RESPONSE OF PLANT-FEEDING, PREDATORY, AND SOIL-INHABITING INVERTEBRATES TO ACREMONIUM ENDOPHYTE AND NITROGEN-FERTILIZATION IN TALL FESCUE TURF

The endophytic fungus Acremonium coenophialum Morgan-Jones and Gams co nveys resistance to herbivory in tall fescue, Festuca arundinacea Schr eber. In contrast, nitrogen fertilization generally enhances plant qua lity for herbivores. We studied the main effects and interaction of A. coenophialum and fertilization on plant-feeding, predatory, and soil- dwelling invertebrates in tall fescue turf. Fall armyworms, Spodoptera frugiperda (J. E. Smith), developed faster when reared on foliage fro m plots treated with medium or high rates of urea than on unfertilized tall fescue, but development rates were not affected by A. coenophial um. Greenbugs, Schizaphis graminum Rondani, preferred fertilized, endo phyte-free fescue over nonfertilized, endophyte-free grass. Similarly bird cherry-oat aphids, Rhopalosiphum padi (L.), developed fastest on fertilized, endophyte-free tall fescue. Fertilization, however, did no t override the strong, adverse effects of A. coenophialum on both aphi d species. In field plots, densities of leafhoppers, flea beetles, and Staphylinidae were generally higher in fertilized than in nonfertiliz ed turf. Flea beetles and two of the five most abundant species of lea fhoppers were less numerous in endophyte-infected plots. Predatory art hropods, earthworms, oribatid mites, and Japanese beetle grubs were eq ually abundant in endophyte-infected and endophyte-free plots. Fertili zation did not affect tile densities of oribatids or P. japonica, but earthworms were more abundant in fertilized plots on some dates. Resul ts showed variable main effects, and an absence of interactive effects of A. coenophialum and fertilization on invertebrates in tall fescue. Fertilization of tall fescue probably will not nullify the benefits o f endophyte-enhanced resistance.