Recipient Organization
CONNECTICUT AGRICULTURAL EXPERIMENT STATION
PO BOX 1106
NEW HAVEN,CT 06504
Performing Department
Entomology
Non Technical Summary
The increasing prevalence of Lyme disease and emergence of other human tick-associated diseases in the United States has become a major public health concern. Western industrialized countries, including the United States, have also experienced a major resurgence of the common bed bug, Cimex lectularius. It is currently considered a serious building nuisance that feeds on humans. Ticks are nuisance pests, can cause severe toxic, allergic, reactions, and are vectors of numerous viruses, bacteria, protozoa that impact not only humans, but companion animals and domestic livestock. The lone star tick, Amblyomma americanum (L.), is the most common human biting tick in the southeastern United States with roughly 90-95% or more of ticks either collected from vegetation or reported attached to humans. This tick is an aggressive nuisance and associated with at least six human diseases, primarily ehrlichiosis. Populations of lone star ticks have increased in recent years, starting to move up into New York and New England and a new established population has been discovered along coastal Connecticut. This research will evaluate the distribution and risk from emerging lone star tick populations and determine if an emerging population can be controlled with host targeted 4-poster feeding stations that topically apply pesticide to white-tailed deer. The new isoxazoline oral canine tick and flea control products will be examined for their efficacy in controlling ticks on wild rodent hosts. Control of bed bugs is primarily based on intensive application of a limited number of insecticides, mainly pyrethroids, and resistance to these materials is increasing. Other control methods need to be explored. Xenointoxication is a method by which a host is treated to kill a parasite. We will examine the efficacy of ivermectin against feeding bed bugs. Ivermectin, which is on the World Health Organization's list of essential medicines, is one of the most effective and safe medicines for parasites in current use.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
The increasing prevalence of Lyme disease and emergence of other human tick-associated diseases in the United States has become a major public health concern. Ticks are nuisance pests, can cause severe toxic, allergic, reactions, and are vectors of numerous viruses, bacteria, protozoa that impact not only humans, but companion animals and domestic livestock. There are over 20 recognized human diseases or clinical conditions associated with ticks in the United States. The blacklegged tick, Ixodes scapularis Say, is the primary vector for at least seven pathogens that cause human disease. Since Lyme disease was first described in the 1970s, the number of reported human cases in the United States has steadily increased, largely due to the increased geographical range of the blacklegged tick and spread of B. burgdorferi. The actual incidence of human cases is estimated to be at least 10-fold over reported confirmed and suspected cases with »329,000 cases annually.While Lyme disease has been the impetus for recent research on tick ecology and management, the lone star tick, Amblyomma americanum (L.), is the most common human biting tick in the southeastern United States with roughly 90-95% or more of ticks either collected from vegetation or reported attached to humans. Previously considered primarily an aggressive nuisance, it is now associated with at least six human diseases. The diseases linked to A. americanum include ehrlichiosis, caused by Ehrlichia chaffeensis, E. ewingi, and the Panola Mountain Ehrlichia, southern tick-associated rash illness (STARI), red meat allergy, viral diseases caused by newly discovered Hartland virus and Bourbon virus, and likely tularemia and spotted fever rickettsiosis (Rickettsia rickettsii, possibly R. parkeri).Populations of lone star ticks have increased in recent years. Increased abundance, expansion, and human-biting activity of A. americanum has been linked to re-introduction, range expansion, and resurgent host populations, particularly white-tailed deer, Odocoileus virginianus (Zimmermann), eastern coyotes, Canis latrans (Say), and wild turkey, Meleagris gallopavo (L.). Along the Atlantic coast, its northern range extended to New Jersey, became established on the eastern end of Long Island and Fire Island, NY by the early 1990s, and possibly other parts of southern New York. The tick is either established or has been reported in 1,300 counties across 39 states, but based on the criteria used, reports along the northern range may or may not actually indicate an established reproducing population, but rather summer introductions. A population has long been abundant on Prudence Island, RI, and continues to be one of the most northern extensions of its established range. The tick is also becoming