Italian ryegrass does it better: Effect of Lolium multiflorum on Argentine stem weevil parasitism by Microctonus hyperodae

Abstract

This presentation reports on an extensive field investigation conducted at Lincoln (New Zealand) during the 2014-2015. This aimed to assess the effects of two pasture types (i.e. a tetraploid Lolium multiflorum and diploid L. perenne on parasitism rates by the biological control agent Microctonus hyperodae in Listronotus bonariensis (Argentine stem weevil). Results showed that there were significantly higher field parasitism rates of L. bonariensis in the tetraploid L. multiflorum than in the L. perenne. Moreover, a preliminary laboratory test using the plant species with different orientations (i.e. horizontal or vertical tillers) repeated this result. Whether such findings have any bearing on a possible mechanism for observed resistance by L. bonariensis to M. hyperodae particularly in L. perenne is discussed.