scholarly journals Meta-Analysis Suggests Differing Indirect Effects of Viral, Bacterial, and Fungal Plant Pathogens on the Natural Enemies of Insect Herbivores

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 765
Author(s):  
Ussawit Srisakrapikoop ◽  
Tara J. Pirie ◽  
Mark D. E. Fellowes
Keyword(s):  
Natural Enemies ◽  
Indirect Effects ◽  
Plant Pathogens ◽  
Meta Analysis ◽  
Trophic Levels ◽  
Plant Diseases ◽  
Plant Quality ◽  
Insect Herbivore ◽  
Insect Herbivores ◽  
Fungal Plant Pathogens

Indirect effects are ubiquitous in nature, and have received much attention in terrestrial plant–insect herbivore–enemy systems. In such tritrophic systems, changes in plant quality can have consequential effects on the behavior and abundance of insect predators and parasitoids. Plant quality as perceived by insect herbivores may vary for a range of reasons, including because of infection by plant pathogens. However, plant diseases vary in their origin (viral, bacterial or fungal) and as a result may have differing effects on plant physiology. To investigate if the main groups of plant pathogens differ in their indirect effects on higher trophic levels, we performed a meta-analysis using 216 measured responses from 29 primary studies. There was no overall effect of plant pathogens on natural enemy traits as differences between pathogen types masked their effects. Infection by fungal plant pathogens showed indirect negative effects on the performance and preference of natural enemies via both chewing and piercing-sucking insect herbivore feeding guilds. Infection by bacterial plant pathogens had a positive effect on the natural enemies (parasitoids) of chewing herbivores. Infection by viral plant pathogens showed no clear effect, although parasitoid preference may be positively affected by their presence. It is important to note that given the limited volume of studies to date on such systems, this work should be considered exploratory. Plant pathogens are very common in nature, and tritrophic systems provide an elegant means to examine the consequences of indirect interactions in ecology. We suggest that further studies examining how plant pathogens affect higher trophic levels would be of considerable value.

scholarly journals Molecular diagnostics of bacterial and fungal plant diseases

2020 ◽  
Author(s):  
A. V. Sidarenka ◽  
H. A. Bareika ◽  
L. N. Valentovich ◽  
D. S. Paturemski ◽  
V. N. Kuptsou ◽  
...  
Keyword(s):  
Molecular Diagnostics ◽  
Plant Material ◽  
Plant Pathogens ◽  
Dna Isolation ◽  
Plant Diseases ◽  
Specific Primers ◽  
Fungal Plant Pathogens ◽  
Pcr Conditions ◽  
Soil And Water

Taxon-specific primers were developed and PCR conditions were optimized for diagnostics of bacterial and fungal plant pathogens. Methods for phytopathogens DNA isolation from plant material, soil and water were selected.

scholarly journals Enemies mediate distance- and density-dependent mortality of tree seeds and seedlings: a meta-analysis of fungicide, insecticide and exclosure studies

2021 ◽  
Vol 288 (1943) ◽  
pp. 20202352
Author(s):  
Xiaoyang Song ◽  
Richard T. Corlett
Keyword(s):  
Density Dependence ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Plant Pathogens ◽  
Meta Analysis ◽  
Seedling Stage ◽  
Forest Community ◽  
Density Dependent ◽  
Density Dependent Mortality ◽  
Dependent Mortality

Conspecific negative distance- and density-dependence is often assumed to be one of the most important mechanisms controlling forest community assembly and species diversity globally. Plant pathogens, and insect and mammalian herbivores, are the most common natural enemy types that have been implicated in this phenomenon, but their general effects at different plant life stages are still unclear. Here, we conduct a meta-analysis of studies that involved robust manipulative experiments, using fungicides, insecticides and exclosures, to assess the contributions of different natural enemy types to distance- and density-dependent effects at seed and seedling stages. We found that distance- and density-dependent mortality caused by natural enemies was most likely at the seedling stage and was greater at higher mean annual temperatures. Conspecific negative distance- and density-dependence at the seedling stage is significantly weakened when fungicides were applied. By contrast, negative conspecific distance- and density-dependence is not a general pattern at the seed stage. High seed mass reduced distance- and density-dependent mortality at the seed stage. Seed studies excluding only large mammals found significant negative conspecific distance-dependent mortality, but exclusion of all mammals resulted in a non-significant effect of conspecifics. Our study suggests that plant pathogens are a major cause of distance- and density-dependent mortality at the seedling stage, while the impacts of herbivores on seedlings have been understudied. At the seed stage, large and small mammals, respectively, weaken and enhance negative conspecific distance-dependent mortality. Future research should identify specific agents of mortality, investigate the interactions among different enemy types and assess how global change may affect natural enemies and thus influence the strength of conspecific distance- and density-dependence.

