Scott C. Williams

Exotic Seed Dispersal by White-tailed Deer in Southern Connecticut

Abstract We examined the role of suburban white-tailed deer (Odocoileus virginianus Zimmerman) in dispersal of exotic plants in forests bordered by medium-density housing in southern Connecticut. Estimated deer density on the research site was 23 deer/km2 with higher local densities along the suburban/woodland interface. In 2002, 90 pellet groups were gathered periodically from September through December. In 2003, eight pellet groups were collected weekly from early June through late December for a total of 236. All pellet groups were vernalized at 5°C for 60 days. Pellet groups were placed in a growing medium in trays in a temperature controlled greenhouse for six months. Seeds germinated from 47% of pellet groups, which included 656 seedlings of 57 species. Seeds (n = 326) of 32 species not native to Connecticut germinated in 23% of pellet groups. We estimated that the deer herd on site had the potential to disperse 586-1046 viable exotic seeds/day/km2 during the 2002 sampling period and 390-696 viable exotic seeds/day/km2 during the 2003 sampling period. Birds, small mammals, and abiotic factors are known dispersal agents for exotic plants, some of which are invasive. Our results indicate that white-tailed deer are another important dispersal agent of exotic species. Thus, white-tailed deer may not only alter vegetation structure through direct browse damage of established plants, but also indirectly by lowering reproductive output of native plants and simultaneously distributing seeds of exotic species.

Managing Japanese Barberry (Ranunculales: Berberidaceae) Infestations Reduces Blacklegged Tick (Acari: Ixodidae) Abundance and Infection Prevalence with Borrelia burgdorferi (Spirochaetales: Spirochaetaceae)

ABSTRACT In many Connecticut forests with an overabundance of white-tailed deer (Odocoileus virginianus Zimmermann), Japanese barberry (Berberis thunbergii DC) has become the dominant understory shrub, which may provide a habitat favorable to blacklegged tick (Ixodes scapularis Say) and white-footed mouse (Peromyscus leucopus Rafinesque) survival. To determine mouse and larval tick abundances at three replicate sites over 2 yr, mice were trapped in unmanipulated dense barberry infestations, areas where barberry was controlled, and areas where barberry was absent. The number of feeding larval ticks/mouse was recorded. Adult and nymphal ticks were sampled along 200-m draglines in each treatment, retained, and were tested for Borrelia burgdorferi (Johnson, Schmid, Hyde, Steigerwalt, and Brenner) presence. Total first-captured mouse counts did not differ between treatments. Mean number of feeding larval ticks per mouse was highest on mice captured in dense barberry. Adult tick densities in dense barberry were higher than in both controlled barberry and no barberry areas. Ticks sampled from full barberry infestations and controlled barberry areas had similar infection prevalence with B. burgdorferi the first year. In areas where barberry was controlled, infection prevalence was reduced to equal that of no barberry areas the second year of the study. Results indicate that managing Japanese barberry will have a positive effect on public health by reducing the number of B. burgdorferi-infected blacklegged ticks that can develop into motile life stages that commonly feed on humans.

Effects of Japanese Barberry (Ranunculales: Berberidaceae) Removal and Resulting Microclimatic Changes on Ixodes scapularis (Acari: Ixodidae) Abundances in Connecticut, USA

ABSTRACT Japanese barberry (Berberis thunbergii de Candolle) is a thorny, perennial, exotic, invasive shrub that is well established throughout much of the eastern United States. It can form dense thickets that limit native herbaceous and woody regeneration, alter soil structure and function, and harbor increased blacklegged tick (Ixodes scapularis Say) populations. This study examined a potential causal mechanism for the link between Japanese barberry and blacklegged ticks to determine if eliminating Japanese barberry could reduce tick abundance and associated prevalence of Borrelia burgdorferi (Johnson, Schmid, Hyde, Steigerwalt, and Brenner). Japanese barberry was controlled at five study areas throughout Connecticut; adult ticks were sampled over three years. Each area had three habitat plots: areas where barberry was controlled, areas where barberry remained intact, and areas where barberry was minimal or absent. Sampled ticks were retained and tested for B. burgdorferi presence. At two study areas, temperature and relative humidity data loggers were deployed in each of the three habitat plots over two growing seasons. Intact barberry stands had 280 ± 51 B. burgdorferi-infected adult ticks/ha, which was significantly higher than for controlled (121 ± 17/ha) and no barberry (30 ± 10/ha) areas. Microclimatic conditions where Japanese barberry was controlled were similar to areas without barberry. Japanese barberry infestations are favorable habitat for ticks, as they provide a buffered microclimate that limits desiccation-induced tick mortality. Control of Japanese barberry reduced the number of ticks infected with B. burgdorferi by nearly 60% by reverting microclimatic conditions to those more typical of native northeastern forests.

