Reductions in root aphid populations by non-toxic endophyte strains in tall fescue

In two separate pot trials, tall fescue plants infected with the endophyte strain AR542, which is non-toxic to livestock, were shown to have lower numbers of root aphid per plant compared with uninfected plants, but more aphids than plants infected with other non-toxic endophytes (AR502, AR510 and AR514). These differences were not always significant when aphid numbers per gram of root were analysed. A Petri dish trial investigated the mechanism of resistance. Aphid survival was lower on endophyte-free fescue than on AR514- and AR542-infected fescue. Compared with endophyte-free, fewer aphids on roots of AR514- and AR542-infected tall fescue showed signs of feeding, as measured by production of wax and honey dew, and more were mobile on and around roots. Keywords: Aploneura lentisci, Festuca arundinacea, Neotyphodium