Repellent effect of synanthropic house mouse urine odor on small forest mammals

In this study we examined an effect of synanthropic house mouse (Mus musculus) urine odor on catching probability of small mammals to live traps. We conducted a series of field experiments in August 2016 and 2017 in natural forest of northwestern Moscow Region (Russia). Small mammals were trapped at two 4-ha fields using capture–mark–recapture technique by setting 200 live traps (100 points, 2 traps per a point) within each field. One trap in each pair was odorless (control) with bait only, while the other one was odor-baited with 20 μL of the urine of synanthropic house mouse. Further analysis was based on the data collected from two rodent species (bank vole Myodes glareolus, Herb field mouse Apodemus uralensis) and three shrew species (common shrew Sorex araneus, Laxmann's shrew S. caecutiens, and Eurasian pygmy shrew S. minutus). As a result, only bank voles significantly avoided odor-baited live traps. Using Generalized Linear Mixed Models, we showed that the choice of a trap by bank voles depended on their age, while the probability of repeated capture to a certain live trap was related to their prior experience. We discuss a possible role of components of synanthropic house mouse urine in population management of exoanthropic small mammals.

Effect of early experience on neuronal and behavioral responses to con- and heterospecific odors in closely related Mus taxa: epigenetic contribution in formation of precopulatory isolation

BACKGROUND

The most effective learning occurs during sensitive periods. Olfactory plasticity to main social olfactory cues is limited to a critical period to a large degree. The objective was to evaluate the influence of early olfactory experience on the behavioral and neuronal responses of males to con- and heterospecific odors of receptive females in two species, M. musculus (subspecies musculus, wagneri) and M. spicilegus, and thus to determine the potential role of epigenetic contribution in the formation of precopulatory isolation.

RESULTS

Males were reciprocally cross-fostered shortly after the birth and were tested for response to con- and heterospecific urine odors of estrus females using two-choice tests at 70-85 days of age. Neuronal activity of non- and cross-fostered males was evaluated at 90-110 days of age in the MOB and AOB to con- and heterospecific female odor using fMRI (MEMRI). Non-cross-fostered males of three taxa demonstrated a strong preference for odor of conspecific females compared to odor of heterospecific ones. Spicilegus-nursed musculus preferred odor of heterospecific females. Wagneri-nursed spicilegus and spicilegus-nursed wagneri did not demonstrate significant choice of con - or heterospecific female odor. The level of MRI signal obtained from the evaluation of manganese accumulation in AOB neurons was significantly higher when the odor of conspecific estrus females was exposed, compared to urine exposure of heterospecific females. The response pattern changed to the opposite in males raised by heterospecific females. Response patterns of neuronal activity in the MOB to con- and heterospecific female odors were different in cross-fostered and control males.

CONCLUSION

The maternal environment, including odor, had a greater effect on the level of MRI signal in the AOB than the genetic relationships of the recipient and the donor of the odor stimulus. Behavioral and neuronal responses to con- and heterospecific odors changed in closely related Mus taxa as a result of early experience. We demonstrated the importance of early learning in mate choice in adulthood in mice and the possibility of epigenetic contribution in the formation of precopulatory reproductive isolation.