Ernst Priesner

Die Riechschwelle des Seidenspinners

ZusammenfassungRiechzellen des SeidenspinnersBombyx mori reagieren auf ein einzelnes Lockstoffmolekül mit einem einzelnen Nervenimpuls. Die mittlere Reaktionszeit beträgt etwa 1/2 sec. Bei schwachen Reizen deckt sich die Häufigkeitsverteilung der Impulse mit der Zufallsverteilung der Molekültreffer. Dabei werden nahezu alle auf die Oberfläche der Riechhaare treffenden Moleküle zu den Wirkorten geleitet. Im Verhaltenstest reagiert ein signifikanter Prozentsatz von Tieren, wenn etwa 1% der Lockstoffrezeptoren der Antenne durch den Duftreiz errget ist. Das Signal-Rauschverhältnis der gesamten Rezeptoren hat dann das theoretische Minimum gerade überschritten. Die Impulsmeldungen können offenbar über mehr als eine Sekunde zentral integriert werden.

AUTODETECTION AND CHEMISTRY OF FEMALE AND MALE PHEROMONE IN BOTH SEXES OF THE TIGER MOTH PANAXIA QUADRIPUNCTARIA

Abstract Female moths of Panaxia quadripunctaria PODA (Lepidoptera, Arctiidae), produce (Z,Z)-6,9-heneicosadiene (I) as the major and (Z,Z)-6,9-eicosadiene (II) as the minor component of a putative pheromone. Related compounds occur in trace amounts. The abdominal scent glands contain 5–10 μg of (I) and 50–100 ng of (II). Recordings of electroantennogram (EAG) responses to (I), (II), and to female glands are of equal amplitude in both sexes. Females are thus capable of pheromone autodetection in contrast to the majority of moths where females are considered to be anosmic for their own attractant. The EAG threshold to (I) was below 1 ng at the odour source. The odour of the male scent gland (corema) elicited significant EAGs in both sexes. The chemical contents of coremata varied with the provenience of the moths. A variety of ethyl esters was always found, yet hydroxydanaidal (up to 20 μg/corema) and traces of danaidal, only in some samples. All these scents might be components of a male pheromone. Peculiar scent scales on the coremata are exposed during the extrusion. Antennae of both sexes have similar inventories of trichoid sensilla.

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.

Die interspezifischen Wirkungen der Sexuallockstoffe der Saturniidae (Lepidoptera)

