About

Lyric Bartholomay is a professor in the Department of Pathobiological Sciences in the School of Veterinary Medicine at the University of Wisconsin-Madison. She serves as the Director of the graduate program in Comparative Biomedical Sciences. Her research focuses on understanding the threat of invasive mosquito species, discovering vector-borne viruses in wildlife, and examining the impacts of mosquito control on the risk of West Nile virus transmission. Dr. Bartholomay is also a co-director of the Midwest Center of Excellence for Vector-Borne Disease, which was established in 2016 with ongoing funding from the Centers for Disease Control and Prevention. The center aims to bring together researchers, public health experts, and vector control professionals to better understand and control mosquitoes, ticks, and the diseases they carry. In 2024, she was awarded the Bernard C. Easterday Professor in Infectious Disease. She is a board member of the American Heartworm Society and a Fellow with the American Society of Topical Medicine & Hygiene.

Research topics

• Medicine
• Environmental health
• Immunology
• Demography
• Biology
• Geography
• Veterinary medicine
• Zoology
• Genetics
• Evolutionary biology

Selected publications

• Resistance to S-Methoprene Correlates with Pyriproxyfen Resistance in Field-Collected Culex pipiens

  Insects · 2026-02-26

  articleOpen access

  The increasing prevalence of insecticide resistance threatens the efficacy of Integrated Mosquito Management (IMM) programs, particularly in regions reliant on chemical control for vector-borne disease prevention. Cross-resistance between active ingredients severely complicates essential resistance management strategies like product rotation. The previous literature suggests that laboratory-induced S-methoprene-resistant Culex species may be somewhat cross-resistant to pyriproxyfen, another juvenile hormone analog. This is a critical concern in the Chicago, IL, USA metropolitan area, where pyriproxyfen is used against mosquitoes with reduced susceptibility to S-methoprene. To determine if S-methoprene-resistant Culex pipiens are cross-resistant to pyriproxyfen in nature, we assessed 31 field-collected populations with significant S-methoprene exposure but varying histories of pyriproxyfen use by dose–response bioassays. Culex pipiens from all 31 sites exhibited high resistance to S-methoprene (RR50 > 10), and 84% were at least moderately resistant to pyriproxyfen (RR50 > 5). Reduced susceptibility to pyriproxyfen was confirmed in pyriproxyfen-unexposed populations, demonstrating potential S-methoprene-mediated cross-resistance. The level of S-methoprene resistance and the level of pyriproxyfen exposure significantly correlated with the level of pyriproxyfen resistance. We report the first widespread, high-level pyriproxyfen resistance in any medically significant mosquito species, underscoring the critical need for routine resistance surveillance and the adoption of integrated resistance management tactics utilizing larvicides with distinct modes of action.

  PublisherOA PDFDOI

• Survey of tick control practices on public lands across 4 states reporting high incidence of Lyme disease

  Journal of Medical Entomology · 2026-01-20

  article

  Ticks and tick-borne diseases pose a significant public health threat in the United States, particularly in the Northeast and Upper Midwest. Tick control operations are predominately focused on private residential properties. Surveys of publicly funded vector control programs have indicated that high use public lands may be viable targets for future tick control activities if funding is available. However, little is known about the feasibility of implementing tick control activities on these properties. We administered a survey to understand current tick control and tick bite prevention educational practices and potential barriers to future tick control on public lands. The survey was distributed to public land managers in Minnesota, New York, Pennsylvania, and Wisconsin and we received 129 responses. The responses indicated that tick control was undertaken on only 10% of the public lands that respondents managed. Landscape management was the most common intervention. Some (40%) of the public land managers indicated interest in using tick control methods in the future, again with landscape management being the preferred intervention. Respondents indicated that there may be significant barriers for the use of acaricides and host-targeted interventions. Currently, tick bite prevention education appears to be the primary protective measure utilized on public land, with 63% of responding land managers offering education to staff or visitors. Our survey indicates that high use public lands may present potential targets for limited tick control operations, but the potential barriers must be addressed and additional evaluation of these interventions on high use public land is required.

  PublisherDOI

• Catch basin larvicide treatments impact adult mosquito West Nile virus vector species in metropolitan Milwaukee, WI, U.S.A.

