scholarly journals Transmission of Xylella fastidiosa to Grapevine by the Meadow Spittlebug

2016 ◽  
Vol 106 (11) ◽  
pp. 1285-1290 ◽  
Author(s):  
D. Cornara ◽  
A. Sicard ◽  
A. R. Zeilinger ◽  
F. Porcelli ◽  
A. H. Purcell ◽  
...  
Keyword(s):  
Xylella Fastidiosa ◽  
Transmission Efficiency ◽  
Access Time ◽  
Insect Vectors ◽  
Bacterial Populations ◽  
Plant Infection ◽  
Basic Parameters ◽  
Pathogen Populations ◽  
The Relationship ◽  
Meadow Spittlebug

There is little information available on Xylella fastidiosa transmission by spittlebugs (Hemiptera, Cercopoidea). This group of insect vectors may be of epidemiological relevance in certain diseases, so it is important to better understand the basic parameters of X. fastidiosa transmission by spittlebugs. We used grapevines as a host plant and the aphrophorid Philaenus spumarius as a vector to estimate the effect of plant access time on X. fastidiosa transmission to plants; in addition, bacterial population estimates in the heads of vectors were determined and correlated with plant infection status. Results show that transmission efficiency of X. fastidiosa by P. spumarius increased with plant access time, similarly to insect vectors in another family (Hemiptera, Cicadellidae). Furthermore, a positive correlation between pathogen populations in P. spumarius and transmission to plants was observed. Bacterial populations in insects were one to two orders of magnitude lower than those observed in leafhopper vectors, and population size peaked within 3 days of plant access period. These results suggest that P. spumarius has either a limited number of sites in the foregut that may be colonized, or that fluid dynamics in the mouthparts of these insects is different from that in leafhoppers. Altogether our results indicate that X. fastidiosa transmission by spittlebugs is similar to that by leafhoppers. In addition, the relationship between cell numbers in vectors and plant infection may have under-appreciated consequences to pathogen spread.

scholarly journals Effect of Temperature, Vector Life Stage, and Plant Access Period on Transmission of Banana bunchy top virus to Banana

2008 ◽  
Vol 98 (6) ◽  
pp. 743-748 ◽  
Author(s):  
M. D. Anhalt ◽  
R. P. P. Almeida
Keyword(s):  
Life Stage ◽  
Plant Viruses ◽  
Transmission Efficiency ◽  
Effect Of Temperature ◽  
Access Time ◽  
Banana Bunchy Top Virus ◽  
Access Period ◽  
Pentalonia Nigronervosa ◽  
The Relationship ◽  
Transmission Biology

The study of the transmission biology of insect-borne plant viruses is important to develop disease control practices. We characterized the transmission of a nanovirus, Banana bunchy top virus (BBTV), by its aphid vector Pentalonia nigronervosa Coquerel (Hemiptera, Aphididae) with respect to temperature, vector life stage, and plant access time. Adult aphids transmitted BBTV more efficiently than third instar nymphs at all temperatures tested. Adult aphids transmitted the virus more efficiently at 25 and 30°C than at 20°C, but temperature had no impact on transmission efficiency by nymphs. By decoupling the relationship between temperature and aphid BBTV acquisition or inoculation, we determined that temperature affected inoculation events more strongly than acquisition. Longer plant access periods increased viral acquisition and inoculation efficiencies in a range of 60 min to 24 h. Both BBTV acquisition and inoculation efficiencies peaked after 18 h of plant access period. We also show that BBTV transmission by P. nigronervosa requires a latent period. Our results demonstrate that vector transmission of BBTV is affected by temperature, vector life stage, and plant access period.

scholarly journals Effect of Environmental Factors and Influence of Rumen and Hindgut Biogeography on Bacterial Communities in Steers

2010 ◽  
Vol 77 (1) ◽  
pp. 258-268 ◽  
Author(s):  
Gustavo A. Romero-Pérez ◽  
Kim H. Ominski ◽  
Tim A. McAllister ◽  
Denis O. Krause
Keyword(s):  
Ambient Temperature ◽  
Bacterial Communities ◽  
Volatile Fatty Acids ◽  
Principal Component ◽  
Population Diversity ◽  
Access Time ◽  
Sample Type ◽  
Bacterial Populations ◽  
Fecal Samples ◽  
Alfalfa Silage

ABSTRACTFeces from cattle production are considered important sources of bacterial contamination of food and the environment. Little is known about the combined effects of arctic temperatures and fodder tannins on rumen and hindgut bacterial populations. Individual rumen liquor and rectal fecal samples from donor steers fed either alfalfa silage or sainfoin (Onobrychis viciifoliaScop.) silage and waterad libitumwere collected weekly on the first three sampling days and fortnightly afterwards. The daily ambient temperatures were registered and averaged to weekly mean temperatures. Steers fed sainfoin silage had lower (P< 0.05) concentrations of branched-chain volatile fatty acids (VFA) than those fed alfalfa silage. All VFA concentrations were higher (P< 0.001) in rumen liquor samples than in fecal samples. The interaction of sample type and diet showed a significant effect (P< 0.05) on the proportions of the bacterial community that were from the phylaProteobacteriaandVerrucomicrobia.Ambient temperature had an indirect effect (P< 0.05) on the phylumFirmicutes, as it affected its proportional balance. The bacterial population diversity in samples appeared to decrease concurrently with the ambient temperature. The phylumFirmicutesexplained the first principal component at 64.83 and 42.58% of the total variance in rumen liquor and fecal samples, respectively. The sample type had a larger effect on bacterial communities than diet and temperature. Certain bacterial populations seemed to be better adapted than others to environmentally adverse conditions, such as less access time to nutrients due to higher motility and rate of passage of digesta caused by extreme temperatures, or antimicrobials such as tannins, possibly due to an influence of their biogeographical location within the gut.

