Pheromone differences between sibling taxaDiachrysia chrysitis (linnaeus, 1758) andD. tutti (Kostrowicki, 1961) (Lepidoptera: Noctuidae).

The noctuid sibling taxaDiachrysia chrysitis s. str. andD. tutti, of yet uncertain taxonomic status, have previously been shown to possess differences in morphology and to be attracted to different mixtures of the two presumed pheromone components (Z)-5-decenyl acetate and (Z)-7-decenyl acetate. TypicalD. tutti males (clearly broken forewing marking) are known to respond to a 2: 100 mixture of the two isomers, whereasD. chrysitis males (unbroken marking) are attracted to a 100: 10 mixture. We investigated female pheromone production and male electroantennographic (EAG) response inDiachrysia families raised in the laboratory from field-collected gravid females. Extracts of individual females from typicalD. tutti andD. chrysitis families were subjected to gas chromatography with simultaneous flame ionization and electroantennographic detection. All females produced mixtures of Z5- and Z7-10:OAc, but femaleD. chrysitis produced predominantly Z5-10:OAc and the antennae of their brothers responded more strongly to the Z5 peak than to the Z7-10:OAc peak, whereas the opposite was true forD. tutti families. The pheromone components were shown to be biosynthesized from hexadecanoic and tetradecanoic acid, respectively by Z11-desaturation followed by chain shortening, reduction, and acetylation. The EAG responses of males trapped with the typicalD. tutti andD. chrysitis blends, as well as with an intermediate blend, were investigated. Males trapped with theD. tutti mixture almost exclusively had a clearly broken wing marking and showed strongest EAG response to Z7-10:OAc. The intermediate blend and theD. chrysitis mixture gave more mixed catches, but with a prevalence of males with an unbroken (or almost unbroken) wing marking and with a higher mean response to Z5-10:OAc. Some males with typicalD. tutti EAG responses were attracted in the field to theD. chrysitis pheromone. In the flight tunnel someD. chrysitis males were attracted also to theD. tutti mixture. This indicates that cross attraction may take place between the two taxa under natural conditions.

Wind-tunnel study on attraction inhibitor in maleColeophora laricella Hbn. (Lepidoptera: Coleophoridae).

Modifying effects of (Z)-5-decenyl acetate, an attraction-inhibitor of maleC. laricella, were studied at different levels of the pheromonal behavioral sequence. When blended with the attractant alcohol (Z)-5-decen-1-ol, 0.001% acetate significantly reduced and 1% almost abolished orientation flights followed by landing at the source. By contrast, 1000% of the acetate placed 5 cm apart did not suppress orientation flights to the alcohol source. Differential modifying effects of the acetate in blends vs. separate sources also occurred with respect to orientation flight duration, landing position, close-range behavior at the source, and the rate of unsuccessful orientation attempts. Our findings support the view that, inC. laricella, pheromonal inhibition results from simultaneous (as opposed to intermittent) perception of attractant and inhibitor. The various effects of the inhibitory acetate observed in the wind tunnel compare to results of earlier field observations.

Intraspecific variation and interspecific differences in sex pheromones of sibling species inCtenopseustis obliquana complex.

The specific status ofCtenopseustis obliquana pheromone-types I, II, and III has been more fully examined. Females of types I and III produce a mixture of (Z)-8- and (Z)-5-tetradecenyl acetates (Z8-14:Ac, Z5-14: Ac). The previously reported different ratios of these two components in females of the two types (type I=80∶20, III=90∶10) have been reinvestigated. The median ratios of each type differed significantly, although there was some overlap in the ranges of these ratios. A field cage trial showed that males of type III are attracted to females of type I, so the observed differences may be ascribed to intraspecific variation. In contrast to females of types I or III, females of type II produce Z5-14∶Ac but no Z8-14∶Ac. The electroantennogram (EAG) profile of antennae of type II males shows a maximum response to Z5-14∶Ac, while the EAG profiles of types I and III show a strong response to Z8-14∶Ac. In wind tunnel tests using mixtures of these two compounds, type II males prefer blends consisting of all or mostly Z5-14: Ac, while type I males showed a preference to a mix of 70% Z8-14∶Ac plus 30% Z5-14∶Ac. We found that type I males are attracted to type I females when offered a choice between type I and type II females in a field cage test and that type II males similarly prefer type II females. Males of types I and II have specialist cells for Z8-14∶Ac and Z5-14∶Ac but differ with respect to relative densities of these cells and to further cell types responsive to other alkenyl acetates. Type IIC. obliquana is considered therefore a sibling species of types I and III. In addition, the amount of Z5-14∶Ac produced by type II females varied geographically. Females from the North Island produced significantly less (median=1.2 ng) Z5-14∶Ac than females from the South Island (median=2.2 ng). Type II populations in the North Island morphologically resembled sympatric type I, rather than type II from the South Island and are designated as type II (North Island). Type II (North Island) populations have so far been found only at Rukuhia (near Hamilton) and from Kerikeri. In contrast, type II populations are sympatric with type III populations over much of the South Island. In a field cage trial, males of types II and II (North Island) were attracted to females of both II and II (North Island). We tentatively ascribe the differences between type II and type II (North Island) to intraspecific variation.

