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Effectiveness of an Aerial Application of Carbaryl in Controlling Ixodes dammini (Acari: Ixodidae) Adults in a High-Use Recreational Area in New Jersey
Abstract
Lyme disease risk reduction through the control of the principal tick vector, Ixodes dammini Spielman, Clifford, Piesman & Corwin, has become a major issue facing public health agencies in many endemic states. Where large tracts of land are involved, established methods of I. dammini control are impractical. An aerial application of carbaryl directed against fall populations of I. dammini adults resulted in 93.8% control after 96 h. Control persisted through the following spring. The usefulness of aerial applications may be limited to areas where logistic constraints obviate the use of conventional ground applications.
... CARBARYL IS A BROAD-SPECTRUM carbamate pesticide that has been used to control various ectoparasites of animals and humans (Schulze et al. 1992, Hoelscher et al. 1994, Burridge et al. 2002, Downs et al. 2002). An early study in Australia demonstrated that carbaryl was highly effective in controlling the southern cattle tick, Boophilus microplus (Canestrini) (Roulston et al. 1965). ...
... This acaricide has been widely used to control B. microplus in many countries, including Rhodesia, India, Jamaica, New Caledonia, and Indonesia (Rawlins and Mansingh 1980, Sharma and Gupta 1982, Brun et al. 1984, Basu and Halder 1994, as well as the blue tick, Boophilus decoloratus (Koch) infesting cattle (Matthewson and Wilson 1976). It also has been used to control ticks that infest dogs (Pathak and Gaur 1985) and other tick species of medical importance, including the blacklegged tick, Ixodes scapularis Say, the vector of the disease agent that causes Lyme disease (Stafford 1991(Stafford , 1997Schulze et al. 1992). ...
Susceptibility to carbaryl in six Mexican strains of the southern cattle tick, Boophilus microplus (Canestrini), was evaluated with the Food and Agricultural Organization larval packet test. Tick strains from the cattle fever tick quarantine zone in Texas were more susceptible to carbaryl than to coumaphos or diazinon. Compared with the susceptible reference (Gonzalez) strain, Mexican tick strains demonstrated 10.9-59.5-fold resistance to carbaryl. Significant cross-resistance was found between carbaryl and the organophosphate acaricides coumaphos and diazinon. Bioassay results with synergists suggested that metabolic detoxification mechanisms did not play a major role in carbaryl resistance. Resistance to carbaryl was likely conferred by insensitive acetylcholinesterase. The implications of carbaryl resistance in tick eradication and control also are discussed.
... Several studies have identified a positive association between DIN and human incidence [39][40][41][42], although the strength of this association varies spatially [43]. Recreational areas have been identified as high risk environments for exposure to infected ticks [44][45][46][47][48], particularly at woodland-lawn ecotones where tick densities are often the greatest [44,49]. In suburban residential yards, frequently cited risk factors for the acarological hazard include proximity to woodland, lack of fencing, log and brush piles in the yard, bird-feeders and pet ownership [42,44,[50][51][52], all of which may enhance the number of hosts and tick off-host survival. ...
Background
The incidence of tick-borne disease has increased dramatically in recent decades, with urban areas increasingly recognized as high-risk environments for exposure to infected ticks. Green spaces may play a key role in facilitating the invasion of ticks, hosts and pathogens into residential areas, particularly where they connect residential yards with larger natural areas (e.g. parks). However, the factors mediating tick distribution across heterogeneous urban landscapes remain poorly characterized.
Methods
Using generalized linear models in a multimodel inference framework, we determined the residential yard- and local landscape-level features associated with the presence of three tick species of current and growing public health importance in residential yards across Staten Island, a borough of New York City, in the state of New York, USA.
Results
The amount and configuration of canopy cover immediately surrounding residential yards was found to strongly predict the presence of Ixodes scapularis and Amblyomma americanum, but not that of Haemaphysalis longicornis. Within yards, we found a protective effect of fencing against I. scapularis and A. americanum, but not against H. longicornis. For all species, the presence of log and brush piles strongly increased the odds of finding ticks in yards.
Conclusions
The results highlight a considerable risk of tick exposure in residential yards in Staten Island and identify both yard- and landscape-level features associated with their distribution. In particular, the significance of log and brush piles for all three species supports recommendations for yard management as a means of reducing contact with ticks.
Graphical Abstract
... For example, in the Mid-Atlantic and Northeastern United States, peridomestic exposure to I. scapularis likely occurs frequently (Falco and Fish 1988, Maupin et al. 1991, Klein et al. 1996, Connally et al. 2006, Feldman et al. 2015, whereas in the North-Central United States, recreational exposures are believed to be more common than peridomestic exposures Kazmierczak 1997, Paskewitz et al. 2001). Regardless of geographic region, previous studies have demonstrated a risk of human exposure to infected host-seeking I. scapularis nymphs in recreational settings (Falco and Fish 1989, Schulze et al. 1992, Oliver and Howard 1998, Paskewitz et al. 2001, Han et al. 2014, Prusinski et al. 2014, Ford et al. 2015. National parks are popular recreation destinations and may represent areas of elevated acarological risk, yet one cannot adequately infer the risk of tick-borne disease for park visitors or employees from the epidemiological surveillance conducted at the county spatial scale (Eisen et al. 2013). ...
