Harderian gland pheromone in the Mongolian gerbilMeriones unguiculatus

The Mongolian gerbil (Meriones unguiculatus) secretes an attractant pheromone from the Harderian gland during a facial groom. The material exits at the external nares and is spread over select areas of the face. Its presence stimulates investigation by conspecifics, as seen by video observations. The half-life of the fluorescence of the material on the face following a groom parallels the half-life of attraction. Shock-avoidance and taste-aversion conditioning indicate that animals can both smell and taste a chloroform extract of Harderian glands. They will also seek out and investigate the extract when presented alone. It is suggested that thermoregulatory grooming, social needs, and chemosignaling are intimately linked.This research was supported by grant No. MH 14076-08 awarded to Dr. D. D. Thiessen.     

Sex pheromone scent marking by females ofPectinophora gossypiella (Lepidoptera: Gelechiidae)

Females of the pink bollworm moth,Pectinophora gossypiella (Saunders), scent marked the substrate to which they were clinging with the extended pheromone gland during nocturnal pheromonereleasing periods. Scent marks were deposited on both natural (cotton leaf) and atypical (glass) substrates. In both situations, the scent marks elicited attraction responses from conspecific males.     

The social role of scent marking in beaver (Castor Canadensis)

Beaver colonies with close neighbors constructed more scent mounds than did isolated colonies, and the number of scent mounds at each active lodge is correlated with the distance to the nearest occupied lodge. The scent mounds were typically located at trails, also on lodges and dams. The beaver rebuilt experimentally removed scent mounds. Experimentally scent-marked unoccupied lodges were less often visited or inhabited than unscented control lodges. Resident beaver responded to artificial scent marks near their lodges with aggressive behavior and increased activity. We conclude that scent mounds serve in delineating family territories and are effective in deterring transient beaver from utilizing existing but uninhabited lodges.     

Responses of reindeer to interdigital secretions of conspecifics

Adult captive European forest reindeer,Rangifer tarandus L., were exposed to hindfoot interdigital (ID) secretion placed on the ground. The animals were tested with blanks and interdigital secretion from themselves and male and female group members, and secretion from excised glands of male and female mountain reindeer. Responses to the stimuli consisted of sniffing, licking, and olfactory searching on the ground. With forest reindeer secretions, each sex responded more to its own ID secretion than to that of the opposite sex. Of the mountain reindeer samples, male ID secretion released stronger responses. The responses did not vary systematically from June to October. The functional significance of the ID secretion in free-ranging reindeer is discussed.     

Some communicatory functions of scent marking in the cotton-top tamarin (Saguinus oedipus oedipus)

The ability of cotton-top tamarins to discriminate between scents from conspecifics and those from other tamarin species, and between scents from conspecific individuals was tested. Cotton-tops scent mark with specialized skin glands in the circumgenital area. Females possess larger glands than males and show more scent-marking behavior. In the first experiment, subjects were presented with a glass rod scented with either material collected from the surface of the scent glands of a conspecific female, with scent material from a female of a related species, or with an unscented rod. Glass rods carrying scent from conspecifics were sniffed more frequently than rods carrying scent from related tamarin species or unscented rods. A second experiment offered a choice between two glass rods, one scent marked by aSaguinus o. oedipus female, the second one scent marked by aSaguinus fusdcollis female. Shelves carrying rods that had been scent marked by conspecifics were contacted more frequently than those carrying rods marked by heterospecific females. Scent marks from conspecific females were also sniffed more frequently. A third experiment compared the level of responses to rods carrying material collected from the scent glands of female individuals to which the subjects had been habituated with their responses to rods carrying scent from females to which they had not been habituated. Contacting and sniffing responses to the scents of novel females were higher than those to the scents of females to which the subjects had been habituated.     

Modulation of exploratory behavior in female mice by protein-borne male urinary molecules

Male pheromones are believed to attract females and repel male mice in open field tests but, when tested in more complex environments, they can attract male mice in usually avoided areas. Females were tested in an apparatus with one dark and one light side, in the absence or presence of male urine or the major urinary proteins (MUPs) bearing the natural ligands. Diestrous females were slower in leaving from the dark area when male urine or MUPs were present in it. Estrogen-primed females showed the opposite behavior, with an increase in the same latency. The light-avoidance behavior of prepubertal females, or females reared without males was not influenced by the presence of male chemosignals. The results show that adult female mice can react to MUP-borne volatiles as to adult male urine and use them as cues of male mice, if they were previously exposed to male cues during infancy. MUP-borne molecules are, thus, the olfactory trace of males in the environment and modulate mice exploratory behavior.     

