Conoideocrella luteorostrata, a potential fungal biocontrol of invasive Christmas tree pest elongate hemlock scale

Hosanna Barrett* (1), Brian Lovett (2), and Matt T. Kasson (2)

1 Department of Biology, West Virginia University, Morgantown WV, 26506; 

2 Division of Plant and Soil Sciences, West Virginia University, Morgantown, West Virginia 26506

Presentation Category: Biological & Biochemical Sciences (Poster Presentation #99)

Student’s Major: Biology

Elongate hemlock scale, or Fiorinia externa, is an invasive scale insect that infests needles of hemlock, spruce, and fir trees. Infestation is of particular concern to Christmas tree farmers since it can weaken trees and reduce their exportability. These scales are currently managed using chemical pesticides, but those interventions may hurt natural predators and ultimately increase scale populations.The goal of this project is to investigate natural fungal pathogens of elongate hemlock scale insects in the eastern U.S. for development into biocontrol agents. In the Summer of 2020, Fraser fir branches with elongate hemlock scales were collected from North Carolina and Virginia and examined for signs of fungal infection. Fungi infecting the crawlers and fungi in the needle microbiome were isolated and cultured, since previously identified fungal scale pathogen, Colletotrichum fioriniae, is able to live within the needles. The main fungus infecting the scales was molecularly identified as Conoideocrella luteorostrata (Clavicipitaceae, Hypocreales, Ascomycota), which is known to infect elongate hemlock scales in their natural range in Southeast Asia. C. luteorostrata was not cultured from the needle, which suggests that its lifestyle relies on the insect host. Formulation of this strain to be applied to Christmas trees as a biocontrol agent will require bioassays of C. luteorostrata strains against the various life stages of elongate hemlock scale, investigation of non-target effects of the fungus, and testing techniques for application on trees.

Funding: Christmas tree promotion board

Program/mechanism supporting research/creative efforts: Biology 486 capstone