Timara Vereen

Vector-borne zoonotic diseases are emerging partly due to increased human-vector interactions, leading to pathogen transmission and increases in reported disease-related cases, such as Lyme disease. While environmental factors influencing tick behavior have been studied, the role of geographic origin remains unclear. By analyzing Ixodes pacificus nymphal questing behavior across two distinct California regions, our findings suggest that geographic origin influences tick activity, helping explain Lyme disease risk distribution.

Vector-borne zoonotic diseases are emerging due to increased human-vector interactions. Human encounters with infected blood meal-seeking vectors can result in pathogen transmission. This interaction has resulted in high reported cases of diseases such as Lyme disease (LD) (caused by the bacteria, Borrelia burgdorferi). Host-seeking behavior is a critical component of human risk of encountering and being bitten by a tick but the factors that shape tick behavior are not well resolved. While previous research has explored environmental influences on vector activity, the role of geographic origin in shaping Ixodes pacificus questing behavior has been understudied. We examined the influence of geographic origin on I. pacificus questing behavior. We collected nymphal ticks from two geographical locations in California that span a large latitudinal range and measured tick questing behavior (e.g. climbing and mobility). Our results show evidence of geographical structuring on I. pacificus activity, suggesting that activity varies by geographic region. These results advance the understanding of the determinants of I. pacificus nymphal questing behavior and help explain the spatial distribution in Lyme disease cases.