial for pest management involving chemical or biological control agents, we have used a molecular approach to identify and characterize specimens of the cotton pest Phenacoccus solenopsis Tinsley (Sternorrhyncha: Pseudococcidae) present in different regions of Pakistan. The specimens were analyzed through DNA sequence analysis of their mitochondrial COI (mtCOI) gene using an improved procedure that could distinguish between the pest and its associated parasitoid. Our analysis showed no variation among the mealybug specimens from different geographical locations of Pakistan and confirmed that this is the same species and haplotype that is infesting cotton plants in other parts of Asia. This information will assist in the development of biological control programs against P. solenopsis in Pakistan and other Asian countries.  相似文献   

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Lethal control of vertebrate animals through the use of firearms is a component of land management in Australia. The reduction in muzzle blast noise in the area surrounding the shooter provides the opportunity to decrease disturbance of nontargeted animals and nearby humans. This study identifies the reduction in environmental noise footprint provided by suppressor use. This suggests that the use of a suppressor to reduce noise from the muzzle blast may increase operational effectiveness of ground shooting while minimising adverse environmental effects.  相似文献   

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蚊属于典型的性二态昆虫,两性在行为上有着巨大差异,雄性成蚊主要依靠植物汁液获取碳源,而雌性只有吸血后卵巢才能够正常发育,这也是蚊传播多种人类疾病的重要基础。蚊的性二态由复杂的性别决定基因通路调控,虽然通路中两个关键因子双性基因(doublesex,dsx)与fruitless(fru)在结构和功能上与其他昆虫具有高度保守性,通过性别可变剪切最终调控下游性别表型与性行为相关基因,但是其性别决定初始信号即雄性决定因子(Male-determining factor,M-factor)无论与其他昆虫相比还是属种间均具有巨大的差异,而从M-factor至dsx的调控通路亦尚未明确。目前,利用已知的蚊性别决定基因对蚊进行基因改造,在实验室已经初步达到了性别逆转或种群抑制的效果。本文综述了蚊性别决定调控通路中初始信号雄性决定因子的进化和作用机制,其下游信号通路的响应模式,以及以性别决定基因为靶点的转基因蚊防制策略,为深入理解蚊性别决定机制与探讨蚊媒防制提供新思路。  相似文献   

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随着种植模式调整、气候变化及交通运输业发展,新的枣树害虫不断出现,已知害虫危害加剧,严重威胁枣产业。本文通过对现有枣树害虫研究文献的综合分析,重点介绍了近年来对枣产业影响较大的害虫种类,并总结了当前具备应用潜力的防治技术。同时,文章对未来枣园害虫管理和研究方向进行了展望,旨在提升公众对枣树害虫危害的认识,促进枣树害虫的基础和综合防治研究,从而保障我国枣产业的健康发展,并为枣农创造更大的经济效益。  相似文献   

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In 2011, Schmallenberg virus (SBV), a novel member of the Simbu serogroup, genus Orthobunyavirus, was identified as the causative agent of a disease in ruminants in Europe. Based on the current knowledge on arthropods involved in the transmission of Simbu group viruses, a role of both midges and mosquitoes in the SBV transmission cycle cannot be excluded beforehand. The persistence of SBV in mosquitoes overwintering at SBV‐affected farms in the Netherlands was investigated. No evidence for the presence of SBV in 868 hibernating mosquitoes (Culex, Anopheles, and Culiseta spp., collected from January to March 2012) was found. This suggests that mosquitoes do not play an important role, if any, in the persistence of SBV during the winter months in northwestern Europe.  相似文献   

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Habitat modification is an established method of effective long-term mosquito management, particularly in salt-marsh environments. It is especially pertinent when mosquitoes are known vectors of life-threatening disease and their larval breeding habitat is in close proximity to residential areas. The Ilparpa Swamp is located less than 10 km from Alice Springs, Northern Territory. Wet season rainfall, often followed by effluent discharges to the swamp from the adjacent sewage treatment plant, create ideal sites for the immature stages of the common banded mosquito Culex annulirostris (Skuse), a major vector of Murray Valley encephalitis (MVEV) and Kunjin (KUNV) viruses. Subsequent to increases in notifications of MVEV disease cases in 2000 and 2001, a drainage system was established in the Ilparpa Swamp in early 2002. This paper evaluates the drainage intervention effects. Results indicate a significant reduction in mosquito numbers following habitat modification, which remain low. There have been no seroconversions in sentinel chickens to MVEV or KUNV and no human infections from these viruses in the Alice Springs urban region since the drains were completed. Habitat modification has successfully reduced mosquito numbers and minimized the risk for mosquito-borne disease to residents in Alice Springs urban and surrounding areas, which has never before been documented in Australia.  相似文献   