scholarly journals Effect of Potassium Bicarbonate (MilStop®) and Insecticides on the Citrus Mealybug, Planococcus citri (Risso), and the Natural Enemies Leptomastix dactylopii (Howard) and Cryptolaemus montrouzieri (Mulsant)

HortScience ◽  
2013 ◽  
Vol 48 (12) ◽  
pp. 1513-1517 ◽  
Author(s):  
Brian K. Hogendorp ◽  
Raymond A. Cloyd
Keyword(s):  
Natural Enemies ◽  
Plant Pathogens ◽  
Application Rate ◽  
Potassium Bicarbonate ◽  
Planococcus Citri ◽  
Cryptolaemus Montrouzieri ◽  
Citrus Mealybug ◽  
Fungal Plant Pathogens ◽  
Percent Mortality ◽  
Leptomastix Dactylopii

Both laboratory and greenhouse experiments were conducted to determine if the fungicide, MilStop® (BioWorks, Victor, NY), which contains the active ingredient, potassium bicarbonate, has direct activity on the citrus mealybug, Planococcus citri Risso. Spray applications of four different rates (4.5, 5.9, 7.4, and 14.9 g·L–1) were applied to green coleus, Solenostemon scutellarioides (L.) Codd., plants infested with citrus mealybugs. In addition, experiments were conducted to assess both the direct and indirect effects of MilStop® on two natural enemies of the citrus mealybug: the parasitoid, Leptomastix dactylopii (Howard), and the coccinellid beetle, Cryptolaemus montrouzieri (Mulsant). MilStop® provided between 56% and 86% mortality of citrus mealybug; however, the highest rate (14.9 g·L–1) was phytotoxic to coleus plants. Percent mortality associated with the second highest rate (7.4 g·L–1) was 82%, which was comparable to acetamiprid (84%) applied at 0.05 g·L–1. For the natural enemies, MilStop® treatment rates of 1.5 and 3.5 g·L–1 resulted in 16% mortality, whereas the 5.5- and 9.0-g·L–1 rates resulted in 33% mortality of L. dactylopii adults. MilStop® treatment rates of 3.5, 5.5, 9.0, and 12.0 g·L–1 resulted in 30%, 60%, 40%, and 90% mortality, respectively, of C. montrouzieri adults. Therefore, depending on the application rate, this fungicide may inadvertently kill citrus mealybugs when used to control fungal plant pathogens. It should not disrupt biological control programs targeting citrus mealybug in greenhouses that involve releases of L. dactylopii when used at low application rates, whereas MilStop® applications should be properly timed when using C. montrouzieri.

Advances in screening approaches for the development of microbial bioprotectants to control plant diseases

2021 ◽  
pp. 33-86
Author(s):  
Wagner Bettiol ◽  
◽  
Flávio Henrique Vasconcelos de Medeiros ◽  
Josiane Barros Chiaramonte ◽  
Rodrigo Mendes ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Plant Protection ◽  
Control Plant ◽  
Control Programme ◽  
Plant Diseases ◽  
Advantages And Disadvantages ◽  
Fungal Plant Pathogens ◽  
Soil Rhizosphere ◽  
Selection Of ◽  
Screening Approaches

The success of a biological control programme depends on the isolation and selection of antagonists. There is an enormous diversity of culturable microbial species in the soil, rhizosphere, phylloplane, spermosphere and carposphere, which can be used in the isolation and selection of antagonists. The structures of fungal plant pathogens concerned with survival and infection may also be sources of antagonists. Although non-culturable microorganisms and microbiome-based strategies have great potential for development as commercial products in disease control, more knowledge is needed to understand the mechanisms involved in interactions between plants and complex microbial communities. Methods of isolation and selection of the most commercially exploited groups of antagonists and their advantages and disadvantages are discussed in this chapter as well as those of non-traditional antagonists. Finally, possible strategies for engineering the soil and host microbiome to actively promote plant protection against pathogens are discussed.