SERUM ANTIBODIES TO BORRELIA BURGDORFERI, ANAPLASMA PHAGOCYTOPHILUM, AND BABESIA MICROTI IN RECAPTURED WHITE-FOOTED MICE

A mark-release-recapture study was conducted during 2007 through 2010 in six, tick-infested sites in Connecticut, United States to measure changes in antibody titers for Borrelia burgdorferi sensu stricto, Anaplasma phagocytophilum, and Babesia microti in Peromyscus leucopus (white-footed mice). There was an overall recapture rate of 40%, but only four tagged mice were caught in ≥2 yr. Sera from 561 mice were analyzed for total antibodies to B. burgdorferi and A. phagocytophilum by using whole-cell or recombinant (VlsE or protein 44) antigens in a solid-phase enzyme-linked immunosorbent assay or to whole-cell B. microti by indirect fluorescent antibody staining. Antibody prevalences were highly variable for B. burgdorferi (from 56% to 98%), A. phagocytophilum (from 11% to 85%), and B. microti (from 11% to 84%) depending on the site and time of sampling. Of 463 mice with antibodies, 206 (45%) had antibodies to all three pathogens. Changes in antibody status for some mice from negative to positive (117 seroconversions) or from positive to negative (55 reversions) were observed. Seroconversions were observed in 10.1% of 417 mice for B. burgdorferi, 18.0% of 306 mice for A. phagocytophilum, and 6.6% of 304 mice for B. microti; reversion rates were 5.3, 5.9, and 4.9%, respectively. Antibodies to all pathogens persisted in some mice over several weeks while, in others, there were marked declines in titration end points to negative status. The latter may indicate elimination of a certain pathogen, such as A. phagocytophilum, or that mouse immune systems ceased to produce antibodies despite an existing patent infection.

Comparing effectiveness and impacts of Japanese barberry (Berberis thunbergii) control treatments and herbivory on plant communities.

