title: Spatial relationships between entomopathogenic nematodes and nematophagous fungi in Florida citrus orchards.
abstract: Relationships between entomopathogenic nematodes (EPNs), nematophagous fungi (NF) and soil physical and chemical properties were studied in a survey of 53 citrus orchards in central ridge and flatwoods ecoregions of Florida. Seven species of NF associated with nematodes were quantified directly using a real time qPCR assay. All nematophagous fungi studied except Arthrobotrys musiformis and Hirsutella rhossiliensis were frequently detected (24-56%) in both regions. Paecilomyces lilacinus and Gamsylella gephyropagumwere encountered more frequently in the flatwoods (P=0.03) and on the ridge (P=0.02), respectively. Redundancy analysis revealed seven abiotic and biotic factors as significantly related to the NF occurrence. Multiple regression of fungi on these variables explained 78%, 66%, 48%, 36%, 23% and 4% of the variation in Catenaria sp., A. musiformis, A. dactyloides, P. lilacinus, A. oligospora and G. gepharopagum, respectively. When the data from citrus were pooled with those reported previously from natural areas and subjected to principle component analysis, the first two principle components explained 43% of the variation in NF communities. The surveys (citrus vs natural areas) were discriminated by PC2 (P<0.001) and the ecoregion by PC1 (P<0.002), and all but one NF species were related (P<0.01) to one or both components. NF communities tended to have more species and greater diversity in the flatwoods, where EPN richness and diversity were the least. However, the strength of associations between individual EPN and NF species as measured by SADIE reflected the associations between each species and ground water depth, suggesting that ecoregion preferences affected the species associations. Within each ecoregion, significant relationships between the individual NF and EPN species measured by stepwise regression tended to be positive. The results did not support the hypothesis that NF modulate the spatial patterns of EPN species between or within these two ecoregions.
authors.affiliation: Citrus Research and Education Center (CREC), University of Florida (UF), 700 Experiment Station Road, Fl 33850, USA; Sam Higginbottom Institute of Agriculture, Technology & Sciences, Allahabad, U.P., India.
authors.forename: Ekta
authors.initials: E
authors.lastname: Pathak
authors.affiliation: Citrus Research and Education Center (CREC), University of Florida (UF), 700 Experiment Station Road, Fl 33850, USA; Instituto de Ciencias Agrarias, CSIC, Serrano 115 Dpdo, Madrid 28006, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Campos-Herrera
authors.affiliation: Citrus Research and Education Center (CREC), University of Florida (UF), 700 Experiment Station Road, Fl 33850, USA; Plant Protection Department, Faculty of Agriculture, Zagazig University, Egypt.
authors.forename: Fahiem E
authors.initials: FE
authors.lastname: El-Borai
authors.affiliation: Citrus Research and Education Center (CREC), University of Florida (UF), 700 Experiment Station Road, Fl 33850, USA. Electronic address: lwduncan@ufl.edu.
authors.forename: Larry W
authors.initials: LW
authors.lastname: Duncan
mesh_terms: D000818:Animals; D002957:Citrus / Q000382:microbiology*; D005431:Florida; D003904:Mitosporic Fungi; D009181:Mycoses; D009348:Nematoda / Q000382:microbiology*; D010572:Pest Control, Biological / Q000379:methods; D060888:Real-Time Polymerase Chain Reaction; D012988:Soil Microbiology
keywords: Entomopathogenic nematodes; Multivariate analysis; Nematophagous fungi; Quantitative real–time PCR; Soil ecology; Species–specific primers and probe