scholarly journals Microbiomes and Pathogen Survival in Crop Residues, an Ecotone Between Plant and Soil

2019 ◽  
Vol 3 (4) ◽  
pp. 246-255 ◽  
Author(s):  
Lydie Kerdraon ◽  
Valérie Laval ◽  
Frédéric Suffert
Keyword(s):  
Disease Management ◽  
Microbial Communities ◽  
Plant Pathogens ◽  
Crop Residues ◽  
Abiotic Factors ◽  
Plant Diseases ◽  
Negative Contribution ◽  
Positive Effects ◽  
Fungal Plant Pathogens ◽  
The Impact

The negative contribution of crop residues as a source of inoculum for plant diseases is well established. However, microbial ecologists have long reported positive effects of residues on the stability of agrosystems and conservation tillage practices have become increasingly widespread. Most studies have suggested that large microbial communities should be taken into account in plant disease management, but we know little about their ecological interaction with pathogens in the crop residue compartment. This review focuses on microbiomes associated with residues within the context of other microbial habitats in cereal-producing agroecosystems such as phyllosphere or rhizosphere. We connected residue microbiome with the survival of residue-borne fungal plant pathogens, thus combining knowledge in microbial ecology and epidemiology, two disciplines still not sufficiently connected. We provide an overview of the impact of residues on cereal disease epidemics and how dynamic interactions between microbial communities of nonburied residues during their degradation, along with soil and multitude of abiotic factors, can contribute to innovative disease management strategies, including next-generation microbiome-based biocontrol strategies. Starting from the classical but still relevant view of crop residues as a source of pathogen inoculum, we first consider possibilities for limiting the amount of residues on the soil surface to reduce the pathogen pressure. We then describe residues as a transient half-plant/half-soil compartment constituting a key fully fledged microbial ecosystem: in other words, an ecotone which deserves special attention. We focus on microbial communities, the changes in these communities over time and the factors influencing them. Finally, we discuss how the interactions between the microbial communities and the pathogens present on residues could be used: identification of keystone taxa and beneficial assemblages, then preservation of these taxa by adapted agronomic practices or development of synthetic communities, rather than the introduction of a single exogenous biocontrol species designed as a treatment product. [Formula: see text] Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals Genomic Instability in Fungal Plant Pathogens

Genes ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 421 ◽  
Author(s):  
Shay Covo
Keyword(s):  
Chromosomal Aberrations ◽  
Plant Pathogens ◽  
Gene Copy Number ◽  
Copy Number Variations ◽  
Plant Diseases ◽  
Gene Copy ◽  
Modern Agriculture ◽  
Fungal Plant Pathogens ◽  
Conserved Genes ◽  
Dna Replication Stress

Fungi and fungal-like organisms (oomycetes) that cause diseases in plants have impacted human communities for centuries and probably from the dawn of agriculture. In modern agriculture, there is a constant race between new strategies to manage fungal plant pathogens and their ability to adapt. An important component in this race is fungal genetic diversity. Mechanisms such as sexual and parasexual recombination that contribute to the creation of novel allele combinations in fungal plant pathogens are briefly discussed in the first part of this review. Advances in genomics have enabled the investigation of chromosomal aberrations of agriculturally important fungal isolates at the nucleotide level. Some of these cases are summarized in the second part of this review; it is claimed that the effect of chromosomal aberrations on pathogenicity should be studied mechanistically. More data on the effect of gene copy number variations on phenotypes that are relevant to agriculture are especially needed. Genome rearrangements through translocations have shaped the genome of fungal plant pathogens by creating lineage-specific chromosome territories encoding for genes participating in plant diseases. Pathogenicity chromosomes are unique cases of such lineage-specific genetic elements, interestingly these chromosomes can be transferred horizontally and thus transforming a non-pathogenic strain to a pathogenic one. The third part of this review describes our attempts to reveal mutators in fungal plant pathogens by identifying fungi that lack important DNA repair genes or respond to DNA damage in an unconventional way. We found that a group of fungal plant pathogens lack conserved genes that are needed for an important Holliday junction resolution pathway. In addition, in Fusarium oxysporum, the rate-limiting step in dNTP production is not induced under DNA replication stress. This is very different from organisms from bacteria to humans. It remains to be seen if these mechanisms promote genetic instability in fungal plant pathogens.

