Larvae of nine species of sawflies (Symphyta) were fed with the foliage of three birch species, a... more 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.
Betula pubescens bud flavonoid aglycones reportedly have negative effects on the performance of f... more 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.
Saproxylic insects play an important part in decomposing dead wood in healthy forest ecosystems, ... more Saproxylic insects play an important part in decomposing dead wood in healthy forest ecosystems, but little is known about their role in the aftermath of large-scale forest mortality caused by pest insect outbreaks. We used window traps to study short-term changes in the abundance and community structure of saproxylic beetles following extensive mortality of mountain birch in sub-arctic northern Norway caused by an outbreak of geometrid moths. Three to five years after the outbreak, the proportion of obligate saproxylic individuals in the beetle community was roughly 10% higher in forest damaged by the outbreak than in undamaged forest. This was mainly due to two early-successional saproxylic beetle species. Facultative saproxylic beetles showed no consistent differences between damaged and undamaged forest. These findings would suggest a weak numerical response of the saproxylic beetle community to the dead wood left by the outbreak. We suggest that species-specific preferences for...
Larvae of nine species of sawflies (Symphyta) were fed with the foliage of three birch species, a... more 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.
Betula pubescens bud flavonoid aglycones reportedly have negative effects on the performance of f... more 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.
Saproxylic insects play an important part in decomposing dead wood in healthy forest ecosystems, ... more Saproxylic insects play an important part in decomposing dead wood in healthy forest ecosystems, but little is known about their role in the aftermath of large-scale forest mortality caused by pest insect outbreaks. We used window traps to study short-term changes in the abundance and community structure of saproxylic beetles following extensive mortality of mountain birch in sub-arctic northern Norway caused by an outbreak of geometrid moths. Three to five years after the outbreak, the proportion of obligate saproxylic individuals in the beetle community was roughly 10% higher in forest damaged by the outbreak than in undamaged forest. This was mainly due to two early-successional saproxylic beetle species. Facultative saproxylic beetles showed no consistent differences between damaged and undamaged forest. These findings would suggest a weak numerical response of the saproxylic beetle community to the dead wood left by the outbreak. We suggest that species-specific preferences for...
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