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Cao Y, Li K, Xia Y. Downregulation of pre-rRNA processing gene Mamrd1 decreases growth, conidiation and virulence in the entomopathogenic fungus Metarhizium acridum. Res Microbiol 2011; 162:729-36. [DOI: 10.1016/j.resmic.2011.05.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Accepted: 04/26/2011] [Indexed: 10/18/2022]
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152
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George J, Blanford S, Domingue MJ, Thomas MB, Read AF, Baker TC. Reduction in host-finding behaviour in fungus-infected mosquitoes is correlated with reduction in olfactory receptor neuron responsiveness. Malar J 2011; 10:219. [PMID: 21812944 PMCID: PMC3162589 DOI: 10.1186/1475-2875-10-219] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 08/03/2011] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Chemical insecticides against mosquitoes are a major component of malaria control worldwide. Fungal entomopathogens formulated as biopesticides and applied as insecticide residual sprays could augment current control strategies and mitigate the evolution of resistance to chemical-based insecticides. METHODS Anopheles stephensi mosquitoes were exposed to Beauveria bassiana or Metarhizium acridum fungal spores and sub-lethal effects of exposure to fungal infection were studied, especially the potential for reductions in feeding and host location behaviours related to olfaction. Electrophysiological techniques, such as electroantennogram, electropalpogram and single sensillum recording techniques were then employed to investigate how fungal exposure affected the olfactory responses in mosquitoes. RESULTS Exposure to B. bassiana caused significant mortality and reduced the propensity of mosquitoes to respond and fly to a feeding stimulus. Exposure to M. acridum spores induced a similar decline in feeding propensity, albeit more slowly than B. bassiana exposure. Reduced host-seeking responses following fungal exposure corresponded to reduced olfactory neuron responsiveness in both antennal electroantennogram and maxillary palp electropalpogram recordings. Single cell recordings from neurons on the palps confirmed that fungal-exposed behavioural non-responders exhibited significantly impaired responsiveness of neurons tuned specifically to 1-octen-3-ol and to a lesser degree, to CO2. CONCLUSIONS Fungal infection reduces the responsiveness of mosquitoes to host odour cues, both behaviourally and neuronally. These pre-lethal effects are likely to synergize with fungal-induced mortality to further reduce the capacity of mosquito populations exposed to fungal biopesticides to transmit malaria.
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Affiliation(s)
- Justin George
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
| | - Simon Blanford
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA
| | - Michael J Domingue
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
| | - Matthew B Thomas
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA
| | - Andrew F Read
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA
| | - Thomas C Baker
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
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153
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Wyrebek M, Huber C, Sasan RK, Bidochka MJ. Three sympatrically occurring species of Metarhizium show plant rhizosphere specificity. MICROBIOLOGY-SGM 2011; 157:2904-2911. [PMID: 21778205 DOI: 10.1099/mic.0.051102-0] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Here we tested the hypothesis that species of the soil-inhabiting insect-pathogenic fungus Metarhizium are not randomly distributed in soils but show plant-rhizosphere-specific associations. We isolated Metarhizium from plant roots at two sites in Ontario, Canada, sequenced the 5' EF-1α gene to discern Metarhizium species, and developed an RFLP test for rapid species identification. Results indicated a non-random association of three Metarhizium species (Metarhizium robertsii, Metarhizium brunneum and Metarhizium guizhouense) with the rhizosphere of certain types of plant species (identified to species and categorized as grasses, wildflowers, shrubs and trees). M. robertsii was the only species that was found associated with grass roots, suggesting a possible exclusion of M. brunneum and M. guizhouense. Supporting this, in vitro experiments showed that M. robertsii conidia germinated significantly better in Panicum virgatum (switchgrass) root exudate than did M. brunneum or M. guizhouense. M. guizhouense and M. brunneum only associated with wildflower rhizosphere when co-occurring with M. robertsii. With the exception of these co-occurrences, M. guizhouense was found to associate exclusively with the rhizosphere of tree species, predominantly Acer saccharum (sugar maple), while M. brunneum was found to associate exclusively with the rhizosphere of shrubs and trees. These associations demonstrate that different species of Metarhizium associate with specific plant types.
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Affiliation(s)
- Michael Wyrebek
- Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St Catharines, ON L2S 3A1, Canada
| | - Cristina Huber
- Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St Catharines, ON L2S 3A1, Canada
| | - Ramanpreet Kaur Sasan
- Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St Catharines, ON L2S 3A1, Canada
| | - Michael J Bidochka
- Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St Catharines, ON L2S 3A1, Canada
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154
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Ying SH, Feng MG. A conidial protein (CP15) of Beauveria bassiana contributes to the conidial tolerance of the entomopathogenic fungus to thermal and oxidative stresses. Appl Microbiol Biotechnol 2011; 90:1711-20. [PMID: 21455593 DOI: 10.1007/s00253-011-3205-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2011] [Revised: 02/07/2011] [Accepted: 02/07/2011] [Indexed: 11/25/2022]
Abstract
Aerial conidia are central dispersing structures for most fungi and represent the infectious propagule for entomopathogenic fungus Beauveria bassiana, thus the active ingredients of commercial mycoinsecticides. Although a number of formic-acid-extractable (FAE) cell wall proteins from conidia have been characterized, the functions of many such proteins remain obscure. We report that a conidial FAE protein, termed CP15, isolated from B. bassiana is related to fungal tolerance to thermal and oxidative stresses. The full-length genomic sequence of CP15 was shown to lack introns, encoding for a 131 amino acid protein (15.0 kDa) with no sequence identity to any known proteins in the NCBI database. The function of this new gene with two genomic copies was examined using the antisense-RNA method. Five transgenic strains displayed various degrees of silenced CP15 expression, resulting in significantly reduced conidial FAE protein profiles. The FAE protein contents of the strains were linearly correlated to the survival indices of their conidia when exposed to 30-min wet stress at 48°C (r (2) = 0.93). Under prolonged 75-min heat stress, the median lethal times (LT(50)s) of their conidia were significantly reduced by 13.6-29.5%. The CP15 silenced strains were also 20-50% less resistant to oxidative stress but were not affected with respect to UV-B or hyperosmotic stress. Our data indicate that discrete conidial proteins may mediate resistance to some abiotic stresses, and that manipulation of such proteins may be a viable approach to enhancing the environmental fitness of B. bassiana for more persisting control of insect pests in warmer climates.
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Affiliation(s)
- Sheng-Hua Ying
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
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155
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Leng Y, Peng G, Cao Y, Xia Y. Genetically altering the expression of neutral trehalase gene affects conidiospore thermotolerance of the entomopathogenic fungus Metarhizium acridum. BMC Microbiol 2011; 11:32. [PMID: 21310069 PMCID: PMC3045870 DOI: 10.1186/1471-2180-11-32] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2010] [Accepted: 02/10/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The entomopathogenic fungus Metarhizium acridum has been used as an important biocontrol agent instead of insecticides for controlling crop pests throughout the world. However, its virulence varies with environmental factors, especially temperature. Neutral trehalase (Ntl) hydrolyzes trehalose, which plays a role in environmental stress response in many organisms, including M. acridum. Demonstration of a relationship between Ntl and thermotolerance or virulence may offer a new strategy for enhancing conidiospore thermotolerance of entomopathogenic fungi through genetic engineering. RESULTS We selected four Ntl over-expression and four Ntl RNA interference (RNAi) transformations in which Ntl expression is different. Compared to the wild-type, Ntl mRNA expression was reduced to 35-66% in the RNAi mutants and increased by 2.5-3.5-fold in the over-expression mutants. The RNAi conidiospores exhibited less trehalase activity, accumulated more trehalose, and were much more tolerant of heat stress than the wild-type. The opposite effects were found in conidiospores of over-expression mutants compared to RNAi mutants. Furthermore, virulence was not altered in the two types of mutants compared to the wild type. CONCLUSIONS Ntl controlled trehalose accumulation in M. acridum by degrading trehalose, and thus affected conidiospore thermotolerance. These results offer a new strategy for enhancing conidiospore thermotolerance of entomopathogenic fungi without affecting virulence.
