Journal of Chemical Ecology, Vol. 8, No. 4, 1982
EFFECTS OF PHEROMONE COMPONENTS AND THEIR DEGRADATION PRODUCTS ON THE RESPONSE OF H e l i o t h i s S P P . T O T R A P S 1'2
T.N. SHAVER,
3 J.D.
LOPEZ,
JR., 3 and A.W. HARTSTACK,
JR. 4
3Cotton Insects Research Laboratory, AR, SEA, USDA P.O. Drawer DG, College Station, Texas 77841 4pest Control Equipment and Methods Research Unit, AR, SEA, USDA Texas .4 &M University, College Station, Texas 77843 (Received June 16, 1981; revised September 8, 1981)
Abstract--None of the isolated degradation products of (Z)-1 l-hexadecenal [(Z)-1 I-HDAL] affected the catches of either tobacco budworm [Heliothis virescens (F.)] or bollworm [H. zea (Boddie)] moths when dispensed with pheromone from cotton dental rolls in cone traps. Also, none of the degradation products of (Z)-9-tetradecenal [(Z)-9-TDAL] had an effect on trap catches of tobacco budworm moths. Two of the three chemicals that have previously been identified in ovipositor washes of tobacco budworms but that are absent in those of bollworms caused a reduction in capture of bollworms: (Z)-9-TDAL (1.0#g/trap) caused a 96% reduction in trap catch and ( Z ) - l l - h e x a d e c e n - l - o l (20.0 /~g/trap) caused a similar reduction. Tetradencenal (40 tzg/trap) had no effect on trap catch. Key W o r d s - - S e x pheromone, Heliothis virescens, tobacco budworm, Heliothis zea, bollworm, virelure, Lepidoptera, Noctuidae. INTRODUCTION
Sex pheromone components have been isolated and identified for the tobacco budworm, Heliothis virescens (F.) (Roelofs et al., 1974; Tumlinson et al., 1975; Klun et al., 1980a) and for the bollworm, Heliothis zea (Boddie) (Klun tin cooperation with the Texas Agricultural Experiment Station, Texas A&M University, College Station, Texas 77843. 2This paper reports the results of research only. Mention of a pesticide in this paper does not constitute a recommendation for use by the U S D A nor does it imply registration under F I F R A as amended. Also, mention of a commercial or proprietary product in this paper does not constitute an endorsement of this product by the USDA. 755
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SHAVER ET AL.
et al., 1980b). (Z)-! 1-Hexadecenal [(Z)- 11-HDAL], (Z)-9-hexadecenal [(Z)9-HDAL], (Z)-7-hexadecenal [(Z)-7-HDAL], and hexadecanal are found in rinses of the ovipositors of both species; however, rinses of the ovipositors of the tobacco budworm also contain (Z)-9-tetradecenal [(Z)-9-TDAL], tetradecanal, and (Z)-l 1-hexadecen-l-ol. Klun et al. (1980a) observed that traps baited with (Z)-I I-HDAL (115.5 keg), (Z)-9-HDAL (4.5/~g), (Z)-7-HDAL (2.6 #g), and (Z)-9-TDAL (6.9 #g) captured tobacco budworm males but no bollworm males, even though adults of that species were concurrently abundant with tobacco budworms in the field. They suggested that (Z)-9TDAL was a deterrant to bollworm attraction and concluded that one or more of the three chemicals found in the rinses of tobacco budworm ovipositors but not in similar rinses from bollworms influenced specificity between the two species. Recently, Shaver and Ivie (1981) isolated and identified several products formed during the degradation of virelure [(Z)-I 1HDAL and (Z)-9-TDAL], the synthetic sex pheromone of the tobacco budworm. These products from (Z)-I 1-HDAL were: (Z)-I 1-hexadecenoic acid, cis- and trans-ll,12-epoxyhexadecanoic acid, cis- and trans-ll,12epoxyhexadecanal, cis- and trans-lO,11-epoxypentadecanal, (Z)-10-pentadecenal, (Z)-5-pentadecene, cis- and trans-5,6-epoxypentadecane, and tetradecene. The products degradation products obtained from (Z)-9-TDAL were: (Z)-9-tetradecenoic acid, cis- and trans-9,10-epoxytetradecanoic acid; cis- and trans-9,10-epoxytetradecanal; cis- and trans-8,9-epoxytridecanal, (Z)-8-tridecenal, (Z)-5-tridecene, cis- and trans-5,6-epoxytridecane, and dodecene. Tests described herein were conducted to determine the effects of (1) the degradation products of vilelure on the entrapment of adult tobacco budworms and bollworms in traps baited with the appropriate pheromone and (2) certain components of the tobacco budworm pheromone on the entrapment of bollworms.
METHODS
AND MATERIALS
Degradation products of (Z)-I 1-HDAL and (Z)-9-TDAL were formed by allowing hexane solutions of these compounds to stand in the laboratory under fluorescent lights for at least 2 weeks. Acidic degradation products were extracted as their salts from the hexane solutions with 0.1 N NaOH. The alkaline solutions were then neutralized with HC1, and the acids recovered with hexane (Shaver and Ivie, 1980). The acidic degradation products of (Z)-I 1-HDAL included (Z)-I 1-hexadecenoic acid (65%), cis-11,12-epoxytetradecanoic acid (31%), and trans-11,12-epoxyhexadecanoic acid (4%), while those of (Z)-9-TDAL included (Z)-9-tetradecenoic acid (68%), cis-9,10epoxytetradecanoic acid (29%), and trans-9,10-epoxytetradecanoic acid (3%).
