Seasonal prevalence of the insect pathogenic fungus Colletotrichum nymphaeae in Brazilian citrus groves under different chemical pesticide regimes |
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| Institution: | 1. Embrapa Arroz e Feijão, Rodovia GO-462, km 12, Zona Rural, C.P. 179, 75375-000, Santo Antônio de Goiás, GO, Brazil;2. Corporación Colombiana de Investigación Agropecuária (CORPOICA), Centro de Investigación “La Selva” A.A. 100 Rionegro, Antioquia, Colombia;3. University of Florida/IFAS, Mid Florida Research and Education Center, Apopka, FL 32703, USA;4. United States Department of Agriculture, Agricultural Research Service, Emerging Pests and Pathogens Research, Robert W. Holley Center for Agriculture & Health, 538 Tower Road, Ithaca, NY 14853, USA;5. Department of Exact Sciences, University of São Paulo, Av. Pádua Dias 11, CP 9, 13418–900, Piracicaba, SP, Brazil;6. Department of Entomology and Acarology, University of São Paulo, Av. Pádua Dias 11, CP 9, 13418–900, Piracicaba, SP, Brazil;1. Crop Bioprotection Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, United States Department of Agriculture, 1815 North University Street, Peoria, IL 61604, USA;2. Embrapa Rice and Beans, Rodovia GO-462, Km 12, Zona Rural, C.P. 179, 75375-000 Santo Antônio de Goiás, GO, Brazil;1. Division of Pathogen Genomics, Translational Genomics Research Institute-North, Flagstaff, AZ, USA;2. Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, AZ, USA;3. Faculty of Medicine, University of Brasília, Brasília-DF, Brazil;4. Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland;5. Westerdijk Fungal Biodiversity Institute, Utrecht, the Netherlands;6. Centre of New Technologies, University of Warsaw, Warsaw, Poland;7. University of Texas Health Science Center at San Antonio, San Antonio, TX, USA;1. Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Passage des Déportés 2, B-5030 Gembloux, Belgium;2. Laboratory of Reproductive Biology, Department of Animal Biology, Faculty of Science and Technology, University Cheikh Anta Diop, B-5005 Dakar Fann, Senegal;3. Medical Entomology, Pasteur Institute, Ambatofotsikely, 101, Antananarivo, Madagascar;4. Functional and Evolutionary Morphology, Department of Biology, Ecology and Evolution, Faculty of Sciences, University of Liege, Allée de la Chimie 3, B-4000 Liège, Belgium;5. Microbial Processes and Interactions, Gembloux Agro-Bio Tech, University of Liege, Passage des Déportés 2, B-5030 Gembloux, Belgium;1. School of Biological Sciences, University of Reading, Berkshire RG6 6AS, UK;2. Plant Protection Department, Agriculture College, University of Kufa, Najaf, Iraq |
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| Abstract: | We report an endemic entomopathogenic fungus, known in Brazil as the 'salmão' fungus and identified here as Colletotrichum nymphaeae (Sordariomycetes: Glomerellales), infecting populations of citrus orthezia scale, Praelongorthezia praelonga. The seasonal prevalence of this pathogen in P. praelonga populations was investigated in three commercial citrus groves maintained under different pesticide regimes. Two citrus groves included inundative releases of another insect pathogenic fungus, Lecanicillium longisporum. Natural epizootics were consistently observed, with up to 84% infection rates being recorded during the warm rainy season. Temporal progression of C. nymphaeae-induced disease varied among the three pesticide regimes. Low infection levels from C. nymphaeae were associated with intensive application of broad spectrum pesticides. However, the prevalence of C. nymphaeae followed a density-dependent pattern with insect host abundance, irrespective of the pesticide regime. High proportions of Lecanicillium-infected insects were observed following infection peaks of C. nymphaeae and both fungi together contributed to 95% overall mortality of citrus orthezia during the wet season. Hence, the combined effect of both fungi considerably improves the biological control of citrus orthezia. We also surmise that the host abundance, environmental conditions, and application frequency of chemical pesticides in citrus groves exert a great influence in the seasonal prevalence of C. nymphaeae-induced disease. Altogether, these results suggest that C. nymphaeae is an important pathogen of P. praelonga and indicate that frequent use of synthetic pesticides may delay or reduce fungal epizootics. |
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| Keywords: | Density-dependence Natural epizootics Entomopathogenic fungi Climatic factors Conservational biocontrol |
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