ENHANCED RESISTANCE TO FALL ARMYWORM (LEPIDOPTERA, NOCTUDIAE) IN ACREMONIUM ENDOPHYTE-INFECTED TURFGRASSES

Variation in resistance to insects in Acremonium endophyte-infected turf-grasses was studied using fall armyworms, Spodoptera frugiperda (J. E. Smith), and southern armyworms, Spodoptera eridania (Cramer). Third instars were fed one of three to four genotypes each of five turfgrass species. Development on Acremonium-infected grasses was compared with development on genetically identical endophyte-free controls. No differences in consumption, weight, survival, or developmental time were detected in fall armyworms fed tall fescue, Festuca arundinacea Schreb., infected with Acremonium coenophialum Morgan-Jones & Gams compared with endophyte-free tall fescue. Fall armyworm development was affected to different degrees in larvae fed four genotypes of perennial ryegrass, Lolium perenne L., infected with Acremonium lolii Latch Christensen & Samuels. Fall armyworms fed hard fescue, Festuca longifolia Thuill, and Chewings fescue, Festuca rubra L. subsp. commutata Gaud, infected with Acremonium spp. showed dramatic reductions in larval weight, consumption, and survival relative to endophyte-free controls. Larvae that fed on infected grasses did not survive to pupation. However, development of fall armyworms fed blue fescue, Festuca glauca Lam., infected with Acremonium spp. did not differ from that of those feeding on endophyte-free blue fescue. Endophyte concentration within blue fescue was less than in the hard and Chewings fescues. In contrast to fall armyworms, southern armyworms preferred and had improved development on endophyte-infected tall fescue. These results indicate that endophyte-enhanced resistance varies among and within species of grasses and endophytes. Researchers need to be aware of the potential of endophytes for breeding purposes and as sources of variation in natural populations.