Intraspecific pheromone discrimination and substrate marking by atlantic salmon parr

Attraction and preference behavior patterns shown by Atlantic salmon (Salmo salar L.) parr towards intraspecific odors were measured. Salmon parr were attracted to tank water in which relatives of their own strain were held but were also attracted to tank water containing another strain of their species. When given a choice between the two types of tank water, water containing their own strain odor was significantly favored over water containing conspecific but nonfamiliar odor, revealing that pheromones are present at intraspecific levels in salmonid juveniles. Competitive experiments with various extracts suggest that the active compounds are most likely produced in the liver and are voided via the intestinal tract, as determined by presence of attractants in intestinal contents and bile. Intraspecific discrimination was not detected with extracts from either skin surface mucus or blood plasma. Extracts from gravel that had been kept below the fish in their rearing tanks, however, induced a strain-related preference behavior. This suggests an ability for substrate marking by salmonid fishes, presumably mediated by deposition of fecal material. Strain discrimination and substrate marking are discussed in relation to stationary behavior and homing of fishes within discrete populations in natural systems.     

Responses to inter- and intraspecific scent marks in pine martens (Martes martes)

In order to analyze intra and interspecific olfactory discrimination, behavioral responses (sniffing and marking) towards various odors were observed in pine martens (Manes martes). Two adult males and two adult females were tested for intraspecific discrimination of abdominal gland odors and urine. Both sexes sniffed and marked objects carrying their own scent less than unscented objects. There were no differences in sniffing or marking objects impregnated with odors from known and unknown conspecifics of the opposite sex or objects carrying the odor of an unknown male or female. A second experiment with two adult females gave no evidence for interspecific discrimination: no differences emerged when comparing reactions towards marks of pine martens, stone martens (a closely related species), or genets. The most obvious result of this study is the reduced response of pine martens towards their own mark. It is suggested that scent marking in martens may reflect autocommunication, the primary effect being to familiarize an animal with its environment.     

Olfactory recognition of individuals by male cavies (Cavia aperea)

In one study, using a habituation procedure, male South American cavies,Cavia aperea, distinguished individual differences in odors collected from three sources: perineal gland secretions, urine, and supracaudal gland secretions. In a second study, male cavies spent more noninvestigatory time and rested more on the side of a cage containing the odor of a familiar subordinate male as compared to the cage side containing the odor of a familiar dominant male. Since the odor source was a glass plate which had been left in the home cage of the donor males for three days, the actual odorous cue to which the test males responded is not known. These studies demonstrate that male cavies distinguish odors of individuals, that individual differences in odors are found in at least three different sources, and that cavies use chemical cues to distinguish between known individuals.     

Studies on the nature of chemical signals in scent marks and urine ofSaguinus fuscicollis (Callitricidae,primates)

The circumgenital scent marks ofSaguinus fuscicollis are mixtures of skin gland secretions, urine, and perhaps vaginal discharge. One of their ingredients, urine, is readily investigated by conspecifics. Female tamarins are able to utilize urine to discriminate between the sexes, but it appears that urine, unlike the scent marks, offers no clues for individual discrimination. Moreover, urine is less attractive to conspecifics than complete scent marks, which signal sex and individuality. The sexual identity of marks is recognized even if the tamarins are prevented from contacting the material directly and seems to be retained in a mixture of scent from both sexes.     

Induction of marking behavior in wild red foxes (Vulpes vulpes L.) by synthetic urinary constituents

A control aqueous solution containing alcohol and polyethylene glycol, and a test solution with the addition of a mixture of eight volatile synthetic compounds identified in red fox urine, Were alternately placed on man-made mounds of fresh snow during January and February, the foxes' courtship season. The foxes preferentially marked those mounds treated with the test solution in the two experimental areas (P < 0.05 and <0.0001). It is concluded that one or more of the volatile substances induces mound marking in this species.     

Partial chemical characterization of urinary signaling pheromone in tree shrews (Tupaia belangen)

Tree shrews of both sexes exhibit marking behavior (chinning) in response to scent marks made by the urine of fertile male conspecifics. To isolate the effective odor components, the urine was fractionated by liquid-liquid extraction and TLC, and the fractions were tested by bioassay. The results show that chinning is elicited by several lipophilic urine fractions, which are more effective in combination than alone. To characterize the complex scent signal, the lipophilic extracts from urine of the two sexes were analyzed by GC-MS and compared. The GC profile of the males is distinguished by pyrazine compounds not detected in the profile of the females. The profiles of the sexes also differ with regard to several volatile monocarboxylic acids, which are present at higher concentrations in male than in female urine. More than 30 urine components have been identified. Synthetic equivalents of these urine components were bioassayed for effectiveness in eliciting chinning and compared with one another as well as with scent substances not normally present in tree-shrew urine. Strong chinning responses were elicited by (1) certain pyrazine compounds and (2) some monocarboxylic acids, when presented at the high concentrations specific to male urine. Marking behavior is usually not elicited by scent substances not contained in tree-shrew urine or by urine components common to mammals in general. The data so far available indicate that the male-specific scent signal of tree shrews is based less on a single unique component than on the qualitative and quantitative characteristics of a multicomponent mixture. In the bioassay, tree shrews of both sexes respond equally to the male specific substances by chinning. As the scent signal represented by these substances has a different meaning to males and females (rival or potential mate, respectively), chinning probably serves several different functions.     

