Journal of Chemical Ecology, Vol. 7, No. 4, 1981
G R O W T H I N H I B I T O R S IN T O M A T O (Lycopersicon) to T O M A T O F R U I T W O R M (Heliothis zea)l
C.A. E L L I G E R , Y. W O N G , B.G. C H A N , a n d A.C. W A I S S , J R . Western Regional Research Center, USDA, SEA-A R Berkeley, California 94710
(Received July 1, 1980; revised October 22, 1980) Abstract--Several compounds that retard the larval growth of the tomato fruitworm, Heliothis zea (Boddie) have been isolated and identified from tomato leaves, Lycopersicon esculentum Mill. The major allelochemics are a-tomatine (I), chlorogenic acid (I1), rutin (III), and a new caffeyl derivative of an aldaric acid (IV). The isolation, analyses, and toxicity of these compounds to H. zea are presented. Key Words--Lycopersicon esculentum, Lycopersicon hirsutum f. glabratum Heliothis zea, iLepldoptera, Noctuidae, a-tomatine, rutin, chlorogenic acid, caffeyl aldaric acid, allelochemics, tomato, tomato fruitworm.
INTRODUCTION T o m a t o f r u i t w o r m , H e l i o t h i s zea, is an i m p o r t a n t insect pest o f t o m a t o , L y c o p e r s i c o n e s c u l e n t u m , p a r t i c u l a r l y in the s o u t h e a s t e r n U.S. Efforts to establish the n a t u r e o f resistance a n d to i m p r o v e t o m a t o ' s resistance a g a i n s t this insect t h r o u g h b r e e d i n g have been m a d e by a n u m b e r of researchers. F e r y a n d C u t h b e r t (1975) r e p o r t e d v a r y i n g degrees o f a n t i b i o s i s a m o n g excised foliage of t o m a t o species. T h e y f u r t h e r s h o w e d t h a t a n e t h a n o l i c e x t r a c t f r o m t o m a t o leaves was r e s p o n s i b l e for r e d u c i n g survival rates o f H. zea larvae. Both a n t i x e n o s i s a n d antibiosis a g a i n s t t o m a t o f r u i t w o r m in c o m m e r c i a l t o m a t o e s were o b s e r v e d b y C o s e n z a a n d G r e e n (1979). M o r e r e c e n t l y 2t r i d e c a n o n e , a t o x i c a n t to several t o m a t o insects, was i s o l a t e d f r o m the wild ~Reference to a company and/or product named by the department is only for purposes of information and does not imply approval or recommendation of the product to the exclusion of others which may also be suitable. 753
ELLIGERETAL.
754
tomato L. hirsutum f glabratum C.H. Mull. (Williams et al., 1980). This paper reports the isolation procedures, biological activities, and analyses of antigrowth factors of a-tomatine (I), cholorogenic acid (II), rutin (III), and caffeyl aldarate (IV) (Scheme 1) in the "fresh market" tomato cultivar Ace,
CHa
CH 3
~ RO...i~~
V
CH3 ~OH Ho~O
~
~
TOMATINE
(I), R=;0-LYCOTETRAOSE
"O-R~INOSE 0
RUTiN (Jill)
(CHOH)3 I CO2H
__••OH
HO2C
Off
~ OH
OH
CHLOROGENIC ACID (11")
CAFFEYL ALDARIC ACID (IV)
SCHEME1 "processing" tomato cultivar Campbell 29, and wild tomato L. hirsutum f glabratum (P.I. 134417). METHODS AND MATERIALS Tomato cultivar Ace and L. hirsutum f glabratum (P.I. 134417) were field grown in Albany, California, and Campbell 29 was field grown in Davis, California. Young fully expanded leaves of these varieties were collected during the middle of July 1979 (daylength ca. 15 hr). Extraction and Purification. In the typical extraction and purification procedure, 100 g of freeze-dried tomato leaves (cultivar Ace, dried to 17.6% of fresh weight) were ground with 800 ml of acetone in a 2-liter beaker for 5 rain using a Polytron grinder at maximum speed. The mixture was filtered through a sintered glass funnel, and the residue was extracted again with three more portions of acetone. The combined extract was diluted to 2.5 liters and kept in the refrigerator at 5~ C. The extracted residue was further extracted with four 800-ml portions of methanol and water, respectively. The weights of materials from the solvent extraction were 4.4 g from acetone, 9.0 g from methanol, 22.5 g from water, and 64 g of residue. Aliquots of extracts were tested for antigrowth activity against first instar H. zea. larvae (Figure 1). Methanol extract, equivalent to 30 g of dried leaves, was purified through 500 ml of Amberlite XAD-2 by a previously reported procedure of Waiss et al. (1979), and the methanol eluent was chromatographed through a 4 • 110-cm Sephadex LH-20 column, a-Tomatine (I), chlorogenic acid (II), and rutin (III) were separated.