Heliothis
RESPONSE TO TRAPS
757
The relative amounts of the acids were determined by first converting them to the respective methyl esters by reaction with diazomethane and then analyzing the reaction mixtures with gas chromatography on 1.7-m X 0.65-cm glass columns packed with 1.95% SP2401 + 1.6% SP2250 on 80/100 mesh Supelcoport. The hydrocarbon products formed during the degradation of (Z)-I IH D A L and (Z)-9-TDAL were separated by elution from silica gel columns with hexane. Hydrocarbons produced during the degradation of (Z)-I IH D A L included (Z)-5-pentadecene (85%) and tetradecene (position of nnsaturation not determined, 15%), and those formed from (Z)-9-TDAL included (Z)-5-tridecene (90%) and dodecene (position of unsaturation not determined, I0%). Other degradation products were isolated by preparative gas chromatography on 1.7-m X 0.65-cm glass columns packed with 1.95% SP2401 + 1.6% SP2250 on 80/100 mesh Supelcoport. These degradation products were cis- and trans-9,10-epoxytetradecanal (95% eis isomer) and (Z)-8-tridecenal from (Z)-9-TDAL and cis- and trans-9,10-epoxyhexadecanal (95% cis isomer) and (Z)-10-pentadecenal from (Z)-I 1-HDAL. Cotton dental roll dispensers containing virelure [(Z)-I 1-HDAL, 245/zg and (Z)-9-TDAL, 15/~g] were used as standards in tests to assess the effects of each degradation product on trap catch of tobacco budworms. Similar dispensers containing all four components of the bollworm pheromone [(Z)l l - H D A L , 231 /ag; (Z)-9-HDAL, 9.0 #g; (Z)-7-HDAL, 5.2 #g; and hexadecanal, 22 tag] were used as standards for bollworm tests. Three pheromone components that are found in tobacco budworms but not in bollworms [(Z)-9-TDAL, tetradecanal, and (Z)-I l-hexadecen-l-ol] were tested individually with the bollworm pheromone for their effects on trap catches of bollworm moths. In the first test, (Z)-9-TDAL was added in concentrations of 0.05, 0.2, and 1 #g/dispenser; this corresponds to 0.02%, 0.035%, and 0.37% of the total mixture, respectively. We originally had planned to add up to twice the relative concentration found in rinses of tobacco b u d w o r m ovipositors (5.5% of total pheromone), but preliminary tests showed that trap catches of bollworm were reduced to zero with as much as half the relative amount found in tobacco budworm ovipositor rinses. This test was conducted for six nights, with six replicates per night. In another test, (Z)-9-TDAL was formulated in rubber septa (formulation 1171 red, The West Co., Phoenixville, Pennsylvania) with 2.5 mg of the four-component bollworm pheromone to give 0.01%, 0.1%, 1%, and 5% (Z)-9-TDAL. The test was run for four nights with six replicates per night, and fresh baits were prepared after the second night. All tests of tobacco budworm adults were conducted in a cotton field. Bollworm tests were conducted in corn fields (May-June) and cotton fields (July-September). All fields were located in Burleson County, Texas. Cone
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traps ( H a r t s t a c k et al., 1979) were set up in straight lines at the perimeters of the fields a n d t r e a t m e n t s were r a n d o m i z e d nightly. Dispensers were prepared each night a n d placed in the traps between 9:30 a n d 11:00 P M so that the most volatile c o m p o u n d would be available d u r i n g the period of peak m o t h activity.
RESULTS AND DISCUSSION None of the d e g r a d a t i o n products of ( Z ) - I 1 - H D A L caused a significant change in the response of b o l l w o r m m o t h s to traps baited only with the f o u r - c o m p o n e n t b o l l w o r m p h e r o m o n e (Table 1). A l t h o u g h the traps baited with p h e r o m o n e + the acidic d e c o m p o s i t i o n products of ( Z ) - l l - H D A L caught more insects t h a n traps c o n t a i n i n g the p h e r o m o n e alone (35.1 m o t h s / n i g h t c o m p a r e d to 30.2 m o t h s / n i g h t ) , the difference is n o t significant.
TABLE 1. EFFECT OF DEGRADATION PRODUCTS OF (Z)-I 1-HDAL ON TRAP CATCHES OF H e I i o t h i s z e a MALES IN CONE TRAPS BAITED WITH COTTON DENTAL ROLL DISPENSERS CONTAINING 267.2/~g OF A FOUR-COMPONENT PHEROMONEa Degradation products Test 1 Pheromone only (Z) + (E)-ll,12-Epoxyhexadecanal, 190 #gb (Z) + (E)-ll,12-Epoxyhexadecanal, 900 ~g Test 2 Pheromone only (Z) + (E)-HDAL acids, 200 ,ga Test 3 Pheromone only (Z)-10-Pentadecenal, 5/~g (Z)-10-Pentadecenal, 25 ~g Test 4 Pheromone (Z)-ll-HDAL hydrocarbons (25 gg)e
X _+SE/trap/night 39.6 +-2.04 a c 58.6 +-4.29 a 44.7 +_3.79 a 30.2 -+1.51 a 35.1 +-1.66 a 117.1 -+5.4 a 120.2 -+7.1 a 95.0 +-5.5 a 48.6 +-1.8 a 46.5 +-1.4 a
aThe amounts (%) of each component in each dispenser were: (Z)-I 1-hexadecenal, 231.0 #g (87%); (Z)-9-hexadecenal, 9.0 ~g (3%); (Z)-7-hexadecenal, 5.2 #g (2%); and hexadecenal, 22 ~g (8%). bCa. 95% Z isomer. CNumbers followed by the same letter are not significantly different, P = 0.05, Duncan's new multiple-range test. dMixture of (Z)-11,hexadecenoic acid (65%) and cis + trans-11,12-epoxyhexadecanoic acid [31% eis, 4% trans]. eMixtures of (Z)-5-pentadecene (85%) and tetradecene (15%).