  PLoS ONE · 2026-04-15

  articleOpen accessSenior author

  Roadside stormwater catch basins are frequently treated with larvicides in metropolitan areas because they are ideal larval growth sites for West Nile virus (WNV) vector species Culex pipiens Linnaeus and Cx. restuans (Theobald). Despite the wide-spread implementation of catch basin treatments in integrated vector management programs, there is little entomological evidence to suggest catch basin larvicide treatments reduce adult mosquito abundance and thereby impact WNV risk. We evaluated the impact of treating catch basins at three of four sites (700-1000 basins each) with a formulation of Lysinibacillus sphaericus using a stepped-wedge cluster trial approach in metropolitan areas in Wisconsin, U.S.A in 2019. Treatment effects were measured by evaluating immature stage mosquito abundance in catch basins and general additive models (GAM) to analyze changes of the integrated adult female Culex spp. abundance and population stability sampled from host-seeking and gravid mosquito traps. We observed catch basin treatments to effectively suppress immature stages in catch basins (94% reduction of pupae). The GAM found catch basin treatment duration to significantly reduce the integrated abundance of gravid Culex spp. mosquitoes, with a total mean percent reduction of 37% at treated sites. Treatment duration was also observed to impact the stability of the gravid Culex spp. integrated abundance, with differences between untreated and treated sites, and among sites that differed in treatment duration. These results support the treatment of catch basins with biorational larvicides as a mosquito management tool for WNV vector species in similar metropolitan habitats provided adequate suppression of immature stage mosquitoes.

  PublisherDOI

• A multi-assay assessment of insecticide resistance in Culex pipiens (Diptera: Culicidae) informs a decision-making framework

  PLoS ONE · 2025-06-09 · 2 citations

  articleOpen accessSenior authorCorresponding

  Insecticide resistance (IR) is an increasing problem globally, making control of vector-borne diseases more difficult. Reduced susceptibility to permethrin in Culex pipiens, an important vector for West Nile virus, has been reported across the US based on a standardized laboratory method: the CDC bottle bioassay. This bioassay uses a rapid phenotypic outcome to reveal evidence for IR, but how this translates to the effectiveness of formulated products used in an operational setting is unclear. Therefore, other methods for IR monitoring are recommended to quantify IR or evaluate formulated products against field populations in real-world conditions. To compare some of the available methods, we collected populations of Cx. pipiens from six sites in the Northwest Mosquito Abatement District (Cook Co., Illinois), and used a susceptible laboratory strain of Cx. pipiens as a control, to test for IR to pyrethroids using CDC bottle bioassays, caged field trials, and topical applications. CDC bottle bioassays suggested that Cx. pipiens from this area exhibit IR to both etofenprox and Sumithrin®. Caged field trials with ultra-low volume Anvil® 10 + 10 (Sumithrin®) demonstrated resistance to the product and underscored the need for inclusion of a susceptible control to differentiate IR from inadequate product distribution. Topical applications revealed low to high levels of resistance to synergized and unsynergized pyrethroids (etofenprox, Sumithrin®, and deltamethrin) in all field populations. Based on these data, we provide a new decision-making tree for mosquito control professionals which will guide selection of the most optimal assay for IR surveillance based on their goals, needs, and resources.

  PublisherDOI

• Comparative analysis of duck Tembusu virus Cluster 1 and Cluster 2.1 in Culex tritaeniorhynchus: Insights into viral characteristics, infectivity, and innate immune response

  Current Research in Parasitology and Vector-Borne Diseases · 2025-01-01 · 2 citations

  articleOpen access

  The disease caused by the duck Tembusu virus (DTMUV) is one of the most prevalent arthropod-borne viral diseases in poultry. DTMUV is classified into three distinct clusters based on significant genetic divergence: Cluster 1, Cluster 2 (subdivided into 2.1 and 2.2), and Cluster 3. The virulence of DTMUV in ducks is potentially associated with the virus genotype. The evaluation of different clusters of DTMUV is based predominantly on the characterization of infected duck hosts, and limited attention has been paid to understanding viral virulence toward the infected mosquito vectors. In this study, we explore the infectivity patterns of DTMUV cluster 1 (DTMUV 1) and cluster 2.1 (DTMUV 2.1) in the primary mosquito vector, Culex tritaeniorhynchus . Our objective was to explore the relationship between the mosquito vector and DTMUV genotype, intending to determine whether the mosquito vector alters viral biology, thereby influencing the consequential infectivity characteristics in the host cells. We found that variation in viral nonstructural protein-5 (an RNA-dependent RNA polymerase) may influence the antigenicity process in Cx. tritaeniorhynchus . Our results revealed DTMUV1 underwent higher replication than DTMUV2.1 in mosquito salivary glands and saliva. Furthermore, DTMUV1 derived from mosquito saliva produced larger plaque sizes in baby hamster kidney-21 (BHK-21) cells than DTMUV2.1 derived from mosquito saliva. Interestingly, DTMUV2.1 was more efficient than DTMUV1 in inducing the production of mRNAs for macroglobulin complement-related factor, thioester-containing protein, and antimicrobial peptides (cecropin family) within the mosquito salivary gland. Our findings collectively suggest that Cx. tritaeniorhynchus can influence an environment conducive to modifying the amino acid composition of DTMUV1 and DTMUV2.1 in a manner that may affect the innate immune response, consequently augmenting viral virulence. • DTMUV1 and DTMUV2.1 differ in infectivity in Culex tritaeniorhynchus mosquitoes. • Nonstructural protein-5 variations may influence viral replication and immune response. • The connection between NS5 mutations and antigenicity has not been directly validated. • DTMUV1 triggers a weaker mosquito immune response than DTMUV2.1. • Reduced immune response may contribute to the higher replication and transmission of DTMUV1.

