Sequestration of Furostanol Saponins by Monophadnus Sawfly Larvae
- 25 January 2007
- journal article
- Published by Springer Science and Business Media LLC in Journal of Chemical Ecology
- Vol. 33 (3), 513-524
- https://doi.org/10.1007/s10886-006-9232-7
Abstract
Sawfly larvae of the tribe Phymatocerini (Hymenoptera: Tenthredinidae), which are specialized on toxic plants in the orders Liliales and Ranunculales, exude a droplet of deterrent hemolymph upon attack by a predator. We investigated whether secondary plant metabolites from Ranunculaceae leaves are sequestered by phymatocerine Monophadnus species, i.e., Monophadnus alpicola feeding upon Pulsatilla alpina and Monophadnus monticola feeding upon Ranunculus lanuginosus. Moreover, two undescribed Monophadnus species were studied: species A collected from Helleborus foetidus and species B collected from Helleborus viridis. Comparative high-performance liquid chromatographic–photodiode array detection–electrospray ionization–mass spectrometric analyses of plant leaf and insect hemolymph extracts revealed the presence of furostanol saponins in all samples. Larvae of species A and B actively sequestered (25R)-26-[(α-l-rhamnopyranosyl)oxy]-22α-methoxyfurost-5-en-3β-yl O-β-d-glucopyranosyl-(1→3)-O-[6-acetyl-β-d-glucopyranosyl-(1→3)]-O-β-d-glucopyranoside (compound 1). This compound occurred at a 65- to 200-fold higher concentration in the hemolymph of the two species (1.6 and 17.5 μmol/g FW, respectively) than in their host plant (0.008 and 0.268 μmol/g FW, respectively). In M. monticola, compound 1 was found at a concentration (1.2 μmol/g FW) similar to that in the host plant (1.36 μmol/g FW). The compound could not be detected consistently in M. alpicola larvae where, however, a related saponin may be present. Additional furostanol saponins were found in H. foetidus and H. viridis, but not in the two Monophadnus species feeding on them, indicating that sequestration of compound 1 is a highly specific process. In laboratory bioassays, crude hemolymph of three Monophadnus species showed a significant feeding deterrent activity against a potential predator, Myrmica rubra ant workers. Isolated furostanol saponins were also active against the ants, at a concentration range similar to that found in the hemolymph. Thus, these compounds seem to play a major role for chemical defense of Monophadnus larvae, although other plant secondary metabolites (glycosylated ecdysteroids) were also detected in their hemolymph. Physiological and ecological implications of the sequestered furostanol saponins are discussed.This publication has 20 references indexed in Scilit:
- Defence effectiveness of easy bleeding sawfly larvae towards invertebrate and avian predatorsChemoecology, 2005
- Furostanol saponins and quercetin glycosides from the leaves of Helleborus viridis L.Phytochemistry, 2004
- Insect Chemical DefensePublished by Springer Science and Business Media LLC ,2004
- Why does the larval integument of some sawfly species disrupt so easily? The harmful hemolymph hypothesisOecologia, 2003
- Host specificity and host recognition in a chemically‐defended herbivore, the tenthredinid sawfly Rhadinoceraea nodicornisEntomologia Experimentalis et Applicata, 2002
- Structural characterization of steroidal saponins by electrospray ionization and fast‐atom bombardment tandem mass spectrometryRapid Communications in Mass Spectrometry, 2002
- Chemo-Ecological Role of Spirostanol Saponins in the Interaction between Plants and InsectsPublished by Springer Science and Business Media LLC ,2000
- Iridoid glycosides ofChelone glabra (Scrophulariaceae) and their sequestration by larvae of a sawfly,Tenthredo grandis (Tenthredinidae)Journal of Chemical Ecology, 1993
- Sequestration of Plant Natural Products by InsectsAnnual Review of Entomology, 1980
- The co-occurrence of ecdysones with bufadienolides and steroidal saponins in the genus HelleborusPhytochemistry, 1976