Parametric Design of Spiral Bevel Gear Based on Pro/E

2012 ◽  
Vol 490-495 ◽  
pp. 2454-2458
Author(s):  
Wei Wang ◽  
Wei Liu ◽  
Yan Chi ◽  
Xiao Mei Cui
Keyword(s):  
3D Model ◽  
Parametric Design ◽  
Bevel Gear ◽  
Spiral Bevel Gear ◽  
Design And Manufacturing ◽  
Basic Parameters ◽  
Base Circle ◽  
Spiral Bevel ◽  
Cutter Head ◽  
The Relationship

Considering the influence of the cutter head plane on manufacturing of spiral bevel gear, the method of 3D model for spiral bevel gear is built based on Program Pro/E. The relationship between the geometric parameters (such as addendum circle, dedendum circle and base circle) and the basic parameters (such as modulus and the number of teeth) of spiral bevel gear is established by using the inner program. The parametric solid model of spiral bevel gear can be obtained automatically by rotation, sweep, blend, and pattern after inputting the basic parameters. This method is significant to improve the accuracy of design and manufacturing of spiral bevel gear.

Study on the Relationship between Canal System Conveyance Efficiency and Basic Physical Parameters of Gravity Irrigation Districts

2014 ◽  
Vol 955-959 ◽  
pp. 3422-3426
Author(s):  
Hong Wei Jia ◽  
Ke Ke Hu ◽  
Fei Su
Keyword(s):  
Physical Parameters ◽  
Irrigation Canal ◽  
Canal System ◽  
Positive Role ◽  
Engineering Construction ◽  
Irrigation Districts ◽  
Basic Parameters ◽  
Irrigation Engineering ◽  
Operation Status ◽  
The Relationship

Canal system conveyance efficiency (CSCE ) is a basic parameter of engineering construction and water management of the irrigation districts, either the response of operation status of an irrigation canal system. It plays great significance in searching quantity relationship between ICSCE and other basic parameters reflecting the condition of irrigation engineering. This paper, gravity irrigation districts in Zhejiang province as an example, sets up the relationship between basic parameters such as irrigation canal lining rate, canal flow and the CSCE, based on determining the CSCE in 61 typical gravity irrigation districts. And it also reflects the influence of basic parameters on CSCE, having a certain accuracy. This result plays a positive role on the further research and actual work on CSCE.

scholarly journals Experimental Nets for a Protection System against the Vectors of Xylella fastidiosa Wells et al.

Agriculture ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 32 ◽  
Author(s):  
Sergio Castellano ◽  
Antonella Di Palma ◽  
Giacinto Germinara ◽  
Marco Lippolis ◽  
Giuseppe Starace ◽  
...  
Keyword(s):  
Field Experiments ◽  
Xylella Fastidiosa ◽  
Mesh Size ◽  
Olive Tree ◽  
Cross Sectional ◽  
Wooden Frame ◽  
Field Nursery ◽  
Pass Through ◽  
Laboratory Bioassays ◽  
Meadow Spittlebug

The effectiveness of experimental nets in preventing the access of adult meadow spittlebug Philaenus spumarius L., the main vector of Xylella fastidiosa Wells et al. subspecies pauca, sequence type (ST) 53, in olive tree nurseries and orchards was evaluated. To optimize the net design, mesh size, kind of fabric, thread typology, and radiometric properties, six nets with different mesh sizes and kinds of fabric were evaluated in laboratory and in field experiments. Laboratory bioassays evaluating the capability of adult spittlebugs to pass through nets with different mesh sizes (1.2, 1.8, 2.4 mm) showed that all nets with a mesh size equal to or lower than 2.4 mm prevented insect crossing. These results were confirmed in field conditions using an experimental net box apparatus. Further laboratory tests showed a positive correlation between porosity and radiometric properties of the nets. Three prototypes of thermally stabilized flat woven nets made of circular cross-sectional yarns, knitted net with strips, and knitted nets made of yarns were tested after the evaluation of their potential usability in terms of porosity stability. The knitted net features were found to be the most suitable. The net transmissivity of the total and direct component of solar radiation in the photosynthetically active radiation and the infrared ranges increased with the net porosity. A prism-shaped wooden frame with a triangular base covered with the knitted net with a 2.4 mm mesh confirmed the insect’s capability of reaching considerable heights, up to 2.85 m. Hence, based on our results, the monowire knitted net with a 2.4 mm mesh can be used in open field nursery and olive orchards to prevent the access of P. spumarius adults and to shield the openings of greenhouse nurseries.

