Integrated Tick Management in the Upper Midwest: Impact of Invasive Vegetation Removal and Host-targeted Acaricides on Ixodes scapularis Infestation and Borrelia burgdorferi Prevalence of Small Mammals

Integration of tick management strategies has been suggested to overcome ecological variation in tick, host, pathogen, and habitat, yet empirical evidence assessing combined treatment effect on blacklegged ticks, Ixodes scapularis Say, is limited. In this 5-year study (2014-2018) we tested whether combining two methods targeting tick/mammal interactions could reduce juvenile I. scapularis parasitism of two small mammal species, Peromyscus leucopus Rafinesque and Tamias striatus Linnaeus. Infection of small mammals with Borrelia burgdorferi was used to evaluate host exposure to feeding ticks. Using a factorial design, removal of invasive vegetation (Amur honeysuckle, Lonicera maackii Ruprecht and common buckthorn, Rhamnus cathartica Linnaeus) was coupled with deployments of permethrin-treated cotton nesting materials (tick tubes) and evaluated against control sites. Removal of invasive vegetation resulted in lower captures of T. striatus suggesting that treatment impacted reservoir activity in the plots. Deployments of permethrin-treated cotton were effective at reducing the frequency of juvenile I. scapularis parasitism of P. leucopus by 91% across the study compared to controls. However, tick tubes did not offer consistent protection against mouse exposure to B. burgdorferi exposure. An additive negative effect was detected for juvenile tick intensity on P. leucopus when tick tubes were combined with invasive vegetation removal. We conclude that integration of these two methods provides very limited benefit and that permethrin treatment alone offers the best option for reducing I. scapularis infestation on P. leucopus.

Integrated Tick Management in Guilford, CT: Fipronil-Based Rodent-Targeted Bait Box Deployment Configuration and Peromyscus leucopus (Rodentia: Cricetidae) Abundance Drive Reduction in Tick Burdens

Integrated tick management (ITM) is a comprehensive strategy used to reduce presence of ticks and their associated pathogens. Such strategies typically employ a combination of host and non-host targeted treatments which often include fipronil-based, rodent-targeted bait boxes. Bait boxes target small-bodied rodents, specifically white-footed mice (Peromyscus leucopus Rafinesque) that not only play a crucial role in the blacklegged tick (Ixodes scapularis Say (Ixodida: Ixodidae)) life cycle, but also in the transmission of numerous pathogens, primarily Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner (Spirochaetales: Spirochaetaceae), the causal agent of Lyme disease. This study aimed to determine the effect of bait box deployment configuration on tick burden reduction while also further exploring bait consumption and P. leucopus abundances as measures of bait box usage and effectiveness. Boxes were deployed on nine properties within each of six neighborhoods (n = 54) in two different configurations: grid and perimeter. Multiple factors were analyzed as potential predictors for reduction in tick burdens using a backward stepwise selection procedure. Results confirmed the perimeter configuration was a more effective deployment strategy. In addition, overall P. leucopus abundance was a significant predictor of tick burden reduction while bait consumption was not. These findings not only further support the recommended perimeter deployment configuration but provide insight into effective utilization in areas of high P. leucopus abundance. The identification of this significant relationship, in addition to configuration, can be utilized by vector control professionals and homeowners to make informed decisions on bait box placement to make sustained impacts on the I. scapularis vector and associated pathogens within an ITM framework.

Integrated Tick Management in South Central Wisconsin: Impact of Invasive Vegetation Removal and Host-Targeted Acaricides on the Density of Questing Ixodes scapularis (Acari: Ixodidae) Nymphs

