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Hickory shuckworm Cydia caryana: electroantennogram and flight tunnel studies of potential sex pheromone components
Abstract
Electroantennogram (EAG) measurements of male Cydia caryana moth antennal olfactory response to monounsaturated 12 and 14 carbon alcohols and acetates indicated that the ( E )‐8‐, ( E )‐10‐ conjugated double bond system of a dodecadien‐1‐ol acetate is a critical chemical structural component of the C. caryana sex pheromone. Additionally, EAG measurements implicated ( E )‐8‐dodecen‐1‐ol acetate, ( Z )‐8‐dodecen‐1‐ol acetate, ( Z )‐9‐dodecen‐1‐ol acetate and ( Z )‐12‐tetradecen‐1‐ol as potential minor pheromonal components. An EAG dosage‐response study suggested that there were at least two heterologous populations of pheromone acceptors. Behavioral analysis of male moth response in a flight tunnel to compounds which evoked the stronger EAG responses suggested that ( E,E )‐8,10‐dodecadien‐1‐ol acetate and ( Z )‐9‐dodecen‐1‐ol acetate resemble or are C. caryana sex pheromonal components, while ( Z )‐8‐dodecen‐1‐ol acetate and ( E )‐10‐dodecen‐1‐ol acetate are either parapheromones or are minor pheromone components. Behavioral significance of ( Z )‐12‐tetradecen‐1‐ol was difficult to interpret in the flight tunnel.
RÉSUMÉ
Etude par électroantennographie et avec tunnel de vol des constituants potentiels des phéromones sexuelles Cydia caryana ( Lépidoptère, Tortricidae, Olethreutinae ).
Les réponses olfactives antennaires de Cydia caryana , mesurées par électroantennogrammes (EAG), aux alcools et acétates à carbones monounsaturés en positions 12 et 14, ont montré que le système conjugué de double liaison, ( E )‐8‐, ( E )‐10‐ dudodecadien‐1‐ol acétate constitue un composé chimique strutural critique de la phéromone sexuelle de C. caryana.
De plus, les acétates: ( E )‐8‐dodecen‐1‐ol,( Z )‐8‐dodecen‐1‐ol,( Z )‐9‐dodecen‐1‐ol, et le ( Z )‐12‐tetradecen‐1‐ol, se sont révélés en AEG comme des composés secondaires de la phéromone. L'étude par AEG de la relation dose‐réponse a conduit à l'hypothèse de deux catégories de populations de récepteurs de phéromones. L'analyse comportementale des résponses des papillons mâles dans le tunnel de vol aux composés qui ont provoqués les plus forts AEG, on fait estimer que les acétates ( E,E )‐8,10‐dodécadien‐1‐ol et ( Z )‐9‐dodecen‐l***‐ol ressemblent (ou sont) les constituants de la phéromone sexuelle de C. caryana; tandis que les ( Z )‐8‐dodecen‐l***‐ol et ( E )‐10‐dodecen‐l***‐ol sont, soit des paraphéromones, soit des constituants mineurs de la phéromone.
La signification biologique du ( Z )‐12‐tétradécen‐l***‐ol a été difficile à interprêter avec les expériences en tunnel de vol.
Extracts of the sex pheromone glands of femaleCydia caryana were evaluated by electroantennography and gas chromatography-mass spectrometry. These studies suggested the following compounds were potential sex pheromone components: (Z)-8- and/or (E)-9-dodecenyl acetate (50 pg/female), dodecyl acetate (40 pg/female), and (E, E)-8,10-dodecadienyl acetate (25 pg/female). In field tests only the diene produced trap catch, and when the other components were added to the diene, trap catch was not increased. When the diene was formulated in red natural rubber septa, only transient and low catches were obtained, but when gray halobutyl isoprene elastomeric septa were used, high and consistent catches were obtained for eight weeks. Catches depended on the ratio of (E, E)-8,10 to (E, Z)-8,10 isomers. High catches were obtained for anEE toEZ ratio of 100 : 0.6, and insignificant catches were obtained when the ratio was 100 : 3. Equivalent catches were obtained for dosages of 50, 100, and 200 µg/septum.