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Affiliation(s)
- Yajun Leng
- Genetic Engineering Research Center, College of Bioengineering, Chongqing University, Chongqing, China
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156
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Interactions of two insect pathogens, Paranosema locustae (Protista: Microsporidia) and Metarhizium acridum (Fungi: Hypocreales), during a mixed infection of Locusta migratoria (Insecta: Orthoptera) nymphs. J Invertebr Pathol 2011; 106:336-8. [DOI: 10.1016/j.jip.2010.09.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 09/22/2010] [Accepted: 09/24/2010] [Indexed: 11/23/2022]
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157
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Zhang G, Han X, Elser JJ. Rapid top–down regulation of plant C:N:P stoichiometry by grasshoppers in an Inner Mongolia grassland ecosystem. Oecologia 2011; 166:253-64. [DOI: 10.1007/s00442-011-1904-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Accepted: 01/03/2011] [Indexed: 11/28/2022]
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158
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Genome sequencing and comparative transcriptomics of the model entomopathogenic fungi Metarhizium anisopliae and M. acridum. PLoS Genet 2011; 7:e1001264. [PMID: 21253567 PMCID: PMC3017113 DOI: 10.1371/journal.pgen.1001264] [Citation(s) in RCA: 441] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Accepted: 12/01/2010] [Indexed: 12/18/2022] Open
Abstract
Metarhizium spp. are being used as environmentally friendly alternatives to chemical insecticides, as model systems for studying insect-fungus interactions, and as a resource of genes for biotechnology. We present a comparative analysis of the genome sequences of the broad-spectrum insect pathogen Metarhizium anisopliae and the acridid-specific M. acridum. Whole-genome analyses indicate that the genome structures of these two species are highly syntenic and suggest that the genus Metarhizium evolved from plant endophytes or pathogens. Both M. anisopliae and M. acridum have a strikingly larger proportion of genes encoding secreted proteins than other fungi, while ∼30% of these have no functionally characterized homologs, suggesting hitherto unsuspected interactions between fungal pathogens and insects. The analysis of transposase genes provided evidence of repeat-induced point mutations occurring in M. acridum but not in M. anisopliae. With the help of pathogen-host interaction gene database, ∼16% of Metarhizium genes were identified that are similar to experimentally verified genes involved in pathogenicity in other fungi, particularly plant pathogens. However, relative to M. acridum, M. anisopliae has evolved with many expanded gene families of proteases, chitinases, cytochrome P450s, polyketide synthases, and nonribosomal peptide synthetases for cuticle-degradation, detoxification, and toxin biosynthesis that may facilitate its ability to adapt to heterogenous environments. Transcriptional analysis of both fungi during early infection processes provided further insights into the genes and pathways involved in infectivity and specificity. Of particular note, M. acridum transcribed distinct G-protein coupled receptors on cuticles from locusts (the natural hosts) and cockroaches, whereas M. anisopliae transcribed the same receptor on both hosts. This study will facilitate the identification of virulence genes and the development of improved biocontrol strains with customized properties. Aside from playing a crucial role in natural ecosystems, entomopathogenic fungi are being developed as environmentally friendly alternatives for the control of insect pests. We conducted the first genomic study of two of the best characterized entomopathogens, Metarhizium anisopliae and M. acridum. M. anisopliae is a ubiquitous pathogen of >200 insect species and a plant growth promoting colonizer of rhizospheres. M. acridum is a specific pathogen of locusts. Important findings of this study included: 1) Both M. anisopliae and M. acridum have a very large number of genes encoding secreted proteins, and many of these play roles in fungus-insect interactions. 2) M. anisopliae has more genes than M. acridum, which may be associated with adaptation to multiple insect hosts. 3) Unlike M. acridum, the M. anisopliae genome contains many more transposase genes and shows no evidence of repeat-induced point mutations. The lack of repeat-induced mutations may have allowed the lineage-specific gene duplications that have contributed to its adaptability. 4) High-throughput transcriptomics identified the strategies by which these fungi overcome their insect hosts and achieve specificity. These genome sequences will provide the basis for a comprehensive understanding of fungal–plant–insect interactions and will contribute to our understanding of fungal evolution and ecology.
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159
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Fan Y, Pei X, Guo S, Zhang Y, Luo Z, Liao X, Pei Y. Increased virulence using engineered protease-chitin binding domain hybrid expressed in the entomopathogenic fungus Beauveria bassiana. Microb Pathog 2010; 49:376-80. [DOI: 10.1016/j.micpath.2010.06.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 06/21/2010] [Accepted: 06/22/2010] [Indexed: 11/16/2022]
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160
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Polovinko GP, Yaroslavtseva ON, Teshebaeva ZA, Kryukov VY. Dominating species of entomophilous ascomycetes anamorphs in West Siberia, Primorsky krai, and Kyrgyzstan. CONTEMP PROBL ECOL+ 2010. [DOI: 10.1134/s1995425510050024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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161
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Toegel S, Salar-Behzadi S, Horaczek-Clausen A, Viernstein H. Preservation of aerial conidia and biomasses from entomopathogenic fungi Beauveria brongniartii and Metarhizium anisopliae during lyophilization. J Invertebr Pathol 2010; 105:16-23. [DOI: 10.1016/j.jip.2010.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 04/30/2010] [Accepted: 05/04/2010] [Indexed: 11/16/2022]
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162
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Nchu F, Maniania NK, Hassanali A, Eloff KN. Optimizing modes of inoculation of Rhipicephalus ticks (Acari: Ixodidae) with a mitosporic entomopathogenic fungus in the laboratory. EXPERIMENTAL & APPLIED ACAROLOGY 2010; 51:373-382. [PMID: 20082120 DOI: 10.1007/s10493-009-9330-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 12/11/2009] [Indexed: 05/28/2023]
Abstract
The process of strain selection is an important step in the development of insect pathogens for biological control. Bioassays were conducted in the laboratory to evaluate the efficacy of different methods of inoculation using Rhipicephalus pulchellus Gerstäcker (Acari: Ixodidae) as a model. Initially, an oil-based formulation of Metarhizium anisopliae (Metsch.) Sorok. (Ascomycota: Hypocreales) titred at 10(9) conidia ml(-1) was applied to R. pulchellus adults using a Burgerjon spray tower or a microapplicator. Inoculation by microapplicator yielded poor results (25.0% tick mortality) compared to Burgerjon's spray tower (52.3% tick mortality), although the mean number of fungal conidia on R. pulchellus adults was lower (1.5 x 10(4) +/- 1.1 x 10(3) conidia ml(-1)) after spraying by Burgerjon's spray tower compared to 1 x 10(6) conidia ml(-1) obtained with the microapplicator. Thus, inoculation by Burgerjon's spray tower was selected for further investigations. Different modes of inoculation were tested and included direct spray of inoculum on the tick and substrate (SS), direct spray on the substrate and tick followed by transfer of the tick to clean uncontaminated Petri dish (SP) or indirect inoculation of ticks through substrate (SW). The LC(50) values following contamination of nymphs (LC(50) = 1.4 x 10(7) conidia ml(-1)) and adults (LC(50) = 6.7 x 10(7) conidia ml(-1)) in SS were significantly lower compared to SP; nymphs (LC(50) = 5.7 x 10(8) conidia ml(-1)) and adults (LC(50) = 5.3 x 10(9) conidia ml(-1)) and SW; nymphs (LC(50) = 5 x 10(8) conidia ml(-1)). Although the LC(50) value in SS was the lowest, it recorded the highest tick mortality among control ticks (24.2% at 2 weeks post-treatment) and (23.3% at 3 weeks post-treatment) in nymphs and adults respectively compared to SP (2.5 and 5.8%, respectively) and SW (0.0 and 0.0). Results show that among the modes of inoculation tested, SP was the most appropriate for inoculating R. pulchellus adults. SW and SP were identified as appropriate techniques for infecting the R. pulchellus nymphs with conidia formulated in oil.
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Affiliation(s)
- Felix Nchu
- icipe-African Insect Sciences for Food and Health, Nairobi, Kenya.
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163
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Wang J, Xia Y. Construction and preliminary analysis of a normalized cDNA library from Locusta migratoria manilensis topically infected with Metarhizium anisopliae var. acridum. JOURNAL OF INSECT PHYSIOLOGY 2010; 56:998-1002. [PMID: 20470782 DOI: 10.1016/j.jinsphys.2010.05.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 05/05/2010] [Accepted: 05/06/2010] [Indexed: 05/29/2023]
Abstract
The insect immune response to fungal infection is poorly understood at the molecular level. To explore the molecular basis of this process, a novel method to analyze the gene transcripts of insects in response to pathogenic fungus was established. A normalized cDNA library based on the SMART method combined with DSN (duplex-specific nuclease) treatment was constructed using mRNA extracted from the fat body and hemocytes of Locusta migratoria manilensis 6-24h after being topically infected with Metarhizium anisopliae var. acridum. Analysis of 259 unigenes out of 303 sequenced inserts from the cDNA library revealed that the cDNA library was not contaminated with M. anisopliae transcripts and validated the presence of the immune-related genes characterized here. These results suggest that this method overcame the difficulties of contamination from a fungal source in constructing the host cDNA library from mycosed insects and proved that this method is reliable and feasible for investigation of host genes in response to fungal infection. Further studies of the expressed sequence tags from this library will provide insights into the molecular basis of insect immune response to fungal infection.
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Affiliation(s)
- Jie Wang
- Key Laboratory of Biorheological Science and Technology, College of Bioengineering, Chongqing University, Chongqing 400044, PR China
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164
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Hawksworth DL, Wiltshire PEJ. Forensic mycology: the use of fungi in criminal investigations. Forensic Sci Int 2010; 206:1-11. [PMID: 20634009 DOI: 10.1016/j.forsciint.2010.06.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 06/07/2010] [Accepted: 06/10/2010] [Indexed: 10/19/2022]
Abstract
This is the first overview to be published of the whole field of forensic mycology. It is based on all available information located in the literature, together with 13 examples from recent casework. Background information on fungi is given, and this is followed by an outline of the value, and potentially wide application, of mycology in criminal investigation. Applications include roles in: providing trace evidence; estimating time since death (post-mortem interval); ascertaining time of deposition; investigating cause of death, hallucinations, or poisonings; locating buried corpses; and biological warfare. Previous work has been critically evaluated, with particular attention to its evidential value, and suitability for presentation in a court of law. The situations where mycology might assist an investigation are summarised, and issues relating to the further development of the subject are presented. A comprehensive bibliography with 120 citations is provided.
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Affiliation(s)
- David L Hawksworth
- Departamento de Biología Vegetal II, Facultad de Farmacia, Universidad Complutense de Madrid, Plaza Ramón y Cajal, Madrid 28040, Spain.