As tick-borne disease incidence increases and pathogens expand into new areas, the need for effective tick management strategies is paramount. In this 5-yr study (2014–2018) conducted in south central Wisconsin, we assessed whether an integrated tick management approach, deployed during peak tick activity (May–August), was more effective at reducing black-legged ticks (Ixodes scapularis Say (Ixodida: Ixodidae)), than individual interventions. Using a factorial design, invasive vegetation removal (Amur honeysuckle, Lonicera maackii Ruprecht (Dipsacales: Caprifoliaceae) and common buckthorn, Rhamnus cathartica Linnaeus (Rosales: Rhamnaceae)) was coupled with deployments of permethrin-treated cotton nesting materials (tick tubes) that target the white-footed mouse (Peromyscus leucopus Rafinesque (Rodentia: Cricetidae)). Results show that the probability of encountering a larval tick by drag sampling was unaffected by treatments at the cumulative 5-yr level. However, vegetation removal significantly reduced larval encounters in 2014, 2015, and 2018, by 33%, 57%, and 61% respectively, and reduced the density of questing nymphal (DON) ticks by 45% in 2015 compared to controls. Despite the limited effect on DON, vegetation removal significantly reduced the cumulative 5-yr density of Borrelia burgdorferi sensu stricto infected nymphs (DIN) (70%) compared to controls as a result of decreased nymphal infection prevalence. Sites treated with tick tubes had lower DIN (66%) and DON (54%) across the study and nymphs were reduced every year following the initial year of deployment compared to controls. Combining treatments did not further reduce DIN or DONs. We conclude that long-term integration of tick tubes with invasive vegetation removal does not provide additional benefit over individual treatments alone.

Tick-Borne Pathogens and Diseases in Greece

Tick-borne diseases (TBDs) are recognized as a serious and growing public health epidemic in Europe, and are a cause of major losses in livestock production worldwide. This review is an attempt to present a summary of results from studies conducted over the last century until the end of the year 2020 regarding ticks, tick-borne pathogens, and tick-borne diseases in Greece. We provide an overview of the tick species found in Greece, as well as the most important tick-borne pathogens (viruses, bacteria, protozoa) and corresponding diseases in circulation. We also consider prevalence data, as well as geographic and climatic conditions. Knowledge of past and current situations of TBDs, as well as an awareness of (risk) factors affecting future developments will help to find approaches to integrated tick management as part of the ‘One Health Concept’; it will assist in avoiding the possibility of hotspot disease emergencies and intra- and intercontinental transmission. Increased surveillance in Greece is required to ensure clear and effective policies for TBD control.

Humane Use of Cardiac Puncture for Non-Terminal Phlebotomy of Wild-Caught and Released Peromyscus spp.

The cardiac puncture technique for obtaining relatively large volume (50–150 µL) blood samples from sedated rodents has been used in research for nearly a century. Historically, its use to phlebotomize and then release live rodents was more common. However, recently its use in a non-terminal capacity frequently imparts negative connotations in part because exsanguination of sedated animals via cardiac puncture is now an American Veterinary Medical Association-approved euthanasia technique. This association has resulted in ethical concerns by manuscript reviewers and in a few instances, outright refusal by some peer-reviewed journals to publish research that utilized the technique. To counter the perceived negative associations with its non-terminal use, we summarized nearly two decades (2001–2019) of capture and handling data throughout Connecticut, resulting in over 7000 cardiac punctures performed on nearly 5000 sedated, live-captured and released Peromyscus spp. We show that our total handling mortality rate (3.7%) was comparable, if not lower, than similar field studies that utilized other phlebotomy techniques. Many public health, integrated tick management, and vector-borne disease ecology studies require samples from individual wild-caught Peromyscus spp. over time to determine intervention efficacy and pathogen infection monitoring, and in such field studies, post-operative care is not an option. Proper execution of cardiac puncture does not increase susceptibility of individuals to predation upon release as can potential ocular abnormalities or infections that can occur as the result of use of other techniques. We posit that neither exsanguination nor resulting euthanasia are requirements of cardiac puncture and that its use is entirely appropriate for obtaining blood samples from live-captured and released Peromyscus spp. Properly performed cardiac puncture is an excellent technique to obtain blood samples from sedated, individual Peromyscus spp. on multiple appropriately-spaced occasions over single trapping seasons while keeping animal welfare a top priority.