Pheromones, Olfactory Receptors, Structure-response Relationships, Lepidoptera Electroantennogram (EAG) data reflecting response spectra of male pheromone receptors have been analyzed for 16 species of Noctuidae (Lepidoptera). The test compounds included 100 phero mone analogues, altered in chain length, in position and configuration of double bond(s), and in the functional end groups. On comparison of amounts of substance required to elicit an equivalent EAG response, a single compound was determined to be most effective on a given species; these structures, either known or proposed as the natural sex pheromones of the species, were cis-1-dodecen-1-yl acetate, cis-7-tetradecen-1-yl acetate, cts-9-tetradecen-1-yl acetate, Jrarcs-9-tetradecen-1-yl acetate, cis-ll-hexadecen-l-yl acetate, cis-9, trans-12-tetradecadien-l-yl acetate, cis-9-tetradecen-1-yl formate, and cts-9-tetradecen-1-ol, respectively. Elongation (shortening) of the chain by 1 or 2 methylene groups, the movement of a double bond 1 carbon from the optimum, a change to the opposite geometrical isomer, or the introduction of a second double bond invariably reduced EAG responses to 1.8 to 56 times below that observed with the most stimulating compound, in all 16 species. Further alterations in chain length or in double bond position caused even greater reduc tion in activity, as did certain changes in end group (Tables I and II).
A set of distinct rules could be derived from these structure-response relationships; one of these rules concerns the optimum position of the double bond(s) in relation to chain length, and another one the ratios in activity values produced by end group variations, irrespective of chain length. The same rules described here for 16 noctuid species held also for the structure-response relationships observed within various additional groups of Lepidoptera.
From EAG values determined in this study, an attempt has been made to calculate physico chemical propteries of underlying acceptor structures.
A new method for determining half-lives for the evaporation of sex pheromones from formulations has been developed. A previously unexploited mathematical relationship makes possible the determination of half-lives of over 1000 days by collecting evaporated pheromone for 1-4 hr and measuring the amount collected and the amount left in the formulation. Purified nitrogen flows over the test material and the evaporated pheromone is qualitatively collected on an adsorbent of 80-100 mesh silica gel silanized with octadecyltrichlorosilane. Quantitation is by gas chromatography. Quantitative mass balance was achieved and half-lives determined by this new method are in agreement with half-lives previously determined by measuring the amount of pheromone left in septa after a sequence of time intervals. Previously undetermined half-lives for acetates and alcohols are reported.
Electroantennogram studies of female Galleria mellonella showed a two-acceptor system for the sex pheromones, n-nonanal and n-undecanal, produced by the male. The nine carbon pheromone reacts with both acceptors, however, n-undecanal only reacts with the acceptor for the eleven carbon pheromone.
Shorey et al. (1965) presented behavioral and chemical evidence that the female sex pheromones of 2 noctuid moth species, Trichoplusia ni (Hübner), the cabbage looper, and Autographa californica (Speyer), the alfalfa looper, are similar, if not identical. Berger (1966) later identified the sex pheromone of T. ni as cis-7-dodecenyl acetate. In field tests, cis-7-dodecenyl acetate attracts significant numbers of A. californica males. However, the optimum evaporation rate of this chemical for capturing male moths in traps is much lower for A. californica than for T. ni (Kaae et al. 1973).
The design, construction, and uses of a relatively simple and inexpensive wind tunnel for studying responses of flying insects to sex pheromones are presented with special reference to research on moths. A variable-speed continuous belt installed on the tunnel floor proved to be a valuable feature, allowing the observer to manipulate the speed of the responding insect and thus to measure the duration and persistence of sustained anemotactic flights in the pheromone plume. It is concluded that flight tunnels of this kind will prove to be extremely valuable multipurpose tools in pheromone research.
Thesis (M.S. in Entomology)--Texas A & M University.
Thesis (Ph. D.)--University of California, Riverside, 1969. Includes bibliographical references (leaves 97-103).
trans-8, trans-10-Dodecadien-1-ol is a sex attractant of the codling moth, Laspeyresia pomonella. Antennal responses (electroantennograms) to a series of monounsaturated compounds were used in determining the location and configuration of the two double bonds. The synthetic compound is very attractive to male codling moths in the field.
Occurrence of pecan insects- a 10-year summary
- H F Mcqueen
- H. F. McQueen
Neurobiology of pheromone perception
- M S R W Mayer
- Mankin
- M. S. Mayer