Host marking pheromone ofRhagoletis cerasi: Foraging behavior in response to synthetic pheromonal isomers

We studied the foraging behavior ofRhagoletis cerasi females in trees treated with synthetic cherry fruit fly host marking pheromone (HMP) under seminatural conditions (potted trees enclosed in a screen cage). Results show that synthetic HMP (particularly the 8RS-@#@ 15R isomer configuration (racemic mixture)) was highly effective in eliciting behavioral responses similar to those reported in studies using natural HMP. Flies exposed to synthetic pheromone exhibited short tree residence times (i.e., emigrated faster), increased flight frequency rates (measured as number of alightings per/minute), higher irritation indices while on a tree or a fruit, and oviposited fewer eggs per fruit visit than flies exposed to clean trees and fruit (not treated with synthetic HMP). Furthermore, we provide evidence showing that when flies were continuously exposed to an HMP-saturated environment, they exhibited an increased tendency to lay eggs in marked fruit.     

Chemical signals involved in spacing behavior of breeding female bank voles (Clethrionomys glareolus Schreber 1780, Microtidae,Rodentia)

In order to study the mechanism involved in the seasonal territoriality of breeding bank voles, the social behavior and scent marking of paired females were observed throughout a reproductive cycle. Initially unfamiliar females were kept in large laboratory pens provided with individual burrows. After a brief period of hostility, females behaved in a friendly manner towards each other, sharing the same nest even in the presence of a male and until the middle of pregnancy. They scarcely marked with urine. Continuous olfactory assessment appeared to play an important role in maintaining the friendly interactions. In late pregnant and lactating females, on the contrary, the odor of a familiar female triggered aggressiveness and scent marking with urine and probably with flank glands. These reactions may be interpreted as spacing behavior. Moreover, the interaction between females may inhibit reproduction in one of them. These results are discussed in relation with the available ecological data.     

Responses by canids to scent gland secretions of the western diamondback rattlesnake (Crotalus atrox)

Many snakes discharge malodorous fluids from paired scent glands in the base of the tail when they are disturbed. A number of authors suggest that these secretions repel predators. Scent gland secretions of the western diamondback rattlesnake (Crotalus atrox), or dichloromethane extracts of them, were presented to coyotes (Canis latrans) in three field tests, and to domestic dogs (Canis familiaris) in two kennel tests, to determine whether responses of possible benefit to snakes are elicited. Free-ranging coyotes visited and rubbed and rolled at stations containing scent gland secretions in perforated plastic capsules more frequently than at those containing untreated or dichloromethane-treated capsules. Responses to dichloromethane extracts of scent gland secretions subjected to rotary evaporation were not significantly different from those to dichloromethane. Pure and mixed breeds of dogs presented with filter papers treated with dichloromethane or a dichloromethane extract of scent gland secretions mouthed (licked, bit, or ate) secretion-treated papers more frequently. Staffordshire terriers presented with filter papers treated with dichloromethane or dichloromethane extracts of snake scent gland and alligator (Alligator mississippiensis) paracloacal gland secretions exhibited urination postures to snake secretion-treated papers more frequently than to dichloromethane-treated papers, but responses to snake- and alligator-treated papers did not differ significantly. There was no indication that canids are repelled by scent gland secretions.     