Tick-borne pathogens transmitted by Ixodes scapularis Say (Acari: Ixodidae), also known as the deer tick or blacklegged tick, are increasing in incidence and geographic distribution in the United States. We examined the risk of tick-borne disease exposure in 9 national parks across six Northeastern and Mid-Atlantic States and the District of Columbia in 2014 and 2015. To assess the recreational risk to park visitors, we sampled for ticks along frequently used trails and calculated the density of I. scapularis nymphs (DON) and the density of infected nymphs (DIN). We determined the nymphal infection prevalence of I. scapularis with a suite of tick-borne pathogens including Borrelia burgdorferi, Borrelia miyamotoi, Anaplasma phagocytophilum, and Babesia microti Ixodes scapularis nymphs were found in all national park units; DON ranged from 0.40 to 13.73 nymphs per 100 m(2) Borrelia burgdorferi, the causative agent of Lyme disease, was found at all sites where I. scapularis was documented; DIN with B. burgdorferi ranged from 0.06 to 5.71 nymphs per 100 m(2) Borrelia miyamotoi and A. phagocytophilum were documented at 60% and 70% of the parks, respectively, while Ba. microti occurred at just 20% of the parks. Ixodes scapularis is well established across much of the Northeastern and Mid-Atlantic States, and our results are generally consistent with previous studies conducted near the areas we sampled. Newly established I. scapularis populations were documented in two locations: Washington, D.C. (Rock Creek Park) and Greene County, Virginia (Shenandoah National Park). This research demonstrates the potential risk of tick-borne pathogen exposure in national parks and can be used to educate park visitors about the importance of preventative actions to minimize tick exposure.
... A seminal study in New Jersey woodlands demonstrated !97% reduction in the abundance of host-seeking seeking I. scapularis adults 3 d after high-pressure spray application of formulations containing carbaryl or diazinon (Schulze et al. 1987). This was followed by a series of studies in New Jersey demonstrating reduced infestation by I. scapularis immatures on white-footed mice after granular application of carbaryl (62-100% control depending amount of carbaryl applied per ha), diazinon (54%), and chlorpyrifos (81%); and 94% reduction in host-seeking adults 4 d after aerial spray application of carbaryl (Schulze et al. 1991(Schulze et al. , 1992(Schulze et al. , 1994. Moreover, a laboratory study demonstrated that I. scapularis immatures were susceptible to carbaryl and three pyrethroids: cyfluthrin, esfenvalerate, and permethrin (Maupin and Piesman 1994). ...
In the 1980s, the blacklegged tick, Ixodes scapularis Say, and rodents were recognized as the principal vector and reservoir hosts of the Lyme disease spirochete Borrelia burgdorferi in the eastern United States, and deer were incriminated as principal hosts for I. scapularis adults. These realizations led to pioneering studies aiming to reduce the risk for transmission of B. burgdorferi to humans by attacking host-seeking ticks with acaricides, interrupting the enzootic transmission cycle by killing immatures infesting rodent reservoirs by means of acaricide-treated nesting material, or reducing deer abundance to suppress tick numbers. We review the progress over the past three decades in the fields of: 1) prevention of human-tick contact with repellents and permethrin-treated clothing, and 2) suppression of I. scapularis and disruption of enzootic B. burgdorferi transmission with environmentally based control methods. Personal protective measures include synthetic and natural product-based repellents that can be applied to skin and clothing, permethrin sprays for clothing and gear, and permethrin-treated clothing. A wide variety of approaches and products to suppress I. scapularis or disrupt enzootic B. burgdorferi transmission have emerged and been evaluated in field trials. Application of synthetic chemical acaricides is a robust method to suppress host-seeking I. scapularis ticks within a treated area for at least 6-8 wk. Natural product-based acaricides or entomopathogenic fungi have emerged as alternatives to kill host-seeking ticks for homeowners who are unwilling to use synthetic chemical acaricides. However, as compared with synthetic chemical acaricides, these approaches appear less robust in terms of both their killing efficacy and persistence. Use of rodent-targeted topical acaricides represents an alternative for homeowners opposed to open distribution of acaricides to the ground and vegetation on their properties. This host-targeted approach also provides the benefit of the intervention impacting the entire rodent home range. Rodent-targeted oral vaccines against B. burgdorferi and a rodent-targeted antibiotic bait have been evaluated in laboratory and field trials but are not yet commercially available. Targeting of deer-via deer reduction or treatment of deer with topical acaricides-can provide area-wide suppression of host-seeking I. scapularis These two deer-targeted approaches combine great potential for protection that impacts the entire landscape with severe problems relating to public acceptance or implementation logistics. Integrated use of two or more methods has unfortunately been evaluated in very few published studies, but additional field evaluations of integrated tick and pathogen strategies are underway.