established on parts of Cape Cod, MA (Larry Dapsis, Extension Entomologist, Barnstable County, personal communication). The discovery of an established, reproducing population of lone star ticks on an island in Norwalk, CT in June 2017, the increasing submission of this tick by the public to the CAES Tick Testing Laboratory, and demonstrated overwinter survival of adult lone star ticks in Connecticut (KCS, unpublished data) have made the study and control of A. americanum increasingly relevant to Connecticut and New England. White-tailed deer, Odocoileus virginianus (Zimmermann) are a major host for the lone star tick, Amblyomma americanum L. The resurging population of deer in the twentieth century is linked to the emergence of multiple tick-borne pathogens associated with these and other tick species. White-tailed deer serve mainly as the host for the adult stage of these ticks, although immatures stages also feed on deer, and therefore, deer are a keystone species for the reproductive success and abundance of these ticks, similar to their role for the blacklegged tick. White-tailed deer are important reservoirs for E. chaffeensis and E. ewingii.A wide variety of prevention and control strategies have been used or investigated to reduce human exposure to ticks, reduce tick abundance, or the prevalence of tick-borne pathogens in the tick vector. These include personal protection measures, habitat management, biological control (i.e., parasitoids and entomopathogenic fungi), host reduction or exclusion, host-targeted acaricides, host-targeted vaccines, and anti-tick vaccines. There are numerous reasons for the lack of success in prevention and control of ticks and tick-borne diseases. The ecology and human exposure risk for enzootic transmission of tick-borne pathogens is complex and still not fully understood. With few exceptions (e.g., substantial reduction or elimination of white-tailed deer on geographically isolated areas and possibly the acaricidal treatment of deer), single intervention strategies are limited in duration or efficacy and often cannot address different vector life cycles, reservoir hosts, and human behavior and the area-wide application of synthetic chemical acaricides is becoming less acceptable. Host-targeted acaricides help address some of the environmental concerns from broadcast applications and is a proven approach suitable for the control of I. scapularis and A. americanum. Host-targeted acaricides intended for deer have achieved varying degrees of control. Dogs are also susceptible many of the same tick-borne diseases as humans. Canine Lyme disease vaccines are available and many products have been developed for canine flea and tick control, of which some like the isoxazolines, a new class of systemic oral ecto-parasiticides, may have other potential tick control applications.Starting in the late 1990's, western industrialized countries, including the United States, experienced a major resurgence of the highly reclusive human feeding Cimicid, the common bed bug, Cimex lectularius L. henceforth referred to as "bed bug(s)". It is currently considered a serious building nuisance that feeds on humans. It is not a known vector for human or other disease causing pathogens, but this blood-feeding insect is still considered a public health neusance, because of the psychological stress it causes. Social stigma, ignorance, reactive rather than proactive behaviors by the public, and lack of cooperation provide a cultural environment in which bed bugs thrive. Current distribution data is saturated. Except for a few isolated regions in the world, the insect is now ubiquitous. The Connecticut Agricultural Experiment Station (CAES) Insect Inquiry Office has also seen a thousand-fold increase in bed bug inquiries since 1996. In 2017, they represented over 36% (n = 3,603) of the identifications performed by the office. High density housing with disproportionately high minority, elderly, handicapped, and disadvantaged populations experienced the most severe problems with bed bugs, because of the lack of resources. Wealthy demographics with resources quickly manage infestations and inhibit reporting. There can be exceptions, especially when architectural design favors insect harborage. In a number of private New England schools and higher education institutions with buildings that replicate old architectural styles such as Tudor and Cotswold, they contend with persistent bed bug infestations. This is due to elevated cracks, fissures, and imperfections in the design of the building interiors which the insects use.Objectives:To monitor new insular, emergent lone star tick, A. americanum, population in Connecticut and evaluate the 4-poster for the control of this tick.To determine if isoxazoline canine oral flea and tick control compounds can control I. scapularis on laboratory and wild mice for potential tick control for rodent reservoir hosts.To evaluate the efficacy of xenointoxication against bed bugs.
