scholarly journals Physiological and ecological warnings that dodders pose an exigent threat to farmlands in Eastern Africa

2021 ◽  
Author(s):  
Joel Masanga ◽  
Beatrice Njoki Mwangi ◽  
Willy Kibet ◽  
Philip Sagero ◽  
Mark Wamalwa ◽  
...  
Keyword(s):  
Host Range ◽  
Mangifera Indica ◽  
Management Strategies ◽  
Eastern Africa ◽  
Distribution Models ◽  
Resistance Response ◽  
Research Attention ◽  
Cuscuta Reflexa ◽  
Host Growth ◽  
Rapid Spread

Abstract Invasive holoparasitic plants of the genus Cuscuta (dodder) threaten African ecosystems due to their rapid spread and attack on various host plant species. Most Cuscuta species cannot photosynthesize and hence rely on host plants for nourishment. After attachment through a peg-like organ called a haustorium, the parasites deprive hosts of water and nutrients, which negatively affects host growth and development. Despite their rapid spread in Africa, dodders have attracted limited research attention, although data on their taxonomy, host range, and epidemiology are critical for their management. Here, we combine taxonomy and phylogenetics to reveal the presence of field dodder (Cuscuta campestris) and Cuscuta kilimanjari (both either naturalized or endemic to East Africa), in addition to the introduction of the giant dodder (Cuscuta reflexa), a south Asian species, in continental Africa. These parasites have a wide host range, parasitizing species across 13 angiosperm orders. We evaluated the possibility of C. reflexa to expand this host range to tea (Camelia sinensis), coffee (Coffea arabica), and mango (Mangifera indica), crops of economic importance to Africa, for which haustorial formation and vascular-bundle connections in all three crops revealed successful parasitism. However, only mango mounted a successful post-attachment resistance response. Furthermore, species distribution models predicted high habitat suitability for Cuscuta spp. across major tea- and coffee-growing regions of Eastern Africa, suggesting an imminent risk to these crops. Our findings provide relevant insights into a poorly understood threat to biodiversity and economic wellbeing in Eastern Africa, and provide critical information to guide development of management strategies to avert Cuscuta spp. spread.

scholarly journals Physiological and ecological warnings that Dodder pose an exigent threat to farmlands in Eastern Africa

2020 ◽  
Author(s):  
Joel Masanga ◽  
Beatrice Njoki Mwangi ◽  
Willy Kibet ◽  
Philip Sagero ◽  
Mark Wamalwa ◽  
...  
Keyword(s):  
Host Range ◽  
Habitat Suitability ◽  
Management Strategies ◽  
Eastern Africa ◽  
Distribution Models ◽  
Resistance Response ◽  
Research Attention ◽  
Habitat Suitability Modeling ◽  
Rapid Spread ◽  
First Time

AbstractInvasive holoparasitic plants of the genus Cuscuta (dodder) threaten Africa’s ecosystems, due to their rapid spread and attack on various host plant species. Most Cuscuta species cannot photosynthesize, hence rely on host plants for nourishment. After attachment through a peg-like organ called a haustorium, the parasites deprive hosts of water and nutrients leading to their death. Despite their rapid spread in Africa, dodders have attracted limited research attention, although data on their taxonomy, host range and epidemiology are critical for their management. Here, we combine taxonomy and phylogenetics to reveal presence of field dodder (Cuscuta campestris) and C. kilimanjari (both either naturalized or endemic to East Africa), and for the first time in continental Africa, presence of the giant dodder (C. reflexa) a south Asian species. These parasites have a wide host range, parasitizing species across 13 angiosperm orders. Evaluating the possibility of C. reflexa to expand this host range to tea, coffee, and mango, crops of economic importance to Africa, revealed successful parasitism, following haustorial formation and vascular bundle connections in all three crops. However, only mango mounted a successful post-attachment resistance response. Furthermore, species distribution models predicted high habitat suitability for all three Cuscuta species across major tea- and coffee-growing regions of Eastern Africa, suggesting an imminent risk to these crops. Our findings provide relevant insights into a little-understood threat to biodiversity and economic wellbeing in Eastern Africa, and providing critical information to guide development of management strategies to avert their spread.Sentence SummaryMicroscopy and habitat suitability modeling provide an early warning that dodder’s invasion in Eastern Africa poses a threat to important cash crops

scholarly journals ε2-Phages Are Naturally Bred and Have a Vastly Improved Host Range in Staphylococcus aureus over Wild Type Phages

