scholarly journals Root samples provide early and improved detection of Candidatus Liberibacter asiaticus in Citrus

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
W. Evan Braswell ◽  
Jong-Won Park ◽  
Philip A. Stansly ◽  
Barry Craig Kostyk ◽  
Eliezer S. Louzada ◽  
...  
Keyword(s):  
Control Strategies ◽  
Relative Effectiveness ◽  
Management Strategies ◽  
Probability Of Detection ◽  
Economic Consequences ◽  
Fibrous Root ◽  
Accurate Identification ◽  
Liberibacter Asiaticus ◽  
Effective Use ◽  
Detection Strategies

Abstract Huanglongbing (HLB), or Citrus Greening, is one of the most devastating diseases affecting agriculture today. Widespread throughout Citrus growing regions of the world, it has had severe economic consequences in all areas it has invaded. With no treatment available, management strategies focus on suppression and containment. Effective use of these costly control strategies relies on rapid and accurate identification of infected plants. Unfortunately, symptoms of the disease are slow to develop and indistinct from symptoms of other biotic/abiotic stressors. As a result, diagnosticians have focused on detecting the pathogen, Candidatus Liberibacter asiaticus, by DNA-based detection strategies utilizing leaf midribs for sampling. Recent work has shown that fibrous root decline occurs in HLB-affected trees before symptom development among leaves. Moreover, the pathogen, Ca. Liberibacter asiaticus, has been shown to be more evenly distributed within roots than within the canopy. Motivated by these observations, a longitudinal study of young asymptomatic trees was established to observe the spread of disease through time and test the relative effectiveness of leaf- and root-based detection strategies. Detection of the pathogen occurred earlier, more consistently, and more often in root samples than in leaf samples. Moreover, little influence of geography or host variety was found on the probability of detection.

The efficacy of monitoring techniques for detecting small mammals and reptiles in arid environments

2017 ◽  
Vol 44 (7) ◽  
pp. 534 ◽  
Author(s):  
J. Molyneux ◽  
C. R. Pavey ◽  
A. I. James ◽  
S. M. Carthew
Keyword(s):  
Small Mammals ◽  
Relative Effectiveness ◽  
Management Strategies ◽  
Probability Of Detection ◽  
Arid Zones ◽  
Arid Environments ◽  
Monitoring Techniques ◽  
Live Trapping ◽  
Sign Surveys ◽  
Over Time

Context Accurate surveying and monitoring of biodiversity provides essential baseline data for developing and implementing effective environmental management strategies. Land managers in arid zones face the challenge of managing vast, remote landscapes that support numerous cryptic species that are difficult to detect and monitor. Although researchers and land managers are using an increasingly wider variety of monitoring techniques to detect and monitor species, little is known of the relative effectiveness and comparative costs of these techniques. Aims The present study simultaneously assessed the efficacy of three popular monitoring techniques utilised in the spinifex sand plains of arid Australia, namely, live trapping, sign surveys and passive infrared (PIR)-camera trapping. Methods We explored variations in capture rates and species richness for each technique and compared initial and on-going costs of the techniques over time. Key results Sign surveys detected the greatest number of species and groups overall. Detectability of small mammals and reptiles, as a target group, was greater using PIR cameras, although the probability of detection by each technique varied among specific species. PIR cameras were initially the most expensive technique; however, the low ongoing costs of maintaining cameras in the field meant that they became the most cost effective after eight survey periods. Conclusions Each of the techniques tested here showed biases towards the detection of specific groups or species in the spinifex sand-plain habitat of Australia. Regardless, PIR cameras performed better at detecting the greatest diversity of target species and financially over time. Implications To accurately survey species across vast areas and climate variations, studies often extend over long time periods. Many long-term studies would be likely to benefit financially from the increased deployment of PIR cameras alongside or in place of live trapping surveys, with little impact on the ability to monitor the presence of most species in the region.