Summary1.Using electrophysiological methods, the degree of the interspecific effects of the chemically-unknown female sex attractants has been determined for 1,900 species-combinations between 104 saturniid species. The isolated pheromone glands served as stimulus sources. The measure of the excitation of the male receptors were the amplitudes of their summated receptor potentials. Four magnitudes of interspecific reactions were distinguished. For 60 species the results of all the species-comparisons investigated are shown in a chart (Fig. 3); for the other species the main results are mentioned.2.Species fully reacting in both directions were summarized as an reaction group (RG). Their interspecific reactions cannot be distinguished from intraspecific ones. The 104 species are distributed into 19 RGs (Table 2). All the species of the same RG are directly related and can be reduced to a common origin. In two cases an RG is a clearly differing species group of a genus, in seven cases it is a genus, in ten cases a genus group; the largest RG of the family is worldwide distributed in 18 closely related genera. In a comparison of the 19 RGs with the system of the 113 valid saturniid genera (Table 3) it is shown:a)that every RG encompasses a certain section of the system;b)that the 19 RGs established are applicable to the greatest part of the family (1,150 species);c)that differences from the present system can be decided according to the RG-system.3.The distribution of the partial effects between the RGs (Fig. 4) agrees largely, but not completely with their morphological relationship: between closely related genera groups or subfamilies the sex attractants are in most cases strongly intereffective; between not directly related subfamilies they are ineffective. Potent effects of the attractants extend from the oldest saturniid groups into all closely neighboring families.4.Analogously the interspecific effects of the sex attractants have been determined in and between 26 other Lepidoptera families.Zusammenfassung1.Für 1900 Artenkombinationen zwischen 104 Saturniiden-Arten wurde mit elektrophysiologischen Methoden die Höhe der interspezifischen Wirkungen der chemisch noch unbekannten weiblichen Sexuallockstoffe bestimmt. Als Reizquelle dienten isolierte Lockstoffdrüsen, als Maß der Erregung der männlichen Lockstoffrezeptoren die Amplituden ihrer summiert abgeleiteten Rezeptorpotentiale. Es werden 4 Größenklassen interspezifischer Reaktionen unterschieden. Für 60 Arten wird das Endergebnis aller durchgeführten Artenvergleiche in einer Übersichtstafel vollständig wiedergegeben (Abb. 3); für die weiteren Arten werden die Hauptergebnisse genannt.2.Wechselseitig voll aufeinander ansprechende Arten werden als Reaktionsgruppe (RG) zusammengefaßt. Ihre interspezifischen Reaktionen sind von intraspezifischen nicht unterscheidbar. Die 104 Arten verteilen sich auf 19 RGn (Tabelle 2). Alle Arten einer RG sind unmittelbar verwandt und auf einen gemeinsamen Ursprung zurückführbar. In 2 Fällen bildet eine stark abweichende Artengruppe einer Gattung, in 7 Fällen eine Gattung, in 10 Fällen eine Gattungsgruppe die RG; die umfangreichste RG der Familie ist in 18 unmittelbar verwandten Gattungen weltweit verbreitet. In einer Gegenüberstellung der 19 RGn mit dem System der 113 gültigen Saturniiden-Gattungen (Tabelle 3) wird gezeigt:a)daß jede RG einen bestimmten Abschnitt des Systems umfaßt;b)daß die 19 festgestellten RGn bereits für den weitaus größten Teil der Familie (1150 Arten) gelten;c)daß Abweichungen vom vorliegenden System zugunsten des RG-Systems zu entscheiden sind.3.Die Verteilung der partiellen Lockstoffwirkungen zwischen den RGn (Abb. 4) deckt sich weitgehend, jedoch nicht durchwegs, mit deren morphologischer Verwandtschaft: zwischen nahe verwandten Gattungsgruppen oder Unterfamilien bestehen meist hohe, zwischen nicht näher verwandten Unterfamilien keine überschwelligen Lockstoffwirkungen. Starke Wirkungen der Sexuallockstoffe erstrecken sich von den ältesten Saturniiden-Gruppen in alle ihnen im System nächststehenden Familien.4.In analoger Weise wurden die interspezifischen Lockstoffwirkungen in 26 weiteren Lepidopteren-Familien und zwischen diesen erfaßt.

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.

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.

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 101 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 105-fold. This amount was the lowest (10−4 μg) for the positional isomer VI, and the highest (101 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.

Olfactory Receptor Response to the Cockroach Sexual Attractant

The recently isolated sex attractant of the female American cockroach elicits an electical response in the antennae of males, females, and mymphs of this species. These electroantennograms are known to be summated receptor (generator) potentials of many olfactory sensillae stimulated simultaneously. Many other odorous substances also elicit such responses in the cockroach antenna.

A Sex Attractant for the Green Budworm Moth, Hedya nubiferana

Abstract The two major components of the female pheromone blend of Hedya nubiferana have been identified as (E, E)-8,10-dodecadienyl acetate and (Z)-8-dodecenyl acetate. Each compound acts on a specialist receptor type in olfactory hair sensilla of the male antenna. In field screening tests, combinations of the two compounds and dodecanyl acetate were highly attractive to H. nubiferana males. The (Z, E)-8,10 isomer attracted males of Hedya ochroleucana.

Pheromone differences between sibling taxa Diachrysia chrysitis (linnaeus, 1758) and D. 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.