Heliothis
RESPONSE TO TRAPS
759
TABLE 2. EFFECT OF DEGRADATION PRODUCTS OF (Z)-I t-HDAL AND (Z)-9-TDAL ON TRAP CATCHES OF H e l i o t h i s v i r e s c e n s IN CONE TRAPS BAITED WITH COTTON DENTAL ROLL DISPENSERS CONTAINING PHEROMONES a Degradation products Test 1 Virelure standard (Z) + (E)-9,10-Epoxytetradecanal, 15 ~zgb (Z) + (E)-ll,12-Epoxyhexadecanal, 60 ~gb Test 2 Vixelure standard (Z)-9-TDAL acids (250/zg) d (Z)-ll-HDAL acids (250 #g)e Test 3 Vixelure standard (Z)-8-Tridecenal (2 gg) (Z)-10-Pentadecenal (15 ~zg) Test 4 Vi~elure standard (Z)-9-TDAL hydrocarbons (10 #g)f (Z)-I 1-HDAL hydrocarbons (25 t~g)g
X -+ SE/trap/night 5.9 -+0.3 a c 5.1 -+0.2a 4.9 -+0.2 a 9.4 -+0.2 a 8.8 -+0.2 a 10.3 -+0.3 a 13.6 +-0.3 a 12.1 -+0.3 a 13.0 -+0.5 a 14.5 -+0.4 a 14.2 -+0.4 a 17.3 +- 1.3 a
aEach trap was baited with a cotton dental roll containing 245 ug (Z)-ll-hexadecenal + 15 b~g (Z)-9-tetradecenal. Ca. 95% Z isomer. CNumbers followed by the same letter are not significantly different, P = 0.05, Duncan's new multiple-range test. dMixture of (Z)-9-tetradecenoic acid (68%) and cis + trans-9,10-epoxytetradecanoic acid, 29% cis and 3% trans. eMixture of (Z)-I 1-hexadecenoic acid (65%) and cis + trans-11,12-epoxyhexadecanoic acid, f3M1%cis and 4% trans. ixture of (Z)-5-tridecene (90%) and dodecene (10%). gMixture of (Z)-5-pentadecene (85%) and tetradecene (15%).
Likewise, n o n e of the d e g r a d a t i o n p r o d u c t s of ( Z ) - I 1 - H D A L and (Z)-9T D A L significantly affected the p o t e n c y of virelure in a t t r a c t i n g t o b a c c o b u d w o r m s to the trap (Table 2). T r a p s baited with 25 ~ g of ( Z ) - I 1 - H D A L h y d r o c a r b o n s plus virelure c a u g h t a b o u t 19% m o r e m o t h s t h a n traps baited with virelure alone, but this difference was not significant. Th e a d d i t i o n of ( Z ) - 9 - T D A L to the f o u r - c o m p o n e n t b o l l w o r m p h e r o m o n e at a rate as low as 0.2 t~g/trap significantly reduced the capture of b o l l w o r m males (Table 3). T r a p s c o n t a i n i n g 1.0 # g of ( Z ) - 9 - T D A L c o m b i n e d with the f o u r - c o m p o n e n t b o l l w o r m p h e r o m o n e c a u g h t an a v e r a g e of only 0.6 b o l l w o r m m a l e s / t r a p / n i g h t , but also c a u g h t a few t o b a c c o b u d w o r m moths. In this case, the c o n c e n t r a t i o n of ( Z ) - 9 - T D A L represented 0.37% o f the total
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SHAVER ET AL. TABLE 3. EFFECT OF 3 H. v i r e s c e n s PHEROMONE COMPONENTS NOT FOUND IN H. z e a ON TRAP CATCH OF H . z e a IN CONE TRAPS BAITED WITH COTTON DENTAL ROLL DISPENSERS CONTAINING 4 COMPONENTS
Component (Z)-9-Tetradecenal
(Z)-I t-Hexadecen-l-ol
Tetradecanal
Amount (tag/trap) a 0.00 0.05 0.20 1.00 0.00 5.00 10.00 20.00 0.00 10.00 20.00 40.00
(0.02%) (0.07%) (0.37%) (1.85) (3.70) (7.50) (3.7) (7.5) (15.0)
X +--SE/trap/night 17.3 12.8 4.5 0.6 14.7 5.2 3.0 0.6 86.2 88.9 75.8 64.6
+-0.56 a b +-0.43 a +-0.02 b +-0.01 b +-0.09 a +-0.40 b +-0.20 bc +-0.01 c +-4.10 a +-5.40 a -+4.10 a +-3.40 a
aEach dispenser contained (Z)-ll-hexadecenal (231.0 tag), (Z)-9-hexadecenal (9.0 tag), (Z)-7-hexadecenal (5.2 tag), and hexadecenal (22 tag) plus indicated quantity (tag) of test compound. bNumbers followed by the same letter are not significantly different at P = 0.05, Duncan's new multiple-range test. b o l l w o r m p h e r o m o n e m i x t u r e . (Its relative c o n c e n t r a t i o n in h e p t a n e washes of t o b a c c o b u d w o r m o v i p o s i t o r s is ca. 5%.) ( Z ) - I l - H e x a d e c e n - l - o l at 5 # g / t r a p (the lowest c o n c e n t r a t i o n tested), r e d u c e d the c a p t u r e of male b o l l w o r m m o t h s when used with the f o u r c o m p o n e n t p h e r o m o n e (Table 3). T r a p s baited with dispensers c o n t a i n i n g 20 /~g o f ( Z ) - ! 