(Z,Z,E)-3,6,8-Dodecatrien-1-ol, A Major Component of Trail-Following Pheromone in Two Sympatric Termite Species Reticulitermes lucifugus grassei and R. santonensis

Trail-following bioassays show that trails of the two subterranean termites, Reticulitermes lucifugus grassei and R. santonensis, which are sympatric in some areas of southwestern France, are not species specific. Even when tested just above threshold level, trails from pentane extracts of whole workers of R. santonensis are always preferred by both species. If the R. santonensis extract is progressively diluted, the preference is lost. In purified extracts of workers of R. lucifugus grassei that elicited a trail-following response, only one compound is active. It was identified by GC-MS as the same major compound of the trail-following pheromone of R. santonensis: (Z,Z,E)-3,6,8-dodecatrien-1-ol (DTE-OH). The threshold concentration of activity of synthetic DTE-OH was determined to be 10^–3 ng/cm of trail; optimal activity was obtained at 10^–2 ng/cm of trail. The increase of trail-following activity of worker extracts of R. lucifugus grassei after hydrolysis by potassium hydroxide suggests that DTE-OH also is bound to other components in sternal gland secretions. DTE-OH was also identified in alates of R. lucifugus grassei, suggesting that the compound functions both as a trail-following and a sex pheromone, as has been shown to be the case in R. santonensis. This demonstrates the high economy developed by termites in their strategies of chemical communication.     

Trail-Following Pheromones in Basal Termites, with Special Reference to Mastotermes darwiniensis

In the framework of an evolutionary study, trail pheromones have been studied in the most basal extant termite, Mastotermes darwiniensis (Mastotermitidae), and two other basal termites, the Termopsidae Porotermes adamsoni (Porotermitinae) and Stolotermes victoriensis (Stolotermitinae). Although workers of M. darwiniensis do not walk in single file while exploring a new environment under experimental conditions and are unable to follow artificial trails in ‘open field’ experiments, they do secrete a trail-following pheromone from their sternal glands. This unique behavior might reflect a primitive function of communication of the sternal gland. The major component of the pheromone appears to be the same in the three basal species: the norsesquiterpene alcohol (E)-2,6,10-trimethyl-5,9-undecadien-1-ol. This represents a new chemical category of trail-following pheromones for termites. The quantity of pheromone was estimated as 20 pg/individual in M. darwiniensis, 700 pg/individual in P. adamsoni, and 4 pg/individual in S. victoriensis. The activity threshold was 1 ng/cm in M. darwiniensis and 10 pg/cm in P. adamsoni. In M. darwiniensis, the trail pheromone was secreted by sternal gland 4 and to a lesser degree by sternal gland 3, sternal gland 5 being almost inactive. This study highlighted phylogenetic relationships between the Mastotermitidae and two subfamilies of the Termopsidae, the Porotermitinae and the Stolotermitinae. Furthermore, it indicated a heterogeneity within the Termopsidae, with Porotermitinae and Stolotermitinae on one hand, and Termopsinae on the other. Finally, Mastotermitidae and Termopsidae, with C14 trail pheromones, are clearly separated from the Kalotermitidae, Rhinotermitidae, and Termitidae that secrete C12 or C20 trail pheromones.     

Biochemical and behavioral evidence foe hybridization between fire ants,Solenopsis invicta andSolenopsis richteri (Hymenoptera: Formicidae)

Behavioral and biochemical evidence is presented for hybridization between the fire ants,Solenopsis richteri andS. invicta. The response of the two species to extracts of their trail pheromones presented as a point source is clearly species-specific; however, hybrid workers responded to parental Dufour's gland extracts and parental workers responded to Dufour's gland extracts of the hybrid. The behavioral evidence for hybridization was confirmed by gas Chromatograph comparison of the Dufour's gland extracts of the three fire ant forms, which showed a pattern for the hybrid that was intermediate to the two parental species.     

