Abstract:Trapping brown rats is challenging because they avoid newly placed traps in their habitat. Herein, we report the identification of the sex pheromone produced by male brown rats and its effect on trap captures of wild female brown rats. Collecting urine-and feces-soiled bedding material of laboratory-kept rats and comparing the soiled-bedding odorants of juvenile and adult males,aswell as of adult males and females, we found nine compounds that were specific to,o rm ost prevalent in, the odor profiles of sexual… Show more
“…Traps baited with a blend of male rat pheromone components—expectedly—captured significantly more females and significantly fewer males than (testosterone-only) control traps (females: χ 2 = 4.08, P < 0.05; males: χ 2 = 9.48, P < 0.01) (Fig. 4 , bottom), confirming the reported attractiveness and deterrence of male rat pheromone components to female and male rats, respectively 6 . Figure 4 Trap catch data revealing that brown rats stay away from micro-locations (specific trap boxes) indicative of male mouse presence, and that female and male brown rats seek and avoid micro-locations indicative of prospective mates and rival males, respectively.…”
Section: Resultssupporting
confidence: 64%
“…Although rats and mice share some pheromone components (e.g., testosterone, progesterone, estradiol) 22 , the more volatile sex attractant pheromone components of males differ markedly. The ketone blend in urine marks of male brown rats (2-heptanone, 4-heptanone, 3-ethyl-2-heptanone, 2-octanone, 2-nonanone, 4-nonanone 6 ) bears no resemblance to pheromone components emanating from urine marks of male house mice (3,4-dehydro- exo -brevicomin; 2- sec -butyl-4,5-dihydrothiazole 23 , 24 ).…”
Section: Introductionmentioning
confidence: 99%
“…Yet, closely related species in mammalian communities often use similar communication signals 2 which facilitates bi-directional (interspecific) olfactory communication 3 and lowers the relative cost of maintaining sensory receptors 4 . This concept appears to apply to olfactory communication signals of sympatric murine rodents, including the brown rat, Rattus norvegicus, and the house mouse, Mus musculus, because there is overlap in pheromone components of female mice and female rats 5 , 6 . Native to the plains of Asia 7 , 8 , brown rats and house mice co-evolved in a predator–prey relationship, with rats preying on mice 9 , 10 .…”
Section: Introductionmentioning
confidence: 99%
“…Testing the concept of mutual eavesdropping by predator and prey on each other’s pheromones is contingent upon pheromone identification and the availability of synthetic pheromone. When synthetic volatile sex attractant pheromone components of both brown rats (predator of mice 9 ) and house mice (prey of rats 10 ) became available 6 , 22 – 24 , 45 , 46 , the stage was set for testing the counterespionage hypothesis that mice co-opt rat pheromone components as cues to avoid rat predation, and rats co-opt mouse pheromone components as cues to facilitate mouse prey location. Testing these hypotheses, we were cognizant that the natural sex pheromone of mice and rats comprises additional constituents (e.g., urinal and lacrimal proteins 10 , 38 ) which—expense-wise—could not be included in our synthetic pheromone lure, and that these constituents as well as non-pheromonal odors 47 may amplify any counterespionage evidence demonstrated in our study.…”
Mammalian pheromones often linger in the environment and thus are particularly susceptible to interceptive eavesdropping, commonly understood as a one-way dyadic interaction, where prey sense and respond to the scent of a predator. Here, we tested the “counterespionage” hypothesis that predator and prey co-opt each other’s pheromone as a cue to locate prey or evade predation. We worked with wild brown rats (predator of mice) and wild house mice (prey of brown rats) as model species, testing their responses to pheromone-baited traps at infested field sites. The treatment trap in each of two trap pairs per replicate received sex attractant pheromone components (including testosterone) of male mice or male rats, whereas corresponding control traps received only testosterone, a pheromone component shared between mouse and rat males. Trap pairs disseminating male rat pheromone components captured 3.05 times fewer mice than trap pairs disseminating male mouse pheromone components, and no female mice were captured in rat pheromone-baited traps, indicating predator aversion. Indiscriminate captures of rats in trap pairs disseminating male rat or male mouse pheromone components, and fewer captures of rats in male mouse pheromone traps than in (testosterone-only) control traps indicate that rats do eavesdrop on the male mouse sex pheromone but do not exploit the information for mouse prey location. The counterespionage hypothesis is supported by trap catch data of both mice and rats but only the mice data are in keeping with our predictions for motive of the counterespionage.
