Argentine stem weevil adults are affected by meadow fescue endophyte and its loline alkaloids

Abstract

Responses of adult Argentine stem weevil (ASW) to meadow fescue infected with the endophyte Neotyphodium uncinatum and to two loline alkaloids produced by the fungus were investigated. Endophyte in two different meadow fescue seed-lines did not affect adult ASW feeding scores but reduced oviposition compared with endophyte-free controls. In a no-choice experiment, adult ASW were given artificial diets containing N-formyl loline (NFL) or N-acetyl norloline (NANL) at three concentrations or a control diet with no lolines. Mortality was significantly higher at the highest rate of NFL than for lower rates and the control. For NANL, mortality was increased at both the lowest and the highest concentrations. Feeding scores were higher on control than loline diets but only after 4 weeks. In a choice experiment, NFL appeared to have no effect on ASW feeding preference, whereas there was less feeding at the highest concentration of NANL compared with the control diet.