Cuticular hydrocarbons and defensive compounds ofReticulitermes flavipes (Kollar) andR. santonensis (feytaud): Polymorphism and chemotaxonomy

Colonies ofReticulitermes flavipes andR. santonensis were collected from the southeastern United States (Georgia) and the southwest of France (Charente-maritime). Defensive compounds and cuticular hydrocarbons were identified by gas chromatography-mass spectrometry and quantified by gas chromatography using an internal standard for each caste and all colonies. These analyses show that although the cuticular hydrocarbons ofR. santonensis in Europe andR. flavipes in Georgia are identical, their relative proportions are different. However, the defensive compounds synthesized by their soldiers are different. A strong chemical polymorphism between sympatric colonies ofR. flavipes in the SW United States was detected in terms of both the hydrocarbons of the workers and soldiers and in the defensive secretions of the soldiers. The six defensive secretion phenotypes are based on the presence or absence of terpenes whereas the cuticular hydrocarbon phenotypes are based on significant differences in the proportions of the various components. A multivariate analysis (analysis of principal components) clearly permitted discrimination of four phenotypes (three inR. flavipes and one inR. santonensis) without intermediates. The hydrocarbons responsible for these variations were identified, and it was shown that the variations are neither seasonal nor geographic. The phenotypes of the cuticular hydrocarbons (workers and soldiers) and defensive compounds are linked in each colony, forming in three groups inR. flavipes Georgia, one subdivided into four subgroups according to the defensive secretion phenotypes. The role of these polymorphisms is discussed and ethological tests indicate that the chemical polymorphism do not determine aggressive behavior. The taxonomic significance of these results is considered and two hypothesis are formulated: (1) We only detected a strong genetic polymorphism in one unique species, and we believe thatR. santonensis was introduced into Europe in the last century from oneR. flavipes colony. (2) Chemical variability characterizes the sibling species that can be grouped into the same subspeciesR. flavipes. Unknown mechanisms of reproductive isolation separate them.     

Behavioral evidence for multicomponent trail pheromone in the termite,Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae)

Evidence is presented for a multicomponent trail pheromone in the eastern subterranean termiteReticulitermes flavipes (Kollar). Choice tests were used to compare strength and persistency of trails made by termites in glass tubes. Tubes connected to termite nests for 24 hr were marked by termites with an extremely long-lasting chemical that persisted for at least one year, and a highly volatile substance that decayed in 15 min. Individual termites varied the trail they deposited under different circumstances. When removed from the nest and placed in a clean tube, they deposited a highly volatile substance. They left stronger and more persistent trails when exploring clean tubes attached to the nest. When they discovered a new food source, they left trails that were more attractive and far more persistent than trails made by exploring or displaced termites. A food trail made by 15 workers was still effective after 24 hr, whereas a trail made by 50 displaced workers, walking one after another through a tube, lasted only 5 min.     

Trail pheromone of ponerine ant Gnamptogenys striatula: 4-methylgeranyl esters from Dufour's gland

Dufour's gland is the origin of the trail pheromone of Gnamptogenys striatula. Chemical analysis of the glandular extracts revealed a series of new natural products, especially esters of (2E)-3,4,7-trimethyl-2,6-octadien-1-ol (4-methylgeraniol), and (2E)-3,4,7-trimethyl-2,6-nonadien-1-ol (a bishomogeraniol isomer) with medium-chain fatty acids. Bioassays with synthetic racemates of the esters revealed that the 4-methylgeranyl esters are highly active as trail pheromones, while the bishomogeranyl esters are either marginally active or not active at all. Assays with the individual 4-methylgeranyl esters showed each of them to be inferior to the glandular secretion in eliciting trail following. However, the mixture of racemic 4-methylgeranyl octanoate and the corresponding decanoate and dodecanoate, the main Dufour's volatile constituents, is as active as the natural secretion at similar concentration. We conclude that the trail pheromone constitutes a mixture of at least the 4-methylgeranyl esters identified in the gland. Since G. striatula generally preys on small arthropods rather than monopolizing large resources, we assume that trails are rarely used during foraging, but more often during nest migration. Production of new societies in this species is generally performed by budding, a period of considerable predation risk. Utilizing trails for efficient displacement in this context is, therefore, highly adaptive. This behavioral repertoire may also provide the ants with additional means of food resource exploitation.     