Chemosensory genes in the head of Spodoptera litura larvae

2021 ◽  
pp. 1-10
Author(s):  
Lu-Lu Li ◽  
Ji-Wei Xu ◽  
Wei-Chen Yao ◽  
Hui-Hui Yang ◽  
Youssef Dewer ◽  
...  
Keyword(s):  
Spodoptera Litura ◽  
Phylogenetic Trees ◽  
Target Genes ◽  
Control Strategies ◽  
Insect Pest ◽  
Management Strategies ◽  
Food Sources ◽  
Larval Feeding ◽  
Chemosensory System ◽  
Chemosensory Genes

Abstract The tobacco cutworm Spodoptera litura (Lepidoptera: Noctuidae) is a polyphagous pest with a highly selective and sensitive chemosensory system involved in complex physiological behaviors such as searching for food sources, feeding, courtship, and oviposition. However, effective management strategies for controlling the insect pest populations under threshold levels are lacking. Therefore, there is an urgent need to formulate eco-friendly pest control strategies based on the disruption of the insect chemosensory system. In this study, we identified 158 putative chemosensory genes based on transcriptomic and genomic data for S. litura, including 45 odorant-binding proteins (OBPs, nine were new), 23 chemosensory proteins (CSPs), 60 odorant receptors (ORs, three were new), and 30 gustatory receptors (GRs, three were new), a number higher than those reported by previous transcriptome studies. Subsequently, we constructed phylogenetic trees based on these genes in moths and analyzed the dynamic expression of various genes in head capsules across larval instars using quantitative real-time polymerase chain reaction. Nine genes–SlitOBP8, SlitOBP9, SlitOBP25, SlitCSP1, SlitCSP7, SlitCSP18, SlitOR34, SlitGR240, and SlitGR242–were highly expressed in the heads of 3- to 5-day-old S. litura larvae. The genes differentially expressed in olfactory organs during larval development might play crucial roles in the chemosensory system of S. litura larvae. Our findings substantially expand the gene inventory for S. litura and present potential target genes for further studies on larval feeding in S. litura.

Knowledge management strategies for sustaining Lesson Study

2019 ◽  
Vol 9 (2) ◽  
pp. 167-178
Author(s):  
Eric C.K. Cheng
Keyword(s):  
Information Technology ◽  
Knowledge Management ◽  
Hong Kong ◽  
Knowledge Sharing ◽  
Lesson Study ◽  
Structural Equation ◽  
Explicit Knowledge ◽  
Relative Effectiveness ◽  
Management Strategies ◽  
Content Type

Purpose The purpose of this paper is explore the relative effectiveness of people-based and information technology-based knowledge management (KM) strategies as implemented by principals in Hong Kong schools to facilitate and sustain Lesson Study for teachers’ knowledge sharing and internalization. Design/methodology/approach Data from 184 principals in Hong Kong were collected by a cross-sectional quantitative survey. Confirmatory factor analysis and reliability tests have been used to examine the constructed validity and reliability of the instrument. A structural equation model was applied to confirm the predictive effect of people-based and information technology-based KM strategies on teachers’ knowledge sharing and internalization through Lesson Study. Findings Results show that people-based KM strategy predicts knowledge sharing and internalization by and among teachers. However, while information technology-based knowledge management strategies predict teachers’ knowledge sharing, they do not predict how effectively they internalize knowledge. Practical implications Cultivating communities of practice, professional learning communities and mentoring schemes in schools can nurture a knowledge-sharing culture to facilitate and sustain Lesson Study for teacher learning. Institutionalizing an information technology system can help teachers to retrieve, share and store the school’s explicit knowledge. Originality/value The paper not only suggests school management strategies and practices for school leaders to facilitate and sustain Lesson Study, but also brings a new research dimension, KM, to the research area.

