Enhanced Resistance to Three Species of Aphids (Homoptera: Aphididae) in Acremonium Endophyte-Infected Turfgrasses

Abstract

Association of Acremonium endophytes with enhanced resistance to insects in various turfgrasses was studied using three species of aphids; greenbug, Schizaphis graminum (Rondani); bird cherry-oat aphid, Rhopalosiphum padi (L.); and yellow sugarcane aphid, Sipha flava (Forbes). Choice and no-choice tests were used to test resistance in three to four genotypes each of endophyte-infected and endophyte-free perennial ryegrass, Lolium perenne L.; tall fescue, Festuca arundinacea Schreb.; and three species of fine fescues: hard fescue, F. longifolia Thuill; Chewings fescue, F. rubra L. subsp. commutate Gaud.; and blue fescue, F. glauca Lam. Feeding deterrence and antibiosis were significant in endophyte-infected tall fescue for all turfgrass genotypes and aphids tested, with no aphids surviving after 3 d on infected tall fescue. Feeding deterrence and antibiosis to greenbug and yellow sugarcane aphid were significant in endophyte-infected perennial ryegrass with all genotypes tested. None survived on endophyte-infected perennial ryegrass after 72 h. Resistance to bird cherry-oat aphid was dependent on concentration of endophyte hyphae in the host, with significant resistance observed in genotypes with high concentrations. Resistance in endophyte-infected fine-leaved fescues varied with insect and grass species. Preference was generally not significantly affected, but dramatic differences in survival were found in ‘Ensylva’ strong creeping red fescue, blue fescues, Chewings fescues, and hard fescues. Endophyte-enhanced resistance to insects varies between species of grasses and insects, and within species of grasses, suggesting that each endophyte or endophyte-host genotype complex should be evaluated individually.