Newly hatched neonate larvae can glycosylate: the fate of Betula pubescens bud flavonoids in first instar Epirrita autumnata.

Betula pubescens bud flavonoid aglycones reportedly have negative effects on the performance of first instar Epirrita autumnata and, thus, may defend birch leaves from larval defoliation. We hypothesized that the detrimental effects of these lipophilic flavonoids on larvae are due to their high levels in birch buds and/or the inability of naïve neonates to glycosylate them, which we have shown to occur in fifth instars. To test the latter hypothesis, we investigated the biochemical transformation of bud flavonoids in first instar E. autumnata. We found that newly hatched larvae have the ability to glycosylate birch bud/leaf flavonoid aglycones into corresponding glycosides. Moreover, we suggest that glycosylation may depend upon the chemical character of the aglycone and is an important factor in the performance of first instars.