Journal of Chemical Ecology, Vol. 8., No. 4, 1982

S T R U C T U R E - A C T I V I T Y R E L A T I O N S H I P S IN S E X ATTRACTANTS FOR NORTH AMERICAN NOCTUID MOTHS l

WARREN STECK, E.W. UNDERHILL, and M.D. CHISHOLM Prairie Regional Laboratory National Research Council of Canada Saskatoon, Saskatchewan S7N 0 W9 (Received June 2, 1981; revised September 8, 1981)

Abstract Sex attractants known for 145 species of noctuid moths have many c o m m o n features both as to chemical constituents and to their relationships in blends. The great majority of constituents are straight-chain (Z)-alkenols, -alkenals, or -alkenyl acetates of even carbon number (I0 through 16). The unsaturation is nonterminal in odd-numbered positions (5 through 11). In effective lures, these components are blended in specific ratios and the components in a sex p h e r o m o n e or sex attractant blend are structurally related by "one-change" steps. This means that any blend c o m p o n e n t differs from one or more other components by a single structural alteration, such as a change in double bond position, or a change in carbon chain length, or a change in the oxygen function. For the few multicomponent systems known in detail, the central place in the "onechange" framework is occupied by the predominant blend component. Different patterns of occurrence of lure components occur in the subfamilies Acronictinae, Noctuinae, Hadeninae, Cuculliinae, Amphipyrinae, Heliothidinae, Plusiinae, Acontiinae, and Pantheinae, and some subfamilies are as yet without known lures. Some guiding principles for elucidation of blend compositions for unstudied species are presented; these guidelines can also be used in improvement of some synthetic blends of unsatisfactory quality.

Key W o r d s - - A l k e n y l compounds, pheromones, c h e m o t a x o n o m y , decenyl, dodecenyl, tetradecenyl, hexadecenyl, trapping, Lepidoptera, Noctuidae.

~NRCC No. 20081 731 0098-0331 / 82/0400-073 f $03.00/0 9 1982 Plenum Publishing Corporation

732

STECK ET AL. INTRODUCTION

Since 1960 the discovery of chemical systems which can attract male moths over long distances has gone on at an ever-increasing rate. Many sex pheromone blends have been isolated and identified from insect species, and many synthetic sex attractant blends have been demonstrated to behave like sex pheromones. In some cases an artificial blend has subsequently been shown to be essentially the natural pheromone. In this paper the term sex pheromone is used to mean an attractive (or coattractive) compound or compounds shown to be produced by the responding species, and sex attractant to mean any similarly biologically active chemical system whether naturally occurring or not. Moreover it can be assumed that in every case presented here, the virgin female is the pheromone producer and the males the entities attracted by sex pheromones or sex attractants. Since most available information on "attraction" still derives from field trapping data, lure power has here been taken as the prime criterion of sex attractant activity, and field trapping with all its shortcomings has been accepted here as a method for assessing the potency of chemical systems. The topic of this article is not, therefore, the behavioral biology of moths in attractant systems, but rather some aspects of the structural chemistry of successful sex attractants. We believe that an appreciation of these aspects in noctuids can assist future identifications of sex pheromone systems in the Lepidoptera. The Noctuidae family (Lepidoptera) comprises about 1500 species in temperate North America and includes cutworms, armyworms, and some loopers. Most of these species are rare or uncommon, and only a few percent are recognized as significant pests. Adults of most species are nocturnal fliers, although some crepuscular and a few diurnal species (e.g., Heliothis ononis D.&S.) are known. T a x o n o m y of the family has exercised many workers, with highly divergent results (Dyar, 1902; McDunnough, 1938; Forbes, 1954). The system used in this paper is that of M c D u n n o u g h as modified in the Canadian National Collection and exemplified in Rockburne and Lafontaine (1976). Some c o m m o n synonyms have, however, been retained, for example: Euxoa altera for E. lutulenta; Heliothis zea for Helicoverpa zea; and Fehia ducens for F. jaculifera. NATURE AND SOURCES OF DATA

Knowledge of sex attractant systems for lepidoptera has developed mainly by two parallel routes: (1) identification of sex pheromones, and (2) field screening of chemicals for attractancy. In the former route the species is targeted and the chemical identities are unknowns at the outset; in the latter route the chemicals are known but the species to be attracted are not specified.

733

SEX ATTRACTANTS OF NOCTUID MOTHS

TABLE 1. STRUCTURAL GRID OF COMPOUNDS BIOLOGICALLY ACTIVE IN NOCTUID SEX ATTRACTANT BLENDS a

Double bond position Carbon chain length Acetates 10 12 14 16 18 Aldehydes 10 12 14 16 18 Alcohols 10 12 14 16 18

3

5

7

9

11

13

0 0 0 0

10 10 6 1

0 44 15 4

0 5 59 4

0 7 40

0 0

0

0

0

0

0

0

0 0 0 0

0 0 0 0

0 2 3 2

0 0 8 4

0 2 22

0 0

0

0

0

0

0

0

0 0 0 0 0

0 0 0 0 0

0 7 0 0 0

0 0 2 1 0

0 1 20 0

0 0 0

aNumbers are frequency of occurrence of the compound in Table 2. C o m p o u n d s s h o w n by either of these routes to be attractive or coattractive to n o c t u i d male moths are s u m m a r i z e d in Table 1. The general d i s t r i b u t i o n of c o m p o u n d s indicated in this table has already been noted by others (e.g., Priesner et al., 1975; Roelofs, 1979; Steck et al., 1979d). C a u t i o n must be used in i n t e r p r e t i n g field screening results because very slight chemical impurities can give rise to false positive or false negative results (Steck et al., 1980b). Note (Table 2) that m a n y noctuid blends have o p t i m a l m i n o r c o m p o n e n t c o n t e n t s of 1% or less; c o n t e n t s of 0.1% or even 0.01% are quite sufficient for biological activity. Since most chemical lure c o m p o n e n t s have, historically, been less t h a n 99.9% pure even before possible d e g r a d a t i o n in the field, we suspect that some data in the literature result from chemical c o n t a m i n a n t s . In the case of positive t r a p p i n g results with i m p u r e (or at least u n d e f i n e d ) lures, the a t t r a c t i o n m a y be entirely due to the m a j o r lure c o m p o n e n t , m a y be caused by some one impurity, or may arise from a fortuitous m u l t i c o m p o n e n t effect. Possible field d e g r a d a t i o n of highly pure or well-defined lures introduces yet a n o t h e r c o m p l i c a t i o n which p r e s u m a b l y will vary with the chemical n a t u r e of the lure (e.g., m o n o e n e or diene), the releaser system used, a n d the physical e n v i r o n m e n t in which the observations are

734

STECK ET AL.

made (e.g., humid or arid regions, the former favoring hydrolytic degradation). To be recognized as attractive in trapping tests, a chemical or blend must consistently lure male moths into traps in numbers significantly greater than are obtained in unbaited control traps. Where blends are involved, a constituent may be regarded as coattractive if its presence in the lure blend results in significantly increased trapping relative to that with lures lacking the component. Some preconditions must be met in the testing process; for example, that the chemicals used are sufficiently pure for the purpose; that purely mechanical factors, such as "carrier" or "ballast" effects on blend release, are not introduced during tests; or that the traps used are compatible with the purposes of the test. The term "significantly greater" is ultimately arbitrary and depends in part upon the trap design used, With most species, "significance" may be attached to very small numbers of captures; lure efficiency is quite a different matter which requires some independent assessment of the available population. Most of our laboratory's trapping work has employed horizontal cone-orifice live traps (Steck and Bailey, 1978) which, because moths are required to land and enter in very close proximity (2-3 cm) to the dispenser, can furnish some measure of the postflight stages of male response. Of course, for success they must be so baited as to elicit a fairly full spectrum of male response steps. In addition, such traps almost completely exclude chance entry of moths. We have reexamined and confirmed many previously reported noctuid lures, using high-purity materials in field trapping tests. In many cases we have been able to improve earlier systems or to provide better-defined synthetic blends. For the purposes of this manuscript, however, we have accepted at face value all literature reports for which no evaluation has been possible. Besides field trapping and pheromone isolation, the techniques of electrophysiology (receptor site identification and electroantennal scans) and behavioral analysis have provided additional means of assessing the potential and actual responses of male noctuids to pheromone-like chemicals.

GENERAL CHARACTERISTICS OF NOCTUID SEX ATTRACTANTS Table 2 lists sex attractants for about 145 noctuid species found in North America. Underlying many of these data are electroantennogram studies (e.g., Chisholm et al., 1975) and chemical isolations as well as field trapping results. Representing only ca. 10% of the available species, the table is incomplete indeed, but from it some generalizations can be made about the chemical compounds in noctuid sex attractants and the sex attractant blends as systems.

