Effect of Epichloë endophyte strains in Lolium spp. cultivars on Argentine stem weevil parasitism by Microctonus hyperodae

This contribution reports on an extensive field investigation conducted at Lincoln during the 2014-2015 summer/early autumn. This aimed to assess the effects of combinations of novel Epichloë endophytes in Lolium spp. cultivars on parasitism rates by the biological control agent, Microctonus hyperodae in the Argentine stem weevil. Taken across the entire summer, and considering all treatment combinations, no significant differences in parasitism were found in Listronotus bonariensis populations. However, in the early autumn, independent to the endophytes present, significantly higher levels of parasitism were found in a tetraploid Lolium multiflorum cultivar and a tetraploid L. perenne selection compared to the L. perenne cultivars. Whether this has any bearing on a possible mechanism of resistance is discussed.