Previous observations on the effect of endophyte infection in turfgrass on white grub development and natural incidence have been variable and contradictory. We reexamined these white grub-endophyte interactions and expanded them to the previously not studied oriental beetle (Exomala [= Anomala] orientalis Waterhouse). Endophyte infection in strong creeping red fescue (Festuca rubra L. rubra) had no effect on survival and weight gain of neonate Japanese beetle (P. japonica Newman) and E. orientalis larvae in greenhouse pot experiments. In tall fescue (Festuca arundinacea Schreber) in greenhouse pot and in microplot field experiments, endophyte infection had no significant effect on survival and a weak negative effect on weight gain of P. japonica, but reduced E. orientalis survival without affecting its weight gain. In samples taken from tall fescue fields in October, the natural incidence of third instars was higher in endophytic than in nonendophytic turf in 3 of 4 yr. The effect was strongest in oriental beetle and Asiatic garden beetle (Maladera castanea [Arrow]), but generally not significant for Japanese beetle and European chafer (Rhizotrogus majalis [Razoumowsky]). The effect was also more pronounced in samples taken in August 2000 and 2001 among first and second instars (not identified to species) compared with the October samples. Pitfall trap catches in 2002 provided little evidence of endophyte effects on generalist predator activity, suggesting that elevated white grub populations did not result from reduced predation. We hypothesize that ovipositional preferences of adult scarabs could contribute to the higher populations of some white grub species in endophytic versus nonendophytic tall fescue, and that increased efficiency of predation may have contributed to the observed reduction of this difference between August and October. Additional experiments will be required to determine the validity of these hypotheses.
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