E. albipennis (Grote)

Euxoa acornis (Smith)

E. occulta (L.)

Eurois astricta (Morrison)

Euagrotis tepperi (Smith)

A. collaris (G & R) Chersotis ]uncta (Grote) Cryptocala acadiensis (Bethune)

A. vetusta (Walker) A. volubilis (Harvey) Amathes c-nigrum (L.)

Subfamily Acronictinae Acronicta grisea (Walker) Simyra henrici (Grote) Subfamily Noctuinae Aetebia ]ennica (Tauscher) Agrotis ipsilon (Hufnagel) A. orthogonia (Morrison) A. obliqua (Smith) A. venerabilis (Walker)

Species

20 : 1 Z7-14 : Ac + Z5-14 : Ac (H) 1 : 1 Z 7 - 1 4 : Ac + Z9-14 : Ac (M) Z11-16 : Ac + Z11-16 : Aid (L) Z11-16 : Ac + Z9~14 : Ac + Z 9 - 1 4 : Aid (L) 1 0 : 1 : 1 Z l l - 1 6 :Ac + Z 9 - 1 4 : A c + Z 7 - 1 2 : Ac (H) 1 : 5 : 5 Z11-16 : Ac + Z9-14 : Ac + Z l 1 - 1 6 :Aid (M) 30 : 100 : 1 Z 1 1 - 1 6 : Ac + Z 9 - 1 4 : Ac + Z l l - 1 6 :Aid (H) 4 : 1 : 5 Z9-14 : Ac + Z9-14 : Aid + Z l 1 - 1 6 :Ac (H) 10:1:1 Z5-10:Ac-~Z7-12:Ac+ Z 7 - 1 2 : OH (H)

Steck et al., 1979d (A) Hill et al., 1979 (P) Struble and Swailes, 1978 (A)

1 : 1 Z11-14 : Ac + Z 7 - 1 2 : Ac (L) 5 : 1 Z 7 - 1 2 : Ac + Z9-14 : Ac (M) 5 : 1 Z 7 - 1 2 : Ac + Z 5 - 1 2 : Ac (H) Z5-14 : Ac (L) 1 0 0 : 1 0 : 1 Z S - 1 0 : A c + Z 7 - 1 2 :Ac + Z7-12 : Aid (H) 50 : 1 Z11-16 : Ac + Z9-14 : Ac (M) 100 : 1 Z5-14 : Ac + Z7-14 : Ac (L) Z 7 - 1 4 : Ac (L)

Steck et al., 1979c (A)

Underhill et al., 1977b (A)

Steck et a l , 1976 (A)

Underhil/et at., 1977b (A)

Roelofs and Comeau, 1970 (A) Bestmann et al., 1979 (P) Steck et al., 1980b (A) Steck et al., 1979d (A)

Steck et al., 1979c (A)

Steck et al., 1977a

References

Z 7 - 1 2 : Ac + Z 9 - 1 2 : Ac (M) Z7-14 : Aid (L)

Best k n o w n attractant

TABLE 2. SEX ATTRACTANTS FOR SOME N O R T H AMERICAN NOCTUID MOTHS, L I S T E D BY SUBFAMILIES a

~o

"-4

9

Z 9

Z

r

campestris (Grote) cicatricosa (G. & R.) dargo (Strecker) declarata (Walker) divergens (Walker) drewseni (Staudinger) flavicollis (Smith) manitobana ( M c D u n n o u g h ) messoria (Harris) mimallonis (Grote) obeliscoides (Guen4e) ochrogaster (Guen6e)

E. plagigera (Morrison)

E. pestula (Grote)

E. olivia (Morrison) E. perolivalis (Smith)

E. E. E. E. E. E. E. E. E. E. E. E.

E. basal& (Grote)

E. altera (Smith) E. auxiliaris (Grote)

Species 5 0 : 1 Z l 1 - 1 6 :Ac + Z 9 - 1 4 :Ac (M) 100 : 1 : 10 Z 5 - 1 4 : Ac + Z 7 - 1 4 :Ac + Z 9 - 1 4 : Ac (H) 5:5:1 Z7-12:Ac + Z7-12:OH + Z 5 - 1 2 : Ac, or 5:5:1 Z7-12:Ac + Z7-12:OH + Z 5 - 1 0 :Ac (H) Z 5 - 1 0 :Ac (L) Z 7 - 1 2 :Ac (L) 9 : 1 Z 9 - 1 4 : A c + Z 11-16 :Ac (L) Z 5 - 1 0 : Ac (M) 200 : 1 Z 9 - 1 2 : Ac + Z 7 - 1 2 : Ac (L) Z7-14:Ac+ Z5-12:Ac 1000 : 1 Z 9 - 1 4 :Ac + Z 7 - 1 2 :Ac (H) 4 : 1 Z 9 - 1 4 : Ac + Z 7 - 1 4 : Ac (M) 2 0 : 1 Z l l - 1 6 : A c + Z 7 - 1 6 : A c (H) Z 5 - 1 0 :Ac (L) 500 : 1 Z 9 - 1 4 : Ac + Z 7 - 1 2 : Ac (M) 5 0 0 : 5 : 2 : 1 Z 5 - 1 2 : Ac + Z 7 - 1 2 :Ac + Z 9 - 1 2 Ac + Z 5 - 1 0 : Ac (H) 200 : 2 : 1 : 1 - 2 0 0 : 6 : 2 : 1 (same c o m p o u n d s ) (H) Z 5 - 1 0 :Ac (L) 4:5:1 Z11-16:Ac +Z9-14:Ac + Z l 1 - 1 6 :OH 100 : 1 : 1 Z 5 - 1 0 :Ac + Z 7 - 1 2 : Ac + Z 7 - 1 2 : Aid (M) 5 : 1 Z 9 - 1 4 :Ac + Z 9 - 1 4 :OH (M)

Best k n o w n attractant

T A B L E 2. ( C o n t i n u e d )

Steck et al., 1980a (A); Steck et aL, 1982 (A) Struble et al., 1980 (P); Struble, 1981a (A) Underhill et al., 1981 (A) Struble et al., 1977b (A)

Struble et al., 1977a (A)

Struble and Swailes, 1978 (A)

Underhill et al., 1981 (A)

Underhill et at., 1981 (A)

Struble and Swailes, 1977a (A) Struble, 1981b (A)

References

>

*q

rockburnei (Hardwick) scandens (Riley) servita (Smith) tessellata (Harris)

L. linda (Franclemont)

Leucania commoides (Guen6e)

Lacinipolia Iorea (Guende) L. renigera (Stephens) L. vicina (Grote)

Faronta diffum (Walker) Hypocoena rufostrigata (Packard)

Anhimella contrahens (Walker) Ceramica picta (Harris)

Subfamily Hadeninae Aletia oxygala (Grote)

Paradiarsia littoralis (Packard) Peridroma saucia (Htibner) Spaelotis clandestina (Harris)

Feltia ducens (Walker)

E. tristicula (Morrison)

E. E. E. E.

E. ridingsiana (Grote)

E. pleuritica (Grote)

20:1 Z l 1 - 1 6 :Ald + Z l 1 - 1 6 :Ac (M) 10:1 Z l l - 1 6 : A l d + Z l l - 1 6 : O H (M) 200 : 2 : 1 Z11-14 : Ac + Z11-16 : Ac + Z9-14 :Ac (H) 9 : 1 Z11-16 : Ac + Z 11-16 :Aid (M) 1 0 0 : 1 : 1 Z l l - 1 6 :Ald + Z11-16 :OH + Z9-14 :Aid (M) Z7-14 : Ac (L) Z9-14 : Ac (L) 5:5:1 Z11-16:Ac +Z9-14:Ac + Z7-14 : Ac (H) 4:4:1 Z11-16:Ac + Z9-14:Ac + Z l 1 - 1 6 :OH (H) 19:1 Z9-14 :Ac + Z 1 1 - 1 4 : A c

5 : 1 : 1 Z 7 - 1 2 : Ac + Z7-12 :OH + Z 5 - 1 2 : Ac, or 5:1:1 Z7-12:Ac +Z7-12:OH + Z 5 - 1 0 : Ac (H) 5 0 0 : 2 0 : 1 Z 9 - 1 4 : A c + Z l 1 - 1 6 :Ac + Z 7 - 1 2 : Ac(H) Z5-10 :Ac (L) Z7-12 :OH (L) Z7-14 :Ac + Z7-14 :Ald (L) 1:1 Z7-16 :Ac + Z5-16 :Ac, or 200:1 Z7-16 :Ac + Z5-14 :Ac (H) 200 : 1 : 500 Z 9 - 1 2 : Ac + Z9-14 : Ac + Z7-12 : Ac (M) 2000 : 1 : 1 Z l 1 - 1 6 : Ac + Z 9 - 1 4 : Ac + Z7-12 : Ac (M) 100:1 Z7-12 : Ac + Z5-12 :Ac (L) 1 : 1 Z11-16 : Ac + Z9-14 : Ac (M) Z 7 - 1 4 :Aid (M)