Differences in microhabitat selection patterns between a remnant and constructed landscape following management intervention

2017 ◽  
Vol 44 (3) ◽  
pp. 248 ◽  
Author(s):  
Jose W. Valdez ◽  
Kaya Klop-Toker ◽  
Michelle P. Stockwell ◽  
Loren Fardell ◽  
Simon Clulow ◽  
...  
Keyword(s):  
Aquatic Vegetation ◽  
Management Strategies ◽  
Probability Of Detection ◽  
Microhabitat Use ◽  
Microhabitat Selection ◽  
Habitat Creation ◽  
Litoria Aurea ◽  
Use Of Resources ◽  
Detection Probabilities ◽  
Future Management

Context Achieving successful conservation outcomes in habitat creation and reintroductions requires an understanding of how species use their habitat and respond to these interventions. However, few initiatives directly compare microhabitat selection between remnant and managed habitats to measure effectiveness and evaluate outcomes. Probability of detection is also rarely included in studies on microhabitat use, which may lead to erroneous conclusions if detectability varies between variables. Methods In this study, we used the endangered green and golden bell frog (Litoria aurea) to compare differences in microhabitat-use patterns in both a remnant and a constructed habitat. A detectability study was also conducted to determine detection probabilities among microhabitats. Key results Aquatic vegetation was used more than expected in both the remnant and constructed habitats, and rock piles were utilised less than expected in the constructed habitat, despite their recommendation in most habitat templates. We found that detection probabilities altered the outcomes of abundance estimates for nearly all the measured microhabitat variables. Conclusions Future management for this species should focus on providing high proportions of aquatic vegetation. Furthermore, although rock piles have been utilised greatly in past L. aurea habitat creation, placing large rocks on a managed site is expensive and time consuming. Future management initiatives may need to focus on providing smaller proportion of rocks, which would be a more appropriate use of resources. Implications With conservation management projects increasing over the next few decades, understanding habitat use before implementing strategies should be a priority as it will provide important insights and inform decision-making for optimum habitat creation and restoration. Furthermore, accounting for detectability in microhabitat use studies is essential to avoid wrong conclusions that may negatively affect the success of ecological management strategies.

scholarly journals Occurrence, Impact on Agriculture, Human Health, and Management Strategies of Zearalenone in Food and Feed: A Review

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 92
Author(s):  
Dipendra Kumar Mahato ◽  
Sheetal Devi ◽  
Shikha Pandhi ◽  
Bharti Sharma ◽  
Kamlesh Kumar Maurya ◽  
...  
Keyword(s):  
Human Health ◽  
Control Strategies ◽  
Management Strategies ◽  
Structural Similarity ◽  
Fungal Metabolites ◽  
Natural Estrogens ◽  
Food And Feed ◽  
Feed Safety ◽  
And Control ◽  
Different Sources

Mycotoxins represent an assorted range of secondary fungal metabolites that extensively occur in numerous food and feed ingredients at any stage during pre- and post-harvest conditions. Zearalenone (ZEN), a mycotoxin categorized as a xenoestrogen poses structural similarity with natural estrogens that enables its binding to the estrogen receptors leading to hormonal misbalance and numerous reproductive diseases. ZEN is mainly found in crops belonging to temperate regions, primarily in maize and other cereal crops that form an important part of various food and feed. Because of the significant adverse effects of ZEN on both human and animal, there is an alarming need for effective detection, mitigation, and management strategies to assure food and feed safety and security. The present review tends to provide an updated overview of the different sources, occurrence and biosynthetic mechanisms of ZEN in various food and feed. It also provides insight to its harmful effects on human health and agriculture along with its effective detection, management, and control strategies.

Intracellular life cycle of Candidatus Liberibacter asisticus inside psyllid gut cells

2021 ◽  
Author(s):  
Lin Chun-Yi ◽  
Diann Achor ◽  
Amit Levy
Keyword(s):  
Molecular Mechanisms ◽  
Management Strategies ◽  
Bacterial Invasion ◽  
Diaphorina Citri ◽  
Current Management ◽  
Insect Midgut ◽  
Rapid Spread ◽  
Candidatus Liberibacter ◽  
Infected Insect ◽  
Liberibacter Asiaticus