Interspecific effects of pheromones on the attraction of the bark beetles,Dendroctonus brevicomis andIps paraconfusus in the laboratory

Dendroctonus brevicomis was attracted to a mixture of theIps paraconfusus pheromones, ipsenol,cis-verbenol, and ipsdienol at 10^–9 g each/l but was not attracted to these pheromones at higher and lower release rates.I. paraconfusus was not attracted to theD. brevicomis pheromonesexo-brevicomin, frontalin, and myrcene at any release rate tested. Increased release rates of a mixture of the three pheromones ofI. paraconfusus inhibited the attraction ofD. brevicomis to its synthetic pheromones. A mixture of ipsenol + ipsdienol orcis-verbenol alone failed to cause inhibition indicating that at least two of theI. paraconfusus pheromones are required to inhibit the response ofD. brevicomis. The pheromones ofD. brevicomis did not inhibit the attraction ofI. paraconfusus to its pheromones; however, verbenone was a potent inhibitor.Coleoptera: Scolytidae. This paper is based in part upon a dissertation submitted by J.A.B. to the University of California, Berkeley, in partial fulfillment of the requirements for the Ph.D. degree in entomology, June 1978. These studies were supported by the Rockefeller Foundation; USDA Forest Service; Regional research project W-1 10, SEA/ USDA; and the National Science Foundation and Environmental Protection Agency through a grant (NSF GB-34719/BMS 75-04223) to the University of California. The findings, opinions, and recommendations are not necessarily those of the University of California or the funding agencies.     

Chemical communication in the dacetine antDaceton armigerum (Hymenoptera: Formicidae)

Contrary to previous assumptions,Daceton armigerum, the largest ant in the myrmicine tribe Dacetini, employs trail communication. We identified two anatomical sources of trail pheromones: Trails drawn with poison gland contents can last for more than seven days. Trails drawn with the newly discovered sternal glands (in the VIth and VIIth abdominal sternites) are effective but relatively short-lived. In addition, our bioassays revealed that the contents of the mandibular glands elicit alarm behavior, and secretions from the pygidial gland release attraction. When tested with artificial poison gland trails from seven other myrmicine species,Daceton did not exhibit trail following behavior. We confirmed, however, previous findings thatAtta respond toDaceton poison gland trails andSolenopsis followDaceton Dufour's gland trails.     

Hexyl Decanoate, the First Trail Pheromone Compound Identified in a Stingless Bee, Trigona recursa

Foragers of many species of stingless bees guide their nestmates to food sources by means of scent trails deposited on solid substrates between the food and the nest. The corresponding trail pheromones are generally believed to be produced in the mandibular glands, although definitive experimental proof has never been provided. We tested the trail following behavior of recruits of Trigona recursa in field experiments with artificial scent trails branching off from natural scent trails of this stingless bee. First-time recruits (newcomers) did not follow these trails when they were laid with pure solvent or mandibular gland extract. However, they did follow trails made with labial gland extract. Chemical analyses of labial gland secretions revealed that hexyl decanoate was the dominant component (72.4 ± 1.9% of all volatiles). Newcomers were significantly attracted to artificial trails made with synthetic hexyl decanoate, demonstrating its key function in eliciting scent-following behavior. According to our experiments with T. recursa, the trail pheromone is produced in the labial glands and not in the mandibular glands. Hexyl decanoate is the first component of a trail pheromone identified and proved to be behaviorally active in stingless bees.     

Trail-following behavior ofReticulitermes hesperus Banks (Isoptera: Rhinotermitidae)

The behavior ofReticulitermes hesperus Banks pseudergates (workers) was assessed on artificial trails containing different concentrations of sternal gland extract. On nongiadient trails, more pseudergates were recruited to trails of greater pheromone concentration, they traveled a greater distance without pausing, and their rate of locomotion increased over that observed on trails of lesser concentration (positive orthokinesis). Of the individuals pausing before completing trails of high concentration, fewer left the trails or reversed direction (negative klinokinesis) than on trails of lower concentration. Termites walking down concentration gradients failed to complete these trails to the low-concentration termini. At a point representing an average decrease of slightly more than 10-fold in the original concentration of pheromone, individuals reversed their direction of travel and returned to the high-concentration terminus. Termites walking up pheromone gradients proceeded to the high-concentration termini without reversing direction.R. hesperus pseudergates are thus able to orient along a gradient of trail pheromone by longitudinal klinotaxis.     

