Northward Expansion of Amblyomma americanum (Acari: Ixodidae) into Southern Michigan

Fowler, P. D.; Nguyentran, S.; Quantroche, L. M.; Porter, M.; Kobbekaduwa, V.; Tippin, S.; Miller, G.; Dinh, E.; Foster, E.; Tsao, J.

doi:10.1101/2021.12.31.474651

bioRxiv · 10.1101/2021.12.31.474651

Northward Expansion of Amblyomma americanum (Acari: Ixodidae) into Southern Michigan

Fowler, P. D.·Nguyentran, S.·Quantroche, L. M.·Porter, M.·Kobbekaduwa, V.·Tippin, S.·Miller, G.·Dinh, E.·Foster, E.·Tsao, J.

View original source ↗Export metadata ↓

Abstract

Amblyomma americanum (Linnaeus) (Acari: Ixodidae) (lone star tick) is an aggressive, generalist parasite that vectors numerous important human and animal pathogens. In recent decades its geographic range has expanded northwards from endemic regions in the southeastern and southcentral US. In 2019 five questing A. americanum comprising two life stages were detected at one site in Berrien County, in southwestern Michigan, satisfying one CDC criterium for an established population for the first time in the state. To better characterize the northern extent of emerging A. americanum, we conducted active surveillance (i.e., drag sampling) in summer 2020 throughout Michigans southern counties and detected one adult A. americanum from each of six widespread sites, including where they had been detected in 2019. A larger established population was identified at another site in Berrien County, which yielded 691 A. americanum comprising three life stages. Questing tick phenologies at this site were similar to that reported for other regions. Statewide surveillance in 2021 revealed no A. americanum outside of Berrien County, but establishment criteria were met again at the two sites where established populations were first detected respectively in 2019 and 2020. These observations may represent the initial successful invasion of A. americanum into Michigan. Data from passive (1999-2020) and active surveillance (2004-2021) efforts, including a domestic animal sentinel program (2015-2018), are reported to provide context for this nascent invasion. Continued active surveillance is needed to help inform the public, medical professionals, and public health officials of the health risks associated with this vector.

Source connections

Published article ↗

Explore related subjects

ecology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Fowler, P. D., Nguyentran, S., Quantroche, L. M., Porter, M., Kobbekaduwa, V., Tippin, S., Miller, G., Dinh, E., Foster, E., Tsao, J.. 2022-01-02. Northward Expansion of Amblyomma americanum (Acari: Ixodidae) into Southern Michigan. https://doi.org/10.1101/2021.12.31.474651

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Phenotypic variation in divergent mitochondrial haplotypes in migratory three-spined stickleback

Mitochondria are essential components in life-sustaining organismal processes. The mitochondrial genome can be influenced by selection, and divergent mitochondrial haplotypes have substantial potential to affect interspecies variation in life-history and physiology, yet little is known about whole organism phenotypic changes that might accompany mitochondrial genomic divergence. Three-spined stickleback on the Scottish island of North Uist provide a model to study this as their populations exhibit a well-mixed nuclear genome, yet two highly diverged mitochondrial haplotypes ( trans-Atlantic and European). Three-spined stickleback were sampled from six lochs to investigate associations between mitochondrial haplotype and phenotypic traits including organ size, body size, and ovule volume/clutch size, as well as citrate synthase enzyme activity. Results showed that mitochondrial haplotype has an influence on male gonadosomatic index (GSI) and potentially citrate synthase (CS) enzyme activity. Differences in male GSI may be explained by the timing of male spermatogenesis or potentially a need for larger testes in European haplotype fish. While no other phenotypic trait showed differences between mitochondrial haplotypes, there were many differences between sexes and populations e.g. in body size and organ/muscle size.

ecology↗

bioRxiv2026

Gregariousness can promote invasion success of pest insects while higher environmental heterogeneity decreases it

Climate change and environmental homogenization are expected to facilitate the expansion of many forest pest insect species and increase the vulnerability of forest ecosystems to insect outbreaks. At present, we lack empirical data on how the antipredator defence traits of pest insects interact with the local environmental conditions and shape outbreak risk. Here we study this and ask 1) how the antipredator defence strategy of pest insects shapes survival under naturally varying predator community, and 2) how is predation risk shaped by the diversity and structure of forests? We tested these questions by conducting a field predation experiment with artificial prey system (prey items made from edible dough) where we manipulated the gregariousness, unpalatability and defensive colouration of prey and tested their effects on prey survival. Additionally, we measured environmental variables and invertebrate predator community structure along the prey transects to analyse how they shape overall predation risk. Our results show that the predation risk was always lowest for gregarious prey irrespective of other defence strategies. Furthermore, our results indicate that predation pressure was lower in more homogenously structured forest areas or areas with a weak quality deadwood continuum in comparison to locations with more natural state forests and good quality deadwood continuum. Altogether, our results suggest that gregariousness can facilitate pest insects to form outbreaks by increasing their survival against generalist predators. However, by maintaining higher heterogeneity in forests, it is possible to ensure higher predation pressure to regulate their population growth.

ecology↗

bioRxiv2026

Two decades of EU pesticide substitution have not reduced impacts on stream invertebrates

Chemical regulation assumes that withdrawing hazardous substances and replacing them with alternatives reduces environmental harm. We tested this premise within the EU pesticide regulatory framework using a 23-year record of event-driven pesticide exposure and stream-invertebrate communities from 152 German agricultural streams sampled between 1998 and 2021. Neither pesticide toxic pressure nor pesticide-related invertebrate impairment showed a detectable decline over time, and an improvement equivalent to one ecological status class can be excluded. Dominant toxicity drivers shifted from organophosphates to neonicotinoids and subsequently to pyrethroids, yet the relationship between toxic pressure and community effects remained consistent despite their distinct modes of action. Sustained toxic pressure reflected three mechanisms: successive chemical substitution, prolonged approval periods, and continued exposure to substances no longer authorised as plant protection products. Substitution thus changed which chemicals harm streams, not how much. Measured field outcomes must become the benchmark of pesticide regulation.

ecology↗