... Those products act against free-living stages of ticks when they are applied to vegetation layers, acting over determinate stages depending on the tick species and the season. In many cases, the fumigation of the vegetation has shown to be effective for tick population reduction and the potential reduction for human/tick encounters in high-risk areas (Stafford, 1991;Schulze et al., 1992;1994;2005;Piesman and Eisen, 2008). This technique has been referred in public health programs (Korenberg and Kovalevskii, 1999) but deworming of animals is more common to control tick populations Walker, 2011;Ahoussou et al., 2010). ...
Ticks are obligate haematophagous arthropods present all over the world able to produce human diseases . Several factors have increased the abundance, circu lation and distribution of the pathogens transmitte d by ticks, contributing to the change in the vector-bor ne diseases epidemiology in the last years. This re view collects the most important measures for the preven tion and prophylaxis of tick-borne diseases. The pr eexposition measures to avoid tick-borne diseases ar e based on the prevention of tick bites by avoiding tickinfested areas, using of protective clothing, repel lents and controlling tick populations by physical, mechanical, biological and chemical methods. It is also reviewed other measures as the utility of educational programs and the use of human vaccines. On the other hand, we also review some key aspects referred to the measures to carry out after tick bi tes as how to remove a tick correctly and the utili ty of making an antibiotic prophylaxis.
... Given the 2year life cycle of I. scapularis, we would not have anticipated an effect on nymphs or fall adults from the initial 2004 application until 2006. Unlike earlier studies using carbaryl and diazinon (Schulze et al. 1987(Schulze et al. , 1992, these results suggest that deltamethrin may also have affected imma- Table 1. Fall abundance of host-seeking adult Ixodes scapularis at deltamethrin-treated and untreated plots, Wayside Training Area, October-November, 2004-06. ...
Spring acaricide applications directed against nymphal Ixodes scapularis have been shown to be effective, but are perceived by the public as having significant adverse environmental impacts, particularly against nontarget organisms. Targeting the adult stage of I. scapularis in the fall would hypothetically result in indirect control of subsequent subadult stages while avoiding other arthropods that are typically inactive during this period. We demonstrate that single fall applications of deltamethrin for 3 consecutive years immediately reduced fall questing adults, while also rapidly reducing the abundance of all postembryonic stages. Deltamethrin applied to the shrub-layer vegetation resulted in levels of control between 97.1% and 100% at 7 days postapplication. Repeated applications against the reproductive stage of I. scapularis progressively reduced the abundance of larvae and nymphs in treated plots, reaching 91.4% and 100% by the conclusion of the study.
... A variety of methods have been suggested or explored to reduce the risk of humans and livestock contracting these and other tickborne diseases by controlling the tick vectors (Barnard et al. 1989, Jaenson et al. 1991, Barbour and Fish 1993, Schmidtmann 1994. These methods include biological control (Spickett 1987, Hu et al. 1993, area chemical application (Mount 1983;Schulze et al. 1987Schulze et al. , 1992Schulze et al. , 1994Stafford 1991a;Solberg et al. 1992;Curran et al. 1993), pesticide treatment of small mammals (Sonenshine and Haines 1985;Deblinger and Rimmer 1991;Stafford 1991bStafford , 1992, habitat modiÞcation (Hoch et al. 1972, Barnard 1986, Wilson 1986), reduction in host availability (Wilson et al. 1988b, Adler et al. 1992, Daniels et al. 1993, Deblinger et al. 1993, Stafford 1993, Duffy et al. 1994, Daniels and Fish 1995, and integrated pest management (IPM) strategies (Hoch et al. 1971a(Hoch et al. , 1971bBloemer et al. 1990). However, few studies have sought to control free-living tick populations by acaricide treatment of large wild animal hosts (Duncan and Monks 1992), including whitetailed deer (Miller et al. 1989, Pound et al. 1996, Sonenshine et al. 1996. ...
A '4-poster' device that attracts white-tailed deer to a bait source, and as they feed, allows a self-application of a pesticide to the head, ears, and neck to control ticks was designed, constructed, and tested. The device consists of a central bin containing bait to attract deer and two feeding and application stations. These stations each have one bait port and two vertical pesticide-impregnated applicator rollers. This design allows unrestricted vertical retraction of the head to minimize injury to the deer or damage to the posts supporting the pesticide application rollers. Observations using deer demonstrated ready acceptance and repeated use by both antlered and antlerless deer. Results of an initial trial indicate that control values for lone star ticks, Amblyomma americanum (L.), exceeded 92-97% on deer that used the device regularly.
... ADULT TICKS HAVE been collected to address various research objectives, including determining rates of infection (Magnarelli et al. 1986;Schulze et al. 1986; Bartholomew et al. 1992;Amerasinghe and Scott 1993;Rawlings and Teltow 1994;Walker et al. 1994;1996), level of control (Wilson 1986;Schulze et al. 1987Schulze et al. , 1992, and/or geographical distribution/risk assessment (Schulze et al. 1984(Schulze et al. , 1991(Schulze et al. , 1998Fish 1988, 1989;Smith et al. 1990;Maupin et al. 1991;Jordan 1996a, 1996b). Adult ticks have been collected by a variety of techniques, including collection from hosts, CO 2 -baited traps, and walking surveys, but dragging seems to be the most commonly used method and provides data for a greater land area per unit effort (Falco and Fish 1989). ...