  PublisherDOI

• Tick spotting: using mannequins to evaluate individual efficacy at detecting <i>Ixodes scapularis</i> (Acari: Ixodidae)

  Journal of Medical Entomology · 2025-05-19 · 1 citations

  articleOpen access

  Tick checks are a free and accessible personal protection measure used to prevent tick bites and are frequently recommended by public health institutions and vector-borne disease researchers. However, little is known about how successful people are at detecting ticks on themselves or others when using this method. We developed a tool for evaluating factors affecting the efficacy of tick checks using mannequins. In 2022 and 2023, we recruited 207 participants to complete a brief survey and perform a tick check on a mannequin, where dead Ixodes scapularis Say larvae, nymphs, and adults had been glued at various locations. None of the survey results (demographics, knowledge, attitude, and concerns about ticks and tick-borne disease) were associated with likelihood of tick detection. On average, participants detected 42% of nymphs on the mannequin. Adult females were 3 to 4 times more likely to be detected than nymphs. Ticks above the waistline were detected 3 times more frequently than ticks below. Ticks that were on white-colored clothing were 3 times more likely to be detected than those on dark-colored clothing. Ticks that were not covered by hair or clothing were 2 times more likely to be detected than covered ticks. These findings show that there are multiple factors that may limit tick detection during a tick check. Outreach should emphasize the importance of awareness of size variation between stages, completing a thorough whole-body examination including the lower limbs and covered locations, and wearing light-colored clothing.

  PublisherOA PDFDOI

• PERSISTENCE OF AEDES TRISERIATUS DESPITE THE INVASION OF AEDES JAPONICUS IN WESTERN WISCONSIN

  Journal of the American Mosquito Control Association · 2025-05-16

  articleOpen access

  For more than 40 yr, a multicounty vector control program that surrounded the epicenter of the outbreak of La Crosse virus (LACV) was in place to survey and control point sources for the virus transmission vector Aedes triseriatus. During that period, the number of cases of LACV disease declined to 1 and 2 cases in 2003 and 2004, respectively, and 0 reported cases within La Crosse County, WI, since 2005. We surveyed Ae. triseriatus populations in La Crosse and Trempealeau counties, WI, during the summers of 2020-2021 to determine whether the decline in LACV disease cases corresponded to a possible decline in Ae. triseriatus populations, and whether the invasive species, Ae. japonicus, is competing with and replacing Ae. triseriatus. We sampled containers for larvae and collected eggs using oviposition (OP) traps. We collected 606 and 20,020 mosquitoes in 2020 and 2021, respectively. Overall, we found a lower proportion of Ae. japonicas than Ae. triseriatus in natural oviposition sites in 2020 (n = 72 and 224 larvae, respectively; z = 8.78, P < 0.0001), in OP traps in 2020 (n = 5 and 199, respectively; z = 13.51, P < 0.0001), and in OP traps in 2021 (n = 358 and 19,099, respectively; z = 134.31, P < 0.001). Aedes japonicus, therefore, does not appear to be outcompeting native species in western Wisconsin forests. Although there were as few as 4 total cases of LACV disease reported in 2020 and 2021 in Wisconsin, we found ample evidence of Ae. triseriatus activity. These data point to the need for continued surveillance and control efforts in the interest of preventing vector-borne diseases.