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165
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Lee SC, Ni M, Li W, Shertz C, Heitman J. The evolution of sex: a perspective from the fungal kingdom. Microbiol Mol Biol Rev 2010; 74:298-340. [PMID: 20508251 PMCID: PMC2884414 DOI: 10.1128/mmbr.00005-10] [Citation(s) in RCA: 243] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Sex is shrouded in mystery. Not only does it preferentially occur in the dark for both fungi and many animals, but evolutionary biologists continue to debate its benefits given costs in light of its pervasive nature. Experimental studies of the benefits and costs of sexual reproduction with fungi as model systems have begun to provide evidence that the balance between sexual and asexual reproduction shifts in response to selective pressures. Given their unique evolutionary history as opisthokonts, along with metazoans, fungi serve as exceptional models for the evolution of sex and sex-determining regions of the genome (the mating type locus) and for transitions that commonly occur between outcrossing/self-sterile and inbreeding/self-fertile modes of reproduction. We review here the state of the understanding of sex and its evolution in the fungal kingdom and also areas where the field has contributed and will continue to contribute to illuminating general principles and paradigms of sexual reproduction.
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Affiliation(s)
- Soo Chan Lee
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Min Ni
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Wenjun Li
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Cecelia Shertz
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
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166
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Shan LT, Feng MG. Evaluation of the biocontrol potential of various Metarhizium isolates against green peach aphid Myzus persicae (Homoptera: Aphididae). PEST MANAGEMENT SCIENCE 2010; 66:669-675. [PMID: 20201034 DOI: 10.1002/ps.1928] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
BACKGROUND Twenty-three isolates of Metarhizium anisopliae (Metschnikof) Sorokin and M. acridum (Driver & Milner) JF Bischoff, Rehner & Humber from non-aphid host insects around the globe were evaluated for their aphid biocontrol potential, which is not well known. RESULTS The apterous adults of green peach aphid Myzus persicae (Sulzer) were exposed to the fungal sprays of 11.5, 99 and 1179 conidia mm(-2) and blank control in three leaf-dish bioassays. All the tested isolates except one were proven to be infective to the aphid species at 21 +/- 1 degrees C and 14:10 h light:dark photoperiod, causing corrected mortalities of 10.1-95.3% at the high spore concentration. The data from ten isolates causing > 50% mortality at the high concentration were found to fit a time-concentration-mortality model well, yielding parameters for the estimates of their LC(50) and LT(50) that vary with post-spray time and spore concentration respectively. Four isolates of M. anisopliae (ARSEF 759, 4132, 2080 and 576) had LC(50) values of 44-80 conidia mm(-2) on day 8 and LT(50) values of 4.9-6.8 days at 100 conidia mm(-2), with 91-98% of the killed aphids being well mycotised after death. CONCLUSION The Metarhizium infectivity to M. persicae differs greatly among the tested isolates. The four mentioned isolates with desired virulence and sporulation potential are excellent candidates for microbial control of aphids.
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Affiliation(s)
- Le-Tian Shan
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China
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167
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Fernandes EKK, Keyser CA, Chong JP, Rangel DEN, Miller MP, Roberts DW. Characterization of Metarhizium species and varieties based on molecular analysis, heat tolerance and cold activity. J Appl Microbiol 2010; 108:115-28. [PMID: 19664068 DOI: 10.1111/j.1365-2672.2009.04422.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS The genetic relationships and conidial tolerances to high and low temperatures were determined for isolates of several Metarhizium species and varieties. METHODS AND RESULTS Molecular-based techniques [AFLP and rDNA (ITS1, ITS2 and 5.8S) gene sequencing] were used to characterize morphologically identified Metarhizium spp. isolates from a wide range of sources. Conidial suspensions of isolates were exposed to wet heat (45 + or - 0.2 degrees C) and plated on potato dextrose agar plus yeast extract (PDAY) medium. After 8-h exposure, the isolates divided clearly into two groups: (i) all isolates of Metarhizium anisopliae var. anisopliae (Ma-an) and Metarhizium from the flavoviride complex (Mf) had virtually zero conidial relative germination (RG), (ii) Metarhizium anisopliae var. acridum (Ma-ac) isolates demonstrated high heat tolerance (c. 70-100% RG). Conidial suspensions also were plated on PDAY and incubated at 5 degrees C for 15 days, during which time RGs for Ma-an and Ma-ac isolates were virtually zero, whereas the two Mf were highly cold active (100% RG). CONCLUSIONS Heat and cold exposures can be used as rapid tools to tentatively identify some important Metarhizium species and varieties. SIGNIFICANCE AND IMPACT OF THE STUDY Identification of Metarhizium spp. currently relies primarily on DNA-based methods; we suggest a simple temperature-based screen to quickly obtain tentative identification of isolates as to species or species complexes.
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Affiliation(s)
- E K K Fernandes
- Department of Biology, Utah State University, Logan, UT, USA
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168
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Fashing PJ, Nguyen N, Fashing NJ. Behavior of geladas and other endemic wildlife during a desert locust outbreak at Guassa, Ethiopia: ecological and conservation implications. Primates 2010; 51:193-7. [PMID: 20333438 DOI: 10.1007/s10329-010-0194-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Accepted: 02/16/2010] [Indexed: 10/19/2022]
Abstract
Desert locust (Schistocerca gregaria) outbreaks have occurred repeatedly throughout recorded history in the Horn of Africa region, devastating crops and contributing to famines. In June 2009, a desert locust swarm invaded the Guassa Plateau, Ethiopia, a large and unusually intact Afroalpine tall-grass ecosystem, home to important populations of geladas (Theropithecus gelada), Ethiopian wolves (Canis simensis), thick-billed ravens (Corvus crassirostris), and other Ethiopian or Horn of Africa endemics. During the outbreak and its aftermath, we observed many animals, including geladas, ravens, and a wolf, feeding on locusts in large quantities. These observations suggest surprising flexibility in the normally highly specialized diets of geladas and wolves, including the potential for temporary but intensive insectivory during locust outbreaks. To our knowledge, Guassa is the highest elevation site (3,200-3,600 m) at which desert locusts, which require temperatures >20 degrees C for sustained flight, have been reported. Continued monitoring will be necessary to determine whether the June 2009 outbreak was an isolated incident or part of an emerging pattern in the Ethiopian Highlands linked to global warming. The intensive consumption of desert locusts by geladas, wolves, and ravens during the outbreak at Guassa raises concerns about pesticide-based locust control strategies and potential unintended adverse effects on endemic and endangered wildlife.
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Affiliation(s)
- Peter J Fashing
- Department of Anthropology, California State University Fullerton, 800 N. State College Boulevard, Fullerton, CA 92834, USA.
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Amóra SSA, Bevilaqua CML, Feijó FMC, Pereira RHDMA, Alves ND, Freire FADM, Kamimura MT, Oliveira DMD, Luna-Alves Lima EÁ, Rocha MFG. The effects of the fungus Metarhizium anisopliae var. acridum on different stages of Lutzomyia longipalpis (Diptera: Psychodidae). Acta Trop 2010; 113:214-20. [PMID: 19883621 DOI: 10.1016/j.actatropica.2009.10.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 10/22/2009] [Accepted: 10/24/2009] [Indexed: 11/27/2022]
Abstract
The control of Visceral Leishmaniasis (VL) vector is often based on the application of chemical residual insecticide. However, this strategy has not been effective. The continuing search for an appropriate vector control may include the use of biological control. This study evaluates the effects of the fungus Metarhizium anisopliae var. acridum on Lutzomyia longipalpis. Five concentrations of the fungus were utilized, 1 x 10(4) to 1 x 10(8) conidia/ml, accompanied by controls. The unhatched eggs, larvae and dead adults previously exposed to fungi were sown to reisolate the fungi and analysis of parameters of growth. The fungus was subsequently identified by PCR and DNA sequencing. M. anisopliae var. acridum reduced egg hatching by 40%. The mortality of infected larvae was significant. The longevity of infected adults was lower than that of negative controls. The effects of fungal infection on the hatching of eggs laid by infected females were also significant. With respect to fungal growth parameters post-infection, only vegetative growth was not significantly higher than that of the fungi before infection. The revalidation of the identification of the reisolated fungus was confirmed post-passage only from adult insects. In terms of larvae mortality and the fecundity of infected females, the results were significant, proving that the main vector species of VL is susceptible to infection by this entomopathogenic fungus in the adult stage.
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170
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Farenhorst M, Knols BGJ. A novel method for standardized application of fungal spore coatings for mosquito exposure bioassays. Malar J 2010; 9:27. [PMID: 20089180 PMCID: PMC2820041 DOI: 10.1186/1475-2875-9-27] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 01/20/2010] [Indexed: 11/12/2022] Open
Abstract
Background Interest in the use of fungal entomopathogens against malaria vectors is growing. Fungal spores infect insects via the cuticle and can be applied directly on the insect to evaluate infectivity. For flying insects such as mosquitoes, however, application of fungal suspensions on resting surfaces is more realistic and representative of field settings. For this type of exposure, it is essential to apply specific amounts of fungal spores homogeneously over a surface for testing the effects of fungal dose and exposure time. Contemporary methods such as spraying or brushing spore suspensions onto substrates do not produce the uniformity and consistency that standardized laboratory assays require. Two novel fungus application methods using equipment developed in the paint industry are presented and compared. Methods Wired, stainless steel K-bars were tested and optimized for coating fungal spore suspensions onto paper substrates. Different solvents and substrates were evaluated. Two types of coating techniques were compared, i.e. manual and automated coating. A standardized bioassay set-up was designed for testing coated spores against malaria mosquitoes. Results K-bar coating provided consistent applications of spore layers onto paper substrates. Viscous Ondina oil formulations were not suitable and significantly reduced spore infectivity. Evaporative Shellsol T solvent dried quickly and resulted in high spore infectivity to mosquitoes. Smooth proofing papers were the most effective substrate and showed higher infectivity than cardboard substrates. Manually and mechanically applied spore coatings showed similar and reproducible effects on mosquito survival. The standardized mosquito exposure bioassay was effective and consistent in measuring effects of fungal dose and exposure time. Conclusions K-bar coating is a simple and consistent method for applying fungal spore suspensions onto paper substrates and can produce coating layers with accurate effective spore concentrations. The mosquito bioassay was suitable for evaluating fungal infectivity and virulence, allowing optimizations of spore dose and exposure time. Use of this standardized application method will help achieve reliable results that are exchangeable between different laboratories.
