Abstract
In this study, the larval sequestration abilities and
defense effectiveness of four sawfly species of the genus
Athalia (Hymenoptera: Tenthredinidae) that feed as larvae
either on members of the Brassicaceae or Plantaginaceae
were investigated. Brassicaceae are characterized by glucosinolates (GLSs), whereas Plantaginaceae contain iridoid glucosides (IGs) as characteristic secondary compounds. Athalia rosae and A. liberta feed on members of the Brassicaceae. Larvae of A. rosae sequester aromatic and
aliphatic GLSs of Sinapis alba in their hemolymph, as
shown previously, but no indolic GLSs; A. liberta larvae
with a narrower host range sequester aliphatic as well as
indolic GLSs from their host plant Alliaria petiolata.
Larvae of A. circularis and A. cordata are specialized on
members of the Plantaginaceae. Athalia circularis utilizes
mainly Veronica beccabunga as host plant, whereas A.
cordata feeds additionally on Plantago lanceolata. Both
sawfly species sequester the IGs aucubin and catalpol. In V.
beccabunga, catalpol esters and carboxylated IGs also
occur. The high catalpol concentrations in hemolymph of
A. circularis can only be explained by a metabolization of
catalpol esters and subsequent uptake of the resulting
catalpol. The carboxylated IGs of the plant are excreted.
The IG-sequestering sawfly species are able to accumulate
much higher glucoside concentrations in their hemolymph
than the GLS-sequestering species, and the concentration of
IGs in hemolymph increases constantly during larval
development. The defensive effectiveness of hemolymph
that contains GLSs or IGs and of the respective glucosides
was tested in feeding-bioassays against a potential predator, the ant Myrmica rubra (Hymenoptera: Formicidae). Hemolymph of IG-sequestering cryptic A. cordata larvae has a
higher deterrence potential than hemolymph of the GLSsequestering conspicuous A. rosae larvae. The results show that glucoside sequestration is widespread in the genus
Athalia, but that the specific glucoside uptake can result in different defense effectiveness against a predator species.
Original language | English |
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Journal | Journal of Chemical Ecology |
Volume | 36 |
Issue number | 2 |
Pages (from-to) | 148-157 |
ISSN | 0098-0331 |
DOIs | |
Publication status | Published - 2010 |
Keywords
- Tenthredinidae
- Hemolymph
- Iridoid glucosides
- Defense
- Sequestration
- Glucosinolates