Borrelia burgdorferi prevalence and ectoparasite diversity in white-footed mice

• Isabella Kalb, Wildlife Ecology and Conservation, University of Delaware

• Vincenzo Ellis, Entomology and Wildlife Ecology, University of Delaware
• Scarlet Shifflett, Entomology and Wildlife Ecology, University of Delaware

White-footed mice (Peromyscus leucopus) are the most abundant small mammal in Roland Roth Ecology Woods, a 35-acre research site on the University of Delaware’s campus. White-footed mice serve as an important host for many ectoparasites including blacklegged ticks. In the eastern United States, blacklegged ticks are the primary vector for the Lyme disease bacterium Borrelia burgdorferi. We assessed ectoparasite diversity and B. burgdorferi prevalence for white-footed mice in Roland Roth Ecology Woods as part of a long-term disease ecology study. To determine B. burgdorferi prevalence and ectoparasite diversity in white-footed mice, we trapped mice using both Sherman live traps and nest boxes. Captured mice were groomed for ectoparasites (ticks, fleas, botflies, etc.) and an ear biopsy was taken for pathogen testing. All ectoparasites were identified using a Leica stereo microscope and dichotomous key. We extracted DNA from ear biopsy samples and used a real-time polymerase chain reaction (qPCR) to test individual mice for B. burgdorferi. Of the 21 samples ran, 15 mice tested positive for B. burgdorferi. We found ectoparasites on 58% of mice, not supporting the commonly held disease ecology parasite aggregation pattern. There was no significant difference between mice infected with B. burgdorferi based on sex. However, there was a significant difference between mice infected with B. burgdorferi based on age; adults were 80% more likely to test positive for B. burgdorferi compared to juveniles and sub-adults. For ectoparasite status, males were 80% more likely to be found with at least one ectoparasite compared to females, and adults were 90% more likely to be found with at least one ectoparasite compared to juveniles and sub-adults. These findings highlight the ecological role of white-footed mice as reservoirs for B. burgdorferi and further stress the importance of ectoparasite diversity within this host species population.