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Affiliation(s)
- Marit Farenhorst
- Laboratory of Entomology, Wageningen University and Research Centre, PO Box 8031, 6700 EH, Wageningen, The Netherlands.
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Abstract
SUMMARYThe phylum Microspora is ancient and diverse and affects a wide range of hosts. There is unusually high use of vertical transmission and this has significant consequences for transmission and pathogenicity. Vertical transmission is associated with low pathogenesis but nevertheless can have significant impact through associated traits such as sex ratio distortion. The majority of microsporidia have mixed transmission cycles and it is not clear whether they are able to modify their phenotype according to environmental circumstances. There is a great need to understand the mechanisms controlling transmission and one of the first challenges for the genomics era is to find genes associated with life cycle stages. Similarly we cannot currently predict the ease with which these parasites might switch between host groups. Phylogenetic analysis suggests that there are strong relationships between Microsporidia and their hosts. However closer typing of parasite isolates, in relation to host range and disease phenotype, is required to assess future environmental risk from these pathogens.
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Toriello C, Pérez-Torres A, Vega-García F, Navarro-Barranco H, Pérez-Mejía A, Lorenzana-Jiménez M, Hernández-Velázquez V, Mier T. Lack of pathogenicity and toxicity of the mycoinsecticide Metarhizium anisopliae var. acridum following acute gastric exposure in mice. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2009; 72:2153-2157. [PMID: 19535139 DOI: 10.1016/j.ecoenv.2009.05.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2008] [Revised: 05/11/2009] [Accepted: 05/24/2009] [Indexed: 05/27/2023]
Abstract
Metarhizium anisopliae var. acridum, monospore culture EH-502/8 (CNRCB MaPL40), isolated in Mexico from Schistocerca piceifrons ssp. piceifrons (Orthoptera: Acrididae) was tested for acute oral intragastric pathogenicity and toxicity in CD-1 mice. Animals were inoculated with one dose (10(8) conidia/animal) of viable (72 mice), non-viable (24 mice) conidia and compared to 18 control mice. Clinical observations were done daily; mycological and histological tests were performed during necropsies after the inoculation. No mice showed clinical symptoms of illness or died during the study. The fungus was able to persist in some organs until day 3, but did not cause any damage to the host. The gross pathology observed was splenomegaly in mice inoculated with viable and non-viable conidia. Non-germinated conidia, observed in several organs, suggest hematogenous spread, but without any histopathological tissue reaction. Results support the non-pathogenic and non-toxic status of this fungal strain when administered in a single intragastric dose to mice.
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Affiliation(s)
- Conchita Toriello
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México D.F. 04510, México.
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173
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St. Leger RJ, Wang C. Genetic engineering of fungal biocontrol agents to achieve greater efficacy against insect pests. Appl Microbiol Biotechnol 2009; 85:901-7. [DOI: 10.1007/s00253-009-2306-z] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Revised: 10/10/2009] [Accepted: 10/10/2009] [Indexed: 01/19/2023]
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174
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Kryukov VY, Khodyrev VP, Yaroslavtseva ON, Kamenova AS, Duisembekov BA, Glupov VV. Synergistic action of entomopathogenic hyphomycetes and the bacteria Bacillus thuringiensis ssp. morrisoni in the infection of Colorado potato beetle Leptinotarsa decemlineata. APPL BIOCHEM MICRO+ 2009. [DOI: 10.1134/s000368380905010x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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175
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Lewis MW, Robalino IV, Keyhani NO. Uptake of the fluorescent probe FM4-64 by hyphae and haemolymph-derived in vivo hyphal bodies of the entomopathogenic fungus Beauveria bassiana. Microbiology (Reading) 2009; 155:3110-3120. [DOI: 10.1099/mic.0.029165-0] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The entomopathogenic fungus Beauveria bassiana is under intensive study as a pest biological control agent. B. bassiana produces several distinct single-cell types that include aerial conidia, in vitro blastospores and submerged conidia. Under appropriate nutrient conditions these cells can elaborate germ tubes that form hyphae, which in turn lead to the formation of a fungal mycelium. In addition, B. bassiana displays a dimorphic transition, producing in vivo specific yeast-like hyphal bodies during growth in the arthropod haemolymph. The amphiphilic styryl dye FM4-64 was used to investigate internalization and morphological features of in vitro and in vivo insect haemolymph-derived B. bassiana cells. In vitro blastospores and submerged conidia displayed a punctate pattern of internal labelling, whereas aerial conidia failed to internalize the dye under the conditions tested. FM4-64 was also taken up into both apical and subapical compartments of living hyphae in a time-dependent manner, with clearly observable vesicle labelling. Internalization, where occurring, was reversibly disrupted by lowering the temperature of the assay or by treatment with azide/fluoride and latrunculin A. Treatment with cytochalasin D and monensin also caused abnormal vesicle trafficking, although some staining of vesicles was noted. Fungal cells derived from infected Heliothis virescens haemolymph (in vivo cells) actively internalized FM4-64. The in vivo blastospores or hyphal bodies displayed bright membrane and internal vesicle staining, although diffuse staining of internal structures was also visible. These results suggest active uptake by different developmental stages of B. bassiana, including haemolymph-derived cells that can evade the insect immune system.
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Affiliation(s)
- Michael W. Lewis
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
| | - Ines V. Robalino
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
| | - Nemat O. Keyhani
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
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Li J, Ying SH, Shan LT, Feng MG. A new non-hydrophobic cell wall protein (CWP10) of Metarhizium anisopliae enhances conidial hydrophobicity when expressed in Beauveria bassiana. Appl Microbiol Biotechnol 2009; 85:975-84. [PMID: 19557409 DOI: 10.1007/s00253-009-2083-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2009] [Revised: 06/05/2009] [Accepted: 06/08/2009] [Indexed: 11/29/2022]
Abstract
A cell wall protein, CWP10, resolved from the conidial formic acid extract of a Metarhizium anisopliae isolate, was characterized as a new 9.9-kDa protein with a 32-aa signal peptide with a central hydrophobic region (ca. 10 residues) at its N-terminus. This protein was proven neither to be hydrophobic nor glycosylated and encoded by a 363-bp, single-copy gene with three introns. CWP10 was existent in the conidial extracts of seven of 18 tested M. anisopliae isolates and much more abundant (immunogold-labeled) on conidial walls than in cytoplasm. Integrating the gene into a CWP10-absent strain of Beauveria bassiana led to excellent expression of CWP10 in aerial conidia, increasing net conidial hydrophobicity by 10.8% or adhesion to hydrophobic Teflon by 1.3-fold. However, the expressed protein had no effect on conidial tolerance to thermal and ultraviolet stresses. This is the first report on a non-hydrophobic cell-wall protein enhancing conidial hydrophobicity and adhesion of the fungal species.
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Affiliation(s)
- Jun Li
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, People's Republic of China
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177
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Targeting an antimicrobial effector function in insect immunity as a pest control strategy. Proc Natl Acad Sci U S A 2009; 106:12652-7. [PMID: 19506247 DOI: 10.1073/pnas.0904063106] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Insect pests such as termites cause damages to crops and man-made structures estimated at over $30 billion per year, imposing a global challenge for the human economy. Here, we report a strategy for compromising insect immunity that might lead to the development of nontoxic, sustainable pest control methods. Gram-negative bacteria binding proteins (GNBPs) are critical for sensing pathogenic infection and triggering effector responses. We report that termite GNBP-2 (tGNBP-2) shows beta(1,3)-glucanase effector activity previously unknown in animal immunity and is a pleiotropic pattern recognition receptor and an antimicrobial effector protein. Termites incorporate this protein into the nest building material, where it functions as a nest-embedded sensor that cleaves and releases pathogenic components, priming termites for improved antimicrobial defense. By means of rational design, we present an inexpensive, nontoxic small molecule glycomimetic that blocks tGNBP-2, thus exposing termites in vivo to accelerated infection and death from specific and opportunistic pathogens. Such a molecule, introduced into building materials and agricultural methods, could protect valuable assets from insect pests.
