title: Variation in virulence of Beauveria bassiana and B. pseudobassiana to the pine weevil Pissodes nemorensis in relation to mycelium characteristics and virulence genes.
abstract: Entomopathogenic fungi such as Beauveria spp. have potential applications in the biocontrol of insect pests but little is known regarding their infectivity to the pine weevil Pissodes nemorensis. In this study, five isolates of Beauveria pseudobassiana and five isolates of Beauveria bassiana were tested for characteristics correlating with virulence on P. nemorensis. Isolate UAMH301 had the lowest mean lethal concentration value whereas the highest value was obtained with isolate LRC137. Growth rate was negatively correlated with virulence in B. bassiana, because isolate LRC137, the least virulent isolate, grew much more rapidly than the other B. bassiana isolates on SDYA. In contrast, its growth on a hyperosmotic medium was the slowest. Sporulation rate and conidial area were not correlated with virulence. Mycelial cell density was positively correlated with virulence in both species, and the four tested genes appear to be one-copy genes. Bbchit1 and Bbhog1, genes respectively encoding a chitinase and a protein kinase, induced relative expression levels were positively correlated with virulence in B. pseudobassiana. We discuss in terms of previous morphological, physiological and genetic parameters related to virulence in Beauveria and the importance of testing the expression of putative virulence genes in comparison with their basal transcript levels.
authors.affiliation: UPV-EHU, University of Basque Country, Science and Technology Faculty, Department of Zoology and Animal Cell Biology, Sarriena s/n E-48940, Leioa, Spain; FABI, Forestry and Agricultural Biotechnology Institute, TPCP, Tree Protection Co-operative Programme, University of Pretoria, Pretoria, 0002, South Africa. Electronic address: pedro.romon@ehu.eus.
authors.forename: Pedro
authors.initials: P
authors.lastname: Romón
authors.affiliation: FABI, Forestry and Agricultural Biotechnology Institute, TPCP, Tree Protection Co-operative Programme, University of Pretoria, Pretoria, 0002, South Africa.
authors.forename: Hardus
authors.initials: H
authors.lastname: Hatting
authors.affiliation: Université Catholique de Louvain, ELI, Earth and Life Institute, Croix du Sud 2, B-1348 Louvain, Belgium; UPV-EHU, University of Basque Country, Science and Technology Faculty, Department of Zoology and Animal Cell Biology, Sarriena s/n E-48940, Leioa, Spain.
authors.forename: Arturo
authors.initials: A
authors.lastname: Goldarazena
authors.affiliation: UPV-EHU, University of Basque Country, Science and Technology Faculty, Department of Zoology and Animal Cell Biology, Sarriena s/n E-48940, Leioa, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Iturrondobeitia
mesh_terms: D000818:Animals; D052982:Beauveria / Q000235:genetics / Q000472:pathogenicity*; D025282:Mycelium / Q000254:growth & development*; D013172:Spores, Fungal / Q000254:growth & development; D016019:Survival Analysis; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*; D048889:Weevils / Q000382:microbiology* / Q000502:physiology*
chemical_list: D037521:Virulence Factors
keywords: Beauveria spp.; Deodar weevil; Genes expression; Interseptal distance; Mycelium growth