Showing papers in "Journal of Chemical Ecology in 1979"
TL;DR: These leaf volatiles constitute a general green leaf volatile complex, being active in the olfactory orientation of the Colorado beetle and as such are probably of importance to various phytophagous insects.
Abstract: The volatile compounds ofSolanum tuberosum L., a host plant of the Colorado beetle,Leptinotarsa decemlineata Say, were isolated by successive vacuum steam distillation, freeze concentration, and extraction. The main components aretrans-2-hexen-1-ol, 1-hexanol,cis-3-hexen-1-ol,trans-2-hexenal, and linalool. The distribution of these compounds in a variety of plant families and their biosyntheses are reviewed. These leaf volatiles constitute a general green leaf volatile complex, being active in the olfactory orientation of the Colorado beetle and as such are probably of importance to various phytophagous insects.
182 citations
TL;DR: Simulated moth scale particles appear to fill this need since their density can be regulated to provide the optimum frequency of parasitoid stimulation and thus maximum rates of Parasitization at prevailing host densities.
Abstract: In laboratory experiments conducted to compare the kairomonal activity forMicroplitis croceipes (Cresson) of frass fromHeliothis zea (Boddie) larvae fed on different host plants,M. croceipes females responded to extracts of frass from larvae reared on cotton or soybeans but not on corn. The lack of response to frass from larvae reared on corn was shown to be a result of a lack of some appropriate chemical(s) in the corn.
162 citations
TL;DR: In this paper, the chemistry of the defensive secretions of termite soldiers is reviewed and the structural variety of the chemical weapons, uses of these substances in defense, and some potential biosynthetic interrelationships are discussed.
Abstract: The chemistry of the defensive secretions of termite soldiers is reviewed. The structural variety of the chemical weapons, the uses of these substances in defense, and some potential biosynthetic interrelationships are discussed. Classification of the monoterpenes, sesquiterpenes, diterpenes, and various acetate-derived compounds according to termite subfamilies places the known defense substances in a phylogenetic perspective.
143 citations
TL;DR: The female-emitted pheromone ofGrapholitha molesta (Busck), the Oriental fruit moth, was collected by holding females in glass flasks during calling and flask washes were found to contain four peromone components.
Abstract: The female-emitted pheromone ofGrapholitha molesta (Busck), the Oriental fruit moth, was collected by holding females in glass flasks during calling. Flask washes were found to contain four pheromone components: (Z)-8-dodecenyl acetate and (E)-8-dodecenyl acetate in a 100∶7 ratio, and (Z)-8-dodecen-1-ol and dodecanol in a 100∶20 ratio. The ratio of (Z)-8-acetate to (Z)-8-dodecen-1-ol was approx. 100∶30. Approximately 0.1–0.2 ng of pheromone was recovered per female per hour of calling.
119 citations
TL;DR: The chemical basis of an ant-seed interaction was investigated for the ant Aphaenogaster rudis and the ant-dispersed violetViola odorata and suggests that ricinoleic acid is not the lipid eliciting the ant response to violet odorata, as had been previously suggested.
Abstract: The chemical basis of an ant-seed interaction was investigated for the antAphaenogaster rudis and the ant-dispersed violetViola odorata. A laboratory behavioral bioassay was developed to chemically identify the attractant responsible for the interaction. The ant attractant, localized in the elaiosome, was classified as a lipid by both field and laboratory bioassays. Assays of partially purified lipid extracts revealed that the principal attractant may be a diglyceride. Gas-liquid chromatography analysis of the hydrolyzed diglyceride fraction revealed oleic acid as the major fatty acid present, suggesting that either 1,2- or 1,3-diolein may be the attractant. Structure-activity correlations for lipid standards demonstrated a clear preference for the diglyceride 1,2-diolein. The data also suggest that ricinoleic acid is not the lipid eliciting the ant response toViola odorata, as had been previously suggested.
118 citations
TL;DR: Test the hypothesis that interference with chlorophyll metabolism may be one mechanism of inhibition of plant growth in allelopathic interactions by reducing dry weights of soybean seedlings by both 10−3 M and 5 × 10−4 M treatments of ferulic,p-coumaric and vanillic acids.