  PublisherDOI

• Dual S-methoprene and Lysinibacillus sphaericus larvicide use leads to multiple independent, and not cross-resistance in Culex pipiens

  PLoS ONE · 2025-09-29 · 5 citations

  articleOpen accessCorresponding

  S-methoprene, an insect growth regulator, and Lysinibacillus sphaericus (Ls), an entomopathogenic bacterium, are important larvicides used to control Culex pipiens [L.] mosquitoes, the primary vector of West Nile virus, in the Chicago, IL USA region. Resistance to both agents has been documented globally including a report of resistance ratios greater than 100 to S-methoprene in the Chicago region. Laboratory studies have suggested the potential for unidirectional cross-resistance between S-methoprene and Ls, despite differing modes of action. Among wild populations of Cx. pipiens in the Chicago area, this study aimed 1) to assess resistance status to Ls, 2) confirm the presence of S-methoprene resistance ratios >100, 3) determine if higher S-methoprene resistance ratios are associated with higher Ls resistance ratios, or whether Ls resistance arises solely from Ls exposure, and (4) determine the relationship between Ls treatment history and resistance levels of that active ingredient. We assessed susceptibility to both S-methoprene and Ls in 32 Cx. pipiens populations: 19 with S-methoprene exposure but no Ls history, and 13 with multi-year exposure to both larvicide active ingredients. Ls susceptibility was evaluated using dose-response bioassays to estimate LC50, LC90, and resistance ratios. Susceptibility to S-methoprene was tested using diagnostic doses corresponding to resistance ratios of 10 and 100 at the LC50. Resistance ratios to S-methoprene exceeding 10 were detected in 30 of 32 sampled populations. Among the 13 sites with prior Ls exposure, 11 were observed with resistance ratios > 5. In contrast, none of the 19 populations without Ls exposure exhibited Ls resistance, despite exhibiting higher S-methoprene resistance ratios. This lack of overlap supports the conclusion that S-methoprene resistance does not confer cross-resistance to Ls in the studied region. Logistic regression revealed a strong association between Ls treatment history and resistance development. The probability of Ls resistance exceeded 80% after 10 Ls applications within an eight-year period. These findings emphasize the need to develop improved resistance management strategies for larvicidal insecticides.

  PublisherDOI

• Infection-Mediated Shifts in the Microbial Communities of Deer-Fed Ixodes scapularis Ticks

  Microorganisms · 2025-11-20

  articleOpen accessSenior author

  The holobiont of the blacklegged tick (Ixodes scapularis) includes maternally inherited rickettsial endosymbionts and environmentally acquired microbes that may influence tick fitness and vector competence. While previous studies have focused on characterizing the microbiota of I. scapularis ticks, less is known about the influence of tick infection status on microbial assemblages. Here, we collected engorged female I. scapularis ticks from hunter-harvested white-tailed deer (Odocoileus virginianus) across 11 counties in Wisconsin during fall 2022. The ticks were maintained in laboratory conditions for oviposition and then frozen for nucleic acid extraction. The infection status of each tick was determined using qPCR, targeting Borrelia spp., Babesia spp., and Powassan virus. Bacterial and fungal communities were characterized through amplicon-based sequencing targeting the 16S rRNA gene and ITS2 region, respectively. Our targeted pathogen testing revealed that 14.1% of the collected ticks were infected with Babesia odocoilei and 23.3% with Borrelia burgdorferi. The microbial community composition of ticks was significantly influenced by infection status and pathogen identity. Notably, Borrelia-infected ticks exhibited distinct microbiota profiles and increased microbial network connectivity. These findings provide new insights into the microbial ecology of deer-fed I. scapularis ticks and highlight the role of infection in shaping both microbiota and mycobiota communities.

  PublisherDOI

• First experimental evidence of the transovarial transmission of lumpy skin disease virus by Aedes aegypti (Diptera: Culicidae)

  Acta Tropica · 2025-08-19 · 1 citations

  article
  PublisherDOI

Recent grants

• PFI: A platform-based approach to developing and delivering nanoparticle antivirals for disease control in farmed shrimp

  NSF · $600k · 2011–2014

• Parasitology and Vector Biology Training Program

  NIH · $5.4M · 1992–2029

Frequent coauthors

• Susan M. Paskewitz

  University of Wisconsin–Madison

  36 shared

• Bruce M. Christensen

  University of Wisconsin Health

  36 shared

• Gebbiena M. Bron

  23 shared

• Bradley J. Blitvich

  Iowa State University

  22 shared

• Evgeny M. Zdobnov

  University of Geneva

  22 shared

• George F. Mayhew

  22 shared

• Robert M. Waterhouse

  SIB Swiss Institute of Bioinformatics

  21 shared

• David W. Severson

  Indiana University

  21 shared

Awards & honors

• Bernard C. Easterday Professor in Infectious Disease (2024)
• Fellow with the American Society of Topical Medicine & Hygie…