Chemical defense in chrysomelid leaf beetles

Pasteels, Jacques; Eggenberger, F.; Rowell‐Rahier, Martine; Ehmke, Adelheid; Hartmann, Thomas

doi:10.1007/bf01135774

Cited by 63 publications

(51 citation statements)

References 5 publications

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“…One species, 0. cacaliae, has even lost the ability to autogenously produce cardenolides for defense but instead accumulates pyrrolizidine alkaloid N-oxides acquired from its food plant in its defensive secretion (Pasteels et al, 1996). These beetles were found to be better protected against predation by birds than a closely related species which secretes autogenous cardenolides (Rowell-Rahier et al, 1995 …”

Section: Discussionmentioning

confidence: 99%

“…Recent investigations revealed that in a number of alkaloid-sequestering species pyrrolizidine alkaloids are exclusively stored as N-oxides, e.g. Arctiidae (Ehmke et al, 1990;Hartmann et al, 1990;Trigo et al, 1993), Ithomiinae (Trigo et al, 1996), Orthoptera (Biller at al., 1994), chrysomelid leaf beetles (Pasteels et al, 1988(Pasteels et al, , 1996Hartmann et al, 1997). These findings indicate that storage of pyrrolizidine alkaloids as N-oxides must be advantageous to the sequestering species.…”

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confidence: 93%

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The two Faces of Pyrrolizidine Alkaloids: the Role of the Tertiary Amine and its N‐Oxide in Chemical Defense of Insects with Acquired Plant Alkaloids

Lindigkeit

Biller

Buch

et al. 1997

European Journal of Biochemistry

133

119

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Larvae of Creatonotos transiens (Lepidoptera, Arctiidae) and Zonocerus variegatus (Orthoptera, Pyrgomorphidae) ingest 14C-labeled senecionine and its N-oxide with the same efficiency but sequester the two tracers exclusively as N-oxide. Larvae of the non-sequestering Spodoptera littoralis eliminate efficiently the ingested alkaloids. During feeding on the two alkaloidal forms transient levels of senecionine (but not of the N-oxide) are built up in the haemolymph of S. littoralis larvae. Based on these results, senecionine [*80]N-o~ide was fed to C. transiens larvae and Z. variegatus adults. The senecionine Noxide recovered from the haemolymph of the two insects shows an almost complete loss of "0 label, indicating reduction of the orally fed N-oxide in the guts, uptake of the tertiary alkaloid and its re-N-oxidation in the haemolymph. The enzyme responsible for N-oxidation is a soluble mixed function monooxygenase. It was isolated from the haemolymph of the sequestering arctiid Tyria jacobaeue and purified to electrophoretic homogeneity. The enzyme is a flavoprotein with a native M , of 200000 and a subunit M , of 51 000. It shows a pH optimum at 7.0, has its maximal activity at a temperature of 40-45°C and an isoelectric point at pH 4.9. The reaction is strictly NADPH-dependent (K,,, 1.3 pM). From 20 pyrrolizidine alkaloids so far tested as substrates, the enyzme N-oxidizes only alkaloids with structural elements which are essential for hepatotoxic and genotoxic pyrrolizidine alkaloids (i.e. 1,2-double bond, esterification of the allylic hydroxyl group, presence of a second free or esterified hydroxyl group at carbon 7). A great variety of related alkaloids and xenobiotics were tested as substrate, none was accepted. The K, values of senecionine, monocrotaline and heliotrine, representing the three main types of pyrrolizidine alkaloids, are 1.3 pM, 12.5 pM and 290 pM, respectively. The novel enzyme was named senecionine N-oxygenase (SNO). The enzyme was partially purified from two other arctiids. The three SNOs show the same general substrate specificity but differ in their affinities towards the main structural types of pyrrolizidine alkaloids. The enzymes from the two generalists (Creatonotos transiens and Arctia caja) display a broader substrate affinity than the enzyme from the specialist (Tyria jacobaeae). The two molecular forms of pyrrolizidine alkaloids, the lipophilic protoxic tertiary amine and its hydrophilic nontoxic N-oxide are discussed in respect to their bioactivation and detoxification in mammals and their role as defensive chemicals in specialized insects. Pyrrolizidine-alkaloid-sequestering insects store the alkaloids as nontoxic N-oxides which are reduced in the guts of any potential insectivore. The lipophilic tertiary alkaloid is absorbed passively and then bioactivated by cytochrome P-450 oxidase.Keywords: Tyria jacobaeae (Lepidoptera, Arctiidae) ; pyrrolizidine alkaloid; alkaloid uptake; senecionine N-oxygenase ; chemical defense.Pyrrolizidine alkaloids are unique among the some 20 000 p...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 93%

The two Faces of Pyrrolizidine Alkaloids: the Role of the Tertiary Amine and its N‐Oxide in Chemical Defense of Insects with Acquired Plant Alkaloids