The ability of Ixodes scapularis Say and Amblyomma americanum (L.) to remain on drags, once acquired, was tested in sparse and dense shrub layer vegetation. When placed on bottoms of drags, adults of both species remained attached for distances three to four times greater in sparse vegetation compared with dense vegetation. When attached to the tops of drags, the differences in retention of ticks on drags between vegetation densities were significant only for A. americanum. In dense vegetation, drags should be checked at 10-m intervals, whereas in sparse vegetation this distance can be extended to 20 m without significant loss of acquired ticks.
... A recombinant vaccine was approved by the FDA in 1998 with the caveat that its long-term safety should be studied. 27 The vaccine induced high titers of antibodies to B. burgdorferi, which bind to and kill spirochetes; furthermore, these antibodies sterilized the midgut of ticks that fed on vaccinated individuals. 4,9,28 Three injections were needed before the transmission season to ensure efficacy and optimum antibody levels. ...
Lyme disease (borreliosis) incidence continues to increase despite a growing knowledge of primary and secondary prevention strategies. Primary prevention aims to reduce the risk of tick exposure and thereby decrease the incidence of new Lyme disease cases. Secondary prevention targets the development of disease or reduces disease severity among people who have been bitten by infected ticks. Numerous prevention strategies are available, and although they vary in cost, acceptability and effectiveness, uptake has been universally poor. Research in areas where Lyme disease is endemic has demonstrated that despite adequate knowledge about its symptoms and transmission, many people do not perform behaviors to reduce their risk of infection. New prevention strategies should aim to increase people's confidence in their ability to carry out preventive behaviors, raise awareness of desirable outcomes, and aid in the realization that the necessary skills and resources are available for preventive measures to be taken. In this article we evaluate the prevention and treatment strategies for Lyme disease, and discuss how these strategies can be implemented effectively. As many patients with Lyme disease develop arthritis and are referred to rheumatologists it is important that these health-care providers can educate patients about disease-prevention strategies.
... Mice are free ranging and elimination of the deer population pits the values of conservationists against public health advocates. Application of host and habitat acaricide is also effective but only in the short term and has unknown long-term consequences (Mather, Duffy, & Campbell, 1993;Pound, Miller, George, & Lemeilleur, 2000;Schulze, McDevitt, Parkin, & Shisler, 1987;Schulze, Taylor, Jordan, Bosler, & Shisler, 1991;Schulze, Taylor, Vasvary, Simmons, & Jordan, 1992). Pharmacological strategies are currently limited to treating presumed infection with a single dose of 200mg of doxycycline given within 72 hours after an I. Scapularis tick bite (Nadelman et al., 2001). ...
To evaluate a theory-based educational program to prevent Lyme disease and other tick-borne illnesses (TBI), a randomized controlled trial of an educational program was delivered to ferry passengers traveling to an endemic area in southeastern Massachusetts. Rates of TBI and precautionary and tick check behaviors were measured over three summers in 30,164 passengers. There were lower rates of TBI among participants receiving TBI education compared with control participants receiving bicycle safety education (relative risk [RR] = 0.79) and a 60% reduction in risk among those receiving TBI education who visited Nantucket Island for more than 2 weeks compared to control participants (RR = 0.41, 95% confidence intervals = 0.18 to 0.95, p < .038). TBI-educated participants were also significantly more likely to take precautions (use repellent, protective clothing, limit time in tick areas) and check themselves for ticks. The study demonstrates that a theory-based Lyme disease prevention program can increase precautionary behavior and result in a significant reduction in TBI.
... Conventional habitat-targeted acaricide applications have been shown to be an effective and reliable method for suppressing populations of Ixodes scapularis Say (Acari: Ixodidae), the principal vector of the causative agents of Lyme disease, human granulocytic anaplasmosis, and human babesiois in the northeastern United States (Schulze et al. 1987(Schulze et al. , 1991(Schulze et al. , 1992(Schulze et al. , 1994(Schulze et al. , 2000(Schulze et al. , 2001bStafford 1991;Solberg et al. 1992;Curran et al. 1993). But a recent poll of nearly 1,200 households within a New Jersey Lyme disease endemic area revealed that Ͻ25% of residents used acaricides on their properties to control ticks (T.L.S., unpublished data). ...
In fall 2003, we began testing an integrated control strategy to rapidly achieve and sustain reduced numbers of Ixodes scapularis Say (Acari: Ixodidae) in a residential area. We combined two host-targeted technologies in conjunction with single, barrier acaricide applications to sequentially attack each postembryonic life stage of the tick. Granular deltamethrin applied to the lawn-forest interface of participant properties resulted in 100% control of host-seeking nymphs. Nymphal and larval tick burdens on targeted small mammal hosts at treated properties were reduced by 92.7 and 95.4%, respectively, after the first year (2004) of combined interventions. Over the same period, populations of host-seeking nymphs, larvae, and adults were reduced by 58.5, 24.8, and 77.8%, respectively. After interventions in 2005, tick burdens on small mammals were maintained at similar levels, whereas control of host-seeking nymphs, larvae, and adults increased to 94.3, 90.6, and 87.3%, respectively. Prospects for widespread use of these technologies to protect the public's health are discussed.