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178
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Albernaz DAS, Tai MHH, Luz C. Enhanced ovicidal activity of an oil formulation of the fungus Metarhizium anisopliae on the mosquito Aedes aegypti. MEDICAL AND VETERINARY ENTOMOLOGY 2009; 23:141-147. [PMID: 19309438 DOI: 10.1111/j.1365-2915.2008.00792.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The effect of humidity on the activity of Metarhizium anisopliae IP 46 (Metsch.) Sorokin (Hypocreales: Clavicipitaceae) formulated in sunflower oil against Aedes aegypti (L.) (Diptera: Culicidae) eggs was examined. After exposure of eggs at 75% relative humidity (RH) for <or= 25 days, ovicidal activity was not increased by oil-in-water formulated conidia, hyphal bodies or pure-oil formulated conidia, compared with conidia or hyphal bodies prepared in water only. At optimal > 98% RH, eclosion was <or= 13.7% after treatment with oil-in-water formulated propagules in <or= 10% oil, and it was completely inhibited when conidia were applied in pure oil. At 86-100% RH, new conidia were found on eggs treated with oil-formulated conidia and incubated down to 91% RH. Ovicidal activity was still detected at 93% RH and was augmented with increasing humidity and time of exposure of eggs. Eclosion of larvae was distinctly reduced by IP 46 pure-oil formulated conidia after a minimal initial exposure of 3 days at > 98% RH, followed by: (a) a 12-day exposure at 75% RH before submersion in water; (b) a minimal 5-day exposure at > 98% RH and direct subsequent transfer of treated eggs to water, or (c) a minimal daily 20-h exposure at > 98% RH alternating with 4 h at 75% RH for 10 days. We demonstrate that oil-based formulations of conidia of M. anisopliae enhance ovicidal activity at high humidities and conclude that these formulations have potential in the integrated control of Ae. aegypti.
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Affiliation(s)
- D A S Albernaz
- Departmento de Microbiologia, Immunologia, Parasitologia e Patologia, Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, Goiás, Brazil
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Bell AS, Blanford S, Jenkins N, Thomas MB, Read AF. Real-time quantitative PCR for analysis of candidate fungal biopesticides against malaria: technique validation and first applications. J Invertebr Pathol 2009; 100:160-8. [PMID: 19320043 PMCID: PMC2666797 DOI: 10.1016/j.jip.2009.01.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Recent research has indicated that fungal biopesticides could augment existing malaria vector control tools. Here we present a set of methodologies to monitor the in vivo kinetics of entomopathogenic fungi in Anopheles in the presence or absence of malaria parasites using quantitative real-time PCR. Three qPCR assays were successfully developed for counting fungal genomes: “specific” assays capable of distinguishing two well characterized fungal entomopathogens Beauveria bassiana isolate IMI391510 and Metarhizium anisopliae var. acridum isolate IMI330189, both of which have previously been shown to be virulent to Anopheles mosquitoes, and a “generic” fungal assay for determining any fungal burden. A fourth assay to Plasmodium chabaudi enabled quantification of co-infecting malarial parasites. All qPCR assays provide sensitive, target-specific, and robust quantification over a linear range of greater than five orders of magnitude (seven orders of magnitude for the fungal assays). B. bassiana growth within mosquitoes exposed to three different conidial challenge doses was monitored using the B. bassiana-specific assay and represents the first description of entomopathogenic fungal replication within an insect host. This revealed that, irrespective of challenge dose, after several days of relatively little replication, a sudden on-set of substantial nuclear division occurs, accompanied by physical fungal growth (hyphae) within the mosquito haemocoel shortly before death. Exposure to higher densities of conidia resulted in significantly greater pick-up by mosquitoes and to elevated fungal burdens at each time point sampled. High fungal burdens, comparable to those identified in cadavers, were attained more rapidly and mortalities occurred earlier post-exposure with increasing challenge dose. The lines of research made possible by the qPCR assays described here will contribute to optimization of fungal biopesticides against malaria and other vector-borne diseases.
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Affiliation(s)
- Andrew S Bell
- School of Biological Sciences, University of Edinburgh, West Mains Road, Edinburgh EH93JT, UK.
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180
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Blanford S, Read AF, Thomas MB. Thermal behaviour of Anopheles stephensi in response to infection with malaria and fungal entomopathogens. Malar J 2009; 8:72. [PMID: 19379519 PMCID: PMC2683858 DOI: 10.1186/1475-2875-8-72] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Accepted: 04/20/2009] [Indexed: 11/24/2022] Open
Abstract
Background Temperature is a critical determinant of the development of malaria parasites in mosquitoes, and hence the geographic distribution of malaria risk, but little is known about the thermal preferences of Anopheles. A number of other insects modify their thermal behaviour in response to infection. These alterations can be beneficial for the insect or for the infectious agent. Given current interest in developing fungal biopesticides for control of mosquitoes, Anopheles stephensi were examined to test whether mosquitoes showed thermally-mediated behaviour in response to infection with fungal entomopathogens and the rodent malaria, Plasmodium yoelii. Methods Over two experiments, groups of An. stephensi were infected with one of three entomopathogenic fungi, and/or P. yoelii. Infected and uninfected mosquitoes were released on to a thermal gradient (14 – 38°C) for "snapshot" assessments of thermal preference during the first five days post-infection. Mosquito survival was monitored for eight days and, where appropriate, oocyst prevalence and intensity was assessed. Results and conclusion Both infected and uninfected An. stephensi showed a non-random distribution on the gradient, indicating some capacity to behaviourally thermoregulate. However, chosen resting temperatures were not altered by any of the infections. There is thus no evidence that thermally-mediated behaviours play a role in determining malaria prevalence or that they will influence the performance of fungal biopesticides against adult Anopheles.
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Affiliation(s)
- Simon Blanford
- School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland, UK.
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181
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Troemel ER, Félix MA, Whiteman NK, Barrière A, Ausubel FM. Microsporidia are natural intracellular parasites of the nematode Caenorhabditis elegans. PLoS Biol 2009; 6:2736-52. [PMID: 19071962 PMCID: PMC2596862 DOI: 10.1371/journal.pbio.0060309] [Citation(s) in RCA: 168] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 10/31/2008] [Indexed: 11/28/2022] Open
Abstract
For decades the soil nematode Caenorhabditis elegans has been an important model system for biology, but little is known about its natural ecology. Recently, C. elegans has become the focus of studies of innate immunity and several pathogens have been shown to cause lethal intestinal infections in C. elegans. However none of these pathogens has been shown to invade nematode intestinal cells, and no pathogen has been isolated from wild-caught C. elegans. Here we describe an intracellular pathogen isolated from wild-caught C. elegans that we show is a new species of microsporidia. Microsporidia comprise a large class of eukaryotic intracellular parasites that are medically and agriculturally important, but poorly understood. We show that microsporidian infection of the C. elegans intestine proceeds through distinct stages and is transmitted horizontally. Disruption of a conserved cytoskeletal structure in the intestine called the terminal web correlates with the release of microsporidian spores from infected cells, and appears to be part of a novel mechanism by which intracellular pathogens exit from infected cells. Unlike in bacterial intestinal infections, the p38 MAPK and insulin/insulin-like growth factor (IGF) signaling pathways do not appear to play substantial roles in resistance to microsporidian infection in C. elegans. We found microsporidia in multiple wild-caught isolates of Caenorhabditis nematodes from diverse geographic locations. These results indicate that microsporidia are common parasites of C. elegans in the wild. In addition, the interaction between C. elegans and its natural microsporidian parasites provides a system in which to dissect intracellular intestinal infection in vivo and insight into the diversity of pathogenic mechanisms used by intracellular microbes. The small roundworm Caenorhabditis elegans is an important model system for many areas of biology, but little is known about its natural ecology. We have identified an intracellular parasite from C. elegans in its natural habitat isolated near Paris and have named it Nematocida parisii, or nematode-killer from Paris. N. parisii defines a new genus and species of microsporidia. Microsporidia are ubiquitous eukaryotic pathogens that are thought to be highly reduced fungi and are emerging pathogens of humans. The microsporidian N. parisii invades and resides in C. elegans intestinal cells where it goes through a multistep life cycle and eventually escapes out of intestinal cells, leaving holes in the terminal web, an important cellular structure. We have found N. parisii and a related Nematocida species in several wild-caught roundworms, indicating that microsporidian infections may be relatively common for C. elegans in the wild. The C. elegans/N. parisii interaction provides a valuable system in which to study microsporidian infections in a whole animal, and a convenient and inexpensive system in which to screen for anti-microsporidian drugs. A newly identified intracellular pathogen of wild-caughtCaenorhabditis elegans represents a new microsporidian species that will provide a model to study this class of pathogen in humans.
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Affiliation(s)
- Emily R Troemel
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
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182
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Li J, Feng MG. Intraspecific tolerance of Metarhizium anisopliae conidia to the upper thermal limits of summer with a description of a quantitative assay system. ACTA ACUST UNITED AC 2008; 113:93-9. [PMID: 18804165 DOI: 10.1016/j.mycres.2008.08.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 02/10/2008] [Accepted: 08/12/2008] [Indexed: 10/21/2022]
Abstract
Conidial tolerance to the upper thermal limits of summer is important for fungal biocontrol agents, whose conidia are formulated into mycoinsecticides for field application. To develop an efficient assay system, aerial conidia of eight Metarhizium anisopliae, four M. anisopliae var. anisopliae, and six M. anisopliae var. acridum isolates with different host and geographic origins were wet-stressed for <or=180 min at 48 degrees C or incubated for 14 d colony growths at 10-35 degrees C. The survival ratios (relative to unstressed conidia) of each isolate, examined at 15-min intervals, fit a logistic equation (r2>or=0.975), yielding median lethal times (LT50s) of 14.3-150.3 min for the 18 isolates stressed at 48 degrees C. Seven grasshopper isolates from Africa had a mean LT50 of 110 (73-150) min, but could not grow at 10 or 15 degrees C. The mean LT50 of five non-grasshopper isolates capable of growing at 10-35 degrees C was 16 (10-26) min only. Three isolates with typically low (type I), medium (type II), and high (type III) levels of tolerance to 48 degrees C were further assayed for <or=4-d tolerance of their conidia to the wet stress at 38, 40, 42, or 45 degrees C. The resultant LT50s decreased to 20, 53 and 167 min at 48 degrees C from 507, 1612, and 8256 min at 38 degrees C for types I, II and III, respectively. For the distinguished types, the logarithms of the LT50s were significantly correlated to the temperatures of 38-48 degrees C with an inverse linearity (r2>or=0.88). The method developed to assay quantitatively fungal thermotolerance would be useful for screening of fungal candidates for improved pest control in summer.
