3-Acetoxy-fatty acid isoprenyl esters from androconia of the ithomiine butterfly Ithomia salapia
|Author(s)||Mann Florian1, Szczerbowski Daiane1, de Silva Lisa2, McClure Melanie2, 3, Elias Marianne2, Schulz Stefan1|
|Affiliation(s)||1 : Institute of Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
2 : Institut de Systématique Evolution Biodiversité, Centre National de la Recherche Scientifique, MNHN, Sorbonne Université, EPHE, Université des Antilles, 45 rue Buffon, CP 50, 75005 Paris, France
3 : Laboratoire Écologie, Évolution, Interactions des Systèmes Amazoniens (LEEISA), Université de Guyane, CNRS, IFREMER, 97300 Cayenne, France
|Source||Beilstein Journal Of Organic Chemistry (1860-5397) (Beilstein Institut), 2020-11 , Vol. 16 , P. 2776-2787|
|Keyword(s)||fatty acid esters, mass spectrometry, mimicry, pheromones, pyrrolizidine alkaloids|
Male ithomiine butterflies (Nymphalidae: Danainae) have hairpencils on the forewings (i.e. androconia) that disseminate semiochemicals during courtship. While most ithomiines are known to contain derivatives of pyrrolizidine alkaloids, dihydropyrrolizines or g-lactones in these androconia, here we report on a new class of fatty acid esters identified in two subspecies, Ithomia salapia aquinia and I. s. derasa. The major components were identified as isoprenyl (3-methyl-3-butenyl) (Z)-3-acetyloxy-11-octadecenoate, isoprenyl (Z)-3-acetyloxy-13-octadecenoate (12) and isoprenyl 3-acetyloxyoctadecanoate (11) by GC/MS- and GC/IR-analyses, microderivatizations, and synthesis of representative compounds. The absolute configuration of 12 was determined to be R. The two subspecies differed not only in the composition of the ester bouquet, but also in the composition of more volatile androconial constituents. While some individuals of I. s. aquinia contained ithomiolide A, a PA derived g-lactone, I. s. derasa carried the sesquiterpene a-elemol in the androconia. These differences might be important for the reproductive isolation of the two subspecies, in line with previously reported low gene exchange between the two species in regions where they co-occur. Furthermore, the occurrence of positional isomers of unsaturated fatty acid derivatives indicates activity of two different desaturases within these butterflies, D9 and D11, which has not been reported before in male Lepidoptera.