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Rahier, Martine

Nom
Rahier, Martine
Affiliation principale
Fonction
Professeure ordinaire
Email
Martine.Rahier@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/99

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  • Publication
    Accès libre
    Mate Choice and Toxicity in Two Species of Leaf Beetles with Different Types of Chemical Defense
    (2003)
    Labeyrie, Estelle
    ;
    Blanckenhorn, Wolf U.
    ;
    Rahier, Martine 
    Evidence for the use of defensive compounds for sexual purposes is scarce, even though sexual selection might have some importance for the evolution of defensive traits. This study investigates the effect of defense-related traits and body size on mating success in two sister species of leaf beetle differing in their type of chemical defense. Oreina gloriosa produces autogenous cardenolides, whereas O. cacaliae sequesters pyrrolizidine alkaloids from its food plant. Larger O. gloriosa males with more toxin or higher toxin concentration had a mating advantage, likely due to direct or indirect female choice. In the laboratory, particular pairings recurred repeatedly in this species, indicating mate fidelity. O. gloriosa females were also subject to sexual selection, possibly by male choice, because larger females and those with higher toxin concentration mated more readily and more often. In O. cacaliae, in contrast, sexual selection for toxicity and body size was not detected, or at best was much weaker. Because toxicity is heritable in O. gloriosa but environment-dependent in O. cacaliae, individuals of the former species could be choosing well-defended partners with good genes. Our study suggests that sexual selection may contribute to the maintenance of heritable defensive traits.
  • Publication
    Accès libre
    Performance of leaf beetle larvae on sympatric host and non-host plants
    (2000)
    Ballabeni, Pierluigi
    ;
    Rahier, Martine 
    Studies asking the ability of insects to utilize novel host plants often use novel hosts that are allopatric with the insect population under investigation. However, since the outcomes of species interactions are often site-specific, such studies cannot tell us whether a plant would actually be used by a given insect population if the plant grew sympatrically with it. We therefore performed a quantitative genetics experiment to analyse the performance of larvae of the leaf beetle Oreina elongata Suffrian (Coleoptera: Chrysomelidae, Chrysomelinae) on two host and three non-host plants, collected from a site where insects and plants co-occur in the Western Alps. When raised on the non-host Petasites albus (L.), larvae were able to survive equally well as on the two hosts, Adenostyles alliariae (Gouan) and Cirsium spinosissimum (L.), whereas they did not survive on the two other non-hosts, Peucedanum ostruthium (L.) and Rumex alpinus L. On P. albus, growth rate was slightly lower and development time slightly longer than on the two hosts. We found a genotype by environment interaction only for growth rate but not for development time and survival. However, the shape of the reaction norms of growth rates suggests that it is unlikely that selection could favour the inclusion of P. albus into the host range of the study population.Studies asking the ability of insects to utilize novel host plants often use novel hosts that are allopatric with the insect population under investigation. However, since the outcomes of species interactions are often site-specific, such studies cannot tell us whether a plant would actually be used by a given insect population if the plant grew sympatrically with it. We therefore performed a quantitative genetics experiment to analyse the performance of larvae of the leaf beetle Oreina elongata Suffrian (Coleoptera: Chrysomelidae, Chrysomelinae) on two host and three non-host plants, collected from a site where insects and plants co-occur in the Western Alps. When raised on the non-host Petasites albus (L.), larvae were able to survive equally well as on the two hosts, Adenostyles alliariae (Gouan) and Cirsium spinosissimum (L.), whereas they did not survive on the two other non-hosts, Peucedanum ostruthium (L.) and Rumex alpinus L. On P. albus, growth rate was slightly lower and development time slightly longer than on the two hosts. We found a genotype by environment interaction only for growth rate but not for development time and survival. However, the shape of the reaction norms of growth rates suggests that it is unlikely that selection could favour the inclusion of P. albus into the host range of the study population.Studies asking the ability of insects to utilize novel host plants often use novel hosts that are allopatric with the insect population under investigation. However, since the outcomes of species interactions are often site-specific, such studies cannot tell us whether a plant would actually be used by a given insect population if the plant grew sympatrically with it. We therefore performed a quantitative genetics experiment to analyse the performance of larvae of the leaf beetle Oreina elongata Suffrian (Coleoptera: Chrysomelidae, Chrysomelinae) on two host and three non-host plants, collected from a site where insects and plants co-occur in the Western Alps. When raised on the non-host Petasites albus (L.), larvae were able to survive equally well as on the two hosts, Adenostyles alliariae (Gouan) and Cirsium spinosissimum (L.), whereas they did not survive on the two other non-hosts, Peucedanum ostruthium (L.) and Rumex alpinus L. On P. albus, growth rate was slightly lower and development time slightly longer than on the two hosts. We found a genotype by environment interaction only for growth rate but not for development time and survival. However, the shape of the reaction norms of growth rates suggests that it is unlikely that selection could favour the inclusion of P. albus into the host range of the study population.