1 - h e x a d e c e n - l - o l plus the b o l l w o r m p h e r o m o n e m i x t u r e caught an average of o n l y 0.6 m o t h s / n i g h t / t r a p . This c o n c e n t r a t i o n represents ca. 7.5% of the t o t a l b o l l w o r m p h e r o m o n e in the dispensers, a n d is a p p r o x i m a t e l y equal to the c o n c e n t r a t i o n (6%) of ( Z ) - I 1 - h e x a d e c e n - l - o l in h e p t a n e washes of t o b a c c o b u d w o r m ovipositors. T e t r a d e c a n a l had no significant influence on c a p t u r e s of b o l l w o r m moths, even at the highest c o n c e n t r a t i o n ( 4 0 / ~ g / t r a p or 15% o f b o l l w o r m p h e r o m o n e ) tested. This c o m p o u n d c o n s t i t u t e d a b o u t 2% of the t o t a l c o m p o n e n t s of h e p t a n e washes of t o b a c c o b u d w o r m o v i p o s i t o r s (Klun et al., 1979). W h e n ( Z ) - 9 - T D A L was f o r m u l a t e d with the b o l l w o r m p h e r o m o n e m i x t u r e in r u b b e r septa, significant decreases in the c a p t u r e of b o l l w o r m m o t h s were o b t a i n e d with c o n c e n t r a t i o n s as low as 2.5 # g ( Z ) - 9 - T D A L / s e p t u m (Table 4). T r a p s b a i t e d with r u b b e r septa c o n t a i n i n g 2.5 mg b o l l w o r m
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Heliothis RESPONSE TO TRAPS T A B L E 4. E F F E C T OF ( Z ) - 9 - T E T R A D E C E N A L O N T R A P CATCHES OF H e l i o t h i s z e a IN CONE T R A P S WITH P H E R O M O N E F O R M U L A T E D IN R U B B E R SEPTA a
(Z)-9-Tetradecenal/trap (#g) 0 0.25 2.50 25.00 250.00
X moth/trap/night +- SE 25.4 21.0 16.5 1.4 0.1
• 1.03 • 0.88 • 0.69 _+0.18 _+0.01
a~ ab b cc cd
aEach rubber septum contained 2.5 mg of the four-component H. zea pheromone plus the indicated quantity of (Z)-9-tetradecenal. bNumbers followed by the same letter are not significantly different (Duncan's new multiple-range test, P = 0.05). CTraps averaged 6.6 H. virescens/trap/night. dTraps averaged 34,6 H. virescens/trap/night.
p h e r o m o n e plus 25 # g ( Z ) - 9 - T D A L caught an average o f 1.4 b o l l w o r m m o t h s / t r a p / n i g h t , but c a u g h t an average of 6.6 t o b a c c o b u d w o r m m o t h s / t r a p / n i g h t . T r a p s b a i t e d with 2.5 m g b o l l w o r m p h e r o m o n e plus 250 # g ( Z ) - 9 - T D A L c a u g h t an average of 0.1 male b o l l w o r m m o t h s / t r a p / n i g h t a n d 34.6 male t o b a c c o b u d w o r m m o t h s / t r a p / night. The results indicate t h a t the d e g r a d a t i o n p r o d u c t s of ( Z ) - I 1 - H D A L tested had no effect on catches of either t o b a c c o b u d w o r m or b o l l w o r m m o t h s when the t r a p s were b a i t e d with their respective p h e r o m o n e . Also, the d e g r a d a t i o n p r o d u c t s o f ( Z ) - 9 - T D A L t h a t were tested h a d no effect on t r a p catches of t o b a c c o b u d w o r m . Since f o u r of the seven c o m p o u n d s t h a t have been f o u n d in the t o b a c c o b u d w o r m are also f o u n d in the b o l l w o r m , it is likely t h a t the presence o r absence of one or m o r e of the three chemicals f o u n d only in the t o b a c c o b u d w o r m has an i m p o r t a n t role in d e t e r m i n i n g the specificity o f the two species in their response to p h e r o m o n e - b a i t e d t r a p s a n d , possibly, specificity in m a t i n g , as suggested by K l u n et al. (1980a). I n d e e d , in o u r test, two o f the three chemicals d i d influence t r a p catch of b o l l w o r m s . This i n f o r m a t i o n could be useful in p r o g r a m s utilizing m a t i n g d i s r u p t i o n techniques to suppress p o p u l a t i o n s of H e l i o t h i s spp.
REFERENCES HARTSTACK,A.W., WITZ,J.A., and BUCK,D.R. 1979. Moth traps for the tobacco budworm. J. Econ. Entomol. 72:519-522. KLUN,J.A., PLIMMER,J.R., BIERL-LEONHARDT,B.A., SPARKS,A.N., and CHAPMAN,O.C. 1979.
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Trace chemicals: The essence of sexual communication systems in Heliothis species. Science 204: 1328-1330. KLUN, J.A., BIERL-LEONHARDT,B.A., PLIMMER, J.R., SPARKS, A.N., PRIMIANI, M., CHAPMAN, O.L., LEPONE, G., and LEE, G.H. 1980a. Sex pheromone chemistry of the female tobacco budworm moth, Heliothis virescens. J. Chem. Ecol. 6: 177-183. KLUN, J.A., PLIMMER, J.R., BIERL-LEONHARDT,B.A., SPARKS, A.N., PR1M1ANI, M., CHAPMAN, O.L., LEE, G.H., and LEPONE, G. 1980b. Sex pheromone chemistry of the female corn earworm moth, Heliothis zea. J. Chem. Ecol. 6: 165-175. ROELOES, W.L., HILL, A.S., CAROL, R.T., and BAKER, T.C. 1974. Two sex pheromone components of the tobacco budworm moth, Heliothis virescens. Life Sci. 14: 1555-1562. SHAVER, T.N., and IvlE, G.W. 1981. Identification of degradation products of virelure, a pheromone of the tobacco budworm. J. Agric. Food Chem. TUML1NSON, 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. s Chem. Ecol. 1:203-204.
