Resistance to Argentine stem weevil in perennial ryegrass infected with endophytes producing different alkaloids.
Four pot trials were carried out to test the ability of endophytes which produce different alkaloids, to reduce feeding and oviposition by adults of Listronotus bonariensis and larval damage on Nui or Ruanui perennial ryegrass (Lolium perenne). Nui ryegrass with the wild type endophytes which produce peramine, ergovaline and lolitrem B, and two endophytes which produce peramine, but not ergovaline or lolitrem B, had lower adult feeding and oviposition than endophyte-free plants or plants infected with an endophyte (AR37) which produces none of these alkaloids. An endophyte which produces ergovaline, but not peramine or lolitrem B, had a small effect on adult feeding and may reduce oviposition. The wild type and AR37 endophytes, and one of the three endophytes producing peramine, but not lolitrem B or ergovaline, reduced larval tiller damage. Of the peramine-producing endophytes resistance was lowest where mean peramine concn was lowest and highest where mean peramine concn was highest. A significant relationship between peramine and adult feeding was found.