2021 ◽  
Vol 14 (4) ◽  
pp. 325
Author(s):  
David Sáez Moreno ◽  
Zehra Visram ◽  
Michele Mutti ◽  
Marcela Restrepo-Córdoba ◽  
Susana Hartmann ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Detection Limit ◽  
Host Range ◽  
Alternative Treatment ◽  
Standard Of Care ◽  
Wild Type ◽  
Rapid Spread ◽  
Pharmaceutical Properties ◽  
Human Infections

Due to the rapid spread of antibiotic resistance, and the difficulties of treating biofilm-associated infections, alternative treatments for S. aureus infections are urgently needed. We tested the lytic activity of several wild type phages against a panel of 110 S. aureus strains (MRSA/MSSA) composed to reflect the prevalence of S. aureus clonal complexes in human infections. The plaquing host ranges (PHR) of the wild type phages were in the range of 51% to 60%. We also measured what we called the kinetic host range (KHR), i.e., the percentage of strains for which growth in suspension was suppressed for 24 h. The KHR of the wild type phages ranged from 2% to 49%, substantially lower than the PHRs. To improve the KHR and other key pharmaceutical properties, we bred the phages by mixing and propagating cocktails on a subset of S. aureus strains. These bred phages, which we termed evolution-squared (ε2) phages, have broader KHRs up to 64% and increased virulence compared to the ancestors. The ε2-phages with the broadest KHR have genomes intercrossed from up to three different ancestors. We composed a cocktail of three ε2-phages with an overall KHR of 92% and PHR of 96% on 110 S. aureus strains and called it PM-399. PM-399 has a lower propensity to resistance formation than the standard of care antibiotics vancomycin, rifampicin, or their combination, and no resistance was observed in laboratory settings (detection limit: 1 cell in 1011). In summary, ε2-phages and, in particular PM-399, are promising candidates for an alternative treatment of S. aureus infections.

Species composition and host range of fruit-infesting flies (Diptera: Tephritidae) in northern Ghana

2015 ◽  
Vol 35 (03) ◽  
pp. 137-151 ◽  
Author(s):  
K.B. Badii ◽  
M.K. Billah ◽  
K. Afreh-Nuamah ◽  
D. Obeng-Ofori
Keyword(s):  
Host Range ◽  
Plant Species ◽  
Host Plants ◽  
Management Strategies ◽  
Fruit Fly ◽  
Fruit Flies ◽  
Northern Ghana ◽  
Accurate Information ◽  
Wild Host ◽  
Fruit Samples

An important aspect of fruit fly management is accurate information on the species and their host spectrum. Studies were conducted between October 2011 and September 2013 to determine the host range and species diversity of pest fruit flies in the northern savannah ecology of Ghana. Fruit samples from 80 potential host plants (wild and cultivated) were collected and incubated for fly emergence; 65 (81.5%) of the plant species were positive to fruit flies. From records in Africa, 11 plant species were reported to be new hosts to the African invader fly,Bactrocera invadens(Drew, Tsuruta and White, 2005). This study documented the first records ofDacus ciliatus(Loew) andTrirhithrum nigerrimum(Bezzi) in northern Ghana although both species have been previously reported in other parts of the country. Infestation byB. invadenswas higher in the cultivated fruits;Ceratitis cosyradominated in most wild fruits. Cucurbitaceae were mainly infested by three species ofDacusandBactroceracucurbitae, a specialized cucurbit feeder. Among the commercial fruit species, the highest infestations were observed in mango, tomato, sweet pepper and watermelon, whereas marula plum, soursop, tropical almond, sycamore fig, African peach, shea nut, persimmon, icacina and albarillo dominated the wild host flora. The widespread availability of host plants and the incidence of diverse fly species in the ecology call for particular attention to their impact on commercial fruits and the development of sustainable management strategies against these economically important pests in Ghana.

