Oreina beetles

Oreina leaf beetles (Chrysomelidae, Coleoptera) synthesize cardenolides as part of their defensive secretions that are released from specialized exocrine glands.139,140 Some Oreina beetles sequester and secrete PAs, which are taken directly as N-oxides from their Asteraceae food plants.59 It is assumed that PA acquisition evolved in species that already possessed the ability to synthesize and store cardenolides for efficient defense.14 O. cacaliae is the only species in this family that lost the ability to synthesize cardenolides autogenously. Instead the plant-derived PA A-oxides are stored in the body (primarily in the hemolymph) and... 

DOBLER, S., MARDULYN, P., PASTEELS, J.M., ROWELL-RAHIER, M Host-plant switches and the evolution of chemical defense and life history in the leaf beetle genus Oreina. Evolution, 1996,50,2373-2386. 

PASTEELS, J.M., DOBLER, S., ROWELL-RAHIER, M., EHMKE, A., HARTMANN, T., Distribution of autogenous and host-derived chemical defenses in Oreina leaf beetles (Coleoptera Chrysomelidae). J. Chem. Ecol., 1995, 21, 1163-1179. 

HSIAO, T.H., PASTEELS, J.M., Evolution of host-plant affiliation and chemical defense in Chrysolina-Oreina leaf beetles as revealed by mtDNA phytogenies, in Advances in Chrysomelidae Biology, (M.L. Cox, ed.), Backhuys, Leiden, Netherlands. 1999, pp. 312-342. 

Monarch butterflies t.g., Danaus plexipus) combine two sets of natural compounds. Larvae feed on plants rich in cardiac glycosides and use them as chemical defense compounds. Adult butterflies visit plants with PAs, where they collect PAs that are converted to pheromones or transferred to their eggs 4,17,31,33,361,515). A similar PA utilization scheme was observed with larvae of the moth Utetheisa ornatrix 367,516), where the compounds were shown to be deterrent for spiders and birds 225, 525). The chrysomelid beetle Oreina feeds on PA-containing plants, such as Adenostyles, and stores the dieUuy PAs in the defense fluid 463,524). 

None of the PAs tested resulted toxic to the chrysomelid L. decemlineata. Oreina (Chrysomelidae) beetles are able to take up plant alkaloid N-oxides and eliminate tertiary PAs, but are unable to N-oxidize tertiary PAs [55, 67, 68]. Similarly, L. decemlineata adults could eliminate tertiary PAs efficiently enough to avoid poisoning. 

Pasteels, j. M., M. Rowell-Rahier, T. Randoux, J. C. Braek-MAN, and D. Daloze, Pyrrolozidine alkaloids of probable host-plant origin in the pronotal and elytral secretion of the leaf beetle Oreina cacaliae, Ent. Exp. Appl, 49, 55-58 (1988). 

Larvae of the chrysomelid beetle Oreina cacaliae produce seniciphylline A -oxide (12) as a part of their defensive secretions. This pyrrolizidine alkaloid probably is derived from the alkaloids of the host plant Adenostyles leucophylla (Asteraceae Senecioneae) (Pasteels et al., 1988). 

Four out of nineteen subfamilies of the Chrysomelidae (leaf beetles) possess pronotal and elytral glands that produce and release defensive compounds [106]. So far, only a few species of the genus Oreina belonging to the subfamily Chrysomelinae are known to sequester PAs from their host plants [107]. Chemical defense in chrysomelines is primarily autogenous. Thus, Oreina species feeding on Asteraceae, tribe Senecioneae appear to have moved secondarily to host-derived defense [108]. 

The observed switch of Oreina leaf beetles from their original mode of defense (i. e., antogenous production of cardenolides) to host-derived defense (i.e., sequestration of PAs) intensified the discussion about the evolution of host plant affiliation and chemical defense in leaf beetles [108,115]. Evolutionary scenarios favor the role of PAs as efficient defensive compound. Recently, it was... 

Kalberer NM, Turlings TCJ, Rahier M (2001) Attraction of a leaf beetle Oreina cacaliae) to damaged host plants. J Chem Ecol 27 647-6... 

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