Role of (3<Emphasis Type="Italic">Z</Emphasis>,6<Emphasis Type="Italic">Z</Emphasis>,8<Emphasis Type="Italic">E</Emphasis>)-Dodecatrien-1-ol in Trail Following,Feeding, and Mating Behavior of <Emphasis Type="Italic">Reticulitermes hesperus</Emphasis>

Trail pheromones mediate communication among western subterranean termites, Reticulitermes hesperus Banks. Repetitive passages of ≥28 termites were required to establish a pheromone trail and trails needed to be reinforced because they lasted <48 hr. The minimal threshold concentration for inducing responses from termite workers and secondary reproductives was between 0.01 and 0.1 fg/cm of (3Z,6Z,8E)-dodecatrien-1-ol (henceforth, dodecatrienol). Workers showed optimal trail-following behavior to dodecatrienol at a concentration of 10 fg/cm. Trails with concentrations >10 pg/cm were repellent to workers. Workers did not detect pheromone gradients, responding equally to increasing or decreasing gradients of dodecatrienol, and termite workers were not able to differentiate between different concentrations of dodecatrienol. Termites preferred dodecatrienol trails to 2-phenoxyethanol trails. Antennae played a key role in trail pheromone perception. Dodecatrienol acted as an arrestant for worker termites (10 fg/cm²) and male alates (5 ng/cm²), whereas sternal gland extracts from females attracted male alates. Workers and alates, upon contact with filter paper disks treated with higher doses (10 fg/cm² and 5 ng/cm², respectively) of dodecatrienol, were highly excited (increased antennation and palpation) and repeatedly returned to the treated disks. Dodecatrienol did not act as a phagostimulant when offered on a paper towel disk. Reticulitermes hesperus is highly responsive to dodecatrienol, and it may play an important role in orientation of workers and alates.     

Chemical communication in cucujid grain beetles

Males of five sympatric species of economically damaging cucujid grain beetles,Cryptolestes ferrugineus (Stephens),C. pusillus (Schönhen),C. turcicus (Grouvelle),Oryzaephilus mercator (Fauvel), andO. surinamensis (L.), produce macrolide aggregation pheromones especially in the presence of food. Work leading to the isolation, identification, and establishment of biological activity of these semiochemicals is reviewed. The trivial name cucujolide is proposed and used to identify these compounds that are characteristic of the Cucujidae. The twoOryzaephilus share species share a common cucujolide pheromone, whileCryptolestes species use cucujolides that are either enantiomeric, unique to the genus, or released in trace quantities byOryzaephilus spp. and not used as pheromones by the latter species. The major mechanisms for species specificity in chemical communication are: (1) presence of a unique pheromone (C. ferrugineus andC. pusillus); (2) use of pheromones that are inactive alone but synergize response to cucujolides unique to a species (C. pusillus, C. turcicus, andO. surinamensis); (3) response to only one enantiomer of a pheromone (C. ferrugineus, O. surinamensis, andO. mercator); and (4) synergism between enantiomers of a pheromone (C. turcicus). The only species for which cross-attraction was evident wasO. mercator toO. surinamensis. Both sexes ofOryzaephilus spp. produce (R)-1-octen-3-ol, which highly synergizes response to the cucujolide pheromones. Similar synergism occurs between hexanal, octanal, and nonanal and the cucujolide pheromones ofOryzaephilus spp. The males of a sixth cucujid species,Cathartus quadricollis (Guér) produce a different aggregation pheromone, (3R,6E)-7-methyl-6-nonen-3-yl acetate. Trapping ofCryptolestes andOryzaephilus spp. in cardboard traps baited with pheromones is efficient in environments mimicking food-storage areas. Pheromone-baited plastic probe traps are the most efficient at capturing these species in infested grain.Coleoptera: Cucujidae.Presented at the 194th American Chemical Society National Meeting in the Symposium on Insect Chemical Communication: Unifying Concepts (Burdick & Jackson International Award in Pesticide Chemistry honoring Dr. James H. Tumlinson), New Orleans, Louisiana, August 30–September 4, 1987.Research supported by the Natural Sciences and Engineering Research Council of Canada, Strategic Grant No. G1039 and Operating Grants Nos. A3881 and A3706.     