  • Publication
    Accès libre
    Distribution of genetic variance and isolation by distance in two leaf beetle species: Oreina cacaliae and Oreina speciosissima
    (1998)
    Knoll, Steffi
    ;
    Rahier, Martine 
    The distribution of genetic variance was investigated in two closely related Oreina leaf beetle species, Oreina cacaliae and Oreina speciosissima, Populations of these alpine beetles were sampled in mountainous areas of Western Europe, the total sampling area ranging from the Pyrenees to the Czech Republic. Allozyme electrophoresis of 21 (O. cacaliae) and 16 (O. speciosissima) loci revealed high genetic variability as expressed in a high percentage of polymorphic loci (only one monomorphic locus was found in each species) and high heterozygosities. No overall linkage disequilibrium was found in either species. Extensive heterozygote deficits were observed in several samples as reflected by high FIS-values and high overall inbreeding coefficients (FIT) of 0.349 (O. cacaliae) and 0.503 (O. speciosissima). The overall inbreeding coefficient was mainly attributable to within-population differentiation. The high heterozygote deficits are explained by a combination of inbreeding resulting in kinship groups and a sampling effect over several such kinship groups. No explanation of the observed patterns could be found in the host plant use or altitudinal location of the samples. For O. cacaliae, isolation by distance was found, but not for O. speciosissima. Gene flow estimates were in the range of Nm = 0.8 to 1.5.
  • Publication
    Accès libre
    Selective sequestration and metabolism of plant derived pyrrolizidine alkaloids by chrysomelid leaf beetles
    (1997)
    Hartmann, Thomas
    ;
    Witte, Ludger
    ;
    Ehmke, Adelheid
    ;
    Theuring, Claudine
    ;
    Rahier, Martine 
    ;
    Pasteels, Jacques M.
    Pyrrolizidine alkaloids (PAs) are assumed to function as plant defence compounds against herbivory. A number of adapted insects are known to sequester plant derived PAs for their own benefit. Here we summarize the chemical interactions between leaf beetles of the genus Oreina (Coleoptera, Chrysomelidae) and their host plants Adenostyles spp., Senecio nemorensis, and S. fuchsii (Asteraceae, tribe Senecioneae). Seneciphylline N-oxide and senecionine N-oxide, the main PAs of Adenostyles, are sequestered in the bodies and exocrine defensive glands of the leaf beetles. The comparison with the PA patterns of the Senecio host plant indicates a selective PA uptake. The uptake into the body (hemolymph) is less specific, whereas the translocation into the defensive glands is highly specific. Only the N-oxides of macrocyclic retronecine esters of the senecionine type are found in significant amounts in the defensive secretions. Many other PAs such as monoesters and open-chain diesters as well as PAs of other structural types (e.g. monocrotaline N-oxide and senkirkine) are not transferred into the defensive glands. Leaf beetles sequester PAs exclusively as N-oxides. A novel PA not found in the food plants was detected in the defensive secretions of Oreina elongata; it was identified as 13,19-expoxisenecionine N-oxide (oreine), the epoxidation product of seneciphylline N-oxide. Besides this transformation, leaf beetles are able to catalyse further transformations such as the O-dealkylation of heliotrine N-oxide to rinderine N-oxide and the O-deacetylation of acetylseneciphylline N-oxide to seneciphylline N-oxide. The plant-beetle interactions are discussed in the functional context of PAs as powerful plant defensive chemicals.