Abstract: Experiments were designed to test the hypothesis that interference with chlorophyll metabolism may be one mechanism of inhibition of plant growth in allelopathic interactions. Effects of ferulic,p-coumaric, and vanillic acids on soybean and grain sorghum growth and chlorophyll content were quantified and compared after seedlings were treated with these compounds in a nutrient culture. Following a 6-day treatment cycle, dry weights of soybean seedlings were reduced by both 10−3 M and 5 × 10−4 M treatments of ferulic,p-coumaric and vanillic acids. Soybean weight reductions in each case were paralleled by a significant reduction in the concentration (μg Chl/mg dry wt) of chlorophylls a and b and total chlorophyll in the unifoliate leaves. Sorghum seedling growth was also reduced by each of the compounds at the 5 × 10−4 M level, but leaf chlorophyll concentration was not below that of control plants.
113 citations
TL;DR: The major component of the trail pheromone of the South American leaf-cutting ant, Atta sexdens rubropilosa Forel, is 3-ethyl-2,5-dimethylpyrazine, and methyl and ethyl phenylacetate and methyl 4-methylpyrrole-2-carboxylate were identified and may be minor components.
Abstract: The major component of the trail pheromone of the South American leaf-cutting ant,Atta sexdens rubropilosa Forel, is 3-ethyl-2,5-dimethylpyrazine (II). Methyl and ethyl phenylacetate and methyl 4-methylpyrrole-2-carboxylate (I), which is the major component of the trail pheromone ofA. texana (Buckley) andA. cephalotes (L.), were also identified and may be minor components. The pheromone is stored in the poison gland.Atta sexdens sexdens (L.) also responds strongly to the pyrazine, which in large amounts evokes a weak response fromA. texana, A. cephalotes, andAcromyrmex octospinosus (Reich). Foraging workers ofAtta sexdens rubropilosa did not preferentially pick up baits impregnated with the pyrazine. The pyrazine was puffed into the nests ofA. cephalotes, and a particular response called “milling” was noted.
77 citations
TL;DR: (Z,Z)-11,13-hexadecadienal elicited quantitatively similar activation and attraction responses by A. transitella males as did the natural product.
Abstract: A sex pheromone of the navel orangeworm,Amyelois transitella (Walker), was obtained from ether rinses of the sex pheromone gland of calling females. The pheromone was isolated by means of liquid and gas chromatography and was identified as one of four possible geometrical isomers of 11,13-hexadecadienal by means of spectroscopic and microchemical methods. Synthesis and laboratory bioassay of all four isomers revealed that only the (Z,Z) isomer was biologically active. (Z,Z)-11,13-hexadecadienal elicited quantitatively similar activation and attraction responses byA. transitella males as did the natural product.
76 citations
TL;DR: The half-lives (tin1/2) of acetate sex pheromones andn-alkyl acetates were determined on either or both West Co. and Arthur H. Thomas Co. natural rubber septa and the half-life of one nonconjugated diuns saturated acetate was much less than that for the corresponding monounsaturated acetate, whereas the half life of another non Conjugate diunsaturated acetates was similar to the half Life of
Abstract: The half-lives (tin1/2) of acetate sex pheromones andn-alkyl acetates were determined on either or both West Co. and Arthur H. Thomas Co. natural rubber septa. These septa gave equal half-lives. Thet1/2 values covered a large range: e.g.,t1/2 for decyl acetate was 5 days and that for pentadecyl acetate was 1353 days. The expected linear relationship between Int1/2 versus the number of carbon atoms was found for the six acetates fromn-decyl to pentadecyl, but thet1/2 of hexadecyl acetate was only 478 days. This nonlinearity in the plot is attributed to the presence of polymer cross-links which create molecular size cages and produce an effect similar to that produced in gel permeation chromatography wherein large molecules elute faster than smaller ones. Thet1/2 of 4 monounsaturated acetates were close to thet1/2 for the corresponding saturated acetates, but this relationship may not be general. The half-life of one nonconjugated diunsaturated acetate was much less than that for the corresponding monounsaturated acetate, whereas the half-life of another nonconjugated diunsaturated acetate was similar to the half-life of the corresponding monounsaturated acetate. Thet1/2 values determined for the pheromones may be used to estimate evaporation rates, the length of time the evaporation rates will be within a given range, and, with multicomponent pheromones, the ratio of components in the vapor.
70 citations
TL;DR: The secretion from the rectal pheromone glands of male Dacus tryoni and Dacus neohumeralis is largely a mixture of six aliphatic amides, which are similar to those in the two species.
Abstract: The secretion from the rectal pheromone glands of maleDacus tryoni andDacus neohumeralis is largely a mixture of six aliphatic amides. In order of decreasing quantity these areN-3-methylbutylpropanamide,N-3-methylbutylacetamide,N-(3-methylbutyl-2-methylpropanamide,N-2-methylbutylpropanamide,N-2-methylbutylacetamide, andN-(2-methylbutyl)-2-methylpropanamide. The proportions of the various amides in the two species are similar.
