Comparing virulence of North American Beauveria brongniartii and commercial pathogenic fungi against Asian longhorned beetles

Abstract

In the USA, the development and field application of Beauveria brongniartii (Sacc.) Petch (Hypocreales: Clavicipitaceae) to control the 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 an effective pathogen of cerambycids in Japan. However, based on partial sequences of the nuclear intergenic BLOC region the commercially available B. brongniartii strain NBL 851 (Idemitsu Kosan, Tokyo, 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 resulted in lower median survival times (9.5–7.5d) of A. glabripennis adults than two North American B. brongniartii isolates (ARSEF 6215 and ARSEF 10279) (24–31d). The virulence of North American B. brongniartii isolates is not well-documented in the literature. To our best knowledge this is the first account of the virulence of native North American B. brongniartii being evaluated for biological control of any invasive insect pest.