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.

scholarly journals Characterization of SARS-CoV-2 variants B.1.617.1 (Kappa), B.1.617.2 (Delta) and B.1.618 on cell entry, host range, and sensitivity to convalescent plasma and ACE2 decoy receptor

2021 ◽  
Author(s):  
Wenlin Ren ◽  
Xiaohui Ju ◽  
Mingli Gong ◽  
Jun Lan ◽  
Yanying Yu ◽  
...  
Keyword(s):  
Host Range ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Cell Entry ◽  
Decoy Receptor ◽  
Host Tropism ◽  
Entry Inhibitors ◽  
Rapid Spread ◽  
Entry Efficiency

ABSTRACTRecently, highly transmissible SARS-CoV-2 variants B.1.617.1 (Kappa), B.1.617.2 (Delta) and B.1.618 were identified in India with mutations within the spike proteins. The spike protein of Kappa contains four mutations E154K, L452R, E484Q and P681R, and Delta contains L452R, T478K and P681R, while B.1.618 spike harbors mutations Δ145-146 and E484K. However, it remains unknown whether these variants have altered in their entry efficiency, host tropism, and sensitivity to neutralizing antibodies as well as entry inhibitors. In this study, we found that Kappa, Delta or B.1.618 spike uses human ACE2 with no or slightly increased efficiency, while gains a significantly increased binding affinity with mouse, marmoset and koala ACE2 orthologs, which exhibits limited binding with WT spike. Furthermore, the P618R mutation leads to enhanced spike cleavage, which could facilitate viral entry. In addition, Kappa, Delta and B.1.618 exhibits a reduced sensitivity to neutralization by convalescent sera owning to the mutation of E484Q, T478K, Δ145-146 or E484K, but remains sensitive to entry inhibitors-ACE2-lg decoy receptor. Collectively, our study revealed that enhanced human and mouse ACE2 receptor engagement, increased spike cleavage and reduced sensitivity to neutralization antibodies of Kappa, Delta and B.1.618 may contribute to the rapid spread of these variants and expanded host range. Furthermore, our result also highlighted that ACE2-lg could be developed as broad-spectrum antiviral strategy against SARS-CoV-2 variants.

scholarly journals Isolation of the Novel Phage PHB09 and Its Potential Use against the Plant Pathogen Pseudomonas syringae pv. actinidiae

Viruses ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2275
Author(s):  
Yanxi Liu ◽  
Mengjiao Liu ◽  
Ran Hu ◽  
Jun Bai ◽  
Xiaoqing He ◽  
...  
Keyword(s):  
Host Range ◽  
Pseudomonas Syringae ◽  
Management Strategies ◽  
Lytic Bacteriophage ◽  
Bacterial Canker ◽  
Isolation And Identification ◽  
Narrow Host Range ◽  
Development Of Resistance ◽  
Wide Range ◽  
Complete Genome Sequence Analysis

