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Keywords:

  • sulfonylurea herbicides;
  • indirect effects;
  • plant–insect interactions;
  • Gastrophysa polygoni;
  • Fallopia convolvulus;
  • Pieris brassicae;
  • Sitobium avenae

Abstract

Previous work had shown that the sulfonylurea herbicide chlorsulfuron affected the survival of a herbivorous insect species dwelling on a sub-lethally exposed host plant. Further experiments have been conducted to establish whether this negative effect was a single occurrence characteristic for the specific insect–plant interaction and the specific herbicide tested. Three insect–plant interactions were tested for the effects of selected sulfonylurea herbicides, ie metsulfuron-methyl, chlorsulfuron and tribenuron-methyl. The species pairs tested were Pieris brassicae/Brassica napus, Gastrophysa polygoni/Fallopia convolvulus and Sitobium avenae/Triticum aestivium. No significant effects on survival and relative growth rate of P brassicae or G polygoni were found when treating the host plants with sulfonylurea herbicides. However, the host plants had a significantly reduced root and shoot growth rate when treated with herbicide. Treating T aestivium with the recommended field rate of metsulfuron-methyl did not cause any change in development time, growth rate or fecundity of S avenae feeding on the host plants. The data presented suggest that the increased mortality observed for G polygoni larvae feeding on chlorsulfuron-treated host plants observed earlier was characteristic for this herbicide and for the specific plant–insect interaction only.

© 2001 Society of Chemical Industry