TOMATO
FRUITWORM
~" oiv
GROWTH
INHIBITORS
755
I00 'ACE'
I--
METHANOL
80 U
~0--
60
WATER
'CAMPBELL 2 9' METHANOL WATER
o o 20
g 5
3
6
9
EXTRACTS FROM GRAMS DRY LEAVES PER 3 0 G
OF
DIET
FIG. 1. Growth inhibition of H. zea larvae by tomato leaf extracts.
Bioassays. Bioassays for antigrowth activity in tomato leaves, their extracts, and purified compounds were performed according to our earlier reported procedure (Chan et al., 1978). Tests were conducted on samples of ten larvae per level for crude extracts and 20 larvae per level for the pure compounds examined. Standard deviations from the mean were typically about _+15% for controls and became much larger when growth suppression took place. Quantitative Analysis of a-Tomatine. Two grams of freeze-dried leaf were ground with methanol (3 • 50 ml) using a Polytron grinder for 1 min in a 100-ml beaker. The extracted solution was concentrated to about 2 ml in a vacuum rotatory evaporator at 35~ C. For the removal of phenolic compounds, the sample solution was pretreated by passage through a short AG 1 • 8 (OH-form) anion-exchange column (1.3 • 7 cm) followed by elution with an additional 2 ml of methanol. Effluent was collected in a 5-ml volumetric flask and diluted to volume for high-performance liquid chromatographic (HPLC) analysis, a-Tomatine standard solution was prepared similarily. The analysis was carried out under isocratic condition on a/~-Bondapak-NH2 column (3.9 • 300 mm) in reverse-phase mode (20% 0.01 M (NH4)2HPO4 in acetonitrile), and monitored with a differential refractometer. Quantitative Analysis of Chlorogenic Acid and Rutin. One gram of freeze-dried leaf was ground for 1 min with 10 ml of C H C L 3 - M e O H - H 2 0 (6: 4: 1) containing 10 mg of quercitrin (as internal standard) using a Polytron grinder. The residue was separated by filtration, and the filtrate was shaken with 5 ml of water. After centrifugation to separate the phases, the upper aqueous layer was analyzed by H P L C (Ultrasphere octyl column, 4.6 • 250 mm 0.5% aq. HCO2H-MeOH, 60:40).
756
ELLIGER ET AL.
Isolation o f Caffeyl A l d a r a t e (IV). The aqueous extract from the equivalent of 30 g of dried Ace tomato leaves was purified through a 4 • 80cm column of Amberlite XAD-2 and separated by Sephadex LH20 as previously reported (Waiss et al., 1979). Caffeyl aldarate isomers were isolated at approximately I% of dried leaf weight.