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Affiliation(s)
- Jun Li
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China
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183
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Agrobacterium-mediated disruption of a nonribosomal peptide synthetase gene in the invertebrate pathogen Metarhizium anisopliae reveals a peptide spore factor. Appl Environ Microbiol 2008; 74:4366-80. [PMID: 18502925 DOI: 10.1128/aem.00285-08] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Numerous secondary metabolites have been isolated from the insect pathogenic fungus Metarhizium anisopliae, but the roles of these compounds as virulence factors in disease development are poorly understood. We targeted for disruption by Agrobacterium tumefaciens-mediated transformation a putative nonribosomal peptide synthetase (NPS) gene, MaNPS1. Four of six gene disruption mutants identified were examined further. Chemical analyses showed the presence of serinocyclins, cyclic heptapeptides, in the extracts of conidia of control strains, whereas the compounds were undetectable in DeltaManps1 mutants treated identically or in other developmental stages, suggesting that MaNPS1 encodes a serinocyclin synthetase. Production of the cyclic depsipeptide destruxins, M. anisopliae metabolites also predicted to be synthesized by an NPS, was similar in DeltaManps1 mutant and control strains, indicating that MaNPS1 does not contribute to destruxin biosynthesis. Surprisingly, a MaNPS1 fragment detected DNA polymorphisms that correlated with relative destruxin levels produced in vitro, and MaNPS1 was expressed concurrently with in vitro destruxin production. DeltaManps1 mutants exhibited in vitro development and responses to external stresses comparable to control strains. No detectable differences in pathogenicity of the DeltaManps1 mutants were observed in bioassays against beet armyworm and Colorado potato beetle in comparison to control strains. This is the first report of targeted disruption of a secondary metabolite gene in M. anisopliae, which revealed a novel cyclic peptide spore factor.
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184
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Lednev GR, Kryukov VY, Khodyrev VP, Levchenko MA, Duisembekov BA, Sagitov AO, Glupov VV. Dynamics of mortality of the migratory locust under synchronous infection with entomopathogenic fungi (Beauveria bassiana, Metarhizium anisopliae) and bacteria Pseudomonas sp. CONTEMP PROBL ECOL+ 2008. [DOI: 10.1134/s1995425508020069] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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185
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Kraaijeveld AR, Godfray HCJ. Selection for resistance to a fungal pathogen in Drosophila melanogaster. Heredity (Edinb) 2008; 100:400-6. [PMID: 18301441 DOI: 10.1038/sj.hdy.6801092] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
An artificial selection experiment designed to explore the evolution of resistance to a fungal pathogen, Beauveria bassiana, in Drosophila melanogaster is reported here. The experiment was designed to test whether there is sufficient additive genetic variation in this trait for increased resistance to evolve, and, if so, whether there are correlated responses that might represent a cost to defence. After 15 generations of selection, flies from selected lines did not have higher overall fitness after infection compared with control lines. The response to selection for resistance against this pathogen is thus much weaker than against other species, in particular, parasitoids. There was, however, evidence for increased late-life fecundity in selected lines, which may indicate evolved tolerance of fungal infection. This increase was accompanied by reduced early-life fitness, which may reflect the well-known trade-off between early and late reproduction. In the absence of fungal infection, selected flies had lower fitness than control flies, and the possibility that this is also a trade-off with increased tolerance is explored.
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Affiliation(s)
- A R Kraaijeveld
- NERC Centre for Population Biology, Imperial College London, Silwood Park Campus, Ascot, Berks, UK.
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186
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Specific activity of a Bacillus thuringiensis strain against Locusta migratoria manilensis. J Invertebr Pathol 2008; 98:169-76. [PMID: 18359040 DOI: 10.1016/j.jip.2008.02.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Revised: 01/12/2008] [Accepted: 02/13/2008] [Indexed: 11/21/2022]
Abstract
Bacillus thuringiensis (Bt) has played an important role in biocontrol of pests. However, insecticidal activity of B. thuringiensis against locusts has been rarely reported. Bt strain BTH-13 exhibiting specific activity to locusts was isolated from a soil sample in China and characterized. Its bipyramidal parasporal crystal is mainly composed of a protein of 129kDa, and produces a mature toxin of 64kDa after activation. The pattern of total DNA from BTH-13 showed a large and three small plasmid bands. Known delta-endotoxin genes, cry1Aa, cry1Ab, cry1Ac, cry1C, cry3, cry4 and cry7Aa were not found from strain BTH-13 by PCR amplification. The sequence analysis of a DNA fragment produced by PCR amplification with degenerate cry-selective primers revealed that the fragment encoded a delta-endotoxin segment, which exhibited some similarity to several Cry proteins (41% of the highest similarity to Cry7Ba1). Toxicity tests were performed against Locusta migratoria manilensis, and the results demonstrated that trypsin-treated sporulated cultures and crystal proteins had high toxicity to larval and adult locusts. Cry toxin of BTH-13 was detected on the midguts of treated locusts using immunofluorescent technology, which confirmed the site of action of the crystal proteins in their toxicity for locusts.
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187
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Krasnoff SB, Keresztes I, Gillilan RE, Szebenyi DME, Donzelli BGG, Churchill ACL, Gibson DM. Serinocyclins A and B, cyclic heptapeptides from Metarhizium anisopliae. JOURNAL OF NATURAL PRODUCTS 2007; 70:1919-1924. [PMID: 18044842 DOI: 10.1021/np070407i] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Two new cyclic heptapeptides, serinocyclins A (1) and B (2), were isolated from conidia of the entomopathogenic fungus Metarhizium anisopliae. Structures were elucidated by a combination of mass spectrometric, NMR, and X-ray diffraction techniques. Serinocyclin A (1) contains three serine units, a hydroxyproline (Hyp), a beta-alanine (beta-Ala), and two uncommon nonproteinogenic amino acids, 1-aminocyclopropane-1-carboxylic acid (Acc) and gamma-hydroxylysine (HyLys). The peptide sequence established for 1 by NMR is cyclo-(Acc-Hyp-Ser1-HyLys-beta-Ala-Ser2-Ser3). Serinocyclin B (2) has Lys in place of the HyLys unit found in 1. Chiral amino acid analysis indicated the presence in both compounds of one (2 S,4 R)-Hyp, two L-Ser, and one D-Ser residue. A Lys found in the hydrolyzate of 2 was established as D-configured. A crystal structure of 1 established the position of the D-Ser (Ser2) and the absolute configuration of the HyLys unit (2 R,4 S). The absence of methyl groups is unusual among fungal peptides and, along with the charged lysyl side chain and multiple hydroxyl groups, contributes to the polar nature of the compounds. Serinocyclin A produced a sublethal locomotory defect in mosquito larvae at an EC 50 of 59 ppm.
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188
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Interaction between Paranosema locustae and Metarhizium anisopliae var. acridum, two pathogens of the desert locust, Schistocerca gregaria under laboratory conditions. J Invertebr Pathol 2007; 97:203-10. [PMID: 18005982 DOI: 10.1016/j.jip.2007.10.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 09/26/2007] [Accepted: 10/02/2007] [Indexed: 11/22/2022]
Abstract
The interaction between two pathogens, the microsporidian Paranosema locustae Canning and the fungus Metarhizium anisopliae var. acridum Driver and Milner was studied under laboratory conditions in an attempt to develop an improved method of microbial control for the desert locust, Schistocerca gregaria Forskål. Fifth-instar locust nymphs, reared in the laboratory, were treated with various concentrations of one of the two pathogens or with both pathogens. The numbers of locusts killed were recorded each day and the production of pathogen spores within the dead locusts was assessed at the end (day 21) of each experiment. Locust nymphs treated with both P. locustae and M. anisopliae died sooner than nymphs infected with only one of the pathogens. At the lower concentrations of pathogen tested, the effects of the two pathogens were additive. At the higher concentrations the combined effects were synergistic. In terms of locust mortality, there was no evidence of any antagonistic effects between the two pathogens. However, the production of spores by P. locustae was reduced considerably when the host insects were infected also with M. anisopliae. For example, nymphs treated initially with P. locustae and then treated 3 and 10 days later with M. anisopliae produced 3-20 times and 2.5-8 times fewer spores, respectively, than nymphs treated only with P. locustae. Hence, in areas where M. anisopliae is applied, the natural persistence of P. locustae in the local grasshopper and locust populations may be diminished.