... In the past, chemical acaricides were successfully used against Ixodes scapularis adults (Schulze et al., 1987(Schulze et al., , 1992 and nymphs (Schulze et al., 1991(Schulze et al., , 1994(Schulze et al., , 2000(Schulze et al., , 2001Stafford, 1991;Curran et al., 1993). However, such an approach comprises several problems, including the development of resistance against the chemicals, undesirable effects on the environment, possible toxic effects on users, and high costs. ...
In Central Europe, Lyme disease and tick-borne encephalitis (TBE) are transmitted by the tick Ixodes ricinus. In the last years, the prevalence of TBE virus in I. ricinus and also the number of human TBE infections have increased considerably in south-western Germany. A similar development is presumed for Borrelia burgdorferi s.l. For biocontrol of the vector I. ricinus, several options are presently evaluated. Among potential biocontrol agents, entomopathogenic fungi, nematodes, and parasitic wasps are the most promising candidates. In first laboratory experiments, different strains of the fungi Metarhizium anisopliae (five strains), Beauveria bassiana (three strains), and Paecilomyces fumosoroseus (two strains) were tested by placing I. ricinus larvae (fed and unfed) and nymphs (fed and unfed) in Petri dishes with filter paper soaked with conidial or blastospore suspensions (2.4x10(3) to 9.6x10(6)percm(2)). Ticks were exposed to the different fungi for at least 35 days in the dark at temperatures of 21-24 degrees C. The best LT(50) values for unfed larvae (14 days) and unfed nymphs (21 days) were obtained with blastospores of M. anisopliae 97 at 1.4x10(6)percm(2). In order to evaluate the potential of entomopathogenic nematodes, the efficacies of three different species, Steinernema carpocapsae, S. feltiae, and Heterorhabditis bacteriophora, were investigated in the laboratory. I. ricinus nymphs (fed and unfed) and unfed females were placed in Petri dishes containing a wet filter paper with 300 and 600 infective nematode larvae per cm(2). Ticks were exposed to the nematodes for at least 15 days in the dark at an average temperature of 25 degrees C. The highest mortality was observed in unfed female ticks treated with S. carpocapsae. Results show that among the fungi tested the most promising control efficacy was obtained with two isolates of M. anisopliae, whereas S. carpocapsae was most successful among the nematodes tested against I. ricinus.
Few documented control strategies exist for the invasive tick, Haemaphysalis longicornis, despite its potential to reach extremely high numbers and vector human and animal pathogens. In 2020, we evaluated the effects of single applications of five granular and liquid acaricides on H. longicornis in a public park in northern New Jersey. Acaricides tested included pyrethroids (lambda-cyhalothrin, bifenthrin), a carbamate (carbaryl), and the insect growth regulators (IGRs) pyriproxyfen and novaluron. We also monitored the impact of each treatment on non-target soil and above-ground invertebrate species using pitfall and sticky traps, respectively. We recorded over 70,000 H. longicornis ticks in the study area from July to October 2020. An average of 99% control was achieved with lambda-cyhalothrin spray and 95% with granular bifenthrin. In contrast, granular carbaryl did not significantly reduce any life stages of H. longicornis. The IGR (pyriproxyfen/novaluron) resulted in a significant 45% reduction of the larval stage following treatments in July. No other stages were significantly impacted by pyriproxyfen alone or in combination with novaluron. Analysis of non-target species revealed that the community composition of soil-dwelling arthropods was strongly impacted by pyrethroid treatments and, to a lesser extent, by the carbamate treatment. The granular pyrethroid bifenthrin had more pronounced effects and impacted a broader range of non-target groups in the pitfall traps than the liquid pyrethroid lambda-cyhalothrin. Arthropod groups that were negatively impacted included Isopoda, Formicidae, Coleoptera, Araneae, Acari, and Grylloidea. Collembola numbers, however, were elevated in both pyrethroid treatments. The community composition of arthropods collected on the above-ground sticky traps was strongly impacted only in the liquid lambda-cyhalothrin treatment. The primary groups impacted in the sticky trap analysis were Collembola and Hemiptera. Community composition in traps remained distinct in the pyrethroid treatments through the entire survey period up to 62 days post-treatment. The results of this study indicate that pyrethroid acaricides were highly effective at controlling H. longicornis, while other compounds, including carbaryl and IGRs, did not achieve consistent levels of control. Further research is needed to find effective and environmentally sustainable alternatives. Integrated management programs can include the judicious use of pyrethroids to control H. longicornis.