Roelofs et al., 1976 (A)

Struble et al., 1977b (A)

Roelofs and Comeau, 1971 (A)

Underhill et al., 1977b (A)

Struble et al., 1976 (A) Steck et al., 1979d (A)

Steck et al., 1979a (A)

Struble et al., 1981 (A)

Underhill et al., 1981 (A)

Steck et al., 1978 (A)

---1 L~ -M

Scotogramma trifolii ( R o t t e m b u r g )

Pseudorthodes vecors (Guen6e) Scotogramma farnhami (Grote)

P. discalis (Grote) P. grandis (Boisduval) P. ingravis (Smith) P. lilacina (Harvey) P. nevadae (Grote) P. purpurissata (Grote) P. segregata (Smith) P. tacoma (Strecker) Pseudaletia unipuncta (Haworth)

Polia assimilis (Morrison) P. atlantica (Grote)

L. phragmatidicola (Guen~e) Mamestra configurata (Walker) Morrisonia confusa (Hiibner) Nephelodes minians (Guen~e) Orthodes crenulata (Butler) Orthosia hibisci (Guenge)

L. multilinea (Walker)

Species 4 : 4 : 1 Z 1 1 - 1 6 : Ac + Z 9 - 1 4 : Ac + Z l 1 - 1 6 : O H (H) Z 9 - 1 4 : Ac 1 9 : 1 Z 1 1 - 1 6 : A c + Z 9 - 1 4 : A c (H) Z 1 1 - 1 6 : Ac Z l 1 - 1 6 : Aid (L) Z 1 1 - 1 6 : Ac Z 9 , E 1 2 - 1 4 : Aid; or Z 9 - 1 4 :Aid (H); 100 : 1 Z 9 - 1 4 : Aid + Z 1 1 - 1 4 : Aid (H) 1 0 0 : 1 Z l I - 1 4 :Ac + Z 9 - 1 4 :Ac (H) 1000 : 5 : 1 Z 1 1 - 1 6 : Ac + Z 1 1 - 1 6 : Aid + Z l 1 - 1 4 :Aid (H) 10 : 1 Z 9 - 1 4 : Ac + Z 1 1 - 1 4 : Ac (M) E 9 - 1 4 : Ac 1 0 0 : 1 Z 9 - 1 4 : A c + Z l l - 1 6 : A c (M) 10 : 1 Z 7 - 1 4 : Ac + Z 9 - 1 4 : Ac (M) Z 1 1 - 1 6 : Ac + Z 1 1 - 1 6 : Aid (L) 100 : 1 Z 9 - 1 4 : Ac + Z 7 - 1 4 : Ac (L) 10 : 1 Z 7 - 1 4 : Ac + Z l 1 - 1 4 : Ac (M) 100 : 1 Z 9 - 1 4 :Ac + Z 9 - 1 4 : Aid (H) Z l 1 - 1 6 :Ac + Z l 1 - 1 6 :OH (M) 5 0 0 0 : 1 0 : 2 : 1 Z l l - 1 6 :Ac + Z l 1 - 1 6 : O H + Z 1 1 - 1 6 :Aid + Z 9 - 1 4 : Ac (H) Z l t - 1 6 :Ac 1 0 0 : 1 : 1 Z l 1 - 1 6 :Aid + Z 9 - 1 4 :Aid + Z 9 - 1 6 : Aid (M) 9 : 1 Z 1 1 - 1 6 : Ac + Z 1 1 - 1 6 : OH (H)

Best k n o w n attractant

T A B L E 2. ( C o n t i n u e d )

Steck et al., 1982 (A) Struble and Swailes, 1975 (A) Underhill et al., 1976 (P)

Hill and Roelofs, 1980 (P : Z 1 1 - 1 6 : Ac); M c D o n o u g h et al., 1980 (P : Z l 1 - 1 6 : Ac + Z I 1-16 :OH); Steck et al., 1980b (A) Roelofs and Comeau, 1970 (A)

Roelofs and C o m e a u , 1971 (A) Steck et al., 1982 (A)

Steck et al., 1980b (A)

Steck et al., 1982 (A)

Roelofs and Comeau, 1971 (A) Underhill et al., 1977a (P) Roelofs and Comeau, 1970 (A) Underhill et al., 1977b (A) Roelofs and Comeau, 1970 (A) Hill and Roelofs, 1978 (A)

Struble et al., 1977b (A)

References

o,?

ot~

Subfamily Cuculliinae Cucullia florea (Guen~e) C. intermedia (Speyer) C omissa (Dod) C. postera (Guen~e) C. speyeri (Lintner) Fishia hanhami (Grote) F. derelicta ( H a m p s o n ) Homohadena infixa (Walker) Lithomoia solidaginis (Hiibner) Lithophane unimoda (Lintner) L. thaxteri (Grote) Oncocnemis lepipuloides ( M c D u n n o u g h ) 0. piffardi (Walker) Parastich tis discivaria (Walker) Pyreferra citrombra ( F r a n c l e m o n t ) Rancora albida (Guen6e) Sunira bicolorago (Guen6e) Sutyna profunda (Smith) Xanthia lutea (Str6m) S u b f a m i l y Plusiinae Anagrapha falcifera (Kirby) Argyrogramma verruca (Fabricius) Autographa ampla (Walker) A. biloba (Stephens) A. egena (Guen6e) A. califomica (Speyer)

Xylomyges curialis (Walker) X. dolosa (Grote)

Sideridis rosea (Harvey)

10 : 1 Z 7 - 1 2 : Ac + Z 7 - 1 2 : OH (M) 9 4 : 6 Z 7 - 1 2 :Ac + E 7 - 1 2 : A c Z 7 - 1 2 : Ac Z 7 - 1 2 : Ac Z 5 - 1 2 : Ac Z 7 - 1 2 : Ac + Z 7 - 1 2 : F o r m a t e 1 0 : 1 Z 7 - 1 2 : A c + Z 7 - 1 2 : O H (H)

Z 9 - 1 4 : Ac (L) Z 9 - 1 4 : Ac (L) Z 9 - 1 4 : Ac (L) 100 : 1 Z 9 - 1 4 : Ac + Z 9 - 1 4 : Aid (M) Z 9 - 1 4 :Ac (L) 8 : 1 Z 5 - 1 4 :Ac + Z 9 - 1 4 :Ac (H) 3 : 1 Z 7 - 1 2 : Ar + Z 9 - 1 4 : Ac (M) 2 0 0 : 1 Z 7 - 1 4 :Ac + Z 9 - 1 4 :Ac (H) Z l 1 - 1 6 :Aid (L) Z 9 - 1 4 :Ac (L) Z 9 - 1 4 :Ac (L) Z 7 - 1 2 : A c + Z 9 - 1 4 :Ac (M) 5 0 0 : 1 Z 9 - 1 4 :Ac + Z 7 - 1 2 :Ac (M) Z 1 1 - 1 6 : Ac + Z 1 1 - 1 6 : Aid (L) Z 7 - 1 2 : Ac + Z 9 - 1 4 : Ac Z 9 - 1 4 : Ac (L) Z 1 1 - 1 6 : Ac + Z 9 - 1 6 : Ac (L) Z 1 1 - 1 6 : Ac + Z 9 - 1 6 : Ac (L) Z 9 ~ E 1 2 - 1 4 : Aid (L)

10 : 1 Z 9 - 1 4 : Ac + Z 1 1 - 1 4 : Ac; or 2 : 1 Z 9 - 1 4 : Ac + Z 1 1 - 1 6 : Ac (M) Z11-16:OH Z 7 - 1 2 :Ac (L)

1 9 7 9 d (A) at., 1977b (A) 1982 (A) al., 1977b (A)

Steck et al., 1979b (A) McLaughlin et al., 1975 (A) Roelofs a n d Comeau, 1970 (A) Roelofs a n d Comeau, 1970 (A) Kaae et al., 1973 (A) Butler et al., 1977 (A) Steck et al., 1979b (A)

Roelofs and Comeau, 1971 (A)

Steck et al., 1982 (A)

Steck e t a / . , 1979d (A)

