Pyrrolizidine alkaloids in Apocynoideae F I [email protected] Michael Boppré, Eva Kaufmann, John A. Edgar Forstzoologisches Institut, Albert-Ludwigs-Universität, D-79085 Freiburg i.Br., Germany Although the available phytochemical data OH OH on species of the Apocynoideae with respect OH O O - to PAs is very limited, as is knowledge on HO H O O H COO O O O lepidopteran associations with these plants, O OH H + there is great potential to provide data of val- N N ue to the current discussions on the taxon- A B N C omy of Apocynoideae. By using 'PA-insects' CH3O Fig. 2 Structures of as bioindicators of 1,2-dehydropyrrolizidine OH lycopsamine (A), ester alkaloids and their N-oxides, in combi- O parsonsine (B), ano- OCH nation with targeted phytochemical studies, H 3 H O dendrine (C), and ala- it is possible to identify phyletic relationships N fine (D), showing the within the Apocynoideae. Adding chemoeco- D diversity of structures A B C D E F G logical data to morphological and molecular of PAs found in Apocynoideae which eventually Fig. 4 TLC (thin-layer chromatography) is an approaches may assist understanding of the should be correlated with systematics appropriate and fairly facile method to check phylogenies of both certain apocynads and plant material for presence of PAs. Material re- certain Lepidoptera as well as of insect-plant genera Echites, Alafia, Aganosma, and quired simply are air-dried plant parts. These relationships. Holarrhena and have demonstrated the chromatograms (A reference PAs; B-C Par- presence of PAs – thus PAs exhibit a sonsia buruensis (leaves, fruit); D-E Prestonia quinquangularis (leaves, roots); F Alafia cau- PAs in Apocynoideae much wider distribution in the Apocyno- data (roots); G Echites sp. (leaves) exemplify PAs are secondary plant compounds, ideae, i.e. outside the Echiteae. Prob- qualitative and quantitative differences in PA- typical of many Asteraceae (e.g. Sene- ably, many more will be found. Lepido- contents between species and organs cio), Boraginaceae (e.g. Heliotropium) ptera can be used as bioindicators. and Fabaceae (Crotalaria). In the Apo- PA-pharmacophagous Lepidoptera cynaceae PAs have, so far, only been Lepidoptera and PAs (Danainae, Ithomiinae, Arctiinae; Fig.1) reported from species of Parsonsia and Many lepidopteran larvae utilize 'PA- search for and take up PAs independent Prestonia (Echiteae). However, in the plants', often specifically. Not many are of nutritional requirements; opportunisti- literature there are hints that PAs occur known to obtain PAs from Apocyno- cally they utilize any source of 1,2-de- in Echites, Alafia, Anodendron, Aga- ideae (Fig. 1) – however, the subject hydropyrrolizidines. These insects store nosma and others. Thorough chemical has not yet gained much attention. studies are, however, missing; thus differences in chemical structures (Fig. Fig. 3 In, e.g., Creatonotos ∠ 2) cannot yet be interpreted in terms gangis (Arctiidae) PAs trigger ∠ morphogenesis of androconial of a pattern and of systematics of the organs, a trait which can be used A B genera. Interestingly, the distribution for bioassays. These Fig. 5 Males of Amauris ochlea (A) and Greta of PAs in different plant parts seems to pictures show core- oto (B) 'feeding' at dry (PA-containing!) roots of vary greatly. mata of a male fed on Alafia and Aganosma sp. respectively artificial diet and those We have started to look in detail of one fed for the last PAs for defense and are usually apose- into additional species of Parsonsia instar with leaves of matic in colour and behaviour. As PAs and Prestonia and particularly into the Aganosma sp. are sealed in cell vacuoles in living plant tissues, PA-pharmacophages visit only A M E R I C A S A S I A , A U S T R A L I A A F R I C A dead or damaged plant material (Fig. 5) Poliopastea Macrocneme ? Pachyloides Composia ? ? ARCTIINAE from which they extract the chemicals larval Euploea Idea — DANAINAE PA-aquisition by applying a fluid and reimbibing it. Observing these butterflies and moths Aeria Tithorea Tellervo ITHOMIINAE at withered parts or wounds of Apocy- noideae is an effective bioassay for the Mesechites ? PRESTONIA Fernaldia Echites PARSONSIA Aganosma Holarrhena ? Alafi a Forsteronia presence of PAs. Mandevilla A p o c y n o i d e a e Thanks Ithomia, Greta, Melinaea Aeria Tithorea — ITHOMIINAE and other genera We are most grateful to S. Liede-Schumann and (indiscriminent) M. Endress for ID of plants and much advice on Lycorea, Danaus Euploea, Danaus, Tirumala Amauris, Danaus, Tirumala DANAINAE adult and other genera and other genera PA-aquisition Apocynaceae s.l., to O.W. Fischer for valuable Belemnia, Argyta, Eucereon and many other genera Amerila and other genera various genera including Amerila ARCTIINAE discussions, and to M. Siegel and K. Krosse for skillfull technical assistance. Fig. 1 Relationships between (larval and adult) Lepidoptera and Apocynoideae containing PAs or presumed to do so. Prestonia and Parsonsia = recognized to contain PAs; Echites, Aganosma, For details see Holarrhena, Alafia = newly found to contain PAs; other genera = not yet studied; recorded Boppré M, Kaufmann E, Edgar JA (2005) Lepidopteran associations; presumed associations; indoor records only; ? = taxa not yet recogni- associations with and pyrrolizidine alkaloids in Apo- zed but suspected to be involved cynoideae (Apocynaceae). In prep. vii/2005 Figure 1 Australasia is incorrect expression; Africa can be made less wide to give room to tropical Americas (more spp. to be added?!) opportunitstic FZI.