scholarly journals A Frequency Locking Method for ICPT System Based on LCC/S Compensation Topology

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2626
Author(s):  
Yansong Li ◽  
Minhao Wang ◽  
Weiwei Zhang ◽  
Mengmeng Zhao ◽  
Jun Liu
Keyword(s):  
Output Power ◽  
Power Transmission ◽  
Transmission Efficiency ◽  
Maximum Efficiency ◽  
Initial Value ◽  
Frequency Locking ◽  
Inductively Coupled ◽  
Output Characteristics ◽  
The Relationship

Aiming to maximize the transmission efficiency of inductively coupled power transmission (ICPT) system with the designed output power, a frequency locking method for an ICPT system based on LCC/S compensation topology is proposed in this paper. Firstly, the relationship between compensation component Lf1 and output power was deduced by the lossless model, and the initial value of Lf1 was obtained. Then, considering the system loss, the designed output power and frequency were input into the frequency locking program, and Lf1 and other compensation parameters were dynamically tracked. At the same time, the transmission efficiency of the system was calculated, and the frequency that achieved maximum efficiency was automatically locked when the system met the requirements of the designed output power. Finally, based on the method, the output characteristics of the system were verified by experiments.

scholarly journals Studies on the transmission of sugar-beet yellows virus by the aphis, Myzus persicae (Sulz.)

1940 ◽  
Vol 128 (853) ◽  
pp. 535-552 ◽  
Keyword(s):  
Sugar Beet ◽  
Myzus Persicae ◽  
Plant Viruses ◽  
Insect Vectors ◽  
Source Of Infection ◽  
Persistent Viruses ◽  
Beet Yellows Virus ◽  
The Relationship

Previous studies on the relationship between plant viruses and their insect vectors have been carried out which viruses which are easily mechanically transmissible and whose vectors lose their infectivity within a few hours of removal from the source of infection. This type of virus has been called (Watson and Roberts 1939) non-persistent , for it was observed that the property in which viruses of this type resemble each other, and differ from those viruses whose vectors retain their infectivity for long periods, namely, the persistent viruses. It seems that these differences must lie in the nature of the viruses themselves, for viruses of both types can be transmitted by the same vector. Sugar-beet yellows virus (Petherbridge and Stirrup 1935) seems to be a member of the persistent class, for its vector, Myzus persicae , the same insect as was used in previous work on non-persistent viruses (Watson 1936, 1938; Watson and Roberts 1939), remains infective for several days after removal from the source of infection (Roland 1939). Also it is not transmissible mechanically by any of the usual methods (Quanjer 1934, 1936). The present paper, therefore, describes some studies on the vector-virus relationships of this virus by the methods which have been used previously only on the non-persistent types.

scholarly journals Modeling the Distribution Characteristics of Urban Public Bicycle Rental Duration

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Shuichao Zhang ◽  
Kangkang He ◽  
Sheng Dong ◽  
Jibiao Zhou
Keyword(s):  
Theoretical Model ◽  
Radioactive Decay ◽  
Distribution Characteristics ◽  
Theoretical Support ◽  
Study Results ◽  
Basic Parameters ◽  
The Relationship

In order to model the distribution characteristics of public bicycle rental durations, individual journey data for three cities in China (Ningbo, Hangzhou, and Beijing), for weekdays, was obtained. The distribution curves for public bicycle rental duration in the three cities were found to be extremely similar, with small differences among the weekdays. The basic parameters such as the average rental duration, the rental duration corresponding to the maximum rental frequency, and the rental duration corresponding to 75% degree were then calculated. On this basis, the radioactive decay law from physics was used to establish a theoretical model for the relationship between rental frequency and rental duration. The data on public bicycle rental duration in Ningbo, Hangzhou, and Beijing were used to test the model and produce a corrected theoretical model. The results indicate that the relationship between rental frequency and rental duration obeys the decay law. The study results provide important theoretical support for the rental station planning of bicycle sharing systems, as well as the allocation, operation, and dispatch of public bicycles.

Research on Transmission Efficiency of Cycloid Cam Speed Reducer

2011 ◽  
Vol 138-139 ◽  
pp. 310-314
Author(s):  
Jun Kai Yang ◽  
Yun Jie Xu
Keyword(s):  
Rotational Speed ◽  
Influence Factors ◽  
Dynamic Measurement ◽  
Transmission Efficiency ◽  
Working Process ◽  
Load Change ◽  
Speed Reducer ◽  
The Relationship

Cycloid cam speed reducer is a widely used transmission. In practice, there are many kinds influence factors which affect transmission efficiency of cycloid cam speed reducer. In this research, dynamic measurement of the transmission efficiency has carried out by experiment It mainly studies the relationship between speed, load change and transmission efficiency during cycloid cam speed reducer working process. Experiment results show that transmission efficiency of cycloid cam speed reducer could be improved by increasing the load, other methods can also use such as reducing the input rotational speed.

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