Steck et al., Underhill et Steck et al., Underhill et

Roelofs a n d Comeau, 1970 (A)

M c D o n o u g h et al., 1982 (P) Steck et al., 1979d (A)

Struble et al., 1976 (A)

--4

9

~q

X

Enargia infumata (Grote) [pimorpha pleonectusa (Grote) Helotropha reniformis (Grote) Nedra ramulosa (Guen~e) Oligia bridghami (G & R)

A. interoceanica (Smith) A. velata (Walker) OTmodes devastator (Brace)

20 : 1 Z l 1 - 1 6 : Ac + Z 9 - 1 4 : Ac (M) 2 0 : 1 Z l 1 - 1 6 :Ac + Z 9 - 1 4 :Ac (M) Z 7 - 1 2 : Ac + Z 5 - 1 2 : Ac (M) 2 0 0 : 5 0 : 1 Z l l - 1 6 : A c + Z l 1 - 1 6 :OH + Z l 1 - 1 6 :Aid (M) Z 9 - 1 4 : Ac (L) Z 1 1 - 1 6 : Ac 1 0 0 : 5 0 : 2 Z l l - 1 6 : A l d + Z l l - 1 6 :Ac + Z l 1 - 1 6 :OH (H) 500 : 1 Z 1 1 - 1 6 : Ac + Z 9 - 1 4 : Ac (M) 1 0 0 : 1 Z l l - 1 6 :Aid + Z l l - 1 6 :OH (M) 20 : 1 Z 1 1 - 1 6 : Ac + Z 7 - 1 6 : Ac (L) Z l 1 - 1 4 :OH 500 : 1 Z 1 1 - 1 6 : Ac + Z 1 1 - 1 6 : OH (L)

200 : 1 Z 7 - 1 2 :Ae + Z 7 - 1 4 : Ac (M) 96 : 4 Z 7 - 1 2 : Ac + E 7 - 1 2 : Ac

T. oxyg~'amma (Geyer)

Subfamily A m p h i p y r i n a e Agroperina cogitata (Smith) A. dubitans (Walker) Andropolia contacta (Walker) Apamea indela (Smith)

Z 7 - 1 2 :Ac + Z 7 - 1 4 :Ac (M) Z 7 - 1 2 : Ac (L) Z 7 - 1 2 : Ac (L) 1 0 0 : 1 Z 5 - 1 2 : A c + Z 7 - 1 2 : A c (L) 1 : 1 Z 7 - 1 2 : Ac + Z 5 - 1 2 : Ac (M) Z 7 - 1 2 : Ac (L) Z 7 - 1 2 : Ac Z 7 - 1 2 :Ac 2 0 : 1 Z 7 - 1 2 : A c + 1 4 : A c (L) Z 7 - 1 2 : Ac (L) 9 3 : 7 Z 7 - 1 2 : A c + 12 : A c (M);

Best k n o w n a t t r a c t a n t

A. flagellum (Walker) A. precationis (Guen~e) Chrysaspidia contexta (Grote) C putnami (Grote) C. venusta (Walker) Plusia aereoides (Grote) Pseudoplusia includens (Walker) Rachiplusia ou (Guen~e) Syngrapha epigaea (Grote) S. reetangula (Kirby) Trichoplusia ni (Hi~bner)

Species

T A B L E 2. ( C o n t i n u e d )

(A)

(A)

(A) (A)

Struble et al., 1977a (A) Roelofs and Comeau, 1970 (A)

Steck et al., 1980c (A)

Steck et al., 1982 (A) Roelofs and Comeau, 1970 (A) Roelofs and Comeau, 1971 (A)

Underhill et al., 1977a (A) Steck et al., 1977a (A)

Berger, 1966 (P); Bjostad et al.. 1980 (P); Steck et al., 1980b (A) McLaughlin et al., 1975 (A)

Steck et al., 1979d (A) Roelofs and Comeau, 1971 Roelofs and Comeau, 1970 Steck et al., 1982 (A) Steck et al., 1977a (A) Roelofs and Comeau, 1970 T u m l i n s o n et al., 1972 (P) Roelofs and Comeau, 1970

References

2

Z7-12 :OH (L)

Z 5 - 1 2 : A c + Z7-14 :Ac (L)

ZI 1-16 :Ald+ Z9-14 :Aid[+ Z9-16 : Aid, Z7-16:AId + Z l 1 - 1 6 :OH + 14 :Aid + 16 : Aid] ca. 60:1 Z l l - 1 6 :Aid + Z9-16 :Aid [+ Z7-16 : Aid + 16 : Aid] 7:3 Z l l - 1 6 : A l d + Z l 1 - 1 6 :Ac (L) Zl1-16 :Aid (L)

Weatherston et al., 1974

Klun et al., 1979, 1980a (P) Underhill et al., 1977b (A)

Klun et al., 1979, 1980b (P)

Teal et al., 1981 (P) Roelofs et al., 1974 (P); Tumlinson et al., 1975 (P);

Kaae et al., 1973 (A)

Mitchell and Tumlinson, 1973 (A) Jacobson et al., 1970 (P): Mitchell and Doolittle, 1976 (not A) Brady and Ganyard, 1972 (P) Sekul and Sparks, 1967, 1976 (P); Jones and Sparks, 1979 (P) Birch, 1977 (P)

aln references, (A) indicates a synthetic sex attractant, (P) a sex pheromone confirmed synthetically as the attractant demonstrated. Not included are subfamilies such as Agaristinae, Catocalinae, Euteliinae, and Sarrothripinae, which have no known attractants. References are the latest or best sources for more detailed descriptions of species attractants but may in some cases refer to blends less complex than the ones listed in column 2. Unreferenced systems are unpublished work from the authors' laboratory. Systems examined by the authors have been assigned letters L (low), M (medium), or H (high) roughly-and perhaps subjectively-indicating the lure potency as assessed against light traps or other population indicators.

Schinia bina (Guen6e) S. meadi (Grote) Subfamily Acontilnae Lithacodia albidula (Guen6e) Subfamily Pantheinae Raphia frater (Grote)

H. zea (Boddie)

H. virescens (Fabrieius)

Z l l - 1 6 :Aid (L) Z l l - t 6 :Aid (L) Z9-16 :Aid + Z l 1 - 1 6 :Aid + Z9-16 : Ac + Z11-16 :Ac + Z7-16 : Ac[+ Z9-16 :OH + Z l 1 - 1 6 :OH] ca. 30:1 Z l 1 - 1 6 :Aid + Z9-14 :Aid

Z7-12:Ac

Z9,E12-14:Ac 10:1Z9-12:Ac +Z9-14:Ac

S. exigua (Htibner) S. frugiperda (J.E. Smith)

S. praefica (Grote) Subfamily Heliothidinae Heliothis ononis (D & S) H. phloxiphaga (G & R) H. subflexa (Guen6e)

500:1Zll-16:Ac+Zll-16:OH(L) Zll-16:Ald + Z9-14:Ac(L) Z9,E12-14:Ac 4:1Z9-14:Ac +Z9,E12-14:Ac

O. mactata (Guenge) Protagrotis niveivenosa (Grote) Spodoptera dolichos (Fabricius) S. eridania (Cramer)

--3

742

STECK ET AL.

Chemical Components. All the known attractant chemicals are straightchain alcohols, acetates, or aldehydes, the functional group being always on a terminal carbon atom. No branched noctuid pheromones are reported in the literature, although some compounds have electrophysiological activity (Priesner et al., 1977). The carbon chains known are C10, C12, C14 and C~6 ; odd-numbered chain lengths often can substitute but yield inferior systems. All isolated sex pheromones have even-numbered chains. In the vast majority of cases a single double bond is present in the molecule. A few dienes, notably in Spodoptera species, are sex pheromone components, but it should be noted that almost all dienes reported attractive for noctuids are of a type recently shown capable of substituting in some respects for monoolefinic constituents (Chisholm et al., 1980). Some diolefinic sex pheromones are well known in Old World noctuids: (9Z,11E)-9,11tetradecadienyl acetate and (9Z,12E)-9,12-tetradecadienyl acetate from Spodoptera littoralis (Boisduval) and S. litura (Fabricius) (Tamaki and Yushima, 1974); (E)-9,11-dodecadienyl acetate from Diparopsis castanea (Hampson) (Nesbitt et al., 1975); and (10E,12E)-10,12-hexadecadienal from Earias insulana (Kehat et al., 1979; Hall et al., 1980). Also, there are indications that some North American species including Apamea cinefacta (Grote) and Oncocnemis chandleri (Grote) respond only to diolefinic attractants (Chisholm et al., unpublished results). The double bond configuration is Z - - t h a t is, cis--in almost every noctuid sex attractant, and in all noctuid sex pheromones the attractive components are Z isomers. The unsaturation is located in an odd-numbered position on the chain, but a position not lower than 5 nor higher than 11 as counted from the functional group. Terminal unsaturation is not known in North American species. The main compounds so far known to be involved in noctuid sex attraction thus form a tightly limited structural group. Table 1 shows this in a checkerboard of chain length vs. Z unsaturation point, with the number in each square the frequency of occurrence of that radical in Table 2. The majority (75%) of all the attractant chemicals are accounted for by just three radicals: (Z)-7-dodecenyl, (Z)-9-tetradecenyl, and ( Z ) - I 1-hexadecenyl. Frequency distribution is so graded as to suggest that few if any new attractant molecules of this type will be discovered among noctuids of the subfamilies shown in the table. Some peripheral radicals such as (Z)-3-decenyl, (Z)-3dodecenyl, (Z)-ll-octadecenyl, and (Z)-13-octadecenyl are inviting possibilities. We have screened some blends based on (Z)-3- and (Z)-13-analogs, on terminal olefins, and on C8 and C1~ molecules, but with consistently negative results for noctuids.