“…Traps baited with a blend of male rat pheromone components—expectedly—captured significantly more females and significantly fewer males than (testosterone-only) control traps (females: χ 2 = 4.08, P < 0.05; males: χ 2 = 9.48, P < 0.01) (Fig. 4 , bottom), confirming the reported attractiveness and deterrence of male rat pheromone components to female and male rats, respectively 6 . Figure 4 Trap catch data revealing that brown rats stay away from micro-locations (specific trap boxes) indicative of male mouse presence, and that female and male brown rats seek and avoid micro-locations indicative of prospective mates and rival males, respectively.…”
Section: Resultssupporting
confidence: 64%
“…Although rats and mice share some pheromone components (e.g., testosterone, progesterone, estradiol) 22 , the more volatile sex attractant pheromone components of males differ markedly. The ketone blend in urine marks of male brown rats (2-heptanone, 4-heptanone, 3-ethyl-2-heptanone, 2-octanone, 2-nonanone, 4-nonanone 6 ) bears no resemblance to pheromone components emanating from urine marks of male house mice (3,4-dehydro- exo -brevicomin; 2- sec -butyl-4,5-dihydrothiazole 23 , 24 ).…”
Section: Introductionmentioning
confidence: 99%
“…Yet, closely related species in mammalian communities often use similar communication signals 2 which facilitates bi-directional (interspecific) olfactory communication 3 and lowers the relative cost of maintaining sensory receptors 4 . This concept appears to apply to olfactory communication signals of sympatric murine rodents, including the brown rat, Rattus norvegicus, and the house mouse, Mus musculus, because there is overlap in pheromone components of female mice and female rats 5 , 6 . Native to the plains of Asia 7 , 8 , brown rats and house mice co-evolved in a predator–prey relationship, with rats preying on mice 9 , 10 .…”
Section: Introductionmentioning
confidence: 99%
“…Testing the concept of mutual eavesdropping by predator and prey on each other’s pheromones is contingent upon pheromone identification and the availability of synthetic pheromone. When synthetic volatile sex attractant pheromone components of both brown rats (predator of mice 9 ) and house mice (prey of rats 10 ) became available 6 , 22 – 24 , 45 , 46 , the stage was set for testing the counterespionage hypothesis that mice co-opt rat pheromone components as cues to avoid rat predation, and rats co-opt mouse pheromone components as cues to facilitate mouse prey location. Testing these hypotheses, we were cognizant that the natural sex pheromone of mice and rats comprises additional constituents (e.g., urinal and lacrimal proteins 10 , 38 ) which—expense-wise—could not be included in our synthetic pheromone lure, and that these constituents as well as non-pheromonal odors 47 may amplify any counterespionage evidence demonstrated in our study.…”
Mammalian pheromones often linger in the environment and thus are particularly susceptible to interceptive eavesdropping, commonly understood as a one-way dyadic interaction, where prey sense and respond to the scent of a predator. Here, we tested the “counterespionage” hypothesis that predator and prey co-opt each other’s pheromone as a cue to locate prey or evade predation. We worked with wild brown rats (predator of mice) and wild house mice (prey of brown rats) as model species, testing their responses to pheromone-baited traps at infested field sites. The treatment trap in each of two trap pairs per replicate received sex attractant pheromone components (including testosterone) of male mice or male rats, whereas corresponding control traps received only testosterone, a pheromone component shared between mouse and rat males. Trap pairs disseminating male rat pheromone components captured 3.05 times fewer mice than trap pairs disseminating male mouse pheromone components, and no female mice were captured in rat pheromone-baited traps, indicating predator aversion. Indiscriminate captures of rats in trap pairs disseminating male rat or male mouse pheromone components, and fewer captures of rats in male mouse pheromone traps than in (testosterone-only) control traps indicate that rats do eavesdrop on the male mouse sex pheromone but do not exploit the information for mouse prey location. The counterespionage hypothesis is supported by trap catch data of both mice and rats but only the mice data are in keeping with our predictions for motive of the counterespionage.
“…This also raises the possibility that one or more of the five attractive compounds that we originally identified in foods 43 may be pheromonal in nature as pheromones are commonly exaptation’s of compounds that originally had other uses, such as those derived from foods 47 . Intriguingly, three of the five top performing compounds (isopentanol, 1-hexanol and acetoin) have been reported in rat urine, although they have not been formally characterised as pheromones 48 – 50 .…”
There is mounting evidence that single compounds can act as signals and cues for mammals and that when presented at their optimal concentration they can elicit behavioural responses that replicate those recorded for complex mixtures like gland secretions and foods. We designed a rapid bioassay to present nine compounds that we had previously identified in foods, each at seven different concentrations (63 treatments), to wild, free-ranging rats and scored each treatment for attraction and three behavioural responses. Nine treatments (taken from five compounds) statistically outperformed the current standard rat attractant, peanut butter. Attraction to treatments was highest at the two lowest concentrations (0.1 and 0.01 μg g−1) and a statistically significant relationship of increasing attraction with decreasing treatment concentration was identified. Our study identified five compounds not previously associated with behavioural responses by rats that elicit equivalent or more intense behavioural responses than those obtained with peanut butter. Moreover, attraction to treatments was driven by a concentration-dependent relationship not previously reported. This is the first study to identify isopentanol, 1-hexanol, acetoin, isobutyl acetate and 2-methylbutyl acetate as possible semiochemicals/cues for rats. More broadly, our findings provide important guidance to researchers in the ongoing search for mammalian semiochemicals and cues.
Sex hormones of mammals control the expression of sexual characteristics and bodily functions. The male hormone testosterone and the female hormones progesterone and estradiol are known to occur in urine markings of mice. Here, we show that all three hormones are also present in urine of brown rats, and that they are effective sexual communication signals (pheromones) that elicit attraction behavior of prospective mates in both brown rats and house mice. When added as lures to trap boxes in field experiments, synthetic testosterone, for example, increased captures of adult female mice 15-fold, and a blend of progesterone and estradiol increased captures of male mice eightfold and male rats 13-fold. Remarkably, these hormones increased captures even though the food- and pheromone-based baits to which they were added had previously been shown to be superior to current commercial rodent attractants. We predict that these sex hormones will function as sex attractant pheromones in diverse taxa.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