Bacteriophages are viruses that specifically infect target bacteria. Recently, bacteriophages have been considered potential biological control agents for bacterial pathogens due to their host specificity. Pseudomonas syringae pv. actinidiae (Psa) is a reemerging pathogen that causes bacterial canker of kiwifruit (Actinidia sp.). The economic impact of this pest and the development of resistance to antibiotics and copper sprays in Psa and other pathovars have led to investigation of alternative management strategies. Phage therapy may be a useful alternative to conventional treatments for controlling Psa infections. Although the efficacy of bacteriophage φ6 was evaluated for the control of Psa, the characteristics of other DNA bacteriophages infecting Psa remain unclear. In this study, the PHB09 lytic bacteriophage specific to Psa was isolated from kiwifruit orchard soil. Extensive host range testing using Psa isolated from kiwifruit orchards and other Pseudomonas strains showed PHB09 has a narrow host range. It remained stable over a wide range of temperatures (4–50 °C) and pH values (pH 3–11) and maintained stability for 50 min under ultraviolet irradiation. Complete genome sequence analysis indicated PHB09 might belong to a new myovirus genus in Caudoviricetes. Its genome contains a total of 94,844 bp and 186 predicted genes associated with phage structure, packaging, host lysis, DNA manipulation, transcription, and additional functions. The isolation and identification of PHB09 enrich the research on Pseudomonas phages and provide a promising biocontrol agent against kiwifruit bacterial canker.

scholarly journals Genetic and Ecological Relationships of Anastrepha ludens (Diptera: Tephritidae) Populations in Southern Mexico

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 815
Author(s):  
Lorena Ruiz-Montoya ◽  
Rodrigo Verónica Vallejo ◽  
David Haymer ◽  
Pablo Liedo
Keyword(s):  
Sexual Selection ◽  
Genetic Differentiation ◽  
Host Plants ◽  
Control Strategies ◽  
Mangifera Indica ◽  
Random Mating ◽  
Management Strategies ◽  
Fruit Fly ◽  
Anastrepha Ludens ◽  
Southern Mexico

Knowledge of the influence of evolutionary factors that promote either the differentiation or cohesion of pest insect populations is critical for the improvement of control strategies. Here, we explore the extent to which genetic differentiation occurs between populations of the Mexican fruit fly, Anastrepha ludens, in association with four plant hosts (Citrus sinensis, C. paradisi, Mangifera indica and Casimiroa edulis) in the Soconusco region of Chiapas (Mexico). Using variants from six enzymatic loci, we obtained measures of genetic diversity for three sample arrangements: (1) by sex per locality, (2) by locality and (3) by host. The extent of genetic differentiation in populations was assessed using the Analyses of Molecular Variance (AMOVA) method for each array of samples, and moderate to high levels of genetic variation were observed between the sexes, as well as among localities and host plants. A Bayesian approach was then used to assess any population structure underlying the genetic data we obtained, but this analysis showed no significant structuring due to locality or host plant. We also considered whether the observed genotypic frequencies in male and females matched those expected under a hypothesis of random mating. Here we found significant deviations from expected genotypic frequencies, suggesting that sexual selection is acting on these populations. Overall, our results indicate that sexual selection, along with the presence of some heterogeneity in environments provided by both geographical factors and availability of host plants, has influenced the evolution of pest populations in this region of Mexico. Implications for area-wide pest management strategies are discussed.

scholarly journals The Establishment and Rapid Spread of Sagittaria Platyphylla in South Africa

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1472
Author(s):  
Mpilonhle S. Ndlovu ◽  
Julie A. Coetzee ◽  
Menzi M. Nxumalo ◽  
Reshnee Lalla ◽  
Ntombifuthi Shabalala ◽  
...  
Keyword(s):  
South Africa ◽  
Aquatic Macrophyte ◽  
Management Strategies ◽  
Control Measures ◽  
Invasive Weed ◽  
Mechanical Control ◽  
Potential Control ◽  
Control Option ◽  
Rapid Spread ◽  
Lotic System

Sagittaria platyphylla Engelm. (Alismataceae) is a freshwater aquatic macrophyte that has become an important invasive weed in freshwater systems in South Africa, New Zealand, Australia, and recently China. In South Africa, due to its rapid increase in distribution and ineffective control options, it is recognised as one of the country’s worst invasive aquatic alien plants. In this paper, we investigate the spread of the plant since its first detection in 2008, and the management strategies currently carried out against it. Despite early detection and rapid response programmes, which included chemical and mechanical control measures, the plant was able to spread both within and between sites, increasing from just one site in 2008 to 72 by 2019. Once introduced into a lotic system, the plant was able to spread rapidly, in some cases up to 120 km within 6 years, with an average of 10 km per year. The plant was successfully extirpated at some sites, however, due to the failure of chemical and mechanical control, biological control is currently being considered as a potential control option.