62 citations
TL;DR: In this paper, the activation of separate groups of cells by the different pheromones and host compounds was analyzed and it was shown that behaviorally expressed synergistic as well as inhibitory action mainly is due to an interaction in the central nervous system rather than an interaction of the compounds on the receptors.
Abstract: Electrophysiological recordings inIps pini were made from single olfactory cells stimulated by six concentrations of eleven compounds—either pheromones or host constituents. The receptor cells were grouped according to their differential responses to these biologically significant compounds. Cells specialized to either ipsdienol or ipsenol (pheromones for severalIps species) appeared to be relatively uniform in their sensitivity to all compounds tested. Another group of cells specialized tocis- andtrans-verbenol were more variable in their sensitivities to the substances tested. The activation of separate groups of cells by the different pheromones and host compounds shows (by exclusion) that behaviorally expressed syner-gistic as well as inhibitory action mainly is due to an interaction in the central nervous system rather than an interaction of the compounds on the receptors. All “ipsdienol cells” responded to both enantiomers of ipsdienol. Although some differences between responses to the enantiomers by individual cells were observed, these did not form a consistent pattern, and no net differences could be found between the eastern and western populations ofI. pint.
TL;DR: Several quantitative and perhaps qualitative differences were observed in the patterns of cardenolides produced by far distant populations of both Chrysolina polita and C. herbacea, collected in either France and Belgium, or Greece.
Abstract: Cardenolides were looked for in 17 chrysomelid beetles belonging to 11 genera from three subfamilies, and they were found only inChrysolina andChrysochloa species (Chrysomelinae, Chrysolinini). The food plants of these insects are not known to produce cardenolides. TheChrysochloa and mostChrysolina species secrete a complex mixture of cardenolides, butChrysolina didymata secretes a single compound, andChrysolina carnifex, none. Several quantitative and perhaps qualitative differences were observed in the patterns of cardenolides produced by far distant populations of bothChrysolina polita andC. herbacea, collected in either France and Belgium, or Greece. These differences remain constant from one generation to the other, whatever the food plant is, and appear to be genetic. InC. polita from Greece, the pattern is unchanged after four generations bred in the laboratory onMentha ×villosa, which is known to be without cardenolides. In adults, the cardenolides are released with the secretion of the pronotal and elytral defensive glands, but in the larvae which lack the defensive glands, cardenolides are also produced. The total amount of cardenolides and the complexity of their mixture increases through the life cycle of the insects. The six main cardenolides secreted byC. coerulans were identified as: sarmentogenin, periplogenin, bipindogenin, and their corresponding xylosides.C. didymata secretes only sarmentogenin.
TL;DR: A single generation of 610,000 beetles, believed to comprise the entire population in a 65-km2 forest, was estimated to have released 0.78, 3.7, and 370.5 g of frontalin, exo-brevicomin, and myrcene within a 30-day period.
Abstract: Three parameters are described for estimating the natural occurrence of chemically defined insect pheromones: (1) the rate and duration of release by the insect, (2) the density of the pheromone-emitting insect population in both time and space, and (3) dispersal and degradation rates of the chemicals. Each of these parameters, except dispersal, was estimated for a population ofDendroctonus brevicomis LeC, and its three component attractive pheromones. A single generation of 610,000 beetles, believed to comprise the entire population in a 65-km2 forest, was estimated to have released 0.78, 3.7, and 370.5 g of frontalin,exo-brevicomin, and myrcene, respectively, within a 30-day period.
TL;DR: Differential saturation studies with male antennae suggest that there are two different acceptor sites for the two pheromone components of the black cutworm moth, Agrotis ipsilon.
Abstract: (Z)-7-Dodecen-1-yl acetate (I) and (Z)-9-tetradecen-1-yl acetate (II) have been identified as sex pheromone components of the black cutworm moth,Agrotis ipsilon (Hufnagel). They are emitted by the female in approximately a 5∶1 ratio. Differential saturation studies with male antennae suggest that there are two different acceptor sites for the two pheromone components. The most effective lures found in field trapping tests were 30 μg of I plus 10 μg of II on a rubber septum, and a 3∶1 mixture of I and II dispensed from a 0.2-mm-ID glass capillary tube sealed at one end.
TL;DR: In this article, (Z)-11-tetradecen-1-yl acetate was reported as the sex pheromone of the obliquebanded leafroller,Choristoneura rosaceana (Harris).