EFFECTS OF PHEROMONE COMPONENTS AND THEIR DEGRADATION PRODUCTS ON THE RESPONSE OF H e l i o t h i s S P P . T O T R A P S 1'2
T.N. SHAVER,
3 J.D.
LOPEZ,
JR., 3 and A.W. HARTSTACK,
JR. 4
3Cotton Insects Research Laboratory, AR, SEA, USDA P.O. Drawer DG, College Station, Texas 77841 4pest Control Equipment and Methods Research Unit, AR, SEA, USDA Texas .4 &M University, College Station, Texas 77843 (Received June 16, 1981; revised September 8, 1981)
Abstract--None of the isolated degradation products of (Z)-1 l-hexadecenal [(Z)-1 I-HDAL] affected the catches of either tobacco budworm [Heliothis virescens (F.)] or bollworm [H. zea (Boddie)] moths when dispensed with pheromone from cotton dental rolls in cone traps. Also, none of the degradation products of (Z)-9-tetradecenal [(Z)-9-TDAL] had an effect on trap catches of tobacco budworm moths. Two of the three chemicals that have previously been identified in ovipositor washes of tobacco budworms but that are absent in those of bollworms caused a reduction in capture of bollworms: (Z)-9-TDAL (1.0#g/trap) caused a 96% reduction in trap catch and ( Z ) - l l - h e x a d e c e n - l - o l (20.0 /~g/trap) caused a similar reduction. Tetradencenal (40 tzg/trap) had no effect on trap catch. Key W o r d s - - S e x pheromone, Heliothis virescens, tobacco budworm, Heliothis zea, bollworm, virelure, Lepidoptera, Noctuidae. INTRODUCTION
Sex pheromone components have been isolated and identified for the tobacco budworm, Heliothis virescens (F.) (Roelofs et al., 1974; Tumlinson et al., 1975; Klun et al., 1980a) and for the bollworm, Heliothis zea (Boddie) (Klun tin cooperation with the Texas Agricultural Experiment Station, Texas A&M University, College Station, Texas 77843. 2This paper reports the results of research only. Mention of a pesticide in this paper does not constitute a recommendation for use by the U S D A nor does it imply registration under F I F R A as amended. Also, mention of a commercial or proprietary product in this paper does not constitute an endorsement of this product by the USDA. 755
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et al., 1980b). (Z)-! 1-Hexadecenal [(Z)- 11-HDAL], (Z)-9-hexadecenal [(Z)9-HDAL], (Z)-7-hexadecenal [(Z)-7-HDAL], and hexadecanal are found in rinses of the ovipositors of both species; however, rinses of the ovipositors of the tobacco budworm also contain (Z)-9-tetradecenal [(Z)-9-TDAL], tetradecanal, and (Z)-l 1-hexadecen-l-ol. Klun et al. (1980a) observed that traps baited with (Z)-I I-HDAL (115.5 keg), (Z)-9-HDAL (4.5/~g), (Z)-7-HDAL (2.6 #g), and (Z)-9-TDAL (6.9 #g) captured tobacco budworm males but no bollworm males, even though adults of that species were concurrently abundant with tobacco budworms in the field. They suggested that (Z)-9TDAL was a deterrant to bollworm attraction and concluded that one or more of the three chemicals found in the rinses of tobacco budworm ovipositors but not in similar rinses from bollworms influenced specificity between the two species. Recently, Shaver and Ivie (1981) isolated and identified several products formed during the degradation of virelure [(Z)-I 1HDAL and (Z)-9-TDAL], the synthetic sex pheromone of the tobacco budworm. These products from (Z)-I 1-HDAL were: (Z)-I 1-hexadecenoic acid, cis- and trans-ll,12-epoxyhexadecanoic acid, cis- and trans-ll,12epoxyhexadecanal, cis- and trans-lO,11-epoxypentadecanal, (Z)-10-pentadecenal, (Z)-5-pentadecene, cis- and trans-5,6-epoxypentadecane, and tetradecene. The products degradation products obtained from (Z)-9-TDAL were: (Z)-9-tetradecenoic acid, cis- and trans-9,10-epoxytetradecanoic acid; cis- and trans-9,10-epoxytetradecanal; cis- and trans-8,9-epoxytridecanal, (Z)-8-tridecenal, (Z)-5-tridecene, cis- and trans-5,6-epoxytridecane, and dodecene. Tests described herein were conducted to determine the effects of (1) the degradation products of vilelure on the entrapment of adult tobacco budworms and bollworms in traps baited with the appropriate pheromone and (2) certain components of the tobacco budworm pheromone on the entrapment of bollworms.
METHODS
AND MATERIALS
Degradation products of (Z)-I 1-HDAL and (Z)-9-TDAL were formed by allowing hexane solutions of these compounds to stand in the laboratory under fluorescent lights for at least 2 weeks. Acidic degradation products were extracted as their salts from the hexane solutions with 0.1 N NaOH. The alkaline solutions were then neutralized with HC1, and the acids recovered with hexane (Shaver and Ivie, 1980). The acidic degradation products of (Z)-I 1-HDAL included (Z)-I 1-hexadecenoic acid (65%), cis-11,12-epoxytetradecanoic acid (31%), and trans-11,12-epoxyhexadecanoic acid (4%), while those of (Z)-9-TDAL included (Z)-9-tetradecenoic acid (68%), cis-9,10epoxytetradecanoic acid (29%), and trans-9,10-epoxytetradecanoic acid (3%).