  • Publication
    Accès libre
    Reproductive biology of viviparous and oviparous species of the leaf beetle genus Oreina
    (1996)
    Dobler, Susanne
    ;
    Rahier, Martine 
    In five species of the genus Oreina Chevrolat (Coleoptera, Chrysomelidae) we compared the size of offspring, the fecundity of the females, the timing of offspring production and female investment over the season. Two of the species, O. elongata and O. luctuosa, laid eggs, while O. cacaliae, O. gloriosa and O. variabilis gave birth to larvae. Offspring size corrected for female size was similar in the two oviparous species and in the viviparous O. cacaliae. In the two other viviparous species the larvae were two to three times bigger in relation to the female. The greater size of the offspring was not traded off for lower fecundity in these latter two species, yet the production of bigger larvae was associated with a longer laying period and thereby a spreading of reproductive investment over the season. The prediction of life history theory that higher investment in individual offspring should be traded off for lower fecundity could not be confirmed. The investigation of egg and larval development showed that in one of the oviparous species, O. luctuosa, the length of the egg stage was more variable. This corroborates the view that in this species the eggs can be retained for varying times before being laid. Greater size at birth does not necessarily lead to shortened developmental times: the larval periods of O. cacaliae, O. elongata, O. gloriosa and O. variabilis were all comparable although the larvae of the first two species were relatively smaller when laid; only the small larvae of O. luctuosa needed significantly longer for their development. For all growth parameters examined the differences between species were larger than the differences between populations. A comparison of larval growth of the oligophagous species O. cacaliae on three plant genera showed that larval growth rate is influenced by the food plant. However, the plant on which the larvae grew worst is apparently not chosen for oviposition in the field. A comparison with a phylogeny of the species based on allozymes suggests that species with similar reproductive parameters are closely related, yet that viviparity evolved independently in O. cacaliae on one hand and O. variabilis and O. gloriosa on the other.
  • Publication
    Accès libre
    Sequestration of ingested [14C]senecionine N-oxide in the exocrine defensive secretions of chrysomelid beetles
    (1991)
    Ehmke, Adelheid
    ;
    Rahier, Martine 
    ;
    Pasteels, Jacques M.
    ;
    Hartmann, Thomas
    Oreina cacaliae (Chrysomelidae) sequesters in its elytral and pronotal defensive secretion the N-oxides of pyrrolizidine alkaloids (PA N-oxides) from its food plant Adenostyles alliariae (Asteraceae). [14C]Senecionine N-oxide was applied for detailed studies of PA N-oxide sequestration. An average of 11.4% of total radioactivity is taken up by individual beetles which had received [14C]senecionine N-oxide with their food leaves 8 days before. An average of 28.9% of the ingested radioactivity could be recovered from the defensive secretions collected twice, i.e., 5 and 8 days after tracer feeding. The tracer transfer into the secretion seems to be a slow but progressive process as indicated by the high percentage of tracer still recovered from the secretion sampled after 8 days. Chromatographic analysis revealed that [14C]senecionine N-oxide is the only labeled compound in the defensive secretion. Beetles that fed on tertiary [14C]senecionine sequestered only trace amounts of radioactivity (exclusively present as labeled IV-oxide) in their secretions. O. speciosissima, a species also adapted to PA containing food plants, was shown to sequester [14C]senecionine N-oxide with the same efficiency as O. cacaliae. O. bifrons, a specialist feeding on Chaerophyllum hirsutum (Apiaceae), rejected PA treated leaf samples already at very low PA concentrations (10 nmol/leaf piece). In both O. cacaliae and O. speciosissima, [14C]senecionine N-oxide applied by injection into the hemolymph is rapidly transferred into the glands. O. bifrons, not adapted to pyrrolizidine alkaloid containing plants was unable to sequester [14C]-senecionineN- oxide in the secretion but rapidly eliminated the tracer with the frass. Again, only traces of labeled [14C]senecionine N-oxide were found in the defensive secretions of the two PA adapted species if labeled senecionine was injected. It is suggested that the beetles are adapted to the N-oxide form of PAs, similarly as their food plants, and that they lack the ability to efficiently N-oxidize tertiary PAs. No indication forde novo PA synthesis by the beetles was found in tracer feeding experiments with the biogenetic PA precursor putrescine.