scholarly journals Impact of Fungal Endophyte Colonization of Maize (Zea mays L.) on Induced Resistance to Thrips- and Aphid-Transmitted Viruses

Plants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 416 ◽  
Author(s):  
Simon Kiarie ◽  
Johnson O. Nyasani ◽  
Linnet S. Gohole ◽  
Nguya K. Maniania ◽  
Sevgan Subramanian
Keyword(s):  
Integrated Management ◽  
Management Strategies ◽  
Fungal Endophyte ◽  
Eastern Africa ◽  
Maize Seeds ◽  
Fungal Isolates ◽  
Chlorotic Mottle Virus ◽  
Maize Chlorotic Mottle Virus ◽  
Chlorotic Mottle ◽  
Maize Plants

In eastern Africa, Maize lethal necrosis (MLN) is caused by the co-infection of maize plants with Maize chlorotic mottle virus (MCMV) (Tombusviridae: Machlomovirus) and Sugarcane mosaic virus (SCMV) (Potyviridae: Potyvirus). With the disease being new to Africa, minimal effective management strategies exist against it. This study examined the potential of 10 fungal isolates to colonize maize plants and induce resistance against MCMV and SCMV. Maize seeds were soaked in fungal inoculum, sown and evaluated for endophytic colonization. Fungus-treated plants were challenge-inoculated with SCMV and/or MCMV to assess the effects of fungal isolates on the viruses in terms of incidence, severity and virus titers over time. Isolates of Trichoderma harzianum, Trichoderma atroviride and Hypocrea lixii colonized different plant sections. All plants singly or dually-inoculated with SCMV and MCMV tested positive for the viruses by reverse transcription-polymerase chain reaction (RT-PCR). Maize plants inoculated by T. harzianum and Metarhizium. anisopliae resulted in up to 1.4 and 2.7-fold reduced SCMV severity and titer levels, respectively, over the controls but had no significant effect on MCMV. The results show that both T. harzianum and M. anisopliae are potential candidates for inducing resistance against SCMV and can be used for the integrated management of MLN.

scholarly journals Predicting future invaders and future invasions

2019 ◽  
Vol 116 (16) ◽  
pp. 7905-7910 ◽  
Author(s):  
Alice Fournier ◽  
Caterina Penone ◽  
Maria Grazia Pennino ◽  
Franck Courchamp
Keyword(s):  
Papua New Guinea ◽  
Ecosystem Functioning ◽  
Species Distribution Models ◽  
Invasive Alien Species ◽  
Management Strategies ◽  
Central Africa ◽  
Invasive Ants ◽  
Distribution Models ◽  
Proactive Management ◽  
Local Extinctions

Invasive alien species are a great threat to biodiversity and human livelihoods worldwide. The most effective way to limit their impacts and costs is to prevent their introduction into new areas. Identifying invaders and invasions before their occurrence would arguably be the most efficient strategy. Here, we provide a profiling method to predict which species—with which particular ecological characteristics—will invade, and where they could invade. We illustrate our approach with ants, which are among the most detrimental invasive species, as they are responsible for declines of numerous taxa, are involved in local extinctions, disturb ecosystem functioning, and impact multiple human activities. Based on statistical profiling of 1,002 ant species from an extensive trait database, we identify 13 native ant species with an ecological profile that matches that of known invasive ants. Even though they are not currently described as such, these species are likely to become the next global invaders. We couple these predictions with species distribution models to identify the regions most at risk from the invasion of these species: Florida and Central America, Brazil, Central Africa and Madagascar, Southeast Asia, Papua New Guinea Northeast Australia, and many islands worldwide. This framework, applicable to any other taxa, represents a remarkable opportunity to implement timely and specifically shaped proactive management strategies against biological invasions.

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