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The relative amounts of the acids were determined by first converting them to the respective methyl esters by reaction with diazomethane and then analyzing the reaction mixtures with gas chromatography on 1.7-m X 0.65-cm glass columns packed with 1.95% SP2401 + 1.6% SP2250 on 80/100 mesh Supelcoport. The hydrocarbon products formed during the degradation of (Z)-I IH D A L and (Z)-9-TDAL were separated by elution from silica gel columns with hexane. Hydrocarbons produced during the degradation of (Z)-I IH D A L included (Z)-5-pentadecene (85%) and tetradecene (position of nnsaturation not determined, 15%), and those formed from (Z)-9-TDAL included (Z)-5-tridecene (90%) and dodecene (position of unsaturation not determined, I0%). Other degradation products were isolated by preparative gas chromatography on 1.7-m X 0.65-cm glass columns packed with 1.95% SP2401 + 1.6% SP2250 on 80/100 mesh Supelcoport. These degradation products were cis- and trans-9,10-epoxytetradecanal (95% eis isomer) and (Z)-8-tridecenal from (Z)-9-TDAL and cis- and trans-9,10-epoxyhexadecanal (95% cis isomer) and (Z)-10-pentadecenal from (Z)-I 1-HDAL. Cotton dental roll dispensers containing virelure [(Z)-I 1-HDAL, 245/zg and (Z)-9-TDAL, 15/~g] were used as standards in tests to assess the effects of each degradation product on trap catch of tobacco budworms. Similar dispensers containing all four components of the bollworm pheromone [(Z)l l - H D A L , 231 /ag; (Z)-9-HDAL, 9.0 #g; (Z)-7-HDAL, 5.2 #g; and hexadecanal, 22 tag] were used as standards for bollworm tests. Three pheromone components that are found in tobacco budworms but not in bollworms [(Z)-9-TDAL, tetradecanal, and (Z)-I l-hexadecen-l-ol] were tested individually with the bollworm pheromone for their effects on trap catches of bollworm moths. In the first test, (Z)-9-TDAL was added in concentrations of 0.05, 0.2, and 1 #g/dispenser; this corresponds to 0.02%, 0.035%, and 0.37% of the total mixture, respectively. We originally had planned to add up to twice the relative concentration found in rinses of tobacco b u d w o r m ovipositors (5.5% of total pheromone), but preliminary tests showed that trap catches of bollworm were reduced to zero with as much as half the relative amount found in tobacco budworm ovipositor rinses. This test was conducted for six nights, with six replicates per night. In another test, (Z)-9-TDAL was formulated in rubber septa (formulation 1171 red, The West Co., Phoenixville, Pennsylvania) with 2.5 mg of the four-component bollworm pheromone to give 0.01%, 0.1%, 1%, and 5% (Z)-9-TDAL. The test was run for four nights with six replicates per night, and fresh baits were prepared after the second night. All tests of tobacco budworm adults were conducted in a cotton field. Bollworm tests were conducted in corn fields (May-June) and cotton fields (July-September). All fields were located in Burleson County, Texas. Cone
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traps ( H a r t s t a c k et al., 1979) were set up in straight lines at the perimeters of the fields a n d t r e a t m e n t s were r a n d o m i z e d nightly. Dispensers were prepared each night a n d placed in the traps between 9:30 a n d 11:00 P M so that the most volatile c o m p o u n d would be available d u r i n g the period of peak m o t h activity.
RESULTS AND DISCUSSION None of the d e g r a d a t i o n products of ( Z ) - I 1 - H D A L caused a significant change in the response of b o l l w o r m m o t h s to traps baited only with the f o u r - c o m p o n e n t b o l l w o r m p h e r o m o n e (Table 1). A l t h o u g h the traps baited with p h e r o m o n e + the acidic d e c o m p o s i t i o n products of ( Z ) - l l - H D A L caught more insects t h a n traps c o n t a i n i n g the p h e r o m o n e alone (35.1 m o t h s / n i g h t c o m p a r e d to 30.2 m o t h s / n i g h t ) , the difference is n o t significant.
TABLE 1. EFFECT OF DEGRADATION PRODUCTS OF (Z)-I 1-HDAL ON TRAP CATCHES OF H e I i o t h i s z e a MALES IN CONE TRAPS BAITED WITH COTTON DENTAL ROLL DISPENSERS CONTAINING 267.2/~g OF A FOUR-COMPONENT PHEROMONEa Degradation products Test 1 Pheromone only (Z) + (E)-ll,12-Epoxyhexadecanal, 190 #gb (Z) + (E)-ll,12-Epoxyhexadecanal, 900 ~g Test 2 Pheromone only (Z) + (E)-HDAL acids, 200 ,ga Test 3 Pheromone only (Z)-10-Pentadecenal, 5/~g (Z)-10-Pentadecenal, 25 ~g Test 4 Pheromone (Z)-ll-HDAL hydrocarbons (25 gg)e
X _+SE/trap/night 39.6 +-2.04 a c 58.6 +-4.29 a 44.7 +_3.79 a 30.2 -+1.51 a 35.1 +-1.66 a 117.1 -+5.4 a 120.2 -+7.1 a 95.0 +-5.5 a 48.6 +-1.8 a 46.5 +-1.4 a
aThe amounts (%) of each component in each dispenser were: (Z)-I 1-hexadecenal, 231.0 #g (87%); (Z)-9-hexadecenal, 9.0 ~g (3%); (Z)-7-hexadecenal, 5.2 #g (2%); and hexadecenal, 22 ~g (8%). bCa. 95% Z isomer. CNumbers followed by the same letter are not significantly different, P = 0.05, Duncan's new multiple-range test. dMixture of (Z)-11,hexadecenoic acid (65%) and cis + trans-11,12-epoxyhexadecanoic acid [31% eis, 4% trans]. eMixtures of (Z)-5-pentadecene (85%) and tetradecene (15%).