Lindigkeit

Biller

Buch

et al. 1997

European Journal of Biochemistry

133

119

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“…These beetles aggregate apparently for mating purposes and/or a joint rapid exploitation of plants, which reduced exposure to plant defence compounds. It has also been proposed that aggregation helps the beetles to make more efficient use of plant secondary compounds for their own defence (Birch, 1984;Pasteels et al, 1988). These benefits may outweigh detrimental effects such as the risk of attracting natural enemies.…”

Section: Discussionmentioning

confidence: 99%

Herbivore‐induced emissions of maize volatiles repel the corn leaf aphid, Rhopalosiphum maidis

Bernasconi

Turlings

Ambrosetti

et al. 1998

Entomologia Exp Applicata

227

155

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When maize plants, Zea mays L., are mechanically damaged and the damaged sites are treated with caterpillar regurgitant, the plants will release a specific blend of volatiles. It is known that these volatiles can be attractive to natural enemies of herbivores. We hypothesise that the plant volatiles constitute part of the induced plant defence and that herbivores will be affected by the odours as well. In laboratory and semi-field studies this hypothesis was tested for the aphid Rhopalosiphum maidis (Fitch) (Rhynchota, Sternorrhyncha, Aphididae).In a Y-tube olfactometer significantly more aphids chose the odour of healthy, undamaged maize seedlings when tested against clean air or plants treated with regurgitant. Clean air was chosen more often when tested next to the odour of treated plants. This apparently repellent effect of the odour of treated plants was significant for winged aphids, but not for the wingless aphids.In field experiments aphids were released in the centre of circles of eight potted maize plants. Four plants in each circle were damaged and treated with caterpillar regurgitant while the other plants were left unharmed. At different intervals after aphid release, the number of aphids was counted on each plant. Significantly fewer winged and wingless aphids were found back on treated plants than on healthy plants.We suggest that herbivores may be repelled by the odours because they could indicate that: 1) the plant has initiated the production of toxic compounds; 2) potential competitors are present on the plant; 3) the plant is attractive to parasitoids and predators. Aphids may be particularly sensitive to induced maize volatiles because one of the major compounds emitted by the plant is (E)-β-farnesene, which is a common alarm pheromone for aphids. Collections and analyses of the odours emitted by crushed R. maidis confirmed that it too emits (E)-β-farnesene when stressed. The results are discussed in context of plant defence strategies and their possible exploitation for the control of pest insects.

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“…We suggest that such transitions among single-defence metabolisms via a dual chemical strategy is a general pattern in the evolution of chemical defence and host-plant affiliation, as it was observed in three independent lineages characterized by very different chemistries (Hsiao & Pasteels 1999;Termonia et al 2001;this study). Furthermore, quantitative gas chromatographymass spectrometry analyses (Pasteels et al 1996;Termonia & Pasteels 1999) indicated that some leaf beetles exhibiting a dual defence are able to downregulate one of the two defensive metabolisms according to the relative proportions of plant precursors available in the host. If such regulation is indeed adaptive, the dual defence could be a somewhat unstable state, albeit requisite to shifts among more specialized ecological states (i.e.…”

Section: Discussionmentioning

confidence: 99%

Dual chemical sequestration: a key mechanism in transitions among ecological specialization

Termonia

Pasteels²,

Windsor

et al. 2002

Proc. R. Soc. Lond. B

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Platyphora leaf beetles form a vast group of tropical species each feeding on a restricted set of host plants and exhibiting bright coloration warning predators against their chemical protection. These beetles offer an exceptional opportunity for understanding the evolution of phytochemical sequestration. Indeed, qualitative studies of defensive secretions indicate that Platyphora species acquire toxicity via sequestration of plant secondary metabolites. All produce pentacyclic triterpene saponins from sequestered plant amyrins, but our analyses also indicate that many Platyphora species produce a dual chemical defence, that is, they are additionally protected by lycopsamine-type pyrolyzidine alkaloids that they also sequester from their host. This paper reports on the evolution of chemical defence and host affiliation in Platyphora leaf beetles as reconstructed on a molecular phylogeny of mitochondrial and nuclear DNA sequences. The analyses indicate that dual sequestration could be the key mechanistic means by which transitions among ecological specializations (i.e. restricted host-plant affiliations) are made possible.

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Chemical defense in chrysomelid leaf beetles

Cited by 63 publications

References 5 publications

The two Faces of Pyrrolizidine Alkaloids: the Role of the Tertiary Amine and its N‐Oxide in Chemical Defense of Insects with Acquired Plant Alkaloids

The two Faces of Pyrrolizidine Alkaloids: the Role of the Tertiary Amine and its N‐Oxide in Chemical Defense of Insects with Acquired Plant Alkaloids

Herbivore‐induced emissions of maize volatiles repel the corn leaf aphid, Rhopalosiphum maidis

Dual chemical sequestration: a key mechanism in transitions among ecological specialization

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