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

Abstract

This paper reports on an extensive field investigation conducted at Lincoln during the 2014-2015 summer/early autumn. This aimed to assess the effects of a range of novel Epichloë endophytes when present in different cultivars of Lolium spp. on parasitism rates by the biological control agent, Microctonus hyperodae, in Listronotus bonariensis (i.e. The Argentine stem weevil). Results for the entire summer, and including all treatment combinations, did not find any significant differences in parasitism in L. bonariensis populations. However, in the early autumn, independent of 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 finding has any bearing on a possible mechanism of weevil resistance is discussed.