Abstract Two factors that can degrade native plant community composition and structure, and hinder restoration efforts, are invasive species and chronic overbrowsing by ungulates such as white-tailed deer. Beginning in 2007, the effectiveness, costs, and impacts of Japanese barberry control treatments and herbivory on nonnative and native plant communities was examined at eight study areas over 4 to 5 yr. Prescribed burning and mechanical mowing by wood shredder or brush saw were utilized as initial treatments to reduce the aboveground portion of established barberry and were equally effective. Without a follow-up treatment, barberry had recovered to 56 to 81% of pretreatment levels 50 to 62 mo after initial treatment. Follow-up treatments in mid-summer to kill new sprouts included directed heating and foliar herbicide applications. Relative to untreated controls, follow-up treatments lowered barberry cover 50 to 62 mo after initial treatment by at least 72%. Although all follow-up treatments were equally effective, the labor cost of directed heating was four times higher than for herbicide applications. Follow-up treatment type (directed heating vs. herbicide) had minimal impact on species other than barberry. White-tailed deer herbivory had a larger impact on other species than did barberry control treatments. Native grass and fern cover was higher outside of exclosures. Areas inside exclosures had higher cover of Oriental bittersweet and multiflora rose, but not Japanese barberry. Thus, recovery of native communities will require more than simply removing the dominant invasive species where deer densities are high. Excellent reduction of Japanese barberry cover can be achieved using either directed heating or herbicides as follow-up treatments in a two-step process, but other invasive plants may become a problem when barberry is removed if deer populations are low. Nomenclature: Glyphosate, triclopyr, 2,4-D, Japanese barberry, Berberis thunbergii DC. BEBTH, Oriental bittersweet Celastrus orbiculatus Thunb. CELOR, multiflora rose, Rosa multiflora Thunb. ex Murr. ROSMU. Management Implications: Japanese barberry is an invasive shrub in the eastern United States and Canada that forms dense thickets that can inhibit forest regeneration and native herbaceous plant populations, and is associated with elevated populations of blacklegged ticks, which can be infected with the causal agent of Lyme disease, Borrelia burgdorferi. A reasonable objective of controlling an invasive species such as Japanese barberry, is not eradication of the invasive species per se, but the restoration of a community dominated by native herbaceous species and woody regeneration. This study found that a single treatment (e.g., mowing) is ineffective without a follow-up treatment. A variety of techniques using a two-step strategy can successfully control Japanese barberry for a period of at least 4 to 5 yr if there is an immediate follow-up treatment, albeit at a wide range of labor costs. Labor costs for follow-up treatments with a propane torch were at least four times higher than for herbicide applications, although both were equally effective at controlling barberry. However, invasive control by itself was insufficient to restore native communities in these areas with high white-tailed deer densities because deer herbivory had a larger impact on plant communities than control of Japanese barberry. Where deer densities are high, a successful restoration program must incorporate a program to reduce deer density to a level sufficient for native forbs to flower and set fruit and for tree seedlings to grow tall enough to be above browse heights—typically 2 m (6 ft). Successful restoration might also require introduction of locally extirpated species. A successful program should also include strategies to control those invasive species, such as Oriental bittersweet and multiflora rose, that might have been suppressed by dense barberry or deer browse. Although applying control techniques to barberry is justifiable where infestations are severe and there is concern about tick abundance, the chance that one invasive species problem might be traded for another must be anticipated.

SEASONAL PREVALENCE OF SERUM ANTIBODIES TO WHOLE CELL AND RECOMBINANT ANTIGENS OF BORRELIA BURGDORFERI AND ANAPLASMA PHAGOCYTOPHILUM IN WHITE-TAILED DEER IN CONNECTICUT

Whole-blood samples were obtained from 214 white-tailed deer (Odocoileus virginianus) representing 44 sites in Connecticut (USA) during 1992, 1993, 1996, 1999, and 2000 through 2006. Sera were analyzed for total antibodies to whole-cell or recombinant antigens of Borrelia burgdorferi sensu stricto and Anaplasma phagocytophilum, the respective causative agents of Lyme borreliosis and human granulocytic anaplasmosis. Deer sera contained antibodies to both bacteria during different seasons and throughout the 11-yr study. Of the 224 sera tested, 141 (63%) contained antibodies to whole-cell B. burgdorferi in a polyvalent enzyme-linked immunosorbent assay, whereas 124 (55%) were positive to whole-cell A. phagocytophilum by indirect fluorescent antibody staining. Use of highly specific recombinant antigens (VlsE of B. burgdorferi and protein 44 of A. phagocytophilum) provided strong confirmatory results of past or current infections. There was coexistence of antibodies to whole-cell or recombinant antigens of both agents in 72 (32%) sera. Analyses of 18 sera from eight deer that were marked, released, and recaptured, showed minimal changes in antibody titer over sampling time intervals ranging from 17 days to 5.1 yr. Relatively high antibody prevalences for both bacterial agents in different seasons and years reaffirm that there are well-established foci for both tick-borne infections and probably reflect frequent exposure of deer to infected Ixodes scapularis ticks. November and December is a suitable period to obtain blood samples from deer to conduct serosurveillance for both bacteria.

