Notizen 841 Specificity of Synthetic Sex-Attractants confirmed the specific effect of Zll-14:Ac on in Zygaena M oths Z. hippocrepidis males. These authors also demon­ strated high EAG responses of male Z. fdipendulae Ernst Priesner L. to the lepidopteran pheromone (Z)-7-dodecenyl Max-Planck-Institut für Verhaltensphysiologie, acetate (Z7-12:Ac) but failed to attract males of this D-8131 Seewiesen species to synthetic test chemicals in olfactometer Clas M. Naumann* and Johannes Stertenbrink and field tests [1 0 ]. Fakultät für Biologie der Universität, D-4800 Bielefeld We have studied sex-attractant systems through­ out western Palearctic Zygaena moths. In each Z. Naturforsch. 39 c, 841 - 844 (1984); received May 4, 1984 species, the male antennal Sensilla trichodea (generally known to contain pheromone-sensitive Sex-Attractants, Pheromones, (Z)-Alkenyl Acetates, receptor cells in the Lepidoptera) were analyzed Olfactory Receptors, Zygaena, Zygaenidae electrophysiologically with respect to the different Species-specific sex-attractants are reported for western Palearctic Zygaena moths of the carniolica, viciae, fili- cell types present, using test chemicals and experi­ pendulae, and purpuralis species groups. The attractants mental procedures as in similar work on other were established by combined electrophysiological and moths [11]. The “key compounds” of the different field behavioural studies and consist of ternary com­ binations of (Z)-7-dodecenyl/(Z)-9-tetradecenyl acetates cell types found were subsequently exposed in the with a particular further (Z)-alkenyl acetate. Data on field in varying mixture combinations; those mix­ other Zygaenini taxa are included. tures that showed attractancy were further modi­ fied, until response maximum was reached. The distribution of the approx. 100 valid species In some species the type A cell [12] of the of the genus Zygaena F. (“burnet m oths”) is ex­ receptor system responded specifically to Zll-14:Ac. clusively limited to the Palearctic faunal region This pattern applied to Z. transalpina, hippocrepidis, [1-3]. Related genera are found in the Oriental and angelicae and ephialtes (mentioned above), and also Ethiopian faunal regions; all of these form the to Z. dorycnii Ochs., loti Den. et Schiff., armena Ev., monophyletic tribe Zygaenini [3, 4], Usually and laeta Hbn. In some other species, including Zygaena species are day-flying moths, with the Z. hilaris Ochs, and fausta L., receptor systems with period of flight limited to 3-4 weeks in the the type A cell specific to the (£)-11 isomer, summer months. The adult moths have an apo- £ll-14:Ac, were found. The single cell and field sematic pattern which makes field observations on trapping data obtained on these species will be population density and flight behaviour rather considered elsewhere. easy [5, 6 ]. Here we report on a group of Zygaena moths in The chemical composition of the female sex which the type A cell of the pheromone receptor pheromone is unknown for any species of the system responded specifically to either Z7-12:Ac or Zygaenini tribe. However, several authors have the longer-chain homologue, Z9-14:Ac. The species reported captures of Zygaena males in sticky traps studied included: Z. fdipendulae L., trifolii Esp., baited with synthetic pheromones of other lonicerae Schev., viciae Den. et Schiff., lavandulae Lepidoptera. Thus, (Z)-l 1-tetradecenyl acetate Esp., anthyllidis Bsd., exulans Hoch., romeo Dup., (Zll-14:Ac), alone or in combination with the osterodensis Reiss, rhadamanthus Esp., sarpedon corresponding alcohol or (£')-ll isomer, was found Hbn., thevestis Stgr., tamara Chr., minos Den. et to attract males of the four closely-related species Schiff., purpuralis Brünn, and carniolica Scop. To Z. transalpina Esp., hippocrepidis Hbn., angelicae the best of our knowledge, males of these species Ochs, and ephialtes L. [7-9]. Renou and Decamps have not previously been attracted to synthetic com­ [10] provided electroantennogram (EAG) data that pounds in laboratory or field tests. For 12 Zygaena species and two members of the closely related genera Reissita and Epizygaenella the * 35th contribution to the knowledge o f the genus Zygaena Fabricius 1775 and related genera (Insecta, specific cell type combinations found are listed in Lepidoptera, Zygaenidae). Table I. Each of the seven cell types involved Reprint requests to E. Priesner or C. M. Naumann. responded specifically to a particular (Z)-alkenyl 0341-0382/84/0700-0841 $01.30/0 acetate, viz. (Z)-5-, (Z)-7- and (Z)-9-dodecenyl 842 Notizen Table I. Cell type combinations in male olfactory hair sensilla3, and composition of optimized synthetic sex-attractant, for selected species of Zygaena, Reissita and