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Aim The aim of this study is to determine whether changes to the seasonal and circadian timing of propagule release can a have a significant effect on the area covered by resulting aerial dispersal. Location Western Australia. Methods Using the atmospheric pollution model (TAPM), an existing meso‐scale dispersal model, a range of release patterns was simulated and the resulting deposition compared. Comparisons were based on observations of deposition patterns and the calculated area of deposition. Results Small changes to the timing of propagule release were shown to significantly impact on the area experiencing deposition from the resulting aerial dispersal. Main conclusions Simulations performed in this study show that, for small propagules, changes to the timing of release can lead to alternate, clearly differentiable dispersal events. Small changes in both the seasonal and circadian patterns of release can have significant effects on the area that experiences deposition during the resulting dispersal event. This effect is particularly important at the landscape scale and when there is a need to quantify individual dispersal events. Predictive modelling of aerial dispersal needs to be undertaken with an understanding of the manner in which biological and environmental factors that affect the timing of propagule release can influence results. Results presented highlight the need to characterize the epidemiology of pathogenic organisms of importance to biosecurity as much as possible before they arrive.  相似文献   

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Abstract:  A conventional sampling plan for the leafhopper Empoasca kraemeri Ross & Moore (Auchenorrhyncha: Cicadellidae) in common beans (Phaseolus vulgaris L.) is presented based on samples from 51 commercial fields. The research encompassed three phases. The first phase had the objective of determining the most suitable leaf to be used as a precise and representative sampling unit. In the second phase of the project, the available sampling methods for E. kraemeri were compared, including the approach identified in the first phase. In the third phase, the theoretical frequency distribution of the sampling data was assessed and the number of samples necessary for the sampling plan was established. The best leaves to sample adult leafhoppers were the fourth and the fifth from the apex, while the best leaf for sampling nymphs was the fifth from the apex. The best sampling technique for nymphs and adults was the beating of the apical leaves against a plastic tray. The sampling data obtained with this technique were fit to a negative binomial distribution with common aggregation parameter for adults ( K common = 1.04) and nymphs ( K common = 0.47). This sampling plan required 16.8 and 31.2 min to be carried out at an expense of US$ 0.31 and US$ 0.54 for sampling adults and nymphs in a field, respectively.  相似文献   

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Sparse geometric information from limited field-of-view medical images is often used to reconstruct the femur in biomechanical models of the hip and knee. However, the full femur geometry is needed to establish boundary conditions such as muscle attachment sites and joint axes which define the orientation of joint loads. Statistical shape models have been used to estimate the geometry of the full femur from varying amounts of sparse geometric information. However, the effect that different amounts of sparse data have on reconstruction accuracy has not been systematically assessed. In this study, we compared shape model and linear scaling reconstruction of the full femur surface from varying proportions of proximal and distal partial femur geometry in combination with morphometric and landmark data. We quantified reconstruction error in terms of surface-to-surface error as well as deviations in the reconstructed femur’s anatomical coordinate system which is important for biomechanical models. Using a partial proximal femur surface, mean shape model-based reconstruction surface error was 1.8 mm with 0.15° or less anatomic axis error, compared to 19.1 mm and 2.7–5.6° for linear scaling. Similar results were found when using a partial distal surface. However, varying amounts of proximal or distal partial surface data had a negligible effect on reconstruction accuracy. Our results show that given an appropriate set of sparse geometric data, a shape model can reconstruct full femur geometry with far greater accuracy than simple scaling.  相似文献   

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Nanobiomedicine and parasitology are facing a number of key challenges, which mostly deal with the paucity of effective preventive and curative tools against mosquito-borne diseases and cancer. In this scenario, the employ of botanical and invertebrate extracts as reducing, stabilizing and capping agents for the synthesis of nanoparticles is advantageous over chemical and physical methods, since it is one-pot, cheap, and does not require high pressure, energy, temperature, or the use of highly toxic chemicals. Considering the overlooked connection between mosquito vector activity and the spread of cancer in USA, this review focused on the current knowledge available about green synthesized nanoparticles with efficacy against mosquito-borne diseases and cancer. Green fabricated metal nanoparticles showed antiplasmodial activity that often encompasses the efficacy of currently marked drugs for malaria treatment. They have been also reported as growth inhibitors against dengue virus (serotype DEN-2), with moderate cytotoxicity on mammalian cells. However, this feature is strongly dependent to the botanical agents employed during nanosynthesis. In addition, green nanoparticles have been successfully used to reduce mosquito young instar populations in the field. The final section focuses on some issues for future research, with special reference to the chemical standardization of the botanical extracts used for nanosynthesis and the potential effects on green fabricated nanoparticles on non-target organisms.  相似文献   

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The effects of organophosphates (mevinphos, phenamiphos, trichlorfon), carbamates (carbofuran, methomyl, oxamyl), a formamidine (chlordimeform), a synthetic pyrethroid (fenvalerate), a chlorinated hydrocarbon (methoxychlor). and an insect growth regulator (diflubenzuron) on in vitro development and reproduction of Neoaplectana carflocapsae were tested by incorporating each chemical into a nematode rearing medium. Organophosphates and carbamates adversely affected development and reproduction at concentrations ≥ 0.1 mg/ml. Phenamiphos was the most toxic, with no nematode reproduction at 0.01 mg/ml. Inoculated infective juveniles developed to adults with some of the organophosphates and carbamates, but limited or no reproduction occurred. Chlordimeform inhibited development at 1.0 mg/ml, while diflubenzuron, fenvalerate, and methoxychlor did not significantly (P > 0.05) reduced reproduction at 1.0 mg/ml. The organophosphate and carbamate nematicides in use for control of plant-parasitic nematodes may be toxic to N. carpocapsae in the soil.  相似文献   

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