Biology, ecology, and management of the Asian longhorned tick, Haemaphysalis longicornis, in New Jersey
Creators: name: Bickerton, Matthew W.
Publisher: name: No Publisher Supplied
Year: 2024

description: The Asian longhorned tick, Haemaphysalis longicornis is an invasive tick species native to eastern Asia and currently present in parts of eastern and central US. Its parthenogenetic mode of reproduction enables rapid population growth in new areas. In the U.S., it has been implicated in the transmission of pathogens to cattle, but its public health significance is less clear. H. longicornis is not highly anthropophilic, yet it can reach extremely high densities in public parks and is a known vector of human pathogens in its native range. The primary goals of my dissertation are to review the potential impacts of this tick on the health of humans and domestic animals and to develop management strategies focused on the biology of the species while minimizing nontarget impacts. In doing so, I investigate its susceptibility to acaricides and the potential for acaricide resistance and provide a comprehensive analysis of the seasonal dynamics of H. longicornis in New Jersey.In Chapter 1, I document the first report of multiple human bites by larvae of Haemaphysalis longicornis Neumann in the U.S. Exposure occurred in October in a public park with an extremely high tick population. Although it is not an anthropophilic species, high populations of this tick can increase exposure risk to humans. Despite its ability for rapid population growth and its ability to vector human and animal pathogens, current research on controlling H. longicornis in public spaces is limited. In Chapter 2, I assessed the efficacy of a pyrethroid acaricide (lambda-cyhalothrin) applied in a public park at different intervals according to the seasonal activity of different life stages. Nymphs were most abundant in the spring, followed by adults in mid-summer, and larvae in the fall. Applications of lambda-cyhalothrin timed at the peak of each life stage provided 100% control for 5-7 weeks. Ticks re-established after each application, however, at greatly reduced levels in the mid and late summer applications. To further explore H. longicornis control strategies, in Chapter 3 I evaluated acaricides with different modes of action (pyrethroids, a carbamate, and insect growth regulators [IGR’s]) and delivery methods (spray &amp; granule) to control H. longicornis in an infested park, as well as nontarget impacts of these acaricides on soil and above-ground invertebrate communities. Pyrethroids were the most effective control agents by far and controlled &gt; 95% of the population for the duration of the year. However, pyrethroid applications prompted enduring changes in soil-dwelling arthropod communities, which failed to recover during our survey period. Further research is needed to identify effective and environmentally sustainable alternatives. Acaricide resistance is a common problem worldwide for numerous tick species that infest livestock. However, baseline acaricide susceptibility, which is critical for resistance determination, has not previously been reported for H. longicornis in the U.S. or elsewhere. In Chapter 4, I examined the susceptibility of a U.S. H. longicornis population to three different acaricide classes using the standard larval packet test. H. longicornis was highly susceptible to propoxur, carbaryl, and coumaphos, and moderately susceptible to permethrin. I concluded that acaricide resistance is not presently a concern for H. longicornis, however, responsible management and resistance monitoring should be employed to ensure the sustainability of tick control products. As reported in Chapter 2, the phenology of H. longicornis shows considerable overlap in life stages throughout the year likely attributed to the presence of different cohorts. In Chapter 5, I demonstrate in laboratory studies that total lipids provide a good approximation for the physiological condition in H. longicornis, and subsequently measure lipids in field-collected H. longicornis from March to October to give insight into the overlapping generations in its life cycle. Overall this analysis identified two cohorts of nymphs which overlap in the spring, two cohorts of adults which overlap in the spring and summer, and two cohorts of larvae which do not overlap during the year. These results help explain the complex seasonality of the species and indicate that all stages overwinter in New Jersey.