RESULTS A N D D I S C U S S I O N
Using Ace tomato leaves, we found that, while the acetone extract showed no antigrowth activity, sequential extraction of tomato leaf with solvents of increasing polarity showed incorporation of methanol and water extracts deterred appreciably the growth ofH. zea larvae (Figure 1). Similar results were obtained from leaf extracts of Campbell 29. Purification of the methanolic extract through absorption on XAD-2 followed by chromatographic separation with LH20 afforded three H. zea growth inhibitors, namely, a-tomatine, chlorogenic acid, and rutin (Table 1). These allelochemics are well-known phytochemicals, and their identities were confirmed by comparing spectroscopic (UV and NMR) and chromatographic patterns with those of authentic, commercially available compounds. Tomatine was first isolated from tomato by Fontaine and coworkers (1948). While the toxicity of a-tomatine to fungi, potato insects, and mammals has been reviewed (Roddick, 1974), its antibiotic activity toward H. zea has not been well documented. Chlorogenic acid and rutin are ubiquitous in higher plants. Rutin has been isolated as the coloring matter of tomato stems (Blout, 1933) and its growth inhibitory effect to Heliothis species in cotton has been reported (Chan et al., 1978b). The presence of chlorogenic acid in tomato and Solanaceae has been reported by Politis (1948), but its antibiotic effect toward TABLE 1. CONCENTRATION AND
EDs0 OF ot-TOMAT1NE,
CHLOROGENIC ACID,
AND RUTIN IN TOMATO FOL1AGEa
a -Tomatine
Chlorogenic acid
Rutin
0.76 0.61 2.45
1.2 0.8 0.3
2.3 1.3 Not detectable
0.40
2.5
2.4
L. esculentum
Ace Campbell 29 L. hirsutumf glabratum
P.I. 134417 EDs0 Milligrams per gram fresh weight.
TOMATOFRUITWORMGROWTHINHIBITORS
757
t o m a t o fruitworm has not been recorded. Chlorogenic acid is toxic to greenbug (Todd et al., 1971). The effective dosage to reduce the larval growth of t o m a t o fruitworm (bioassayed at first instar stage) to 50% of growth attained on synthetic diet (EDs0) for the allelochemics I, II, and III were estimated through bioassays of these compounds at several concentrations (Table 1). The water extract of t o m a t o leaves, after extraction with methanol, gave a new compound which was identified as a caffeyl aldaric acid (IV) through chemical degradation and derivatization, UV, IR, [1H]NMR,[13 C ] N M R , and mass spectroscopy. Details of structural determination will be reported elsewhere. The c o m p o u n d occurs as a mixture of isomeric esters and lactones and is present as approximately 1% of the dry t o m a t o (Ace) leaf. The antibiotic activity of this new allelochemic (EDs0) is similar to that of chlorogenic acid. This observation is not unexpected since we have o b s e r v e d that the growth inhibitory activity is derived from the catechol moiety of the molecule (Elliger et al., 1980). It appears from the results presented above that the chemically based growth inhibiting properties of L. e s c u l e n t u m toward H. zea are derived from the combination of a - t o m a t i n e and the three phenolic allelochemics II, III, and IV. It is worthwhile to note that the presence of 2-tridecanone in L. h i r s u t u m f , g l a b r a t u m as reported by Williams and coworkers (1980) may explain in part the high level of resistance of this wild t o m a t o (Fery and Cuthbert, 1975), but the high level of a - t o m a t i n e in the foliage and its importance in pest resistance should not be minimized. The presence and diversity of the allelochemics in the foliage of t o m a t o present an opportunity for plant breeders to manipulate the concentration Of one or all of these resitance factors tailored to a specific feeding site and time for the protection of the plant. We hope that the analytical procedures presented in this paper facilitate this endeavor. Acknowledgments--The authors thank Mr. Jim Street for the supply of Campbell 29, Mr. Jim Baker for the Heliothis bioassay, and Drs. H. Chan, G.G. Kennedy, R.L. Fery, and H.B. Green for their valuable discussion and contributions.
REFERENCES BLOt/T, B.K. 1933. The colouring matter on the stem of the tomato. J. Chem. Soc.
1933:1528-1529. CnAN, B.G., WAISS, A.C., JR., STANLEY,W.L., and GOODBAN,A.E. 1978a. A rapid diet preparation method for antibiotic phytochemicalsbioassays.J. Econ. EntomoL 71:366-368. CnAN, B.G., WAISS, A.C., JR., BINDER, R.G., and ELLIGER,C.A. 1978b. Inhibition of lepidopterous larval growth by cotton constituents. EntomoL Exp. AppL 24:294-300. COSEr~ZA,G., and GREEN,H.B. 1979. Behavior of the tomato fruitworm, Heliothis zea (Boddie), on susceptible and resistant lines of processing tomatoes. Hortic. Sci. 14:171-173.
