New Types of Flavonol Oligoglycosides Accumulate in the Hemolymph of Birch-Feeding Sawfly Larvae
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Larvae of nine species of sawflies (Symphyta) were fed with the foliage of three birch species, after which the larval hemolymph composition was studied by HPLC–DAD and HPLC–ESI–MS. The hemolymph of sawfly larvae contained high concentrations of flavonol oligoglycosides (tri-, tetra-, penta-, and hexaglycosides) that could not be found in the larval foliar diet. In addition, there were significant between-sawfly species differences in both flavonoid composition and concentration (from 0.6 to 12.3 mg/ml) of the hemolymph. This suggested that the studied species have different biosynthetic activities for the synthesis of flavonoid oligoglycosides. Variation in the foliar diets did not cause differences in the hemolymph composition. Our hypothesis is that sawflies use foliar flavonoid monoglycosides rather than flavonoid aglycones to produce these new types of oligoglycosides. These findings open up new possibilities for understanding the more holistic role of flavonoids in insect biochemistry and complex interactions between plants and herbivores.
Key WordsSawfly larvae Hemolymph Flavonol oligoglycosides Mass spectrometry
We thank Maarit Karonen and Vladimir Ossipov for their comments on the earlier versions of the manuscript. This work was supported by a grant from Magnus Ehrnrooth Foundation and grant no. 119659 from the Academy of Finland.
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