Endophyte-Enhanced Resistance in Perennial Ryegrass and Tall Fescue to Bluegrass Webworm, Parapediasia teterrella

Abstract

Perennial ryegrass cultivars grown in field plots were assessed for damage caused by the bluegrass webworm, Parapediasia teterrella. Cultivars infected with an Acremonium endophyte were hardly damaged, and no larvae were detected in these plots. By contrast, plots of endophyte-free cultivars were extensively damaged by feeding webworm, and contained larvae. Laboratory feeding assay using petri dishes showed an endophyte inhibitory effect with seedlings as young as 3-day old. A choice test showed that bluegrass webworm larvae prefer endophyte-free ryegrass leaves to those infected with the Acremonium endophyte. First instar larvae fed on endophyte-infected perennial ryegrass had lower survival rates than those fed on endophyte-free plants. Death may result from starvation because larvae will not eat infected leaves. Tall fescue plants infected with an Acremonium endophyte also showed resistance to the bluegrass webworm, but resistance was confined to the leaf sheaths.