title: Weak responses of pine sawfly larvae to high needle flavonoid concentrations in scots pine.
abstract: Responses of sawfly larvae (Hymenoptera, Diprionidae) to the flavonoid taxifolin glucoside in their host plant were studied in a laboratory experiment. Larvae ofNeodiprion sertifer andDiprion pini were raised from egg hatch to cocoon spinning on two Scots pine (Pinus sylvestris) chemotypes, one without needle taxifolin glucoside (-) and the other containing 2-4% taxifolin glucoside (+). The (+) chemotype had somewhat lower concentrations of needle terpenoids (resin acids) than the (-) chemotype. Current-year needles had higher taxifolin glucoside concentrations than mature needles. There were no differences in survival or body size betweenN. sertifer larvae that fed on the (+) chemotype and those that fed on the (-) chemotype. FemaleD. pini larvae raised on (+) needles developed 6% more slowly than larvae fed (-) needles. The results from this study are contrary to earlier findings showing that flavonoid glucosides have strong negative effects on insect performance. Possible explanations for the different outcomes are discussed.
authors.affiliation: Department of Plant and Forest Protection, Swedish University of Agricultural Sciences, P.O. Box 7044, S-750 07, Uppsala, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Larsson
authors.forename: L
authors.initials: L
authors.lastname: Lundgren
authors.forename: C P
authors.initials: CP
authors.lastname: Ohmart
authors.forename: R
authors.initials: R
authors.lastname: Gref