SEX ATTRACTANTS OF N O C T U I D MOTHS

743

This subfamily qualification is important, for throughout many subfamilies (e.g., Agaristinae, Catocalinae, Euteliinae, Sarrothripinae) not a single species has been linked to a defined attractant. This may reflect a lack of investigative attention or even the absence of sex pheromones, but it suggests that these taxa may require sex attractant molecules fundamentally different from those effective in Noctuinae, Hadeninae, Cucullinae, Amphipyrinae, Plusiinae, and Heliothidinae. Sex Attractant Blends. Because such a limited number of molecular structures are potential attractants, it is not surprising that blends, exploiting "permutation-combination" possibilities, always seem to be needed for efficient and specific attraction of noctuid males. Single pure compounds are seldom, if ever, satisfactory lures, and occasional reports of high attractancy--especially in the earlier literature--probably indicate coattractive trace contaminants in the chemical samples used. Considering the results in Table 2, these generalizations about blends can be offered: 1. Blends are always required for maximal attractancy. 2. A very wide range of optimal component ratios is possible, from 1 : 1 up to at least 5000:1 (Pseudaletia unipuncta). 3. Blends of three or more eoattractants are required with a considerable number of species, and complex sex pheromones may prove general in the noctuids. 4. Olefinic components in an effective blend are nearly always structurally related by "one-change" steps. That is, components may, from one to another, have different carbon chain lengths, or different double bond positions (counted from either end of the chain), or different functional groups, but only one of these differences. Thus, for example, Heliothis virescens' main coattractive sex pheromone constituents are Z l 1-16: Ald and Z 9 - 1 4 : A l d (double bond in this case at position 5 from the terminal methyl end) differing only in carbon chain length. The compounds 14:Ald, 16:Aid, Z7-16: Ald, Z9-16: Ald, and ZI 1-16: OH, also reported from H. virescens females (Klun et al., 1980b), are only "one change" removed from Z1116:Ald or Z 9 - 1 4 : A l d . In Heliothis zea p h e r o m o n e the coattractive constituents are Z 11-16:Ald and Z9-16:Ald, differing only in double bond position. The compounds ! 6 :Ald and Z 7-16 :Ald were also found in this sex pheromone (Klun et al., 1980a). The structural "one-change" relationships in these pheromone blends can be shown diagrammatically: Zll-16:OH

I I -\ I Z9-14:Ald--Z9-16:Ald

16 : A l d - - Z 11-16 : AId--Z 7-16 :Ald

I

14:Ald--

744

STECK ET AL.

In the multicomponent sex pheromone of Euxoa ochrogaster (Struble et al., 1980) the relationships are: E5-12:Ac 12:Ac--Z5-12:Ae--Z9-12:Ac

The sex pheromone of the a r m y w o r m (Pseudaletia unipuncta) is reported as Z 11-16 : Ac + Z 11-16 : OH (Hill and Roelofs, 1980; McDonough et al., 1980), but high attractancy in lures requires in addition 0.02-0.05% Z 11-16 : Ald and 0.01-0.02% Z 9-14 : Ac (Steck et al., unpublished results). The blend relationships are thus: Z 11-16 : O H - - Z 11-!6: A c - - Z 11-16: Ald Z9-14:Ac A final example concerns a synthetic blend for Euxoa albipennis in which each component contributes to overall potency: Z7-12:Ac--Z7-12:OH

I \

Z 5 - 1 0 : A c - - Z 5 - 1 2 : Ac Of all the entries of Table 2, only two (Actebia fennica and Protagrotis niveivenosa) violate the "one-change" rule. Neither of these blends is a strong lure and both are probably parapheromone mixtures. We can offer no biochemical explanation for the "one-change" phenomenon, although its universal occurrence in lepidopterous lures suggests that a fundamental biogenetic or sensory principle is involved. In most cases, too, the lines of relationship are most numerous around the principal component of the blend. Where the difference between two coattractants in a blend is one of bond position, the two positions are usually nearest odd-numbered carbons such as 5 and 7, 7 and 9, or 9 and 11. This is not necessarily so, however. For Fishia hanhami (blend Z 5 - 1 4 : A c + Z 9 - 1 4 : A c ) the compound Z 7 - 1 4 : A c is a powerful trapping inhibitor even at 0.1% content, and for Polia segregata (blend Z 7-14 : Ac + Z 11-14 : Ac) the analog Z 9-14: Ac is similarly inhibitory (Steck et al., 1979d). On the other hand trace quantities of Z 9 - 1 6 : A c in the lure (Z 7-16: Ac + Z 11-16 : Ac) for Euxoa rnessoria may enhance the attraction of males (Steck et al., unpublished results),

745

SEX ATTRACTANTS OF NOCTUID MOTHS

FACTORS

AFFECTING

POTENCY AND SPECIFICITY

OF SEX ATTRACTANTS

Some of these have already been suggested. Specifically there exist five physical-chemical factors of prime importance in structure-activity relationships: Right Constituents. This is not so obvious as it seems, because parapheromones, compounds which are not natural to a species but nonetheless have pheromone-like action upon the males, are commonly encountered in noctuid lures. Table 2 lists alternative lures of roughly comparable potency for Euxoa basalis, E. pleuritica, E. tessellata, Orthosia hibisci, and Sideridis rosea. In each case a parapheromone seems to be operative in (at least) one lure system. Our experiences indicate that there is usually a better and a poorer system in such instances, and we might regard the more attractive system as having the "right" constituents. However, this is not always so, and a judgment is not always feasible as to what is "right." For the purposes of this manuscript we therefore accept both members of dual systems which have comparable lure power, realizing that one, if not both, of the systems may be parapheromonal in nature. On the subject of parapheromones, we have found in general that they retain the same functional group and formal Z double bond position as the component or components for which they substitute. Different carbon chain lengths are a c o m m o n feature, so that Z 11-16 : Ac or Z 11-15 : Ac substitute to some extent for Z 11-14:Ac in lures for Sideridis rosea; Z 5-11: Ac for Z 510:Ac or Z 5 - 1 2 : A c in Euxoa ochrogaster (Struble 1981a); Z 5 - 1 6 : A c or Z5-15 :Ac for Z 5 - 1 4 : A c in Amathes c-nigrum (Steck et al., unpublished results); and so forth. Chisholm et al. (1980) have shown the parapheromonal action of some dienes among noctuids, while Priesner et al. (1977) have indicated possible parapheromonal properties of alkyl-branched pheromone analogs. Completeness of Blends. As in other insect families, complete blends are critical to lure power and specificity in noctuid lures. Males of the red-backed cutworm Euxoa ochrogaster, unresponsive to pure Z 5 - 1 2 : A c , can be attracted t o 100 : 1 blends of Z 5-12 : Ac + Z 7-12 : Ac (Steck et al., 1980a), but addition of 0.2-0.3% of either of Z 5 - 1 0 : A c or Z 9 - 1 2 : A c increases trap captures 2- to 3-fold. Addition of traces of both these components gives a 6- to 8-fold overall increase in captures (Steck et al., 1982; Struble 198 la), so that the trapping effects (although not necessarily the behavioral effects) of these two components in this system are the same. If Z 5 - 1 2 : A c is omitted from lures, the attractancy of the remaining blend not surprisingly falls to zero. Moreover, if Z 7 - 1 2 : A c is lacking in an otherwise complete lure, trapping similarly drops to near zero. Thus there appears to be a hierarchical order for blend components with the primary component (here Z 5-12:Ac) necessary