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189
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Pedrini N, Crespo R, Juárez MP. Biochemistry of insect epicuticle degradation by entomopathogenic fungi. Comp Biochem Physiol C Toxicol Pharmacol 2007; 146:124-137. [PMID: 17052960 DOI: 10.1016/j.cbpc.2006.08.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Revised: 08/15/2006] [Accepted: 08/20/2006] [Indexed: 11/27/2022]
Abstract
The biochemical interaction between fungal pathogens and their insect host epicuticle was studied by examining fungal hydrocarbon degrading ability. As a contact insecticide, entomopathogenic fungi invade their host through the cuticle, covered by an outermost lipid layer mainly composed of highly stable, very long chain structures. Strains of Beauveria bassiana and Metarhizium anisopliae (Deuteromycotina: Hyphomycetes), pathogenic both to the blood-sucking bug Triatoma infestans (Hemiptera: Reduviidae) and the bean-weevil Acanthoscelides obtectus (Coleoptera, Bruchidae), were grown on different carbon sources. Alkane-grown cells showed a lipid pattern different from that of glucose-grown cells, evidenced by a major switch in the triacylglycerol and sterol components. Radiolabelled hydrocarbons were used to investigate the catabolic pathway and the by-product incorporation into fungal cellular components. The first oxidation round is presumably carried out by a cytochrome P450 enzyme system, the metabolites will traverse the peroxisomal membrane, and after successive transformations will eventually provide the appropriate fatty acyl CoA for complete degradation in the peroxisomes, the site of beta-oxidation in fungi. In this review, we will show the relationship between fungal ability to catabolize very long chain hydrocarbons and virulence parameters.
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Affiliation(s)
- Nicolás Pedrini
- Instituto de Investigaciones Bioquímicas de La Plata, Facultad de CienciasMedicas, calles 60 y 120, La Plata, 1900, Argentina
| | - Rosana Crespo
- Instituto de Investigaciones Bioquímicas de La Plata, Facultad de CienciasMedicas, calles 60 y 120, La Plata, 1900, Argentina
| | - M Patricia Juárez
- Instituto de Investigaciones Bioquímicas de La Plata, Facultad de CienciasMedicas, calles 60 y 120, La Plata, 1900, Argentina.
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190
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Wang C, Cao Y, Wang Z, Yin Y, Peng G, Li Z, Zhao H, Xia Y. Differentially-expressed glycoproteins in Locusta migratoria hemolymph infected with Metarhizium anisopliae. J Invertebr Pathol 2007; 96:230-6. [PMID: 17658547 DOI: 10.1016/j.jip.2007.05.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 05/21/2007] [Accepted: 05/21/2007] [Indexed: 10/23/2022]
Abstract
Glycoproteins play important roles in insect physiology. Infection with pathogen always results in the differential expression of some glycoproteins, which may be involved in host-pathogen interactions. In this report, differentially-expressed glycoproteins from the hemolymph of locusts infected with Metarhizium anisopliae were analyzed by two-dimensional electrophoresis (2-DE) and PDQuest software. The results showed that 13 spots were differentially expressed, of which nine spots were upregulated and four were downregulated. Using MS/MS with de novo sequencing and NCBI database searches, three upregulated proteins were identified as locust transferrin, apolipoprotein precursor, and hexameric storage protein 3. These proteins have been reported to be involved in the insect innate immune response to microbial challenge. Due to the limited available genome information and protein sequences of locusts, the possible functions of the other 10 differentially-expressed spots remain unknown.
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Affiliation(s)
- Chutao Wang
- Genetic Engineering Research Center, Chongqing University, Chongqing 400030, PR China
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191
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Abstract
Recent research has raised the prospect of using insect fungal pathogens for the control of vector-borne diseases such as malaria. In the past, microbial control of insect pests in both medical and agricultural sectors has generally had limited success. We propose that it might now be possible to produce a cheap, safe and green tool for the control of malaria, which, in contrast to most chemical insecticides, will not eventually be rendered useless by evolution of resistance. Realizing this potential will require lateral thinking by biologists, technologists and development agencies.
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192
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Leffler AJ, Peek MS, Hipps L, Ivans S, Ryel RJ, Caldwell MM. POTENTIAL CONTRIBUTION OF RESPIRATION BY ANABRUS SIMPLEX (MORMON CRICKETS) TO NET CO2EXCHANGE IN THREE GREAT BASIN ECOSYSTEMS. WEST N AM NATURALIST 2007. [DOI: 10.3398/1527-0904(2007)67[109:pcorba]2.0.co;2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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193
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Krasnoff SB, Sommers CH, Moon YS, Donzelli BGG, Vandenberg JD, Churchill ACL, Gibson DM. Production of mutagenic metabolites by Metarhizium anisopliae. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2006; 54:7083-8. [PMID: 16968066 DOI: 10.1021/jf061405r] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
NG-391 (1) and NG-393 (2), previously reported from undescribed Fusarium species as nerve-cell growth stimulants, were identified from fermentation extracts of the entomopathogenic fungus Metarhizium anisopliae. These compounds are 7-desmethyl analogues of fusarin C and (8Z)-fusarin C, mutagenic toxins from Fusarium species that contaminate corn. A mutant strain of M. anisopliae (KOB1-3) overproduces 1 and 2 by ca. 10-fold relative to the wild-type strain, ARSEF 2575, from which it was derived. Overproduction of these compounds in KOB1-3 imparts a yellow pigmentation to the culture medium of the fungus. These compounds were inactive at 100 mug/disk in antimicrobial disk diffusion assays. Compound 1 was inactive at 100 ppm in a mosquitocidal assay. However, like their fusarin analogues, 1 and 2 exhibited potent S9-dependent mutagenic activity in the Salmonella mutagenicity test. Discovery of these highly mutagenic mycotoxins in M. anisopliae suggests that screening for production of NG-391 and NG-393 in strains that are used as biocontrol agents would be a prudent course of action. The impact of these findings on the use of M. anisopliae as a biocontrol agent is currently unknown and requires further investigation.
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Affiliation(s)
- Stuart B Krasnoff
- USDA-ARS-Plant Protection Research Unit, Tower Road, Ithaca, New York 14853, USA.
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194
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Dong C, Zhang J, Chen W, Huang H, Hu Y. Characterization of a newly discovered China variety of Metarhizium anisopliae (M. anisopliae var. dcjhyium) for virulence to termites, isoenzyme, and phylogenic analysis. Microbiol Res 2006; 162:53-61. [PMID: 16949807 DOI: 10.1016/j.micres.2006.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Revised: 06/20/2006] [Accepted: 07/03/2006] [Indexed: 10/24/2022]
Abstract
The efficacy of a new virulent Metarhizium anisopliae variety (M. anisopliae var. dcjhyium, DQ288247) obtained from Odontotermes formosanus in China was evaluated against the subterranean termite, O. formosanus, in the laboratory. The new variety was compared with four other virulent M. anisopliae isolates and was found to be highly infectious and virulent against termites. M. anisopliae var. dcjhyium could cause approximately 100% mortality of termites 3 days post-inoculation in the concentration of 3x10(8) conidia/ml. There were also differences in relative hyhal growth and isoenzymes. M. anisopliae var. dcjhyium showed a different isoenzyme band pattern from the four isolates of M. anisopliae (AB027337, AB099510, AB099941 and AF280631). The phylogenetic tree of the 18S rDNA sequences revealed the taxonomic and evolutionary position of M. anisopliae var. dcjhyium. M. anisopliae var. dcjhyium and four isolates of M. anisopliae formed a monophyletic group, supported by a 99% bootstrap value. M. anisopliae var. dcjhyium formed a distinct variety, which had a special characterization of unique bands of isoenzyme, high virulence and low repellency against termites when compared with four other isolates of M. anisopliae.
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MESH Headings
- Animals
- Base Sequence
- China
- DNA, Fungal/chemistry
- DNA, Fungal/isolation & purification
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/isolation & purification
- Genes, rRNA
- Hyphae/growth & development
- Isoenzymes/analysis
- Isoptera/microbiology
- Metarhizium/classification
- Metarhizium/enzymology
- Metarhizium/isolation & purification
- Metarhizium/pathogenicity
- Microscopy
- Microscopy, Electron, Scanning
- Molecular Sequence Data
- Phylogeny
- RNA, Fungal/genetics
- RNA, Ribosomal, 18S/genetics
- Sequence Analysis, DNA
- Survival Analysis
- Virulence
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Affiliation(s)
- Changjin Dong
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
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195
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Kalkar O, Carner GR, Scharf D, Boucias DG. Characterization of an Indonesian isolate of Paecilomyces reniformis. Mycopathologia 2006; 161:109-18. [PMID: 16463094 DOI: 10.1007/s11046-005-0133-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2005] [Accepted: 10/13/2005] [Indexed: 10/25/2022]
Abstract
An entomopathogenic fungus (IndGH 96), identified as Paecilomyces reniformis, was isolated from long-horned grasshoppers (Orthoptera: Tettigoniidae) in Sulawesi, Indonesia. The phenotypic and molecular data identified the IndGH 96 as a P. reniformis. We present the first comprehensive characterization of this species using morphological features, sequencing of the ITS1-5.8s-ITS2 region, D1/D2 region of 28S of rDNA, and a portion of the tubulin gene, and laboratory bioassays. Distinguishing features include a hyphal body stage during vegetative growth and the production of distinctly curved, light-green conidia. High dosage bioassays showed that IndGH 96 was infectious to both long-horned and short-horned grasshoppers but not to the house cricket, Acheta domestica, or to the lepidopterans velvetbean caterpillar, Anticarsia gemmatalis or fall armyworm, Spodoptera frugiperda. Phenotypic and genetic analyses suggest that IndGH 96 and other isolates of P. reniformis are more closely related to Nomuraea rileyi than to other species of Paecilomyces.
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MESH Headings
- Animals
- Base Sequence
- DNA, Fungal/chemistry
- DNA, Fungal/genetics
- DNA, Ribosomal Spacer/chemistry
- DNA, Ribosomal Spacer/genetics
- Grasshoppers/microbiology
- Indonesia
- Microscopy, Electron, Scanning
- Paecilomyces/classification
- Paecilomyces/genetics
- Paecilomyces/isolation & purification
- Paecilomyces/metabolism
- RNA, Ribosomal, 28S/chemistry
- RNA, Ribosomal, 28S/genetics
- Sequence Alignment
- Tubulin/chemistry
- Tubulin/genetics
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Affiliation(s)
- O Kalkar
- Department of Biology, Kahramanmaras Sütçü Imam University, Kahramanmaraş, Turkey.