Effectiveness of Two-Stage Control Strategies for Japanese Barberry (Berberis thunbergii) Varies by Initial Clump Size

Abstract Japanese barberry is listed as an invasive shrub in 20 states and four Canadian provinces. Control of Japanese barberry was evaluated using several two-step processes over 16 mo using a total of 1,100 clumps at six study areas. Initial treatments in spring (prescribed burning, mechanical mowing with a brush saw or rotary wood shredder) reduced the size of established barberry clumps. Follow-up treatments in midsummer to kill new ramets that developed from surviving root crowns were foliar applications of triclopyr or glyphosate, directed heating with a propane torch, and untreated controls. Mortality was defined as the absence of ramets from a root crown and not the mortality of individual ramets of a given clump. Clump mortality and size of new ramets did not differ among initial treatments. However, larger clumps had higher survival and larger sprouts than smaller clumps 16 mo after initial treatment. Effectiveness of follow-up treatments varied by clump size. Two follow-up treatments of directed heating using propane torches were as effective as herbicides for clumps that were initially smaller than 120 cm. For clumps with pretreatment sizes of 120 cm and larger, clump mortality following herbicide treatments (90%) and directed heating (65%) was greater than for clumps that had no follow-up treatments (35%). Although clump sizes did not differ between follow-up methods 1 yr after treatment, both follow-up treatments resulted in smaller clumps than untreated controls. Effective control of Japanese barberry can be achieved in a single growing season by integrating an early-season initial treatment (prescribed fire or mechanical) that kills the aboveground tissues with a midseason follow-up treatment such as directed heating or targeted herbicide application. Nomenclature: Glyphosate; triclopyr; Japanese barberry, Berberis thunbergii DC. BEBTH.

Expansion of zoonotic babesiosis and reported human cases, Connecticut, 2001-2010.

ABSTRACT To document the expansion of human babesiosis in Connecticut, we analyzed reservoir host sera for seroreactivity to Babesia microti Franca and reviewed Connecticut human surveillance case data collected during 2001–2010. Sera from white-footed mice, Peromyscus leucopus Rafinesque, from 10 towns in 5 counties, collected at 4–7-yr periods between 2001 and 2010, were tested for total immunoglobulins. The prevalence of B. microti-positive mice was compared with confirmed and probable human case reports tabulated by the Connecticut Department of Public Health. The highest babesiosis and rodent seroprevalence rates were in New London County, where this protozoan disease was first documented in the state. However, human cases and reservoir host infection increased significantly from 2001–2005 to 2005–2010 and in other parts of the state. Clinicians should be aware that the disease is not confined to long-established endemic areas of the state.

Controlling an Invasive Shrub, Japanese Barberry (Berberis thunbergii DC), using Directed Heating with Propane Torches

ABSTRACT: Japanese barberry (Berberis thunbergii DC) is a non-native shrub currently found in 31 states and four Canadian provinces. We examined the effectiveness of directed heating using 400,000 BTU backpack propane torches to control Japanese barberry infestations at two study areas in southern Connecticut. Each study area had eight 50-m × 50-m plots. Treatment combinations included a pre-leafout or post-leafout initial treatment with propane torches to reduce the size of established clumps and an early (late June), mid (early July), or late (late July) follow-up treatment to kill sprouts that developed from surviving root crowns. All treatment combinations were equally effective and reduced barberry abundance (a surrogate for cover) from 31% prior to treatment to only 0.5% the following autumn (i.e., a 98% reduction). All treatment combinations were also equally effective in reducing the size of surviving barberry to an average of only 11 cm compared with 74 cm for untreated clumps. Estimated labor costs using propane torches for both initial and follow-up treatment was 2.5 hr/ha for every 1% pretreatment abundance (e.g., 25 hr for a 1-ha stand with 10% abundance). Because timing of initial treatments (pre-leafout vs. post-leafout) and follow-up treatment (early, mid, late) were equally effective in reducing Japanese barberry abundance and height of surviving stems, initial treatments can be completed from March–June and follow-up treatments can be completed from June–August in southern New England. For habitat restoration projects on properties where herbicide use is restricted, directed heating with propane torches provides a non-chemical alternative that can effectively control invasive Japanese barberry.

A targeted immunomic approach identifies diagnostic antigens in the human pathogen Babesia microti

Babesia microti is a protozoan parasite responsible for the majority of reported cases of human babesiosis and a major risk to the blood supply. Laboratory screening of blood donors may help prevent transfusion‐transmitted babesiosis but there is no Food and Drug Administration–approved screening method yet available. Development of a sensitive, specific, and highly automated B. microti antibody assay for diagnosis of acute babesiosis and blood screening could have an important impact on decreasing the health burden of B. microti infection.