746

STECK ET AL.

before the secondary component (Z 7-12:Ac) can have a behavioral effect, and both components necessary before tertiary and quaternary components such as z g - 1 2 : A c and Z 5 - 1 0 : A c can come into play. In P. unipuncta the hierarchical order is (1) Z 11-16 : Ac, (2) Z 11-16 : OH, (3 and 4) Z 11-16 : Aid and Z 9 - 1 4 : A c ; in E, albipennis the order is (1) Z 5 - 1 0 : Ac, (2) Z 7 - 1 2 : A c , (3 and 4) Z 7-12 : OH and Z 5-12: Ac. In all examples known to us, the primary component is also the principal mass component of the blend. It is not yet known whether component hierarchies reflect behavioral responses to individual chemicals or whether concerted actions are involved. Attractant blends are usually improved by incorporating progressively smaller quantities of minor components, some or all of which may be trace constituents. Without these, the lure will perform below its potential. The principle of "one-change" structural relationships and the structureactivity grid give rise to guidelines for candidate components which can be useful for completing a sex pheromone or sex attractant whose composition is incompletely known. For example, the only Z compounds related by "onechange" steps to main component Z 11-16:Ac and within the biologically active limits of Table 1 are Z 7-16: Ac,Z 9-16: Ac, Z 9-14: Ac, Z 11-14: Ac, Z 1 I - 16: OH, and Z 11-16 : Aid. If one accepts (1) the need for blends, (2) the noctuid requirement for Z isomer, (3) the structure-activity grid of Table 1, and (4) the "one-change" rule, then it follows not merely that one or more of the six related compounds above may be present, but rather that one or more must be present--perhaps as trace coattractants--in a noctuid sex attractant blend based on Z 11-16: Ac. The noctuid sex attractants and pheromones now known almost all accord with this conclusion, which holds equally well for principal components other than Z l l-16:Ac. We have found this a very useful hypothesis in development of multicomponent synthetic attractants for noctuids. Where other coattractant compounds are present in a sex attractant, they can be expected to relate in a "one-change" way to the principal coattractant, or to one another, or in both these ways. Thus for the example of Z 11-16:Ac and Z 9-14:Ac as principal and secondary coattractants, respectively, these further coattractants are known: Z 7-12:Ac (Fehia ducens and Euagrotis tepperi); Z 7-14:Ac (Lacinipolia vicina); Z 1 l - 1 6 : O H (Leucania commoides, L. muhilinea, and Euxoa perolivalis); Z I I - 1 6 : A l d (Eurois astricta and E. occulta); and Z9-14:Ald (Euxoa acornis and Cryptocala

acadiensis ). Optimal Ratios in Blends. Multicomponent attractants function best at a unique composition. Deviations from this composition cause loss of trapping power and possibly loss of trapping specificity also. The components Z I l 16:Ac and Z 9-14:Ac together give sex attractant lures for many noctuids depending on their ratio in the blend; 500: 1 lures Enargia infumata whereas

SEX ATTRACTANTS OF NOCTUID MOTHS

747

50 : 1 attracts Mamestra configurata, 1 : I brings Peridroma saucia to traps, 1:4 brings Eurois occulta, and 1"100, Polia Ingravis. Ratios affects specificity in three-component lures too: Z11-16: Ac + Z11-16 : OH + Z 11-16: Ald lures any of Crymodes devastator (25 : 1 : 50), Apamea indela (200 : 50:1)0 Polia atlantica (2000:1:5), or Pseudaletia unipuneta (5000:10: 1). An interesting and but recently appreciated subject is the use of lures containing "trace" coattractant compounds which function best at levels below I% of the total blend. "Trace" blends have been reported in Heliothis spp. (Klun et al., 1979, 1980a,b; Teal et al., 1981); for Polia atlantica and Pseudaletia unipuneta (Steck et al., 1980b); and in Euxoa ochrogaster (Struble et al., 1980; Struble, 1981a). More than two dozen additional examples appear in Table 2. Trace components are probably key factors in performance of most noctuid sex attractants; use of very-high-ratio lure blends is then critical for optimal attraction. Use of insufficiently pure synthetic compounds has from time to time led some workers (including the authors) to believe that a lure is simpler than is really the case. Two examples are instructive. Pseudaletia unipuncta (Hill et al., 1980) and Feltia ducens (Underhill et al., unpublished results) both yield Z l l - 1 6 : A c as the only readily detectable sex pheromone component. F. ducens females attract P. unipuncta males in the field and both species are lured by pure synthetic Z 11-16:Ac. Yet the full blends for these species also contain, respectively, Z l l - 1 6 : O H + Z l l - 1 6 : A l d + Z 9 - 1 4 : A c and Z 7 12:Ac + Z9-14:Ac + other possible components. Blend Release Rate. Sex attractants perform best near a unique release rate, with much higher or lower release rates giving inferior performance in trapping. The actual parameter involved may be the number of attractant molecules reaching the insect sensory apparatus per unit time, but release rate from the lure source is the most easily measured control of this. In field situations release rates suffer night-to-night variations because of changes in factors such as temperture and wind velocity. Male response potential may also fluctuate with these and other factors, so that field captures cannot always be neatly expressed in release rate terms. In general it is safe to say that, experimentally, trapping increases from zero linearly with the logarithm of release rate up to a maximum, following which an analogous decrease to zero occurs. While differences in the maximum point certainly exist among species, the majority of noctuids seem to respond best to release rates of 10-100 ng/h of total blend, under field trapping conditions. In blends where components have different volatilities (i.e., different vapor pressures), the applied composition will not be the composition released into the air. Initially the most volatile component makes up a somewhat greater fraction of the airborne blend that expected from the

748

STECK ET AL.

applied composition, but as this component is lost from the dispenser it later makes up less of the blend than expected. The compositions given in Table 2 are applied ratios. Chemical Discriminators. Lure specificity as well as potency usually increases in blended lures, and a positive correlation exists between a compound's ability to enhance a given lure's potency and its ability to inhibit the approach of nontarget species which would otherwise be attracted to the same lure. Some instances of this have been noted already (Ganyard and Brady, 1971; Steck et al., 1977b; Klun et al., 1980b). This effect opens the possibility of interspecies communication in nature by chemicals; the available evidence suggests this happens wherever components are emitted with a sex pheromone, which (whether they elicit any conspecific response or not) selectively inhibit the approach of alien species. Such compounds have been termed chemical discriminators (Steck et al., 1979b); they are useful in achieving sex attractant specificity in synthetic blends. For species where calling periods serve to distinguish chemically similar pheromones, specificity may not be attainable with synthetic lures (Teal et al., 1978; Underhill et al., 1981). C H E M O T A X O N O M I C VALUE OF SEX A T T R A C T A N T C H E M I C A L S

At the species or genus levels, patterns of sex attractant components appear to have little chemotaxonomic significance. For example, the genus Euxoa uses a bewildering array of olefinic blends. In a few instances where extremely close taxonomic relationships exist, the sex attractants involved are also very similar. Examples include the Euxoa groupsflavicollis, obeliscoides, ridingsiana (Z 9-14: Ac + Z 7-12: Ac) and campestris, declarata, rockburnei (Z5-10:Ac); species of the genus Cucullia (Z9-14:Ac); and Heliothis spp. (Z 11-16: Ald). The trio Eurois (formerly Peridroma) occulta, E. astricta, and Peridroma saucia all share Z 11-16:Ac + Z 9 - 1 4 : A c as sex attractant components. Some other obvious close relations can be seen in Table 2, but against them must be set the chemical diversity evident in the large genera Agrotis, Euxoa, and Polia. The overall lack of chemotaxonomic relationships may reflect in part the unsettled (or at least artificial) nature of lepidopteran t a x o n o m y at these levels, genera being frequently distinguished by characteristics which in other phyla or classes would not serve to differentiate species [see D y a r (1902) and Forbes (1954) for alternative taxonomic treatments of the Noctuidae]. It is at the subfamily level that sex attractants take on clearer chemotaxonomic relationships. The distribution of olefinic components in sex attractants of various noctuid subfamilies is far from homogeneous. Table 3 shows the patterns based on available data. Insufficient data make generalizations on many groups impossible, but in the main subfamilies we note:

5 (5) 26(26) 3 (3)

5 (5) 9(9) 24 (23) 1 (1)

1 (1) 3 (3) 0 15 (15)

0 1 (33) 1 (33)

0 1 (33) 0 0

0 0 0 0

Z5-12 Z7-12 Z9-12

Z5-14 Z7-14 Z9-14 Zl1-14

Z5-16 Z7-16 Z9-16 Zl1-16

abased on data of Table 2.