In April, 1994, a workshop was held in Lincoln, Nebraska, to update the IPM document that resulted from a similar workshop in Manhattan, Kansas, in 1979 (Anonymous 1979). The workshop was initiated by Dr. Ralph A. Bram, USDA National Program Leader, and organized by Drs. Gustav D. Thomas, USDA-ARS, Lincoln, and John B. Campbell, University of Nebraska, North Platte. Participants were charged with assessing the current status of IPM programs for pests of veterinary importance, identifying needs for program improvements, and recommending future research and extension priorities. Participants, invited from federal and state government research and extension organizations, and the private sector, from the U.S. and Canada, were selected because of their expertise in various sectors of the field of veterinary entomology.
IPM needs of eight animal commodity groups were addressed at the Lincoln workshop: 1) poultry; 2) dairy cattle; 3) range beef cattle; 4) confined beef cattle; 5) swine; 6) sheep and goats 7) horses; and 8) dogs and cats. A subcommittee representing each commodity group prepared the chapters contained in the report. Formats vary somewhat from one chapter to another according to the subcommittees' needs, however each chapter contains an overall summary at the beginning, followed by a discussion of the major pests, research and extension needs, and issues pertaining to the animal group. The texts for these chapters were originally prepared in 1995 and updated in 2000-2001.
References
Anonymous. 1979. Proceedings of a Workshop on Livestock Pest Management: To Assess National Research and Extension Needs for Integrated Pest Management of Insects, Ticks, and Mites Affecting Livestock and Poultry, March 5 7, 1979, Kansas State University, Manhattan, Kansas. USDA, 322pp.
West Nile virus (WNV) was detected in the metropolitan New York City (NYC) area during the summer and fall of 1999. Sixty-two human cases, including seven fatalities, were documented. The New York State Department of Health (NYSDOH) initiated and implemented a statewide mosquito and WNV surveillance system. We developed a WNV response plan designed to provide local health departments (LHD) a standardized means to begin to assess basic mosquito population data and to detect WNV circulation in mosquito populations. During the 2000 arbovirus surveillance season, local health agencies collected 317,676 mosquitoes and submitted 9,952 pools for virus testing. NYSDOH polymerase chain reaction (PCR) testing detected 363 WNV-positive pools. Eight species of mosquitoes were found to be infected. Of the 26 counties conducting mosquito surveillance, WNV-positive mosquitoes were detected only in NYC, on Long Island, and in four counties in the lower Hudson River valley region. LHD larval surveillance provided initial or enhanced mosquito habitat location and characterization and mosquito species documentation. Adult mosquito surveillance provided LHD information on species' presence, density, seasonal fluctuations, virus infection, minimum infection ratios (MIR) and indirect data on mosquito control efficacy after larval or adult control interventions. Collective surveillance activities conducted during 1999 and 2000 suggest that WNV has dispersed throughout the state and may affect local health jurisdictions within NYS, adjacent states, and Canada in future years. Vector surveillance will remain a critical component of LHD programs addressing public health concerns related to WNV.
Lyme disease is the most common tick borne disease and is caused by Borrelia burgdorferi sensu lato. Ticks of the genus Ixodes are the vectors that transmit the infection to host mammals in endemic foci. Ixodes is infected by Borrelia at larval stage when it feeds on infected mammals. Man is an occasional host. The infection risk is linked to interaction between human and the natural environment. Strategies for prevention are closely related to the enzootic cycle of the Ixodes tick. Environmental measures to reduced tick density or host mammals are expensive, need to be repeated annually and cannot be applied to large areas. The primary prevention could be reduced to personal preventive measures such as reducing the amount of exposed skin and frequent checking for ticks. The risk of Lyme disease transmission after a tick bite is relatively low, and remains under 4%. The transmission rate depends on the duration of feeding. A rapide tick removal with fine tweezers or preferably special forceps and disinfection of the bite site appear to be the best technique. The absence of scientific evidence, and the risk of adverse events does not lead to recommending antimicrobial prophylaxis. Follow-up and educating the patients on the disease, clinical manifestation, and later primary prevention should be undertaken.
Ixodes scapularis Say adults, nymphs, and larvae were treated with the entomopathogenic fungus Metarhizium anisopliae in a combination of field and laboratory experiments to assess sublethal effects of the fungus on I. scapularis fecundity and body mass. Postengorgement and egg mass weights were 33 and 50% lower, respectively, in adult females treated with M. ansiopliae in the field before engorging on laboratory rabbits. M. anisopliae did not significantly reduce egg mass weight, conversion efficiency, or oviposition period in I. scapularis females treated with the fungus after engorging on white-tailed deer, although only 33% of treated females oviposited. Engorged nymphs and larvae treated with M. anisopliae converted significantly lower percentages of their engorged weight to their molted adult and nymphal weights. This study indicates that M. anisopliae reduces fitness (fecundity and body mass) in all active I. scapularis stages and indicates that its impact as a biocontrol agent might be higher than that suggested by direct mortality alone.
This series of articles describes the first large-scale experiment designed to explore the efficacy of reducing the risk of tick-borne disease in highly endemic communities of the northeastern and Mid-Atlantic United States through deployment of a self-application device that treats white-tailed deer with acaricide to prevent feeding by adult Ixodes scapularis ticks and all stages of Amblyomma americanum ticks where both species occur. The results of the multicenter study are reported in the accompanying articles in this issue. This article describes the background and rationale for this experiment by reviewing relevant literature on current tick-borne disease epidemics and previous efforts to reduce the public health burden of Lyme disease and other tick-borne diseases.