scholarly journals Importance of Molecular Data to Identify Fungal Plant Pathogens and Guidelines for Pathogenicity Testing Based on Koch’s Postulates

Pathogens ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1096
Author(s):  
Chitrabhanu S. Bhunjun ◽  
Alan J. L. Phillips ◽  
Ruvishika S. Jayawardena ◽  
Itthayakorn Promputtha ◽  
Kevin D. Hyde
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Molecular Data ◽  
Plant Diseases ◽  
Koch’S Postulates ◽  
Disease Symptoms ◽  
Fungal Plant Pathogens ◽  
Bradford Hill ◽  
Pathogenicity Testing ◽  
Koch's Postulates

Fungi are an essential component of any ecosystem, but they can also cause mild and severe plant diseases. Plant diseases are caused by a wide array of fungal groups that affect a diverse range of hosts with different tissue specificities. Fungi were previously named based only on morphology and, in many cases, host association, which has led to superfluous species names and synonyms. Morphology-based identification represents an important method for genus level identification and molecular data are important to accurately identify species. Accurate identification of fungal pathogens is vital as the scientific name links the knowledge concerning a species including the biology, host range, distribution, and potential risk of the pathogen, which are vital for effective control measures. Thus, in the modern era, a polyphasic approach is recommended when identifying fungal pathogens. It is also important to determine if the organism is capable of causing host damage, which usually relies on the application of Koch’s postulates for fungal plant pathogens. The importance and the challenges of applying Koch’s postulates are discussed. Bradford Hill criteria, which are generally used in establishing the cause of human disease, are briefly introduced. We provide guidelines for pathogenicity testing based on the implementation of modified Koch’s postulates incorporating biological gradient, consistency, and plausibility criteria from Bradford Hill. We provide a set of protocols for fungal pathogenicity testing along with a severity score guide, which takes into consideration the depth of lesions. The application of a standard protocol for fungal pathogenicity testing and disease assessment in plants will enable inter-studies comparison, thus improving accuracy. When introducing novel plant pathogenic fungal species without proving the taxon is the causal agent using Koch’s postulates, we advise the use of the term associated with the “disease symptoms” of “the host plant”. Where possible, details of disease symptoms should be clearly articulated.

Interactions Among Three Trophic Levels: Influence of Plants on Interactions Between Insect Herbivores and Natural Enemies

1980 ◽  
Vol 11 (1) ◽  
pp. 41-65 ◽  
Author(s):  
P W Price ◽  
C E Bouton ◽  
P Gross ◽  
B A McPheron ◽  
J N Thompson ◽  
...  
Keyword(s):  
Natural Enemies ◽  
Trophic Levels ◽  
Insect Herbivores

scholarly journals Diagnosis of Fungal Plant Pathogens Using Conventional and Molecular Approaches

2021 ◽  
Author(s):  
Monika C. Dayarathne ◽  
Amin U. Mridha ◽  
Yong Wang
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Economic Loss ◽  
Rapid Identification ◽  
Plant Diseases ◽  
Morphological Observation ◽  
Pathogen Identification ◽  
Molecular Approaches ◽  
Fungal Plant Pathogens ◽  
One Fungus One Name

Fungi are a large group of eukaryotes found as saprophytes, pathogens or endophytes, which distribute in every corner of our planet. As the main pathogens, fungi can cause 70–80% of total plant diseases, leading to huge crop yield reduction and economic loss. For identification of fungal plant pathogens, mycologists and plant pathologists have mainly gone through two stages, viz. morphological observation and morphology/phylogeny, and the next era might be utilizing DNA barcodes as the tool for rapid identification. This chapter accounts i) the brief history of development for fungal identification tools and main concepts, ii) the importance and confusion of “One fungus, one name” for pathogen identification, iii) more or fewer species that we need in agricultural practice, and iv) the foreground of fungal plant pathogen identification. These will help to solve the practical problems of identification of fungal pathogens in agricultural production.

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