10 (10)

Noctuinae (46 spp.)

0

Acronictinae (2 spp.)

Z5-10:

Radical

0 0 2 (3) 31 (46)

0 5 (7) 21 (32) 8 (11)

0 1 (1) 0

0

Hadeninae (34 spp.)

0 0 2 (8) 5 (16)

1 (4) 1 (4) 16 (54) 0

0 4 (14) 0

0

Cu cullinae (19 spp.)

0 0 0 0

0 i (4) 0 0

3 O1) 21 (85) 0

0

Plusiinae (18 spp.)

COMPONENTS IN 7 NOCTUID SUBFAMILIES a

0 1 (3) 0 17 (58)

0 0 7 (24) 1 (3)

1 (3) 2 (6) 1 (3)

0

Ampbipyrinae (19 spp.)

TABLE 3. RADICAL FREQUENCY AND (PERCENT DISTRIBUTION) OF SEX A T T R A C T A N T

0 2 (11) 5 (26) 11 (58)

0 0 1 (5) 0

0 0 0

0

Heliothidinae (7 spp.)

750

STECK ET AL.

1. All Z5-10: radicals, as Z5-10:Ac, occur in Noctuinae. 2. Plusiinae require only the three tightly connected radicals Z5-12:, Z7-12:, and Z7-14: (100% of entries). 3. Heliothidinae require mostly Z 11-16: (58% of entries) as Z l 1-16:Ald (in all species) and seem not to utilize Cn components. 4. Cucullinae and Hadeninae are broadly similar in structural responses but the latter are more frequently associated with Z 11-14: and less frequently with Z7-12:. 5. Amphipyrinae very frequently require Z9-14: and Z 11-16: (82% of entries). 6. Noctuinae have the widest structural scope, weighted towards molecules with double-bond 5 carbons removed from the methyl end (76% of entries). The extent to which diolefinic compounds can elicit male responses in noctuids is not yet known. In some species dienes have been demonstrated as sex pheromone components, and certain types of dienes have been shown to substitute generally for related monoenes (Chisholm et al., 1980). However, diolefinic attractants seem to be the exception rather than the rule among the Noctuidae, and too little is reported to allow a meaningful dicussion of their distribution patterns. Hill noted (1979) that some Catocala moths could be attracted to traps baited with lures "similar" to live female Hyphantria cunea (Drury) (family Arctiidae). No details were given, however, nor were the species named.

CONCLUSION

The noctuids use, for attractant purposes, a rather restricted repertory of chemicals, potency and specificity being largely matters of compound combinations and ratio permutations. The systems are not random, however, but follow consistent patterns which give rise to generalizations of a predictive nature concerning the chemical arrays that will prove attractive to male moths--especially in cases where a principal pheromone or attractant is already known. If the generalizations above are correct, future discovery of sex pheromones and development of synthetic sex attractants for noctuids will be governed by these factors: 1. In Noctuinae, Hadeninae, Cucullinae, Amphipyrinae, Heliothidinae, Plusiinae, and probably other subfamilies, the chemical structures involved will be restricted to those indicated in Table 1. 2. Multicomponent blends will be required whose components are related b y the "one-change" rule. 3. Most new or improved attractants will contain one or more trace components.

SEX ATTRACTANTS OF NOCTUID MOTHS

751

4, I n s u b f a m i l i e s as yet u n s t u d i e d n e w s t r u c t u r a l t y p e s o f a t t r a c t a n t s m a y be f o u n d . Note Added in Proof--The sex pheromone of the Catocalinae species Caenurgina erechtea (Cramer) has been shown to consist of (3Z, 6Z, 9Z)-3, 6, 9-eicosatriene and (3Z, 6Z, 9Z)-3, 6, 9-heneicosa-triene (Underhill et al., in preparation). Acknowledgments We thank B.K. Bailey, S.J. Peesker, V.J. Gerwing, and D. Porter for technical assistance in chemistry and biology; the staff of the Biosystematics Research Institute (Agriculture Canada) for taxonomic advice; and P. Palaniswamy for helpful suggestions during preparation of the manuscript.

REFERENCES BERGER, R.S. 1966. Isolation, identification and synthesis of the sex attractant of the cabbage looper Trichoplusia ni. Ann. EntomoL Soe. Am. 59:767-71. BESTMANN,H.J., VOSTROWSKY,O., PLATZ, H., BROSCnE,Th., and KOSCHATZKY,K.H. 1979. (Z)-7Tetradecenylacetat, ein Sexuallockstoff ffir M~innchen von Amathes c-nigrum (Noctuidae, Lepidoptera). Tetrahedron Lett. 1979:497-500. B1RCn, M.C. 1977. Response of both sexes of Trichoplusia ni (Lepidoptera: Noctuidae) to virgin females and to synthetic pheromone. Ecol. Entomol. 2:99-104. BJOSTAD, L.B., GASTON, L.K., NOBLE, L.L., MOYER, J.H., and SHOREY, H.H. 1980. Dodecyl acetate, a second pheromone component of the cabbage looper moth, Trichoplusia ni. A Chem. Ecol. 6:727-734. BRADY, U.E., and GANYARD,M.C., JR. 1972. Identification of a sex pheromone of the female beet armyworm, Spodoptera exigua. Ann. Entomol. Soc. Am. 65:898-899. BUTLER, L.I., HALFHILL,J.E., MCDONOUGH, L.M., and BUTT, B,A. 1977. Sex attractant of the alfalfa looper Autographa californica and the celery looper Anagraphafalcifera. J. Chem. Ecol. 3:65-70. CHISHOLM, M.D., STECK,W.F., ARTHUR,A.P., and UNDERnILL,E.W. 1975. Evidence for cis-11hexadecen-l-ol acetate as a major component of the sex pheromone of the bertha armyworm. Can. Entomol. 107:361-366. CHISHOLM, M.D., STECK, W., and UNDERHILL,E.W. 1980. Effect of additional double bonds on some olefinic moth sex attractants. 9'. Chem. Ecol. 6:203-212. DYAR, H.G. 1902. A list of North American Lepidoptera. BulL U.S. Natl. Museum 52: xix + 723 pp. FORBES, W.T.M. 1954. Lepidoptera of New York and neighboring states, Part III: Noctuidae. Cornell University Agric. Expt. Station Memoir 329. 433 pages. GANYARD, M.C., JR., and BRADY, U.E. 1971. Inhibition of attraction and cross-attraction by interspecific sex pheromone communication in Lepidoptera. Nature 234:415-416. HALL, D.R., BEEVOR,P.S., LESTER, R., and NESBITT, F. 1980. (E,E)-10,12-Hexadecadienal: A component of the female sex pheromone of the spiny bollworm, Earias insulana (Boisd.) (Lepidoptera: Noctuidae). Experientia 36:152-154. HtLL, Ada S. 1979. Sex pheromones of lepidoptera: Recent discoveries with emphasis on the Fall Webworm moth (Hyphantria cunea) system. Proc. EUCHEM Conf. Chem. of Insects. HILL, A.S., and ROELOFS,W.L. 1978. Two sex attractants for male speckled green fruitworm moths, Orthosia hibisci (Guen~e). J. N. Y. EntomoL Soc. 86:296. HILL, A.S., and ROELOFS,W.L. 1980. A female-produced sex pheromone component and attractant for males in the Armyworm moth, Pseudaletia unipuncta. Environ. Entomol. 9:408-411.