Lyme disease was ranked second to acquired immune deficiency syndrome (AIDS) in the degree of public concern generated in USA, and is now recognized as a multi-focal pandemic. A cost-benefit study of drug treatment has been undertaken in USA because in endemic areas of Lyme disease the ratio of false positives, with non-specific myalgia and fatigue, to true positives was approximately 4:1. The Centers for Disease Control (CDC) Clinical Case Definition of Lyme Disease in the USA was devised as a means of epidemiological assessment. Ixodes dammini was the tick principally implicated in the early years of Lyme disease reporting in the eastern USA. Ixodid ticks including I .dammini have a life cycle in which feeding takes place three times, once by each of the three stages, each on a fresh host. The three stages (larvae, nymphs, and adults) complete the life cycle over a period of 2–6 years. The disease has three stages: (1) flu-like symptoms and localized erythema migrans (EM) and lymphocytoma, (2) weeks to months later, acute neurological, arthritic and/or cardiac symptoms, multiple EM lesions, and (3) months to years later, persistent or remitting for 6–12 months, arthritis and chronic neurological symptoms and other organ manifestations,. The first treatment regimes for Lyme disease were with penicillin but later trials have indicated that tetracyclines are more effective in the control of early symptoms.
Lyme disease or Lyme borreliosis, which is caused by three groups of the spirochete Borrelia burgdorferi, is transmitted in North America, Europe, and Asia by ticks of the Ixodes ricinus complex. The primary areas around the world that are now affected by Lyme disease are near the terminal moraine of the glaciers 15,000 years ago. The emergence of Lyme disease in the United States in this century is thought to have occurred because of ecological conditions favorable for deer. From 1982 through 1991, 40,195 cases occurring in 47 states were reported to the Centers for Disease Control, but enzootic cycles of B. burgdorferi have been identified in only 19 states. During the last several decades, the disease has spread to new areas and has caused focal outbreaks, including locations near Boston, New York, and Philadelphia. Lyme disease is like syphilis in its multisystem involvement, occurrence in stages, and mimicry of other diseases. Diagnosis of late neurologic abnormalities of the disorder has created the most difficulty. A recent phenomenon is that a number of poorly understood conditions, such as chronic fatigue syndrome or fibromyalgia, are misdiagnosed as "chronic Lyme disease." Part of the reason for misdiagnosis is due to problems associated with diagnostic tests. The various manifestations of Lyme disease can usually be treated successfully with oral doxycycline or amoxicillin, except for objective neurologic manifestations, which seem to require intravenous therapy. Vector control of thick-borne diseases has been difficult and, therefore, reduction of the risk of infection has been limited primarily to personal protection measures.
Four state parks located in Lyme disease endemic regions of Wisconsin were surveyed for the presence of Ixodes scapularis Say during May and June of 1998 by drag sampling along hiking trails. Nymphal abundance varied between parks, with the average number of nymphs encountered in 1 h ranging from 6.2 +/- 3.8-47.1 +/- 36.3 (mean +/- SD). Questing nymphs were tested for the presence of Borrelia burgdorferi by culture in BSK medium and 7-12% was found to be infected. The average risk of encountering an infected nymph (entomologic risk index) ranged from 0.5 to 5.2 infected nymphs per hour. The highest entomological risk index was recorded from a small island park in northwestern Wisconsin during the last week in May (8.0 infected nymphs per hour). These results indicate a lower risk for human Lyme disease exposure in Wisconsin state parks in comparison with highly endemic areas of the northeastern United States.
A single barrier application of granular deltamethrin to the woodland edges of a forested residential community in late spring significantly reduced the abundance of Ixodes scapularis Say nymphs. The application also suppressed the population of Amblyomma americanum (L.) nymphs, which recently became established in the study area. The efficacy of deltamethrin is compared with other commonly used acaricides.
The Healthy People 2010 public health goals targeted a 44% decrease in the incidence of Lyme disease, the most commonly reported tick-borne illness in the United States. To review Lyme disease prevention, clinical trials, epidemiological and experimental studies, and predictive models were evaluated. Geographic distribution of ixodid vectors and local landscape predict Lyme disease risk. Density of infected ticks correlates with incidence and prevalence of Lyme disease, but risk quantitation is made uncertain by tick aggregation and inability to predict tick-human interactions. Outdoor activities are inconsistently or weakly associated with risk, and most infections likely occur in residential areas during routine activities. Tick control (burning or removing vegetation, acaricide use, and deer elimination) reduces Ixodes scapularis populations by up to 94%, and acaricide application to wildlife decreases nymphal I scapularis populations by up to 83%. The effect of these strategies on incidence of Lyme disease in humans is unknown. Studies show that only 40% to 50% of adults take precautions against tick bites even when they are aware of Lyme disease. Effective protection afforded by personal precautions (wearing protective clothing, avoiding ticks, and using insect repellant) has not been shown prospectively. Antimicrobial prophylaxis of tick bites is not warranted. Clinical trials showed vaccines containing recombinant OspA of Borrelia burgdorferi to be efficacious and well tolerated. Currently, vaccination is the only empirically demonstrated method to prevent Lyme disease. The best evidence supports prevention efforts focused on practices that encourage immunization, Lyme disease awareness, and possibly treatment of deer.
