Characterization of the entomopathogenic fungal species Conoideocrella luteorostrata on the scale insect pest Fiorinia externa infesting the Christmas tree Abies fraseri in the USA

We characterized the entomopathogenic fungal species, Conoideocrella luteorostrata (Zimm.) D. Johnson, G.H. Sung, Hywel-Jones & Spatafora (Hypocreales: Clavicipitaceae), on the elongate hemlock scale, Fiorinia externa Ferris (Hemiptera: Diaspididae), infesting Fraser fir Christmas tree, Abies fraseri (Pursh) Poir (Pinaceae). Fraser fir Christmas trees that were cultivated in Michigan, North Carolina, and Virginia were intercepted in Florida during plant inspection. This study is based on the isolation in pure culture, and morphological and molecular characterization using a 4-locus (ITS, LSU, SSU, tell) and represents the first record of C. luteorostrata on F. externa. In addition, we reviewed all previously reported natural enemies of F. externa in the USA, discussed their potential as biological control agents, and concluded the need to explore a new natural enemy of F. externa. We recommend using C. luteorostrata as a biocontrol agent for F. externa. We also suggest that our isolate could be a source of new uncharacterized active compounds and could be used in the biological control of whiteflies and scale insects, as demonstrated in other C. luteorostrata strains. We also discussed the importance of investigating biological control agents in pest and pathogen interception samples.