Influence of pheromone chirality on response byOryzaephilus surinamensis andOryzaephilus mercator (Coleoptera: Cucujidae)

The response of the sawtoothed grain beetle,Oryzaephilus surinamensis (L.), and the merchant grain beetle,O. mercator (Fauvel), to synthetic racemic and chiral macrolide aggregation pheromones was assessed in pitfall olfactometers.O.mercator utilizes theR enantiomers of (Z)-3-dodecen-11-olide and (Z,Z)-3,6-dodecadien-11-olide.O. surinamensis utilizes theR enantiomers of (Z,Z)-3,6-dodecadien-11-olide and the Synergist (Z,Z)-5,8-tetradecadien-13-olide in combination with achiral (Z,Z)-3,6-dodecadienolide. For both species, the racemates of the respective chiral pheromones were effective attractants. The respectiveS enantiomers were inactive for both species and had no effect on the biological activity of the active antipodes. No diel periodicity in responsiveness to pheromones was detected inOryzaephilus spp. reared either on a 1212 light-dark photoperiod or in darkness. Nonpheromone macrolides, naturally released in trace amounts byOryzaephilus spp., did not affect the aggregation response of either species to its pheromones when these additional macrolides were combined with the pheromone mixtures.Research supported by the Natural Sciences and Engineering Research Council of Canada, Operating Grant A3881, A0851, and A3785, and Strategic Grant G0958.     

(Z,E,E)-dodecatrien-1-ol: A minor component of trail pheromone of termite,Coptotermes formosanus Shiraki

In the course of the elucidation of the primary structure of an isolated trail pheromone fromC. formosanus, a minor component that had the same molecular weight as the major trail pheromone, (Z,Z,E)-3,6,8-dodecatrien-1-ol [(Z,Z,E)-DTE-OH], was detected in the mass chromatogram ofm/z 180 of capillary GC-MS. The mass spectrum of the minor component showed a prominent pattern of dodecatrien-1-ol. Chemical analysis demonstrated that the complete structure was (Z,E,E)-DTE-OH. Furthermore, capillary GC-MS-HR-SIM analysis indicated that the component existed only in the workers ofCoptotermes formosanus Shiraki and was not present in workers ofReticulitermes speratus (Kolbe). This minor component may be a species-specific factor ofC. formosanus, although this was not suggested by a two-choice bioassay.     

Electrophysiological and Olfactometer Responses of Two Histerid Predators to Three Pine Bark Beetle Pheromones

We measured electrophysiological responses in the antennae of two predaceous hister beetles, Platysoma parallelum and Plegaderus transversus, exposed to racemic mixtures of primary aggregation pheromones of scolytid bark beetle prey, ipsenol, ipsdienol, and frontalin. No significant differences were found for either histerid species between male and female antennal responses to any of the three pheromones. Measurement of antennal threshold responses indicated that Pla. parallelum has increasing antennal sensitivity to ipsdienol, ipsenol, and frontalin. In contrast, Ple. transversus exhibited similar detection thresholds to all three pheromones. Pla. parallelum antennae exhibited different response amplitudes to the three pheromones at quantities above the detection threshold, while Ple. transversus had similar responses to each. Behavioral responses to the same three pheromones were evaluated for both histerid species using pedestrian olfactometer bioassays. Both species were attracted to frontalin and ipsenol, but not ipsdienol. Pla. parallelum was significantly more attracted to frontalin than ipsenol, while Ple. transversus showed no significant preference for either compound. Our results suggest that histerids that prey upon pine bark beetles may have different host or host habitat preferences, which could reduce interspecific competition.     

Determination of distribution of harmful click beetle species (Coleoptera,Elateridae) by synthetic sex pheromones

By means of pheromone traps containing synthetic sex pheromones, areas of the most harmful click beetle species,Agriotes obscurus,A. lineatus, A. sputator, A. gurgistanus, A. ustulatus, A. tauricus Heyd, andA. lineatus, occurring in southern regions and differing biologically from the so-called northern species, have been specified and charted in the European and central Siberian areas of the former USSR.     

Interactions Between Host-plant Volatiles and the Sex Pheromones of the Bird Cherry-oat Aphid, <Emphasis Type="Italic">Rhopalosiphum padi</Emphasis> and the Damson-hop Aphid, <Emphasis Type="Italic">Phorodon humuli</Emphasis>