Abstract: Previously, (Z)-11-tetradecen-1-yl acetate was reported as the sex pheromone of the obliquebanded leafroller,Choristoneura rosaceana (Harris). A mixture of 92% (Z)-11-tetradecen-1-yl acetate and 8% (E)-tetradecen-1-yl acetate has been reported as an attractant for this insect. (E)-11-tetradecen-1-yl acetate and (Z)-11-tetradecen-1-ol have now been isolated and identified from female tip extracts and shown to be behaviorally active; in addition, there is some evidence for the presence of (E)-11-tetradecen-1-ol in these extracts. TheZ∶E ratio for both the acetates and the alcohols in these tip extracts was about 98∶2; the proportion of alcohols was rather variable, but the acetates always predominated. Maximum trap catches fn the field during the course of this study were obtained with 5 mg of 95∶5 (Z)∶(E)-11-tetradecen-1-yl acetates containing 0.5–10% (Z)-11-tetradecen-1-ol (approx. 1%Eisomer) in polyethylene caps. No evidence was found for the presence of (Z)-11-tetradecenal in female tip extracts, and this compound was found to be ineffective in increasing trap catches.
TL;DR: FemaleChilo partellus (Swinhoe) abdominal tip extracts were examined by gas-liquid chromatography (GLC) combined with simultaneous electroantennographic (EAG) recording from the male moth, showing that compound (I) was highly attractive to maleC.
Abstract: FemaleChilo partellus (Swinhoe) abdominal tip extracts were examined by gas-liquid chromatography (GLC) combined with simultaneous electroantennographic (EAG) recording from the male moth. Two olfactory stimulants were detected and identified as (Z)-11-hexadecenal (I) and (Z)-11-hexadecen-1-ol (II) by their GLC behavior, microchemical reactions, and comparison with synthetic materials. Both compounds were detected in volatiles emitted by the “calling” female moth. Synthetic (Z)-9-tetradecenyl formate, a structural analog of aldehyde (I), also elicited a significant EAG response from the male moth. Field trials carried out in India using synthetic (I) and (II) as bait in water traps showed that compound (I) was highly attractive to maleC. partellus; compound (II) was not attractive, and its addition to (I) significantly reduced trap catches.
TL;DR: By means of gas chromatography-mass spectrometry, hydrogenation, infrared analysis, and NMR analysis, the overall structure of periplanone-B was identified as (1Z,5E)-1,10(14)-diepoxy-4(15),5-germacradien-9-one, and this structure was confirmed by comparison with a synthetic, biologically active epimer of each compound.
Abstract: The sex pheromone of the American cockroach,Periplaneta americana, consists of two compounds, which we have named periplanone-A and periplanone-B. The two compounds can be isolated from fecal material in a ratio of 1∶10, and periplanone-B can also be isolated from intestinal tracts. A total amount of 200 μg of periplanone-B has been isolated from both fecal material and alimentary tracts. By means of gas chromatography-mass spectrometry, hydrogenation, infrared analysis, and NMR analysis, we were able to identify periplanone-B as (1Z,5E)-1,10(14)-diepoxy-4(15),5-germacradien-9-one. The overall structure was confirmed by comparison with a synthetic, biologically active epimer of periplanone-B.
TL;DR: Results confirm that 4,6,6-lineatin (I) is a population aggregation pheromone for T. lineatum.
Abstract: Authentic 4,6,6-lineatin (3,3,7-trimethyl-2,9-dioxatricyclo-[3.3.1.04,7]nonane) (I) was produced in low yield via three synthetic pathways. In field tests, microgram amounts of the product from all three syntheses attracted large numbers ofTrypodendron lineatum of both sexes. These results confirm that 4,6,6-lineatin (I) is a population aggregation pheromone forT. lineatum.
TL;DR: A total of 21 new taxa of New World pit vipers responded by elevating the middle portion of the body in a defensive posture (body bridge) when exposed to the skin substances of certain colubrid snakes (Colubridae).
Abstract: A total of 21 new taxa of New World pit vipers (Serpentes: Crotalinae) responded by elevating the middle portion of the body in a defensive posture (body bridge) when exposed to the skin substances of certain colubrid snakes (Colubridae). Newborn snakes from two of the three species tested gave the response. Several new species of colubrid snakes also are documented as capable of eliciting a response, and it is suggested that the termophiophage defensive response be used to denote body bridging and associated defensive behaviors instead of the restrictive “kingsnake defense posture.” Most of the snakes which elicit the response in crotaline snakes are known to feed on lizards and/or snakes. There is no apparent correlation between the stimulus snakes' ability to elicit a response in the crotaline snakes and sympatry with the crotaline snakes.