Unfed adult Ixodes scapularis Say were treated with spores of the entomopathogenic fungus Metarhizium anisopliae Metschnikoff in the laboratory and in the field. An M. anisopliae suspension containing 4 x 10(9) spores per milliliter caused 96% mortality in the laboratory, versus 53% mortality among field-treated ticks. The LC50 value for unfed adult I. scapularis in the laboratory was 4 x 10(7) spores per milliliter. Our results indicate that M. anisopliae was highly pathogenic to unfed adult ticks and showed potential for controlling questing adult I scapularis.
We report an attempt by an offshore island community to control the vector tick of Lyme disease by providing ivermectin-treated corn to an isolated herd of free-ranging white-tailed deer, Odocoileus virginianus Zimmerman. Medicated corn was supplied in troughs within the island village and from automatic feeders at remote sites during 5 consecutive fall and spring adult tick questing seasons. Acaricide consumption was monitored by assaying its presence in fresh deer pellets and its concentration in deer sera. Its effectiveness was evaluated by recording the number of adult ticks collected from the hides of deer, the number of females becoming sufficiently engorged to oviposit, and the success of subsequent oviposition and eclosion. Entomologic risk was monitored by collecting immature ticks from hosts and adult ticks from vegetation. Estimates based on a subsequent deer reduction program indicated that up to twice as many deer had been present during the project as originally presumed. For this and other reasons related to deer behavior, target levels of serum ivermectin were achieved in a minority of deer. Nevertheless, > 90% control of female tick infestation, subsequent oviposition, and larval eclosion was obtained in those 8 of 16 sampled deer with serum ivermectin levels of > or = 15 ng/ml. In addition, the ratio of females to males, the numbers of females engorging > 10 mg body weight, and the numbers of those eventually hatching, were all significantly less among ticks from island deer in comparison with ticks from untreated deer. No consistent changes in the numbers of ticks found on immature-stage hosts or removed from vegetation were noted within 3 yr of the cessation of treatment.
A single application of granular carbaryl approaching the lowest recommended rate to the shrub layer of a forested area in late spring significantly reduced the abundance of Ixodes scapularis Say nymphs throughout their peak activity period, but had little effect on Amblyomma americanum L. nymphs. Factors influencing the efficacy of the application are discussed. The possible explanations for the lack of efficacy of granular carbaryl against A. americanum, including behavior, formulation, and application rate, are discussed.
Effectiveness of the entomopathogenic fungus Metarhizium anisopliae, for controlling nymphal Ixodes scapularis, was tested in laboratory and field trials. In the laboratory, M. anisopliae (Metschnikoff) Sorokin strain ESC1 was moderately pathogenic, with an LC50 of 10(7) spores/ml and induced 70% mortality at 10(9) spores/ml. In a field study, however, 10(9) spores/ml M. anisopliae did not effectively control questing I. scapularis nymphs, and significant differences were not detected in pre- and post-treatment densities. For nymphs collected and returned to the laboratory for observation, mortality was low in treatment groups, ranging from 20 to 36%. To assess whether a chemical acaricide would synergistically enhance pathogenicity of the fungus, we challenged unfed nymphal I. scapularis with combinations of M. anisopliae and permethrin, a relatively safe pyrethroid acaricide, in two separate bioassays. Significant interactions between M. anisopliae and permethrin were not observed, supporting neither synergism nor antagonism.
With the incidence of Lyme disease increasing throughout the United States, reducing risk of exposure to the disease is of the utmost concern. In the northeastern U.S., the blacklegged tick, Ixodes scapularis, is the primary vector and the white-footed mouse, (Peromyscus leucopus), the primary reservoir for Borrelia burgdorteri, the bacterium causing Lyme disease. Targeting I. scapularis engorging on white-footed mice with an effective biological control agent, such as the fungus Metarhizium anisopliae, could be an effective and relatively safe control technique. In 2002-2003, we performed laboratory and field experiments to determine whether M anisopliae-treated nesting material could effectively control larval I. scapularis ticks engorging on white-footed mice, and therefore reduce the number of infected nymphal I. scapularis questing the following summer. Our laboratory experiment demonstrated a strong negative effect of M. anisopliae-treated nesting material on survival of I. scapularis larvae feeding on P. leucopus, with 75% versus 35% larval mortality in treatment versus control nests. Our field trials caused only modest, localized reductions in nymphal abundance and had no effect on the proportion of nymphal I. scapularis infected with B. burgdorferi. Field results probably could be improved by increasing the density of nestboxes to allow fungal delivery to a higher proportion of the mouse population and by deploying nestboxes in an area with lower mammalian diversity, such as a suburban landscape.
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