Submitted to: Biological Control
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/12/2014
Publication Date: 2/22/2014
Citation: Goble, T.A., Rehner, S.A., Long, S.J., Gardescu, S., Hajek, A.E. 2014. A comparison of the virulence of North American Beauveria brongniartii and commercial pathogenic fungal species against Asian longhorned beetles, Anoplophora glabripennis. Biological Control. 72(1):91-97. Interpretive Summary: The Asian long-horned beetle is an invasive wood-boring insect that threatens the health and survival of many North American hardwood trees. Chemical methods to control this insect are ineffective and alternative efforts to control it using native North American fungal biological control agents are being investigated. A Japanese strain of the insect pathogen Beauveria asiatica has been selected and commercialized as an effective biological control agent against the beetles in Asia. However, due to its non-native status, this fungus species cannot be released in North America. Two North American strains of the closely related Beauveria brongniartii and one strain of a U.S. registered mycoinsecticidal fungus, Metarhizium anisopliae, were tested for their virulence against the beetles. Results of bioassays showed that neither North American B. brongniartii were virulent to the beetles, however, the M. anisopliae strain was comparable to M. asiatica in virulence. Results of this study indicate that M. anisopliae is a promising candidate for biological control of Asian longhorn beetles and that future efforts to develop new fungal biocontrol agents should focus on fungi isolated from native species of longhorn beetles. This research will be used by insect pathologists prospecting for potential biological control fungi to control the Asian long-horned beetle.
Technical Abstract: In the United States (US) the development and field application of Beauveria brongniartii (Sacc.) Petch (Hypocreales: Clavicipitaceae) to control invasive Asian longhorned beetle, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) have been hampered because it was unknown whether this fungal species is native to North America. With the recent confirmation of the occurrence of B. brongniartii in North America there is renewed interest in this species, particularly as it is believed to be the most important pathogen of cerambycids in Japan. However this study reports, based on partial sequences of the nuclear intergenic region BLOC region, that the previously described commercially available B. brongniartii strain NBL 851 (Nitto Denko, Osaka, Japan) belongs instead to the species Beauveria asiatica Rehner and Humber. Further, bioassays using two inoculation methods confirmed that commercially available strains of B. asiatica (NBL 851) and Metarhizium brunneum (F52) (Hypocreales: Clavicipitaceae) were significantly more virulent and had lower median survival times (9.5 d-7.5 d) than two US native B. brongniartii isolates (ARSEF 6215 and ARSEF 10279) (24 d-31 d) against A. glabripennis adults. The study results indicate that biological control efforts against this invasive insect species should focus on host-specific, virulent strains within the fungal species B. asiatica and M. brunneum instead of strains within B. brongniartii. Further, this was the first account of indigenous US B. brongniartii isolates being evaluated for biological control of any insect pest.