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TABLE 2. EFFECT OF DEGRADATION PRODUCTS OF (Z)-I t-HDAL AND (Z)-9-TDAL ON TRAP CATCHES OF H e l i o t h i s v i r e s c e n s IN CONE TRAPS BAITED WITH COTTON DENTAL ROLL DISPENSERS CONTAINING PHEROMONES a Degradation products Test 1 Virelure standard (Z) + (E)-9,10-Epoxytetradecanal, 15 ~zgb (Z) + (E)-ll,12-Epoxyhexadecanal, 60 ~gb Test 2 Vixelure standard (Z)-9-TDAL acids (250/zg) d (Z)-ll-HDAL acids (250 #g)e Test 3 Vixelure standard (Z)-8-Tridecenal (2 gg) (Z)-10-Pentadecenal (15 ~zg) Test 4 Vi~elure standard (Z)-9-TDAL hydrocarbons (10 #g)f (Z)-I 1-HDAL hydrocarbons (25 t~g)g
X -+ SE/trap/night 5.9 -+0.3 a c 5.1 -+0.2a 4.9 -+0.2 a 9.4 -+0.2 a 8.8 -+0.2 a 10.3 -+0.3 a 13.6 +-0.3 a 12.1 -+0.3 a 13.0 -+0.5 a 14.5 -+0.4 a 14.2 -+0.4 a 17.3 +- 1.3 a
aEach trap was baited with a cotton dental roll containing 245 ug (Z)-ll-hexadecenal + 15 b~g (Z)-9-tetradecenal. Ca. 95% Z isomer. CNumbers followed by the same letter are not significantly different, P = 0.05, Duncan's new multiple-range test. dMixture of (Z)-9-tetradecenoic acid (68%) and cis + trans-9,10-epoxytetradecanoic acid, 29% cis and 3% trans. eMixture of (Z)-I 1-hexadecenoic acid (65%) and cis + trans-11,12-epoxyhexadecanoic acid, f3M1%cis and 4% trans. ixture of (Z)-5-tridecene (90%) and dodecene (10%). gMixture of (Z)-5-pentadecene (85%) and tetradecene (15%).
Likewise, n o n e of the d e g r a d a t i o n p r o d u c t s of ( Z ) - I 1 - H D A L and (Z)-9T D A L significantly affected the p o t e n c y of virelure in a t t r a c t i n g t o b a c c o b u d w o r m s to the trap (Table 2). T r a p s baited with 25 ~ g of ( Z ) - I 1 - H D A L h y d r o c a r b o n s plus virelure c a u g h t a b o u t 19% m o r e m o t h s t h a n traps baited with virelure alone, but this difference was not significant. Th e a d d i t i o n of ( Z ) - 9 - T D A L to the f o u r - c o m p o n e n t b o l l w o r m p h e r o m o n e at a rate as low as 0.2 t~g/trap significantly reduced the capture of b o l l w o r m males (Table 3). T r a p s c o n t a i n i n g 1.0 # g of ( Z ) - 9 - T D A L c o m b i n e d with the f o u r - c o m p o n e n t b o l l w o r m p h e r o m o n e c a u g h t an a v e r a g e of only 0.6 b o l l w o r m m a l e s / t r a p / n i g h t , but also c a u g h t a few t o b a c c o b u d w o r m moths. In this case, the c o n c e n t r a t i o n of ( Z ) - 9 - T D A L represented 0.37% o f the total
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SHAVER ET AL. TABLE 3. EFFECT OF 3 H. v i r e s c e n s PHEROMONE COMPONENTS NOT FOUND IN H. z e a ON TRAP CATCH OF H . z e a IN CONE TRAPS BAITED WITH COTTON DENTAL ROLL DISPENSERS CONTAINING 4 COMPONENTS
Component (Z)-9-Tetradecenal
(Z)-I t-Hexadecen-l-ol
Tetradecanal
Amount (tag/trap) a 0.00 0.05 0.20 1.00 0.00 5.00 10.00 20.00 0.00 10.00 20.00 40.00
(0.02%) (0.07%) (0.37%) (1.85) (3.70) (7.50) (3.7) (7.5) (15.0)
X +--SE/trap/night 17.3 12.8 4.5 0.6 14.7 5.2 3.0 0.6 86.2 88.9 75.8 64.6
+-0.56 a b +-0.43 a +-0.02 b +-0.01 b +-0.09 a +-0.40 b +-0.20 bc +-0.01 c +-4.10 a +-5.40 a -+4.10 a +-3.40 a
aEach dispenser contained (Z)-ll-hexadecenal (231.0 tag), (Z)-9-hexadecenal (9.0 tag), (Z)-7-hexadecenal (5.2 tag), and hexadecenal (22 tag) plus indicated quantity (tag) of test compound. bNumbers followed by the same letter are not significantly different at P = 0.05, Duncan's new multiple-range test. b o l l w o r m p h e r o m o n e m i x t u r e . (Its relative c o n c e n t r a t i o n in h e p t a n e washes of t o b a c c o b u d w o r m o v i p o s i t o r s is ca. 5%.) ( Z ) - I l - H e x a d e c e n - l - o l at 5 # g / t r a p (the lowest c o n c e n t r a t i o n tested), r e d u c e d the c a p t u r e of male b o l l w o r m m o t h s when used with the f o u r c o m p o n e n t p h e r o m o n e (Table 3). T r a p s baited with dispensers c o n t a i n i n g 20 /~g o f ( Z ) - ! 