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196
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Mullen LM, Goldsworthy GJ. Immune responses of locusts to challenge with the pathogenic fungus Metarhizium or high doses of laminarin. JOURNAL OF INSECT PHYSIOLOGY 2006; 52:389-98. [PMID: 16413931 DOI: 10.1016/j.jinsphys.2005.10.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Revised: 10/18/2005] [Accepted: 10/18/2005] [Indexed: 05/06/2023]
Abstract
Two isolates of Metarhizium anisopliae var acridum were tested for their effects on the locust immune system and for comparison with the effects of challenge by injection with laminarin. Isolate IMI 330189 (referred to hereafter as Met 189) is highly pathogenic whether applied topically as conidia or injected as blastospores. However, isolate ARSEF 728 (referred to hereafter as Met 728) is pathogenic only when injected as blastospores, suggesting that the lack of pathogenicity of topically applied conidia from this isolate is due to a failure to penetrate the insect cuticle and gain access to the haemocoel. After topical application of conidia from Met 189, no activation of prophenoloxidase is detected, but injection of blastospores from Met 189 brings about a transient increase in phenoloxidase activity in the haemolymph in both adult locusts and 5th instar nymphs, although this does not prevent fungal-induced mortality. Co-injection of adipokinetic hormone-I (AKH-I) with blastospores prolongs the activation of prophenoloxidase in the haemolymph of adult locusts, and enhances it in nymphs. It is argued that the lack of activation of prophenoloxidase in nymphs shown previously (Mullen, L., Goldsworthy, G., 2003. Changes in lipophorins are related to the activation of phenoloxidase in the haemolymph of Locusta migratoria in response to injection of immunogens. Insect Biochemistry and Molecular Biology 33, 661-670), reflects differences in the sensitivity of the immune system between adults and nymphs rather than distinct qualitative differences, and this is confirmed in this study by the demonstration that doses of laminarin higher than those used previously (>or=100 microg) do activate the prophenoloxidase cascade in 5th instar nymphs. Nodules are formed in locusts of all ages in response to fungal infection or injection of laminarin, although there is wide variation in the number, size and distribution of nodules formed. During the examination of 5th instar nymphs for nodule formation, a previously unknown phenomenon was observed in which the salivary glands melanise in response to injections of blastospores or high doses of laminarin. In c. 85% of such nymphs, this reaction is so strong that the whole salivary gland is intensely black. Such a response is not observed in the salivary glands of mature adult locusts.
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Affiliation(s)
- Lisa M Mullen
- Department of Biology, School of Biological and Chemical Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
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197
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Tinsley MC, Blanford S, Jiggins FM. Genetic variation in Drosophila melanogaster pathogen susceptibility. Parasitology 2006; 132:767-73. [PMID: 16497252 PMCID: PMC1847563 DOI: 10.1017/s0031182006009929] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Revised: 12/26/2005] [Accepted: 01/03/2006] [Indexed: 11/06/2022]
Abstract
Genetic variation in susceptibility to pathogens is a central concern both to evolutionary and medical biologists, and for the implementation of biological control programmes. We have investigated the extent of such variation in Drosophila melanogaster, a major model organism for immunological research. We found that within populations, different Drosophila genotypes show wide-ranging variation in their ability to survive infection with the entomopathogenic fungus Beauveria bassiana. Furthermore, striking divergence in susceptibility has occurred between genotypes from temperate and tropical African locations. We hypothesize that this may have been driven by adaptation to local differences in pathogen exposure or host ecology. Genetic variation within populations may be maintained by temporal or spatial variation in the costs and benefits of pathogen defence. Insect pathogens are employed widely as biological control agents and entomopathogenic fungi are currently being developed for reducing malaria transmission by mosquitoes. Our data highlight the need for concern about resistance evolution to these novel biopesticides in vector populations.
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Affiliation(s)
- M C Tinsley
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK.
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198
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Polonais V, Prensier G, Méténier G, Vivarès CP, Delbac F. Microsporidian polar tube proteins: highly divergent but closely linked genes encode PTP1 and PTP2 in members of the evolutionarily distant Antonospora and Encephalitozoon groups. Fungal Genet Biol 2005; 42:791-803. [PMID: 16051504 DOI: 10.1016/j.fgb.2005.05.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Revised: 05/11/2005] [Accepted: 05/14/2005] [Indexed: 10/25/2022]
Abstract
The spore polar tube is a unique organelle required for cell invasion by fungi-related microsporidian parasites. Two major polar tube proteins (PTP1 and PTP2) are encoded by two tandemly arranged genes in Encephalitozoon species. A look at Antonospora (Nosema) locustae contigs (http://jbpc.mbl.edu/Nosema/Contigs/) revealed significant conservation in the order and orientation of various genes, despite high sequence divergence features, when comparing with Encephalitozoon cuniculi complete genome. This syntenic relationship between distantly related Encephalitozoon and Antonospora genera has been successfully exploited to identify ptp1 and ptp2 genes in two insect-infecting species assigned to the Antonospora clade (A. locustae and Paranosema grylli). Targeting of respective proteins to the polar tube was demonstrated through immunolocalization experiments with antibodies raised against recombinant proteins. Both PTPs were extracted from spores with 100mM dithiothreitol. Evidence for PTP1 mannosylation was obtained in studied species, supporting a key role of PTP1 in interactions with host cell surface.
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Affiliation(s)
- Valérie Polonais
- Equipe Parasitologie Moléculaire et Cellulaire, Laboratoire Biologie des Protistes, UMR CNRS 6023, Université Blaise Pascal, 24 Avenue des Landais 63177 Aubière Cedex, France
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199
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Luz C, Batagin I. Potential of oil-based formulations of Beauveria bassiana to control Triatoma infestans. Mycopathologia 2005; 160:51-62. [PMID: 16160769 DOI: 10.1007/s11046-005-0210-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2004] [Accepted: 01/01/2005] [Indexed: 11/25/2022]
Abstract
The in vitro development of Beauveria bassiana conidia was monitored when immersed in six concentrations of seven non-ionic (MP 6400, MP 600, Renex 60, Renex 95, Span 80, Tween 20 and Tween 80) and three anionic (DOS 75, Hostapaval BVQ 9 and Surfax 220) surfactants and 11 vegetable oils (linseed, soybean, groundnut, rapeseed, thistle, sunflower, olive, sesame, corn, castor, and babassu). The influence of the oils on the settling behavior of Triatoma infestans nymphs and the activity of an oil-water formulation of the fungus against this vector under laboratory and simulated field conditions were also determined. With exception of DOS 75 and Surfax 220 germination of conidia on complete medium was >98% at 24 h after exposure to surfactants up to 10%. Elevated rates of germination (>25%) were observed in 10% corn, thistle and linseed oil 8 days after incubation. Pure oils had a significant repellent effect to T. infestans. Repellency decreased generally at 10% of the oil and some oils showed some attractiveness for nymphs when tested at 1%. Nymphs were highly susceptible to oil-water formulated conidia, even at unfavorable moisture for extra-tegumental development of the fungus on the insect cuticle.
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Affiliation(s)
- C Luz
- DMIPP, Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás (UFG), CP 131, 74001-970, Goiânia, GO, Brazil.
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200
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Danyk T, Mackauer M, Johnson DL. The influence of host suitability on the range of grasshopper species utilized by Blaesoxipha atlanis (Diptera: Sarcophagidae) in the field. BULLETIN OF ENTOMOLOGICAL RESEARCH 2005; 95:571-8. [PMID: 16336704 DOI: 10.1079/ber2005388] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Blaesoxipha atlanis (Aldrich) is a common parasitic fly of agriculturally important grasshoppers in Canada. The suitability of Camnula pellucida (Scudder), Melanoplus bivittatus (Say), Melanoplus packardii Scudder, and Melanoplus sanguinipes (Fabricius) as hosts was studied in the laboratory. Grasshoppers were singly-parasitized or left unparasitized and reared for 9 days. Melanoplus bivittatus and M. packardii did not support parasite development, i.e. were non-permissive hosts. In both species, parasite larvae were melanized and encapsulated, but development proceeded further in M. packardii. Melanoplus sanguinipes and C. pellucida were permissive host species with, respectively, 70% and 35% of the implanted larvae emerging from their hosts of which 86% and 50% developed into adults. Parasite development time was longer in C. pellucida. Adult B. atlanis dry mass varied with host species and host mass at parasitism, but not with host sex. Parasites developing in M. sanguinipes were larger in terms of dry mass than counterparts developing in C. pellucida. In permissive species, unparasitized grasshoppers gained in body mass while parasitized insects lost mass during the 9-day observation period. In non-permissive species, all insects gained in body mass, but parasitized females gained less mass than unparasitized conspecifics. All unparasitized grasshoppers survived while 75-95% of permissive and 30-40% of non-permissive hosts died. Variation in the intensity of field parasitism among grasshopper species may be explained, at least in part, by qualitative differences in suitability between potential host species. Novel pest management strategies emphasize preservation of a small proportion of the pest population for natural enemies. Consideration of the outcome of specific host-parasite interactions should improve the understanding of grasshopper population dynamics and increase the predictive value of models that assess potential crop losses.
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Affiliation(s)
- T Danyk
- Agriculture and Agri-Food Canada, Alberta, Canada.
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