TL;DR: Pseudaletia unipuncta to the two major components of the presumed pheromone associated with the male anterior abdominal scent brushes vary with age, and the age of maximum responsiveness differs according to the sex and to the compound tested.
Abstract: Electroantennogram responses of male and femalePseudaletia unipuncta to the two major components of the presumed pheromone associated with the male anterior abdominal scent brushes vary with age. There is a postemergence period of maturation of responsiveness, followed by senescence. The age of maximum responsiveness differs according to the sex and to the compound tested.
TL;DR: The defensive secretion of the coconut stick insect, Graeffea crouani Le Guillou (Phasmatodea: Phasmatidae) from the Pacific Islands has, as major constituents:trans,trans- andtrans,cis-iridodials and nepetalactone.
Abstract: The defensive secretion of the coconut stick insect,Graeffea crouani Le Guillou (Phasmatodea: Phasmatidae) from the Pacific Islands has, as major constituents:trans,trans- andtrans,cis-iridodials and nepetalactone.Cis,trans-iridodial is a minor constituent. A minor iridoid has yet to be identified. Male and female insects yield the same constituents.
TL;DR: It is concluded that female mosquitoes (Anopheles quadrimaculatus Say) are attracted in significant numbers primarily by chemical emanations other than carbon dioxide and water.
Abstract: An apparatus has been assembled which permits storage and injection, at the same flow rate, of air containing human emanations into one port and air containing no emanations into the other port of a dual-port olfactometer, while monitoring the two flows for differences in temperature, relative humidity, and carbon dioxide level. Results of bioassays so conducted have led us to conclude that female mosquitoes (Anopheles quadrimaculatus Say) are attracted in significant numbers primarily by chemical emanations other than carbon dioxide and water.
TL;DR: The growth and yield of rice plants were significantly affected by cultural treatment; thus the ammonium sulfate dressing treatment resulted in higher yields than the potassium nitrate treatment and the NH4+—N treatment had an antagonistic effect on the phytotoxic nature of rice straw decomposed in soil.
Abstract: Ammonium sulfate and potassium nitrate added as a top dressing and rice straw were incorporated into soil to understand their effect on the chemical nature of the paddy soil and on the growth and yield of rice plants during two successive crop seasons. Redox potential (Eh) determination indicated that the paddy soil appeared to be the reduced form in mixture with rice residues. The amounts of ammonium nitrogen (NH4+—N) and nitrate nitrogen (NO3−—N) were significantly higher in the second crop than in the first crop, and the quantity of NH4+—N was about 10 times greater than that of NO3−—N. The incorporation of rice straw decreased both the available nitrogen and the soil cations, Zn2+, Cu2+, Ca2+, Mn2+, and Na+. The quantity of Zn2+, Cu2+, Mg2+, and Na+ was significantly lower in the second crop that that in the first. The growth and yield of rice plants were significantly affected by cultural treatment; thus the ammonium sulfate dressing treatment resulted in higher yields than the potassium nitrate treatment. The NH4+—N treatment had an antagonistic effect on the phytotoxic nature of rice straw decomposed in soil. The phytotoxicity (primarily phenolic type compounds) of aqueous extracts of soil varied between treatments and was significantly higher in the soil which had been mixed with rice straw. This finding correlated well with the higher amounts of phytotoxic plant phenolics produced by the decomposing rice residues in the soil.
TL;DR: Diet was found to significantly affect the kairomonal activity of the frass although the diets themselves were not active and Microplitis croceipes (Cresson) was determined.
Abstract: Heliothis zea (Boddie) larvae were reared on fresh plant material (cowpea cotyledons) or on an artificial laboratory diet. Effect of these two diets on the kairomonal activity of the frass and cuticle from the larvae, as well as the kairomonal activity of the diets themselves, forMicroplitis croceipes (Cresson) was determined. Diet was found to significantly affect the kairomonal activity of the frass although the diets themselves were not active.
TL;DR: Comparative behavioral analysis with 11 species of Leptothorax demonstrated a subgenus specificity of the tandem calling pheromone between the subgeneraLeptothsorax andMychothorAX.