Candidatus Liberibacter asiaticus (CLas), the devastating pathogen related to Huanglongbing (HLB), is a phloem-limited, fastidious, insect-borne bacterium. Rapid spread of HLB disease relies on CLas propagates efficiently in its vector, the Asian citrus psyllid, Diaphorina citri, in a circulative manner. Understanding the intracellular lifecycle of CLas in psyllid midgut is fundamental to improve current management strategies. Using a microscopic approach within CLas-infected insect midgut, we observed the entry of CLas into gut cells inside vesicles by endocytosis, termed Liberibacter containing vacuoles (LCVs). Endocytosis is followed by the formation of endoplasmic reticulum-related and replication permissive vacuoles (rLCVs). rLCVs then further develop into bigger double membrane autophagosome-like structure, termed autophagy-related vacuole (aLCV). Vesicles, containing CLas egress from aLCV and fuse with the cell membrane. Immunolocalization studies showed that CLas employs endo/exocytosis-like mechanisms that mediates bacterial invasion and egress. Upregulation of autophagy-related genes indicated subversion of host autophagy by CLas in psyllid vector to promote infection. These results indicate that CLas interacts with host cellular machineries to undergo a multistage intracellular cycle through endocytic, secretory, autophagic and exocytic pathways via complex machineries. Potential tactics for HLB controlling can be made depending on further investigations on the knowledge of the molecular mechanisms of CLas intracellular cycle.

A new system configuration design and power management strategies for a multi-source hybrid truck

2018 ◽  
Vol 232 (8) ◽  
pp. 1053-1062 ◽  
Author(s):  
Zhenhe Li ◽  
Yanjun Huang ◽  
Hong Wang
Keyword(s):  
Fuel Consumption ◽  
Power Management ◽  
Hybrid System ◽  
Dynamic Models ◽  
Control Strategies ◽  
Management Strategies ◽  
Operating Conditions ◽  
System Structure ◽  
System Configuration ◽  
Power Management Strategy

In this article, a novel system configuration with multiple energy sources is proposed for a hybrid truck in order to reduce fuel consumption and overcome the drawbacks of using a single energy source. The energy-saving characteristics of the hybrid system can be displayed after analyzing its system structure and performances. In order to validate the advantages of this presented system, the dynamic models of the system components are established in a MATLAB/Simulink environment, and initial and improved power management strategies with rule-based algorithms are developed. Then, the hybrid system is simulated based on the models and control strategies over the urban dynamometer driving schedule driving cycle. The simulation results show that the fuel consumption employing the initial power management strategy is 12.49 L/100 km, and there is a significant decrease with around 13.6% based on the improved strategy. The results also verify that the better fuel economy can be achieved by the proposed multi-source system compared to the counterparts under the same operating conditions.

Probing the application of OmpA-derived peptides to disrupt the acquisition of ‘Candidatus Liberibacter asiaticus’ by Diaphorina citri

2021 ◽  
Author(s):  
Marcus Vinicius Merfa e Silva ◽  
Eduarda Regina Fischer ◽  
Mariana de Souza e Silva ◽  
Carolina Sardinha Francisco ◽  
Helvécio Coletta-Filho ◽  
...  
Keyword(s):  
Control Strategies ◽  
Insect Vector ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
In Planta ◽  
Host Interaction ◽  
Vector Population ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Bacterial Outer Membrane

Huanglongbing (HLB) is currently the most devastating disease of citrus worldwide. Both bacteria ‘Candidatus Liberibacter asiaticus’ (CLas) and ‘Ca. Liberibacter americanus’ (CLam) are associated with HLB in Brazil, but with a strong prevalence of CLas over CLam. Conventionally, HLB management focuses on controlling the insect vector population (Diaphorina citri; also known as Asian citrus psyllid – ACP) by spraying insecticides, an approach demonstrated to be mostly ineffective. Thus, development of novel more efficient HLB control strategies is required. The multifunctional bacterial outer membrane protein OmpA is involved in several molecular processes between bacteria and their hosts and has been suggested as a target for bacterial control. Curiously, OmpA is absent in CLam in comparison to CLas, suggesting a possible role on host-interaction. Therefore, in the current study, we have treated ACPs with different OmpA-derived peptides aiming to evaluate the acquisition of CLas by the insect vector. Treatment of psyllids with 5 µM of Pep1, Pep3, Pep5 and Pep6 in artificial diet significantly reduced the acquisition of CLas, while increasing the concentration of Pep5 and Pep6 to 50 µM abolished this process. In addition, in planta treatment with 50 µM of Pep6 also significantly decreased the acquisition of CLas and sweet orange plants stably absorbed and maintained this peptide for as long as three months post the final application. Together, our results demonstrate the promising use of OmpA-derived peptides as a novel biotechnological tool to control CLas.