Quantitative and qualitative effects of larval diet on male scent secretions ofEstigmene acrea,Phragmatobia foliginosa,andPyrrharctia isabella (Lepidoptera: Arctiidae)

In feeding experiments with insects reared in the laboratory, the presence of the dihydropyrrolizines hydroxydanaidal and danaidal in the male scent organs (coremata) of the arctiids,Estigmene acrea (Drury),Phragmatobia fuliginosa (L.), andPyrrharctia isabella (J.E. Smith), was shown to depend on the presence of a source of pyrrolizidine alkaloids (PAs) in the larval diet.Phragmatobia males given an artificial diet supplemented with the powdered roots of the PA-containing plantSymphytum officinale L. (comfrey) produced more hydroxydanaidal than danaidal, whereas males given an artificial diet supplemented with dried whole plants of another PA-containing species,Senecio vulgaris L., produced more danaidal than hydroxydanaidal.Pyrrharctia males produced hydroxydanaidal with little if any danaidal, whether the source of PAs was comfrey orS. vulgaris. A behavioral bioassay showed that the coremata of PA-deniedPyrrharctia male progeny of PA-denied parents were pheromonally inactive, whereas those of PA-denied male progeny of PA-supplied parents (male and/or female) were often active. This indicates that a small amount of pheromone is made from PAs transferred from the female to her eggs and that males effect copulatory transfers of PAs that are, in turn, passed to the eggs by the mated female. Field observations ofPhragmatobia andPyrrharctia larvae feeding on sources of PAs were reported. The PA monocrotaline was shown to be a feeding stimulant forPyrrharctia larvae.     

Reduction of rodent fertility by plant consumption

The present study investigates the possibility that plants used in traditional medicine for birth control may also reduce reproduction in their natural herbivores. Ten species of plants utilized by Bedouins for birth control were selected. These were dried, ground, and mixed with the standard diet and offered to female laboratory rats. Six plant species (60%) were found to reduce reproduction rate in white female rats, and the shoots and fruit of one of the effective species,Ziziphus spina-christi, when offered to its natural herbivore,Meriones tristrami, at the level of 35% of the standard diet, postponed female puberty and significantly reduced offspring survival. Plants that are known to be an effective factor in human birth control may have similar effects on their natural mammalian herbivores. In such cases, when the seeds of the plant are part of the herbivore diet, a certain percentage of the seeds will be dispersed and germinate, while the resulting population control of the animal achieved by its consumption of the seeds will prevent overgrazing, thus maintaining a mutual balance. It is suggested that ethnopharmacological data may assist in uncovering plants that, under the following conditions, have the potential to regulate reproduction in mammalian herbivores (with implications for human reproduction): (1) the plant is an important component of the animal's diet and (2) the active secondary metabolites of the plant directly interact with the physiological systems governing reproduction in the herbivore.     

Foraging Behavior of Anastrepha Ludens, A. obliqua, and A. serpentina in Response to Feces Extracts Containing Host Marking Pheromone

Following oviposition, females of many Tephritid flies deposit host marking pheromones (HMPs) to indicate that the host fruit has been occupied. We describe the foraging behavior of these three economically important species (Anastrepha ludens and A. obliqua from the fraterculus species group and A. serpentina from the serpentina species group) when they encounter an artificial fruit (green agar spheres wrapped in Parafilm) marked with intra- and interspecific feces extracts that contain, among other substances, host marking pheromone. When flies encountered fruit treated with either 1 or 100 mg/ml feces extract, there were drastic and statistically significant reductions in tree residence time, mean time spent on fruit, and in the number of oviposition attempts or actual ovipositions when compared to the control treatment (clean fruit). These responses were almost identical irrespective of extract origin (i.e., fly species), indicating complete interspecific HMP cross-recognition by all three Anastrepha species tested. We discuss the ecological and practical implications of our findings.     

Urinary signaling pheromone and specific behavioral response in tree shrews (Tupaia belangeri)

As soon as they encounter the scent marks made by the urine of fertile male conspecifics, tree shrews of both sexes cover the scent marks with their own sternal-gland secretion by chinning. The urine of other species, female conspecifics, or castrated male conspecifics does not elicit this behavior; that is, overmarking with sternal-gland secretion is a reaction to a specific chemical signal. The intensity of the overmarking reaction, i.e., the chinning score in response to the urine sample, decreases as the urine is diluted. The urine of different male conspecifics elicits overmarking of varying intensity; an animal's own urine is in general not overmarked. This behavioral reaction meets all the criteria for a bioassay of potential use in isolating the tree-shrew pheromone from urine.     

Behavioral responses of male and female Mexican fruit flies,Anastrepha ludens,to male-produced chemicals in laboratory experiments

The behavioral responses of male and female Mexican fruit flies elicited by male abdominal extracts were measured in laboratory cages where pheromone was applied to the undersides of some leaves on a treated tree but to none of the leaves on a control tree. After arrival to the treated tree, females came directly to pheromone sources. Females on the treated tree visited leaves and fought other females at higher rates than on the control tree. Females stayed on treated leaves and trees longer than on control leaves and trees. In separate experiments, the number of males on pheromone-treated trees and leaves was higher than on controls, but other behavior was unchanged. The results indicate that the pheromone stimulates a complex of behavior involved in the mating ecology of the species.