Epizygaenella. Test species Specialist receptor cell forb Synthetic attractant Z5-12: Z7-12; Z9-12: Z7-14: Z9-14: Z ll-1 4 : Z ll-1 6 : Ac Ac Ac Ac Ac Ac Ac Z. filipendulae x xA X Z 5 -12:A c/Z 7-12:Ac, Z9-14:Ac, ratio 3/100/10 Z. trifolii X xA ? X same compounds, ratio 100/100/30 (100/100/10) Z. lonicerae X xA X Z. viciae X xA X ? same compounds, ratio 10/100/10 Z. anthyllidis ? xA ? X Z. exulans XX xA Z. sarpedon XX xA Z. thevestis X xA X Z. tamara xA X XX Z. minos X 9 xA X Z. purpuralis xA ? X X Z 7 -12: Ac /Z 7 -14: Ac /Z 9 -14: Ac, ratio 100/10/100 Z. carniolica xA XX X Z 7 -12:A c/Z 9-14: Ac /Z 11 -16: Ac, ratio 100/30/3 R. simonyi X ? xA X E. caschmirensis ? xA X X a x, presence of cell type fully established (A, type A cell of receptor system); ?, questionable evidence; empty space, cell type not found in indicated species. b The seven (Z)-alkenyl acetates are listed with first the position of the olefinic double bond and secondly the number (— 12 till — 16) of C atoms in the alcohol moiety. acetate (Z5-12:Ac, Z7-12:Ac, Z9-12:Ac); (Z)-7-, yet unidentified female pheromones of these (Z)-9- and (Z)-l 1-tetradecenyl acetate (Z7-14:Ac, species. All 16 species listed had receptor cells for Z9-14:Ac, Zll-14:Ac); and (Z)-l 1-hexadecenyl both Z7-12:Ac and Z9-14:Ac, combined with 1 or 2 acetate (Zll-16:Ac). There was no evidence for any further cell types in each species (Table I). additional cell type (responsive to a further, mono- The above (Z)-alkenyl acetates were tested for enic or dienic acetate, or an alcohol or aldehyde attractancy towards wild Zygaena males in approx. analogue) present in the 12 Zygaena species listed. 100 mixture combinations. Most experiments were The above (Z)-alkenyl acetates elicited nerve im­ carried out on the basis of visual observations of pulse responses from the respective cell type at the male flight responses, while in the beginning we low stimulus amount of 1 0 ~ 2 ng, the usual threshold used sticky traps. The compound mixtures (major value obtained with lepidopterous pheromone component(s), 1 0 0 ng) were applied to red serum receptor cells under the chosen experimental setup. bottle caps ( 0 1.8 cm) which were fixed to strips of In addition, the graded responses of these cells cardboard (8x2 cm). These “bait-strips” were towards a broader set of analogous test chemicals suspended from a horizontally-stretched string at a (not listed here) closely conformed with the re­ height of 0.7 m and at distances of 2 m from each sponse spectra reported for (Z)-alkenyl acetate other. The relative positions of the “bait-strips” receptor cells in other moth species [11, 14-17], were altered during the course of the experiments including species known to use these compounds as and the numbers of Zygaena males attracted, and pheromone components. This is further evidence eventual landing and close-range responses [18] were that the above alkenyl acetates should be the true noted continuously. Given a responsive male “key compounds” of these male Zygaena receptor population and appropriate external test conditions cells and, thus, the candidate structures for the as [18], the order of preference among 2 0 different Notizen 843 lures could thus be established within approx. tures of Z7-12:Ac/Z9-14:Ac/Zll-16:Ac (see Table I) 2 hours. whereas in some test populations from eastern For the Zygaena species treated here, the optim­ Turkey the males were more responsive to combi­ ized sexual attractants all consisted of combinations nations of Z7-12:Ac/Z9-14:Ac with another “key of Z7-12:Ac/Z9-14:Ac with a particular third com­ compound”, Z9-12:Ac. Such data indicate the need pound, in a specific mixture ratio. Ternary com­ of systematically testing the synthetic attractant binations with Z5-12:Ac attracted Z.filipendulae, mixtures over the geographic range of distribution viciae and trifolii (for optimum ratio, see Table I), in some Zygaena species. and also Z. lonicerae (optimum ratio yet to be Included in Table I were Reissita simonyi Rebel determined). Males of Z. purpuralis and Z. carnio­ and Epizygaenella caschmirensis Koll. These two lica did not respond to these mixtures but were genera exhibit a number of morphological characters highly attracted to ternary combinations with that are considered to link Zygaena with the phylo- Z7-14:Ac and Zll-16:Ac, respectively (Table I). genetically more ancient Ethiopic Zygaenini [3, 4]. In Zygaena species where the type A cell responded R. simonyi (a species endemic to the Arabian specifically to Z9-14:Ac (such as the high-alpine Peninsula) appears to use the same four cell types as Z. exulans ), only mixtures based on this compound found in Z. carniolica, whereas in E. caschmirensis as the major constituent were attractive.