758
ELLIGER ET AL.
ELLIGER, C.A., CHAN, G.B., and WAISS,A.C., JR., 1980. Flavonoids as growth inhibitors: Structural factors governing toxicity. Naturwissenshaften. 67: 338-9. FERY, R.L., and CUTHBERT, F.P., Ja. 1975. Antibiosis in Lycopersicon to tomato fruitworm (Heliothis zea). J. Am. Soc. Hortic. Sci. 100:276-278. FOUNTAINE,T.D., IRVING,G.W., POOLE,R. M., and DOOLITTLE,S.P. 1948. Isolation and partial characterization of crystalline tomatine, an antibiotic agent from tomato plant. Arch. Biochem. 18:467-475. POLITIS, J. 1948. Distribution of chlorogenic acid in Solanaceae and the organs of these plants. Compt. Rend. 229:692-693. RODDICK, J.G. 1974. The steroidal glycoalkaloid a-tomatine. Phytochemistry 13:9-25. TODD, G.W., GETCHUM,A., and CRESS,D.E. 1971. Resistance in barley to greenbug, Schizaphis graminum L. Toxicity of phenolic and related compounds and related substances. Ann. Entomol. Soc. Am. 64:718-722. WA1SS,A.C. JR., CHAN, B.G., ELLIGER, C.A., WISEMAN,B.R., McMILLIAN, W.W., WIDSTROM, N.W., ZUBER,M,S., and KEASTER,A.J. 1979. Maysin, a flavone glycoside from corn silks with antibiotic activities toward corn earworm. J. Econ. Entomol. 72:256-258. WILLIAMS,W.G., KENNEDY, G.G., YAMAMOTO,R.T., THACKER, J.D., and BORDNER, J. 1980. 2-Tridecanone: A naturally occurring insecticide from the wild tomato Lycopersicon hirsutum f glabratum. Science 207:888-889.
G R O W T H I N H I B I T O R S IN T O M A T O (Lycopersicon) to T O M A T O F R U I T W O R M (Heliothis zea)l
C.A. E L L I G E R , Y. W O N G , B.G. C H A N , a n d A.C. W A I S S , J R . Western Regional Research Center, USDA, SEA-A R Berkeley, California 94710
(Received July 1, 1980; revised October 22, 1980) Abstract--Several compounds that retard the larval growth of the tomato fruitworm, Heliothis zea (Boddie) have been isolated and identified from tomato leaves, Lycopersicon esculentum Mill. The major allelochemics are a-tomatine (I), chlorogenic acid (I1), rutin (III), and a new caffeyl derivative of an aldaric acid (IV). The isolation, analyses, and toxicity of these compounds to H. zea are presented. Key Words--Lycopersicon esculentum, Lycopersicon hirsutum f. glabratum Heliothis zea, iLepldoptera, Noctuidae, a-tomatine, rutin, chlorogenic acid, caffeyl aldaric acid, allelochemics, tomato, tomato fruitworm.
INTRODUCTION T o m a t o f r u i t w o r m , H e l i o t h i s zea, is an i m p o r t a n t insect pest o f t o m a t o , L y c o p e r s i c o n e s c u l e n t u m , p a r t i c u l a r l y in the s o u t h e a s t e r n U.S. Efforts to establish the n a t u r e o f resistance a n d to i m p r o v e t o m a t o ' s resistance a g a i n s t this insect t h r o u g h b r e e d i n g have been m a d e by a n u m b e r of researchers. F e r y a n d C u t h b e r t (1975) r e p o r t e d v a r y i n g degrees o f a n t i b i o s i s a m o n g excised foliage of t o m a t o species. T h e y f u r t h e r s h o w e d t h a t a n e t h a n o l i c e x t r a c t f r o m t o m a t o leaves was r e s p o n s i b l e for r e d u c i n g survival rates o f H. zea larvae. Both a n t i x e n o s i s a n d antibiosis a g a i n s t t o m a t o f r u i t w o r m in c o m m e r c i a l t o m a t o e s were o b s e r v e d b y C o s e n z a a n d G r e e n (1979). M o r e r e c e n t l y 2t r i d e c a n o n e , a t o x i c a n t to several t o m a t o insects, was i s o l a t e d f r o m the wild ~Reference to a company and/or product named by the department is only for purposes of information and does not imply approval or recommendation of the product to the exclusion of others which may also be suitable. 753
ELLIGERETAL.
