Biological pest control potential of symbiotic fungal endophytes of cool-season grasses

Epichloe <spacing diaeresis> fungi, which are endophytic, live in symbiotic relationships with many cool-season grasses. These symbiotic relationships change the vegetative, morphological, and physiological traits of the host grasses, which helps them grow and be more resistant to different stresses. This research aimed to explore the biological control of Elm-grass root aphid ( Tetraneura ulmi ) and barley aphid ( Sipha maydis Passerini) in native Iranian tall fescue (utilized in urban green spaces as lawns) naturally infected with Epichloe <spacing diaeresis> endophytic fungi. In the free-choice assay (antixenosis), significant differences were observed between endophyte-infected (E + ) and endophytefree (E - ) clones, with aphids being attracted to E - colonies. Consequently, E + plants exhibited lower susceptibility to S. maydis compared to E - plants. Additionally, E + plants harbored significantly fewer Elm-grass root aphids than E - plants. In the no-choice assay (antibiosis), the mean comparison revealed varied growth times, with Fa 83A-E + and Fa 83A-E - treatments having the shortest (3.62 days) and longest (7.72 days) durations, respectively. Moreover, the reproduction period of aphids in Fa 83A-E + (4.92) was notably lower than Fa 83A-E - (14.60). Fa 83A-E + and Fa 83C-E + treatments had 2.30 and 2.40 nymphs per female per day, respectively, while Fa 83C-E - exhibited the highest rate at 4.0 nymphs. In summary, symbiotic fungi show promise in boosting tall fescue grass resistance to pests, offering potential biological control in urban green spaces.