title: Identification, pathogenicity and abundance of Paracremonium pembeum sp. nov. and Graphium euwallaceae sp. nov.--two newly discovered mycangial associates of the polyphagous shot hole borer (Euwallacea sp.) in California.
abstract: Fusarium euwallaceae is a well-characterized fungal symbiont of the exotic ambrosia beetle Euwallacea sp. (polyphagous shot hole borer [PSHB]), together inciting Fusarium dieback on many host plants in Israel and California. Recent discoveries of additional fungal symbionts within ambrosia beetle mycangia suggest these fungi occur as communities. Colony-forming units of Graphium euwallaceae sp. nov. and Paracremonium pembeum sp. nov., two novel fungal associates of PSHB from California, grew from 36 macerated female heads and 36 gallery walls collected from Platanus racemosa, Acer negundo, Persea americana and Ricinus communis. Fungi were identified based on micromorphology and phylogenetic analyses of the combined internal transcribed spacer region (nuc rDNA ITS1-5.8S-ITS2 [ITS barcode]), elongation factor (EF 1-α), small subunit (18S rDNA) sequences for Graphium spp., ITS, EF 1-α, calmodulin (cmdA), large subunit of the ATP citrate lyase (acl1), β-tubulin (tub2), RNA polymerase II second largest subunit (rpb2) and large subunit (28S rDNA) sequences for Paracremonium spp. Other Graphium spp. recovered from PSHB in Vietnam, Euwallacea fornicatus in Thailand, E. validus in Pennsylvania and Paracremonium sp. recovered from PSHB in Vietnam were identified. F. euwallaceae was recovered from mycangia at higher frequencies and abundances in all hosts except R. communis, in which those of F. euwallaceae and P. pembeum were equal. P. pembeum was relatively more abundant within gallery walls of A. negundo and R. communis. In all hosts combined F. euwallaceae was relatively more abundant within PSHB heads than gallery walls. All three fungi grew at different rates and colonized inoculated excised stems of P. americana and A. negundo. P. pembeum produced longer lesions than F. euwallaceae and G. euwallaceae on inoculated avocado shoots. Results indicate PSHB is associated with a dynamic assemblage of mycangial fungal associates that pose additional risk to native and nonnative hosts in California.
authors.affiliation: Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521Center for Conservation Biology, University of California, Riverside, California 92521.
authors.forename: Shannon Colleen
authors.initials: SC
authors.lastname: Lynch
authors.affiliation: AgBiome, Inc., 104 T.W. Alexander Drive, Building 1, Research Triangle Park, North Carolina 27709.
authors.forename: Mathias
authors.initials: M
authors.lastname: Twizeyimana
authors.affiliation: Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521.
authors.forename: Joey Sal
authors.initials: JS
authors.lastname: Mayorquin
authors.affiliation: Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521.
authors.forename: Danny Ho
authors.initials: DH
authors.lastname: Wang
authors.affiliation: Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521.
authors.forename: Francis
authors.initials: F
authors.lastname: Na
authors.affiliation: Department of Plant Protection, Faculty of Agriculture, University of Çukurova, Balcali 01330, Adana, Turkey.
authors.forename: Mukaddes
authors.initials: M
authors.lastname: Kayim
authors.affiliation: Division of Plant and Soil Sciences, West Virginia University, Morgantown, West Virginia 26506.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Kasson
authors.affiliation: Forest Protection Research Center, Vietnamese Academy of Forest Sciences, 46 Dong Ngac Road, Duc Thang, Northern Tu Liem, Hanoi, Vietnam.
authors.forename: Pham Quang
authors.initials: PQ
authors.lastname: Thu
authors.affiliation: Department of Entomology, University of Florida, Gainesville, Florida 32611.
authors.forename: Craig
authors.initials: C
authors.lastname: Bateman
authors.affiliation: Department of Entomology, University of California, Riverside, California 92521.
authors.forename: Paul
authors.initials: P
authors.lastname: Rugman-Jones
authors.affiliation: School of Forest Resources and Conservation, University of Florida, Gainesville, Florida 32611.
authors.forename: Jiri
authors.initials: J
authors.lastname: Hulcr
authors.affiliation: Department of Entomology, University of California, Riverside, California 92521.
authors.forename: Richard
authors.initials: R
authors.lastname: Stouthamer
authors.affiliation: Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521 akif.eskalen@ucr.edu.
authors.forename: Akif
authors.initials: A
authors.lastname: Eskalen
mesh_terms: D000818:Animals; D001203:Ascomycota / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D002140:California; D001517:Coleoptera / Q000382:microbiology*; D005260:Female; D027421:Persea / Q000382:microbiology; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology
keywords: ambrosia fungi; avocado; fungal associates; fungal pathogens; mycangia; symbiosis