754
tomato L. hirsutum f glabratum C.H. Mull. (Williams et al., 1980). This paper reports the isolation procedures, biological activities, and analyses of antigrowth factors of a-tomatine (I), cholorogenic acid (II), rutin (III), and caffeyl aldarate (IV) (Scheme 1) in the "fresh market" tomato cultivar Ace,
CHa
CH 3
~ RO...i~~
V
CH3 ~OH Ho~O
~
~
TOMATINE
(I), R=;0-LYCOTETRAOSE
"O-R~INOSE 0
RUTiN (Jill)
(CHOH)3 I CO2H
__••OH
HO2C
Off
~ OH
OH
CHLOROGENIC ACID (11")
CAFFEYL ALDARIC ACID (IV)
SCHEME1 "processing" tomato cultivar Campbell 29, and wild tomato L. hirsutum f glabratum (P.I. 134417). METHODS AND MATERIALS Tomato cultivar Ace and L. hirsutum f glabratum (P.I. 134417) were field grown in Albany, California, and Campbell 29 was field grown in Davis, California. Young fully expanded leaves of these varieties were collected during the middle of July 1979 (daylength ca. 15 hr). Extraction and Purification. In the typical extraction and purification procedure, 100 g of freeze-dried tomato leaves (cultivar Ace, dried to 17.6% of fresh weight) were ground with 800 ml of acetone in a 2-liter beaker for 5 rain using a Polytron grinder at maximum speed. The mixture was filtered through a sintered glass funnel, and the residue was extracted again with three more portions of acetone. The combined extract was diluted to 2.5 liters and kept in the refrigerator at 5~ C. The extracted residue was further extracted with four 800-ml portions of methanol and water, respectively. The weights of materials from the solvent extraction were 4.4 g from acetone, 9.0 g from methanol, 22.5 g from water, and 64 g of residue. Aliquots of extracts were tested for antigrowth activity against first instar H. zea. larvae (Figure 1). Methanol extract, equivalent to 30 g of dried leaves, was purified through 500 ml of Amberlite XAD-2 by a previously reported procedure of Waiss et al. (1979), and the methanol eluent was chromatographed through a 4 • 110-cm Sephadex LH-20 column, a-Tomatine (I), chlorogenic acid (II), and rutin (III) were separated.
TOMATO
FRUITWORM
~" oiv
GROWTH
INHIBITORS
755
I00 'ACE'
I--
METHANOL
80 U
~0--
60
WATER
'CAMPBELL 2 9' METHANOL WATER
o o 20
g 5
3
6
9
EXTRACTS FROM GRAMS DRY LEAVES PER 3 0 G
OF
DIET
FIG. 1. Growth inhibition of H. zea larvae by tomato leaf extracts.