The bird cherry-oat aphid, Rhopalosiphum padi (L.), and the damson-hop aphid, Phorodon humuli (Schrank), migrate at the same time of year and colonize closely related Prunus spp. as primary hosts, but utilize (1R,4aS,7S,7aR)-nepetalactol and (1RS,4aR,7S,7aS)-nepetalactol, respectively, as sex pheromones. Interactions between these sex pheromones and benzaldehyde and methyl salicylate, plant volatiles common to primary hosts of both species, were investigated to assess whether they confer reproductive isolation between these species. Female autumn migrants (gynoparae) and males of these two species were caught in the field with water traps baited with their respective sex pheromones. Rhopalosiphum padi gynoparae and males also responded positively to benzaldehyde. Release of either benzaldehyde or methyl salicylate with the conspecific sex pheromone increased catches of both species of aphid. However, releasing both plant volatiles with the sex pheromone of R. padi increased catches of gynoparae and males, but reduced those with the sex pheromone of P. humuli. These results support the hypothesis that specific plant volatiles synergize responses of autumn migrating aphids to their sex pheromone. Because these interactions are species-specific, they may be important in allowing males to discriminate between conspecific sexual females (oviparae) and those of other aphid species.     

Kairomonal Effects of Sawfly Sex Pheromones on Egg Parasitoids

The response of the two eulophid egg parasitoid species Chrysonotomyia ruforum and Dipriocampe diprioni to sex pheromones of their sawfly hosts Diprion pini and Neodiprion sertifer was studied in olfactometer bioassays. Females of C. ruforum were arrested when exposed to odor of the tested major sex pheromone components of Diprion pini [acetate and propionate of (2S,3R,7R)-3,7–dimethyl-2–tridecanol] or Neodiprion sertifer [(2S,3S,7S)-3,7–dimethyl-2–pentadecyl acetate]. This behavioral response of C. ruforum was observed whether (1) parasitoid females had oviposition experience with D. pini eggs or not, (2) parasitoid females emerged from D. pini eggs of a French population or from N. sertifer eggs of a Finnish population, and (3) the tested sex pheromone concentration was low (1 ng/l hexane) or high (100 ng/l hexane). However, C. ruforum did not behaviorally respond to a stereoisomer of the major sex pheromone component of N. sertifer, which is known to act as a sex pheromone antagonist [antagonist = (2S,3R,7R)-3,7–dimethyl-2–pentadecyl acetate]. Thus, C. ruforum responded stereospecifically to the S,S,S configured pheromone of N. sertifer, but not to the S,R,R configuration. Females of the parasitoid D. diprioni were also arrested by the tested major sex pheromone components of the host D. pini. The kairomonal effects of diprionid host sex pheromones on these egg parasitoids are compared to known responses of egg parasitoids to lepidopteran sex pheromones.     

Cuticular hydrocarbons ofReticulitermes virginicus (Banks) and their role as potential species- and caste-recognition cues

The cuticular hydrocarbon components of four castes ofReticulitermes virginicus (Banks) have been identified and quantitated. Components identified includen-alkanes; 2-, 3-, 11-, 13-, and 15-methyl-alkanes; 11,15-dimethylalkanes, (Z)-9-alkenes; (Z,Z)-7,9-dienes; and (E/Z)-6,9-dienes ranging in carbon number from C₂₁ to C₄₀. All caste forms ofR.virginicus contained the same components, but showed caste-specific proportions. Comparison of these hydrocarbons with those of the sympatric termiteR. flavipes (Kollar) suggest that cuticular hydrocarbons might serve as species- and caste-recognition cues. A bioassay was developed to test this species-recognition hypothesis, with the experimental results supporting the hypothesis.Isoptera: Rhinotermitidae.     

Role of secondary metabolites in feeding associations between a predatory nudibranch,two grazing nudibranchs,and a bryozoan

The carnivorous nudibranchRoboastra tigris preys preferentially upon two nudibranchs,Tambja abdere andT. eliora, that in turn feed upon the bryozoanSessibugula translucens. All four organisms contain tambjamines A–D (I–IV) that were shown to be fish feeding inhibitors. When attacked byRoboastra, T. abdere secretes a distasteful mucus containing a total of 3 mg of the tambjamines that sometimes causes theRoboastra to break off the attack. Under similar circumstancesT. eliora attempts to swim away; it presumably contains insufficient of the tambjamines to deterRoboastra. Roboastra follows the slime trail of nudibranchs using contact chemoreception and reverses direction when the trail is broken. The slime trail ofT. abdere contains low concentrations of the tambjamines. In Y-maze experiments,T. eliora was attracted towards seawater containingS. translucens and seawater containing 10^–10 M tambjamines A and B (11) but was repelled by seawater containing > 10^–8 M tambjamines A and B. At higher concentrations the mixture of tambjamines may be recognized as an alarm pheromone.