Abstract: Ants of the genusLeptothorax recruit to new nest sites and newly discovered food sources by tandem running. This involves one ant directly leading a nestmate to the target area. Pheromones from the poison gland have proved the most important signal employed during this recruitment behavior. Comparative behavioral analysis with 11 species ofLeptothorax demonstrated a subgenus specificity of the tandem calling pheromone between the subgeneraLeptothorax andMychothorax.
TL;DR: Electroantennograms in two populations of Ips pini were very similar, even though previous work documented behavioral specificity and revealed that the populations produce different ratios of the enantiomers of the aggregating pheromone ipsdienol.
Abstract: Electroantennograms in two populations ofIps pini (Idaho and New York) were very similar, even though previous work documented behavioral specificity and revealed that the populations produce different ratios of the enantiomers of the aggregating pheromone ipsdienol. The insect- and host-produced compounds tested evoked characteristic response curves in both populations. EAG amplitude was highest to ipsdienol and the aggregation inhibitor ipsenol. Among the other compounds tested, responses were generally higher to the beetle-produced odorants (linalool, verbenone,trans-verbenol) than to host terpenes (1-octanol, α-pinene). The antennal club and its sensory receptors are described and illustrated by scanning electron micrographs.
TL;DR: Greenhouse bioassays and field tests have shown that the compounds are independently attractive to male San Jose scale and these structures are compared with those of other known scale pheromones.
Abstract: The sex pheromone of the San Jose scale,Quadraspidiotus perniciosus (Comstock), was isolated from airborne collections on Porapak Q. Two components, present in approximately equal amounts, were identified as (Z)-3,7-dimethyl-2,7-octadien-1-yl propanoate and 3-methylene-7-methyl-7-octen-1-yl propanoate. Greenhouse bioassays and field tests have shown that the compounds are independently attractive to male San Jose scale. These structures are compared with those of other known scale pheromones.
TL;DR: The larval defensive secretions of Linaeidea aenea Linné and Plagiodera versicolora distincta Baly were identified as plagiolactone and epiplagiolact one and chrysomelidial and the acetates of hexadecanol, octade canol and (Z)-I 1-eicosenol from the former insect were identified.
Abstract: The larval defensive secretions ofLinaeidea aenea Linne andPlagiodera versicolora distincta Baly were identified as plagiolactone and epiplagiolactone. In addition to these compounds, chrysomelidial and the acetates of hexadecanol, octadecanol and (Z)-I 1-eicosenol from the former insect, and plagiodial and epichrysomelidial from latter insect were identified.
TL;DR: The stereospecificity of the sawfly pheromone 3,7-dimethyl-2-pentadecanol acetate against Neodiprion lecontei was studied and it was found that only one isomer with (−)-erythro configuration (2S, 3S) had biological activity.
Abstract: The stereospecificity of the sawfly pheromone 3,7-dimethyl-2-pentadecanol acetate againstNeodiprion lecontei was studied. Twoerythro and a 1∶1 mixture ofthreo isomers (C-2 and C-3) were synthesized for this purpose. It was found that only one isomer with (−)-erythro configuration (2S, 3S) had biological activity. The potency of this synthetic pheromone was roughly identical to the one shown by the naturally occurring pheromone in this species.
TL;DR: Arguments are presented suggesting that the behaviorally effective dose ofDMDS is several orders of magnitude less than 500 fg, and that DMTS seems to suppress the activity of DMDS.
Abstract: The responses of normal male hamsters to the odors of several components of estrous female hamster vaginal discharge (FHVD) were quantified with a two-bottle preference test in order to clarify the role of dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) in the attraction of males to females. These two compounds were originally isolated and identified in two separate, behaviorally active fractions of FHVD, one containing DMDS and the second containing DMTS. However, only authentic DMDS proved to be attractive to males; DMTS was inactive in the amounts tested (50 ng to 10 μg). When smaller amounts of highly purified samples of DMTS (0.03–3.32 ng) are assayed, measurable amounts of activity are obtained. This activity of authentic DMTS is not due to any intrinsic activity of its own but rather can be ascribed to the activity of the residual DMDS (0.07%) that it contains. Highly purified samples of authentic DMDS (containing 0.03% DMTS) were again found to be attractive to males. Doses as small as 500 fg were significantly active when compared to controls. Arguments are presented suggesting that the behaviorally effective dose of DMDS is several orders of magnitude less than 500 fg. Deliberate mixtures of DMDS and DMTS failed to show any synergistic effects. In fact, at the two lowest doses examined (0.1 and 0.46 ng total sulfides), the response obtained with the mixture was smaller than that expected if DMDS were the only odorant in the solution. Therefore, DMTS seems to suppress the activity of DMDS.