1 - h e x a d e c e n - l - o l plus the b o l l w o r m p h e r o m o n e m i x t u r e caught an average of o n l y 0.6 m o t h s / n i g h t / t r a p . This c o n c e n t r a t i o n represents ca. 7.5% of the t o t a l b o l l w o r m p h e r o m o n e in the dispensers, a n d is a p p r o x i m a t e l y equal to the c o n c e n t r a t i o n (6%) of ( Z ) - I 1 - h e x a d e c e n - l - o l in h e p t a n e washes of t o b a c c o b u d w o r m ovipositors. T e t r a d e c a n a l had no significant influence on c a p t u r e s of b o l l w o r m moths, even at the highest c o n c e n t r a t i o n ( 4 0 / ~ g / t r a p or 15% o f b o l l w o r m p h e r o m o n e ) tested. This c o m p o u n d c o n s t i t u t e d a b o u t 2% of the t o t a l c o m p o n e n t s of h e p t a n e washes of t o b a c c o b u d w o r m o v i p o s i t o r s (Klun et al., 1979). W h e n ( Z ) - 9 - T D A L was f o r m u l a t e d with the b o l l w o r m p h e r o m o n e m i x t u r e in r u b b e r septa, significant decreases in the c a p t u r e of b o l l w o r m m o t h s were o b t a i n e d with c o n c e n t r a t i o n s as low as 2.5 # g ( Z ) - 9 - T D A L / s e p t u m (Table 4). T r a p s b a i t e d with r u b b e r septa c o n t a i n i n g 2.5 mg b o l l w o r m
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Heliothis RESPONSE TO TRAPS T A B L E 4. E F F E C T OF ( Z ) - 9 - T E T R A D E C E N A L O N T R A P CATCHES OF H e l i o t h i s z e a IN CONE T R A P S WITH P H E R O M O N E F O R M U L A T E D IN R U B B E R SEPTA a
(Z)-9-Tetradecenal/trap (#g) 0 0.25 2.50 25.00 250.00
X moth/trap/night +- SE 25.4 21.0 16.5 1.4 0.1
• 1.03 • 0.88 • 0.69 _+0.18 _+0.01
a~ ab b cc cd
aEach rubber septum contained 2.5 mg of the four-component H. zea pheromone plus the indicated quantity of (Z)-9-tetradecenal. bNumbers followed by the same letter are not significantly different (Duncan's new multiple-range test, P = 0.05). CTraps averaged 6.6 H. virescens/trap/night. dTraps averaged 34,6 H. virescens/trap/night.
p h e r o m o n e plus 25 # g ( Z ) - 9 - T D A L caught an average o f 1.4 b o l l w o r m m o t h s / t r a p / n i g h t , but c a u g h t an average of 6.6 t o b a c c o b u d w o r m m o t h s / t r a p / n i g h t . T r a p s b a i t e d with 2.5 m g b o l l w o r m p h e r o m o n e plus 250 # g ( Z ) - 9 - T D A L c a u g h t an average of 0.1 male b o l l w o r m m o t h s / t r a p / n i g h t a n d 34.6 male t o b a c c o b u d w o r m m o t h s / t r a p / night. The results indicate t h a t the d e g r a d a t i o n p r o d u c t s of ( Z ) - I 1 - H D A L tested had no effect on catches of either t o b a c c o b u d w o r m or b o l l w o r m m o t h s when the t r a p s were b a i t e d with their respective p h e r o m o n e . Also, the d e g r a d a t i o n p r o d u c t s o f ( Z ) - 9 - T D A L t h a t were tested h a d no effect on t r a p catches of t o b a c c o b u d w o r m . Since f o u r of the seven c o m p o u n d s t h a t have been f o u n d in the t o b a c c o b u d w o r m are also f o u n d in the b o l l w o r m , it is likely t h a t the presence o r absence of one or m o r e of the three chemicals f o u n d only in the t o b a c c o b u d w o r m has an i m p o r t a n t role in d e t e r m i n i n g the specificity o f the two species in their response to p h e r o m o n e - b a i t e d t r a p s a n d , possibly, specificity in m a t i n g , as suggested by K l u n et al. (1980a). I n d e e d , in o u r test, two o f the three chemicals d i d influence t r a p catch of b o l l w o r m s . This i n f o r m a t i o n could be useful in p r o g r a m s utilizing m a t i n g d i s r u p t i o n techniques to suppress p o p u l a t i o n s of H e l i o t h i s spp.
REFERENCES HARTSTACK,A.W., WITZ,J.A., and BUCK,D.R. 1979. Moth traps for the tobacco budworm. J. Econ. Entomol. 72:519-522. KLUN,J.A., PLIMMER,J.R., BIERL-LEONHARDT,B.A., SPARKS,A.N., and CHAPMAN,O.C. 1979.
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Trace chemicals: The essence of sexual communication systems in Heliothis species. Science 204: 1328-1330. KLUN, J.A., BIERL-LEONHARDT,B.A., PLIMMER, J.R., SPARKS, A.N., PRIMIANI, M., CHAPMAN, O.L., LEPONE, G., and LEE, G.H. 1980a. Sex pheromone chemistry of the female tobacco budworm moth, Heliothis virescens. J. Chem. Ecol. 6: 177-183. KLUN, J.A., PLIMMER, J.R., BIERL-LEONHARDT,B.A., SPARKS, A.N., PR1M1ANI, M., CHAPMAN, O.L., LEE, G.H., and LEPONE, G. 1980b. Sex pheromone chemistry of the female corn earworm moth, Heliothis zea. J. Chem. Ecol. 6: 165-175. ROELOES, W.L., HILL, A.S., CAROL, R.T., and BAKER, T.C. 1974. Two sex pheromone components of the tobacco budworm moth, Heliothis virescens. Life Sci. 14: 1555-1562. SHAVER, T.N., and IvlE, G.W. 1981. Identification of degradation products of virelure, a pheromone of the tobacco budworm. J. Agric. Food Chem. TUML1NSON, 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. s Chem. Ecol. 1:203-204.