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ROELOFS, W.L., and COMEaU,A. 1971. Sex attractants in Lepidoptera. Proc. 2nd Entomol. Cong. Pest Chem., IUPAC, Tel Aviv, 1971. ROELOFS, W.L., HILL, A.S., CARDi, R.T., and BAKER, T.C. 1974. Two sex pheromone components of the tobacco budworm moth, Heliothis virescens. Life Sci. 14:1555-1562. ROELOFS, W., CARDE, A., HILL, A., and CARD~ R. 1976. Sex pheromone of the tbreelined leafroller, Pandemis limitata. Environ. Enlomol. 5:649-652. SEKUL, A.A., and SPARKS,A.N, 1967. Sex pheromone of the fall armyworm moth: Isolation, identification and synthesis. J. Econ. EntomoL 60:1270-1272. SEKUL, A.A., and SPARKS,A.N. 1976. Sex attractant of the fall armyworm moth. USDA Tech. Bull 1542. 6 pages. STECK, WARREN,and BAILEY,B.K. 1978. Pheromone traps for moths: Evaluation on cone trap designs and design parameters. Environ. Entomol. 7:449-455. STECK,W.F., BAILEY, B.K., UNDERHILL,E.W., and CHISHOLM,M.D. 1976. A sex attractant for the great dart Eurois occulta: A mixture of (Z)-9-tetradeeen-l-ol acetate and (Z)-llhexadecen-l-ot acetate. Environ. Entomol. 5:523-526. STECK, W., UNDERHILL, E.W., CmSHOLM, M.D., BAILEY,B.K., LOEFFLER,J., and DEVLIN,C.G. 1977a. Sex attractants for males of 12 moth species found in western Canada. Can. Entomol. 109:157-160. STECK, W., UNDERHILL, E.W. and CmSr~OLM, M.D. 1977b. Attraction and inhibition in moth species responding to sex attractant lures containing Z-1 l-bexadecen-l-yl acetate. J. Chem. Ecol. 3:603-612. STECK, W., BAILEY, B.K., CHISrlOLM, M.D., and UNDERHILL, E.W. 1978. A sex attractant for males of the cutworm Euxoa pleuritica (Lepidoptera: Noctuidae). Can. Entornol. 110: 775-777. STEC~, W.F., STRUBLE, D.L., LILLY, C.E., CHISHOLM, M.D., UNDERmLL, E.W., and SWAILES, G.E. 1979a. A sex attractant for males of the early cutworm, Euxoa tristicula (Morrison). Can. Entomol. 111:337-341. STECK, W.F., UNDERHILL,E.W., CHISUOLM,M.D., and GERBER,H.S. 1979b. Sex attractant for male alfalfa looper moths, Autographa californica (Speyer). Environ. Entomol. 98:373375. STECK, W.F, UNDERmLL, E.W., CHISHOLM, M.D., and BYERS, H.R. 1979c. Sex attractants for Agrotis venerabilis Wlk. and Euxoa albipennis Grt. based on (Z)-5-decenyl acetate and (Z)-7-dodecenyl acetate. Environ. Entomol. 8:1126-1128. STECK, W.F., CHISHOLM, M.D., BAILEY, B.K., and UNDERHILL,E.W. 1979d. Moth sex attraetants found by systematic field testing of 3-component acetate-aldehyde candidate lures. Can. Entomol. 111 : 1263-1269. STECK, W., CHISHOLM, M.D., UNDERHILL,E.W., and PETErtS,C.C. 1980a. Optimized conditions for sex attractant trapping of male redbacked cutworm moths, Euxoa ochrogaster (Guen8e). J. Chem. Ecol. 6:585-591. STECK, W.F., UNDERHILL,E.W., and CHISHOLM, M.D. 1980b. Trace components in lepidopterous sex attractants. Environ. EntomoL 9:583-585. STECK, W.F., UNDERnlLL, E.W., BAILEY, B.K., and CHISHOLM, M.D. 1980c. Improved sex attractant blend for adult males of the glassy cutworm, Crymodes devastator (Lepidoptera: Noctuidae). Can. Entomol. 12:751-752. STECI~, W.F., UNDERnlLL,E.W., BAILEY,B.K. and CHISHOLM,M.D. 1982. Trace co-attractants in synthetic sex lures for 22 noctuid moths. Experientia 38:94-96. STRUBLE, D.L. 198 la. A four-component pheromone blend for optimum attraction of redbacked cutworm males, Euxoa ochrogaster (Guende). J. Chem. Ecol. 7:615-625. STRUBLE, D.L. 1981b. Modification of the attraetant blend for adult males ofthearmycutworm, Euxoa auxiliaris (Grote), and the development of an alternate 3-component attractant blend for this species. Environ. Entomol. 10:167-170. STRUBLE, D.L., and SWAILES,G.E. 1975. A sex attraetant for the Clover Cutworm Scotogramrna

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trifolii (Rottenberg): A mixture of Z-I l-hexadecen-l-ol acetate of Z-11-hexadecen-l-ol. Environ. Entomol. 4:632-636. STRUBLE, D.L., and SWAILES, G.E. 1977a. A sex attractant for the adult males of the cutworm Euxoa auxiliaris: A mixture of Z-5-tetradecenyl acetate and E-7-tetradeeenyl acetate. Environ. Entomol. 6:719-724. STRUBLE, D.L., and SWAILES, G.E. 1977b. Sex attractant for clover cutworm, Scotogramma trifolii: Field tests with various ratios of Z-I l-hexadecen-l-yl acetate and Z-I l-hexadecen1-ol and with various quantities of attractant on two types of carriers. Can. Entomol. 109:369-373. STRUBLE, D.L., and SWAILES, G.E. 1978. A sex attractant for adult males of the pale western cutworm. Agrotis orthogonia (Lepidoptera: Noctuidae). Can. Entomol. 110:769-773. STRIJBLE, D.L., SWAILES, G.E., STECK, W.F., UNDERHILL, E.W., and CHISHOLM, M.D. 1976. A sex attractant for the adult males of the variegated cutworm Peridroma saucia. Environ. Entomot. 5:988-990. SXRUBLE, D.K., SWAILES,G.E., and AYRE, G.L. 1977a. A sex attractant for males of the darksided cutworm, Euxoa messoria (Lepidoptera: Noctuidae). Can. Entomol. 109:975-980. STRUDEL, D.L., SWAILES, G.E., STECK, W.F., UNDERHILL, E.W., and CHISHOLM, M.D. 1977b. A sex attractant for Leucania commoides Gn: A mixture of Z-9-tetradecen-l-yl acetate, Z-1 I-hexadecen-l-yl acetate and Z-1 l-hexadecen-l-ol Can. Entomol. 109:1393-1398. STRUBLE, D.L., BUSER, H.R., ARN, J., and SWAILES, G.E. 1980. Identification of sex pheromone components of redbacked cutworm, Euxoa ochrogaster, and modification of sex attractant blend for adult males. J. Chem. Ecol. 6:573-584. STRUBLE, D.L., STECK,W.F., SWAILES,G.E., CHISHOLM,M.D., UNDERHILL,E.W., and LILLY, C.E. 1981. Two 2-component sex attractant blends for adult males of the striped cutworm Euxoa tesseltata (Lepidoptera: Noctuidae). Can. Entomol. In press. TAMAKI, Y., and YUSHIMA, T. 1974. Sex pheromone of the cotton leafworm, Spodoptera littoralis. J. Insect Physiol. 20:1005-1014. TEAL, P.E. A~, BVERS, J. R., and PHILOGffNE, B.J.R. 1978. Differences in female calling behavior of three interfertile sibling species of Euxoa (Lepidoptera: Noctuidae). Ann. Entomol. Soc. Am. 71:630-634. TEAL, P.E.A., HEATH, R.R., TUMHNSON, J.H.}and MCLAUGHLIN, J.R. 1981. Identification of a sex pheromone of Heliothis subflexa (Gn.) (Lepidoptera: Noctuidae) and field trapping studies using different blends of components. J. Chem. Ecol. 7:1011-1022. TUMLINSON, J.H., MITCHELL, E.R., BROWNER, S.M., and LINDQUIST, D.A. 1972. A sex pheromone for the soybean looper. Environ. Entomol. 1:466-468. TUMLINSON,J.H., HENDRICKS, D.E., MITCHELL, E.R., DOOLITTLE, R.E., and BRENNAN,M.M. 1975. Isolation, identification and synthesis of the sex pheromone of the tobacco budworm. J. Chem. Ecol. 1:203-214. UNDERHILL~ E.W., STECK, W.F., and CHISHOLM, M.D. 1976. Sex pheromone of the Clover Cutworm moth, Scotogramma trifolii: Isolation, identification and field studies. Environ. Entomol. 5:307-310. UNDERHILL,E.W., STECK,W.F., and CHISHOLM,M.D. 1977a. A sex attractant for bertha armyworm moth, Mamestra configurata: A mixture of Z9-tetradecen-l-yl acetate and Z l l hexadecen-l-yl acetate. Can. Entomol. 109:1335-1340. UNDERHILL,E.W., CHISHOLM,M.D., and STECK,W. 1977b. Olefinic aldehydes as constituents of sex attractants for noctuid moths. Environ. Entomol. 6:333-337. UNDERHILL, E.W., STECK, W.F., BYERS, J.R., and CHISHOLM, M.D. 1981. (Z)-5-Decenyl acetate, a sex attractant for three closely related species, Euxoa deelarata, Euxoa campestris and Euxoa roekburnei. Can. EntomoL 113:245-249. WEATHERSTON, J., DAVIDSON, J.M., and SIMONINI, D. 1974. Attractants for several male forest Lepidoptera. Can. Entomol. 106:781-782.

Structure-activity relationships in sex attractants for north American noctuid moths.

Sex attractants known for 145 species of noctuid moths have many common features both as to chemical constituents and to their relationships in blends...
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