  • Publication
    Accès libre
    Sequestration of plant pyrrolizidine alkaloids by chrysomelid beetles and selective transfer into the defensive secretions
    (1991)
    Rahier, Martine 
    ;
    Witte, Ludger
    ;
    Ehmke, Adelheid
    ;
    Hartmann, Thomas
    ;
    Pasteels, Jacques M.
    Oreina cacaliae and O. speciosissima (Coleoptera, Chrysomelidae) sequester in their elytral and pronotal defensive secretions pyrrolizidine alkaloids (PAs) as Noxides (PA N-oxides). The PA N-oxide patterns found in the beetles and their host plants were evaluated qualitatively and quantitatively by capillary gas chromatography/mass spectrometry (GC-MS). Of the three host plants Adenostyles alliariae (Asteraceae) is the exclusive source for PA N-oxide sequestration in the defensive secretions of the beetles. With the exception of O-acetylseneciphylline the N-oxides of all PAs of A. alliariae, i.e. senecionine, seneciphylline, spartioidine, integerrimine, platyphylline and neoplatyphylline were identified in the secretion. PA N-oxides typical of Senecio fuchsii (Asteraceae) were detected in the bodies of the beetles but not in their secretion. No PAs were found in the leaves of the third host plant, Petasites paradoxus (Asteraceae). The results suggest the existence of two distinctive storage compartments for PA N-oxides in the beetle: (1) the defensive secretion, containing specifically PA N-oxides acquired from A. alliariae; (2) the body of the beetle, sequestering additionally but less selectively PA N-oxides from other sources, e.g. S. fuchsii or monocrotaline N-oxide fed in the laboratory. The concentration of PA N-oxides in the defensive secretion is in the range of 0.1 to 0.3 mol/1, which is more than 2.5 orders of magnitude higher than that found in the body of the beetle. No significant differences exist in the ability of the two species of beetles to sequester PA N-oxides from A. alliariae, although O. speciosissima, but not O. cacaliae, produces autogenous cardenolides. A negative correlation seems to exist between the concentrations of plant-derived PA N-oxides andde novo synthesized cardenolides in the defensive secretion of O. speciosissima.
  • Publication
    Accès libre
    Pyrrolizidine alkaloids of probable host-plant origin in the pronotal and elytral secretion of the leaf beetle Oreina cacaliae
    (1988)
    Rahier, Martine 
    ;
    Pasteels, Jacques M.
    ;
    Randoux, T.
    ;
    Braekman, J. C.
    ;
    Daloze, D.
    Oreina cacaliae (Coleoptera, Chrysomelidae) produces in its elytral and pronotal defensive secretion seneciphylline N-oxide together with small amounts of another pyrrolizidine alkaloid tentatively identified as senecionine N-oxide. This is a strong departure from the chemical composition of the defensive secretions in related species, characterized by complex mixtures of cardenolides, synthesized by the beetles from cholesterol. It is suggested that O. cacaliae sequesters the alkaloids from its host-plant, Adenostyles leucophylla. Other specimens of O. cacaliae from far distant populations feeding on Senecio nemorensis, Petasites paradoxus or P. album also produced pyrrolizidine alkaloids, but not O. speciosissima feeding on the same food plants and producing cardenolides. In addition to pyrrolizidine alkaloids, O. cacaliae secretes ethanolamine, which is also found in all the cardenolide-producing species.
  • Publication
    Accès libre
    The chemical ecology of defense in arthropods
    (1983)
    Pasteels, Jacques M.
    ;
    Grégoire, J. C.
    ;
    Rahier, Martine 
    Oreina cacaliae (Coleoptera, Chrysomelidae) produces in its elytral and pronotal defensive secretion seneciphylline N-oxide together with small amounts of another pyrrolizidine alkaloid tentatively identified as senecionine N-oxide. This is a strong departure from the chemical composition of the defensive secretions in related species, characterized by complex mixtures of cardenolides, synthesized by the beetles from cholesterol. It is suggested that O. cacaliae sequesters the alkaloids from its host-plant, Adenostyles leucophylla. Other specimens of O. cacaliae from far distant populations feeding on Senecio nemorensis, Petasites paradoxus or P. album also produced pyrrolizidine alkaloids, but not O. speciosissima feeding on the same food plants and producing cardenolides. In addition to pyrrolizidine alkaloids, O. cacaliae secretes ethanolamine, which is also found in all the cardenolide-producing species.