Bioassays. Bioassays for antigrowth activity in tomato leaves, their extracts, and purified compounds were performed according to our earlier reported procedure (Chan et al., 1978). Tests were conducted on samples of ten larvae per level for crude extracts and 20 larvae per level for the pure compounds examined. Standard deviations from the mean were typically about _+15% for controls and became much larger when growth suppression took place. Quantitative Analysis of a-Tomatine. Two grams of freeze-dried leaf were ground with methanol (3 • 50 ml) using a Polytron grinder for 1 min in a 100-ml beaker. The extracted solution was concentrated to about 2 ml in a vacuum rotatory evaporator at 35~ C. For the removal of phenolic compounds, the sample solution was pretreated by passage through a short AG 1 • 8 (OH-form) anion-exchange column (1.3 • 7 cm) followed by elution with an additional 2 ml of methanol. Effluent was collected in a 5-ml volumetric flask and diluted to volume for high-performance liquid chromatographic (HPLC) analysis, a-Tomatine standard solution was prepared similarily. The analysis was carried out under isocratic condition on a/~-Bondapak-NH2 column (3.9 • 300 mm) in reverse-phase mode (20% 0.01 M (NH4)2HPO4 in acetonitrile), and monitored with a differential refractometer. Quantitative Analysis of Chlorogenic Acid and Rutin. One gram of freeze-dried leaf was ground for 1 min with 10 ml of C H C L 3 - M e O H - H 2 0 (6: 4: 1) containing 10 mg of quercitrin (as internal standard) using a Polytron grinder. The residue was separated by filtration, and the filtrate was shaken with 5 ml of water. After centrifugation to separate the phases, the upper aqueous layer was analyzed by H P L C (Ultrasphere octyl column, 4.6 • 250 mm 0.5% aq. HCO2H-MeOH, 60:40).
756
ELLIGER ET AL.
Isolation o f Caffeyl A l d a r a t e (IV). The aqueous extract from the equivalent of 30 g of dried Ace tomato leaves was purified through a 4 • 80cm column of Amberlite XAD-2 and separated by Sephadex LH20 as previously reported (Waiss et al., 1979). Caffeyl aldarate isomers were isolated at approximately I% of dried leaf weight.
RESULTS A N D D I S C U S S I O N
Using Ace tomato leaves, we found that, while the acetone extract showed no antigrowth activity, sequential extraction of tomato leaf with solvents of increasing polarity showed incorporation of methanol and water extracts deterred appreciably the growth ofH. zea larvae (Figure 1). Similar results were obtained from leaf extracts of Campbell 29. Purification of the methanolic extract through absorption on XAD-2 followed by chromatographic separation with LH20 afforded three H. zea growth inhibitors, namely, a-tomatine, chlorogenic acid, and rutin (Table 1). These allelochemics are well-known phytochemicals, and their identities were confirmed by comparing spectroscopic (UV and NMR) and chromatographic patterns with those of authentic, commercially available compounds. Tomatine was first isolated from tomato by Fontaine and coworkers (1948). While the toxicity of a-tomatine to fungi, potato insects, and mammals has been reviewed (Roddick, 1974), its antibiotic activity toward H. zea has not been well documented. Chlorogenic acid and rutin are ubiquitous in higher plants. Rutin has been isolated as the coloring matter of tomato stems (Blout, 1933) and its growth inhibitory effect to Heliothis species in cotton has been reported (Chan et al., 1978b). The presence of chlorogenic acid in tomato and Solanaceae has been reported by Politis (1948), but its antibiotic effect toward TABLE 1. CONCENTRATION AND
EDs0 OF ot-TOMAT1NE,
CHLOROGENIC ACID,
AND RUTIN IN TOMATO FOL1AGEa
a -Tomatine
Chlorogenic acid
Rutin
0.76 0.61 2.45
1.2 0.8 0.3
2.3 1.3 Not detectable
0.40
2.5
2.4
L. esculentum
Ace Campbell 29 L. hirsutumf glabratum
P.I. 134417 EDs0 Milligrams per gram fresh weight.