Population diversity of “Candidatus Liberibacter asiaticus” and Diaphorina citri in Sichuan: A case study for Huanglongbing monitoring and interception

Plant Disease ◽  
2021 ◽  
Author(s):  
Xuejin Cui ◽  
Kehong Liu ◽  
Jie Huang ◽  
Shimin Fu ◽  
Qingdong Chen ◽  
...  
Keyword(s):  
Rural Areas ◽  
Urban Areas ◽  
Control Strategies ◽  
Population Diversity ◽  
Mitochondrial Genomes ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Multiple Sources ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus

Citrus Huanglongbing (HLB) is present in 10 provinces in China and is associated with “Candidatus Liberibacter asiaticus” (CLas), which is transmitted by the Asian citrus psyllid (Diaphorina citri, ACP). To date, HLB and ACP have expanded to Yibin city of Sichuan Province, posing an imminent threat to the citrus belt of upper and middle reach of Yangtze River, an important late maturing citrus-producing area in China. To understand the epidemiological route of CLas and ACP in newly invaded regions of Sichuan and thereby better establish an HLB-interception zone ranging from Leibo to Yibin, we evaluated the molecular variability of 19 CLas draft genomes from citrus or dodder (Cuscuta campestris). They include three type-specific prophage loci, three variable numbers of tandem repeat (VNTR) loci, a miniature inverted-repeat transposable element (MITE) types, and population diversity of 44 ACP mitochondrial genomes. The results indicated that CLas isolates in the newly invaded area (Pingshan) were more diverse than those in the HLB endemic areas (Leibo and Ningnan). Phylogenetic analysis based on mitochondrial genomes demonstrated that ACPs in Leibo, Pingshan and Xuzhou (rural areas) represent a new group (MG4), distinguished by the three unique SNPs in cox1, nad4 and cytb. However, the ACPs sampled from the urban areas of Cuiping and Xuzhou belonged to the southeastern China group (MG2-1). Altogether, our study revealed multiple sources of ACP and CLas in the HLB-interception zone and proposed their transmission route. This study contributes to the formulation of precise HLB prevention and control strategies in the HLB-interception zone in Sichuan and could be useful for HLB management efforts in other regions.

Nematodes.

2021 ◽  
pp. 270-284
Author(s):  
Regina M. D. G. Carneiro ◽  
Marcilene F. A. Santos ◽  
José Mauro C. Castro
Keyword(s):  
Life Cycle ◽  
Cover Crops ◽  
Control Strategies ◽  
Management Strategies ◽  
Genetic Resistance ◽  
Root Knot Nematodes ◽  
Meloidogyne Enterolobii ◽  
Host Status ◽  
Fruit Plants ◽  
Host Parasite

Abstract The following review of the nematodes from cultivated guava is limited to the major problem caused by M. enterolobii, its idenfication and its management strategies. The synonymization of Meloidogyne enterolobii with Meloidogyne mayaguensis and the different methods of identifying Meloidogyne species are discussed. The life cycle, host-parasite relationships, symptoms, damage and dissemination of M. enterolobii are described. The host status of cover crops, maize and fruit plants for M. enterolobii is discussed, as well as the resistance in Psidium spp. to root-knot nematodes. New prospects using genetic resistance in Brazil and some control strategies that can be used in an integrated way are presented.

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