(Z,Z)-7,9-Dodecadienyl acetate, sex pheromone ofEpinotia tedella clerck (Lepidoptera: Tortricidae).

(Z,Z)-7,9-dodecadienyl acetate, a reported male attractant for several New World spp. ofEpinotia, was identified as the primary pheromone of femaleE. tedella (European spruce budmoth) through chemical analysis of pheromone gland washes, the electrophysiological study of male antennal receptor types, and field-trapping tests. The washes contained this compound at a level of approximately 0.4 ng per FE, along with a similar amount of the corresponding alcohol, (Z,Z)-7,9-dodecadien-1-ol. Each compound activated its own specialized type of male receptor cell. No traces of stereoisomers or monoenes were found in the washes. In field-trapping tests conducted in stands of Norway spruce in southern Germany, (Z,Z)-7,9-do-decadienyl acetate as a single chemical proved highly attractive to maleE. tedella over a range of lure doses. The corresponding alcohol or aldehyde did not show attractivity; rather, in binary combinations with the primary pheromone, these compounds, and also the (E,Z)-7,9 stereoisomeric acetate, reduced captures. A 10∶1 blend of (E)-9- and (Z)-9-dodecenyl acetates, reported as anE. tedella male attractant, did not reveal significant captures. No otherEpinotia spp. besidesE. tedella responded to the various 7,9-do-decadienyl test baits during this study.

Responses of male codling moths (Laspeyresia pomonella) to codlemone and other alcohols in a wind tunnel.

The primary pheromone (E,E)-8,10-dodecadien-1-ol (I, codle-mone), 11 further alcohols, and binary blends of both were evaluated for attractiveness as defined by the percentage ofL. pomonella males showing oriented upwind flight terminated by landing at the source within 10 min after release. Sources of I were attractive from 10(-5) µg to 10(1) µg, with approx. 70% males responding at 10(-3)-10(-1) µg. Most other alcohols also showed attractiveness, but the dose-response curves differed greatly with respect to the range of effective lure doses as well as the maximum response level reached at any dose. (E,E)-7,9-Undecadien-1-ol (III) revealed a dose-response curve similar in shape to I but shifted towards higher concentrations. (E,E)-8,10-Tridecadien-1-ol (II) and (E)-8,10-undecadien-1-ol (IV) exhibited threshold values of 10(-5) µg (same as for I) and were effective over, respectively, seven and nine decades of source load, but they did not reach a response level of 40% at any test amount. (E)-9,11-Dodecadien-1-ol (VI) and the monoenes (E)-8-, (E)-10-, and (Z)-10-dodecen-1-ol (VIII-X) showed weak attractivity restricted to one to three test doses. Upwind approaches that broke off a few centimeters from the source were rarely seen in tests with I but frequently occurred with some of the analogs. When combined with 10(-3) µg of I, all alcohol analogs showed "inhibitory" properties, although the amounts required to obtain a significant lowering of response differed by up to 10(5)-fold. This amount was the lowest (10(-4) µg) for the positional isomer VI, and the highest (10(1) µg) for undecan-1-ol (XI) and dodecan-1-ol (XII). With some mixtures, the presence of the inhibitor appeared to cause an alteration in landing behavior. No synergistic effects were seen in these tests. The results are briefly considered with respect to the sensory perception of the test stimuli and the involvement of minor components in the female pheromone blend.

Sex attractant for currant clearwing mothSynanthedon tipuliformis (Clerck) (Lepidoptera: Sesiidae).

The currant clearwing moth,Synanthedon tipuliformis (Clerck) (Lepidoptera: Sesiidae), is a pest in many parts of the world. In field tests it was found that (E,Z)-2,13-octadecadien-1-ol acetate attracts males of this species. The synthesis of this compound and of its geometrical isomer (Z,Z)-2,13-octadecadien-1-ol acetate is described.

2-Phenylethanol, a presumed sexual stimulant produced by the male cabbage looper moth, Trichoplusia ni.

A sex pheromone produced by male cabbage looper moths, Trichoplusia ni (Hübner), has been isolated from the genital scent brushes and identified as 2-phenylethanol. It is shown conclusively to elicit specific behavioural responses in the female (such as wing vibration and abdominal elevation), as determined by a novel behavioural laboratory bioassay. This is taken as further evidence that the male pheromone of T. ni acts as a sexual stimulant (aphrodisiac) prior to mating. 2-Phenylethanol represents the first identification of a genital scent brush pheromone in the family Noctuidae, and of a male pheromone in the subfamily Plusiinae.

Structure-response relationships in noctuid sex pheromone reception. An introductory report.

Electroantennogram (EAG) data reflecting response spectra of male pheromone receptors have been analyzed for 16 species of Noctuidae (Lepidoptera). The test compounds included 100 pheromone 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-7-dodecen-1-y1 acetate, cis-7-tetradecen-1-y1 acetate, cis-9-tetradecen-1-yu acetate, trans-9-tetradecen-1-y1 acetate, cis-11-hexadecen-1-y1 acetate, cis-9, trans-12-tetradecadien-1-y1 acetate, cis-9-tetradecen-1-y1 formate, and cis-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 reduction in activity, as did certain 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 physicochemical propteries of underlying acceptor structures.