TOMATOFRUITWORMGROWTHINHIBITORS
757
t o m a t o fruitworm has not been recorded. Chlorogenic acid is toxic to greenbug (Todd et al., 1971). The effective dosage to reduce the larval growth of t o m a t o fruitworm (bioassayed at first instar stage) to 50% of growth attained on synthetic diet (EDs0) for the allelochemics I, II, and III were estimated through bioassays of these compounds at several concentrations (Table 1). The water extract of t o m a t o leaves, after extraction with methanol, gave a new compound which was identified as a caffeyl aldaric acid (IV) through chemical degradation and derivatization, UV, IR, [1H]NMR,[13 C ] N M R , and mass spectroscopy. Details of structural determination will be reported elsewhere. The c o m p o u n d occurs as a mixture of isomeric esters and lactones and is present as approximately 1% of the dry t o m a t o (Ace) leaf. The antibiotic activity of this new allelochemic (EDs0) is similar to that of chlorogenic acid. This observation is not unexpected since we have o b s e r v e d that the growth inhibitory activity is derived from the catechol moiety of the molecule (Elliger et al., 1980). It appears from the results presented above that the chemically based growth inhibiting properties of L. e s c u l e n t u m toward H. zea are derived from the combination of a - t o m a t i n e and the three phenolic allelochemics II, III, and IV. It is worthwhile to note that the presence of 2-tridecanone in L. h i r s u t u m f , g l a b r a t u m as reported by Williams and coworkers (1980) may explain in part the high level of resistance of this wild t o m a t o (Fery and Cuthbert, 1975), but the high level of a - t o m a t i n e in the foliage and its importance in pest resistance should not be minimized. The presence and diversity of the allelochemics in the foliage of t o m a t o present an opportunity for plant breeders to manipulate the concentration Of one or all of these resitance factors tailored to a specific feeding site and time for the protection of the plant. We hope that the analytical procedures presented in this paper facilitate this endeavor. Acknowledgments--The authors thank Mr. Jim Street for the supply of Campbell 29, Mr. Jim Baker for the Heliothis bioassay, and Drs. H. Chan, G.G. Kennedy, R.L. Fery, and H.B. Green for their valuable discussion and contributions.
REFERENCES BLOt/T, B.K. 1933. The colouring matter on the stem of the tomato. J. Chem. Soc.
1933:1528-1529. CnAN, B.G., WAISS, A.C., JR., STANLEY,W.L., and GOODBAN,A.E. 1978a. A rapid diet preparation method for antibiotic phytochemicalsbioassays.J. Econ. EntomoL 71:366-368. CnAN, B.G., WAISS, A.C., JR., BINDER, R.G., and ELLIGER,C.A. 1978b. Inhibition of lepidopterous larval growth by cotton constituents. EntomoL Exp. AppL 24:294-300. COSEr~ZA,G., and GREEN,H.B. 1979. Behavior of the tomato fruitworm, Heliothis zea (Boddie), on susceptible and resistant lines of processing tomatoes. Hortic. Sci. 14:171-173.
758
ELLIGER ET AL.
ELLIGER, C.A., CHAN, G.B., and WAISS,A.C., JR., 1980. Flavonoids as growth inhibitors: Structural factors governing toxicity. Naturwissenshaften. 67: 338-9. FERY, R.L., and CUTHBERT, F.P., Ja. 1975. Antibiosis in Lycopersicon to tomato fruitworm (Heliothis zea). J. Am. Soc. Hortic. Sci. 100:276-278. FOUNTAINE,T.D., IRVING,G.W., POOLE,R. M., and DOOLITTLE,S.P. 1948. Isolation and partial characterization of crystalline tomatine, an antibiotic agent from tomato plant. Arch. Biochem. 18:467-475. POLITIS, J. 1948. Distribution of chlorogenic acid in Solanaceae and the organs of these plants. Compt. Rend. 229:692-693. RODDICK, J.G. 1974. The steroidal glycoalkaloid a-tomatine. Phytochemistry 13:9-25. TODD, G.W., GETCHUM,A., and CRESS,D.E. 1971. Resistance in barley to greenbug, Schizaphis graminum L. Toxicity of phenolic and related compounds and related substances. Ann. Entomol. Soc. Am. 64:718-722. WA1SS,A.C. JR., CHAN, B.G., ELLIGER, C.A., WISEMAN,B.R., McMILLIAN, W.W., WIDSTROM, N.W., ZUBER,M,S., and KEASTER,A.J. 1979. Maysin, a flavone glycoside from corn silks with antibiotic activities toward corn earworm. J. Econ. Entomol. 72:256-258. WILLIAMS,W.G., KENNEDY, G.G., YAMAMOTO,R.T., THACKER, J.D., and BORDNER, J. 1980. 2-Tridecanone: A naturally occurring insecticide from the wild tomato Lycopersicon hirsutum f glabratum. Science 207:888-889.
