hwa

HEMLOCK WOOLLY ADELGID (HWA). This destructive introduced pest is a major threat to eastern and Carolina hemlock trees throughout their range. It presently infests trees in 11 eastern states and is causing significant mortality of hemlocks in forests and urban communities. Few options are available for control of this pest. The use of pesticides is limited because in forested lands, hemlocks often grow along streams, swamps, or lakes and the threat of aquatic pollution is great. In urban communities the general public does not favor the use of these materials. Alternative management options are needed and the potential use of entomopathogenic fungi is a viable tool for consideration.
Photo: M.S. McClure

What are we doing?

Pathogenicity trials. Isolates have been screened for pathogenicity against thrips, aphids and HWA.

Isolation and identification. All fungi discovered were isolated, established in pure culture and identified.

Exploration. Cooperative efforts in ME, MA, CT, NJ and VA led to the isolation of many insect-killing fungi associated with HWA populations. Exploratory activities were also conducted in China where HWA originated.

Characterization. Isolates have been evaluated to determine their growth, sporulation and germination characteristics.

Biological studies. Hypothesizing that range expansion of HWA is limited, trials were designed to determine the low lethal temperatures of this pest. Tests are also being done to ascertain if HWA populations from different plant coldhardiness zones respond differently to low temperature exposures.

Major accomplishments with HWA

Determined low lethal temperatures for HWA.

Published 3 manuscripts in peer reviewed journals.

Isolated 64 indigenous insect-killing fungi of HWA.

Isolated 36 insect-killing fungi of HWA from China.

Conducted pathogenicity trials of indigenous species.

Selected 6 promising fungal isolates for further development.

Initiated characterization studies at various temperatures and rH.

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WHAT YOU SHOULD KNOW ABOUT THE HEMLOCK WOOLLY ADELGID
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