Project Methods
Objective 1. Collection of host-seeking ticks will be conducted by sweeping or dragging the vegetation with a cloth to generate quantitative estimates of tick population density and the use of CO2 traps, which are effective for A. americanum (but not I. scapularis). Tick sampling will be performed monthly through the nymph and adult seasons (early spring through early autumn). Collected ticks will be preserved in 80% ethanol and identified to species morphologically. Tick density per unit area (100 m2) will be estimated by dragging measured transects and the CO2 traps will provide a separate relative measure of tick numbers. A CO2 trap consists of a reservoir containing sublimating dry ice surrounded by tape to trap attracted ticks. The '4-Poster' passive topical treatment station or device (C.R. Daniels, Inc.) developed by the USDA consists of a central reservoir to hold whole kernel corn. A feeding trough at each end has two vertical paint rollers each, which are manually treated with the acaricide permethrin (10%) (Y-Tex '4-Poster' Tickicide, Cody, WY). Deer rub up against the rollers as they feed. Based on the experience with the plastic commercial version of the '4-Poster' in other studies, the deployment recommendation for the '4-Poster' is one station every 50 acres. Four '4-Posters' will be placed on the property (but up to 6 depending on usage) April or May through September, targeting all life-stages of A. americanum on white-tailed deer through the active tick season. We propose installing the '4-Posters' in Years 1-2 (2019, 2020, and 2021) of the study (already deployed in 2018) with the need for continued treatment determined after the third year of treatment based on tick population assessments in 2021. Devices will be maintained and serviced with acaricide (permethrin) and corn approximately weekly, depending on usage, per label directions. Objective 2. The experiment will be carried out initially with C3H/HeJ mice for proof of concept, and then conducted with P. leucopus mice in subsequent trials. Afoloxoner will be evaluated first, followed by fluralaner and sarolaner, depending on availability. For example, mice will be dosed at 4.4 mg/kg, the middle range of afoloxoner's dose per the drug's monograph. Mice are weighed prior to dosing, and the dosage is based on the mean weight of the mice. Mice will be administered afoloxoner or other isoxazolines orally by mixing ground tablets with peanut butter. This mixture is prepared on day of administration, and given ad libitum to mice in otherwise empty, individual cages so that they could be monitored to ensure ingestion. The day following drug administration, twenty I. scapularis nymphs are applied to the treated mice (n = 3 per rep) and control mice (n= 3 per rep). The mice were then placed in cages with open bottoms over water baths. The number of ticks that fell off immediately due to poor attachment and number of engorged ticks were tracked. The number of living engorged ticks was recorded over the following five days, until ticks ceased to fall from the mice. This entire process will be repeated at 12-14 days and 30 days post-initial drug administration in P. leucopus mice. Objective 3. A New Zealand White male rabbit weighing ~4.54 kg (10.00lb) will be subcutaneously injected using a small gauge needle into the left shoulder by our veterinarian as a single dose treatment before each of two tests. Ivermectin (1% sterile solution) (Noromectin®,Norbrook Laboratories, UK) will be the product used . For bed bug feedings, the rabbit has been trained to sit quietly on a handlers lap while the insects feed on his shaved left hip. Cimex lectularius L. specimens that will be used are descended from insects first collected in a New Haven, Connecticut apartment in 2009. For the tests, twelve populations of 10 males, 10 females, and 10 mixed instar nymphs will be placed into 55 x 25 mm (4 dram) glass vials containing a single piece of 10 x 40 mm card for perching. To keep stress low, vials will be populated with 30 fully sated insects seven days prior to each test and left undisturbed. During this period, populations will be monitored for health, formation of natural aggregation clusters called "refuges," and hunger onset. A 60 x 60mm square of sheer fabric will be secured over the vial mouth with an elastic band. When inverted, the card will slide to the vial mouth, allowing insects to feed through the fabric. When in confined space, C. lectularius specimens often jostle and compete for blood while some do not feed and others delay. Forty five minutes was found to be ample time to accommodate for these behaviors. Controls will be fed prior to injection of the rabbit at the beginning of each test.Sequential post-injection insect feedings in the two planned tests will be: Control (0), the injection, then 1, 6, 12, 24, 36, 48, 72, 96, 120, 144, and 168 hour feedings respectively. Test 1 will look for efficacy of ivermectin against C. lectularius for a duration of 45 days. The second test will include a breath test at day 14 to look for response to feeding cues, followed by two feedings at days 16 and 31. Observation duration will be 64 days. During Test 2, 0.5 mL of blood will be drawn from the rabbit's marginal ear vein by our veterinarian at 0, 6, 12, 24, 36, 48, and 72 hours. The blood will be immediately centrifuged at low speed, frozen to -52°C and shipped on dry ice to Case Western Reserve University Proteomics Core facility, Cleveland, Ohio for testing. Each blood sample will then be mixed with 500 microliters of 3:1 v/v methanol:acetonitrile, then vortexed for 20 seconds, and incubated at 4°C for 30 minutes. The solution will be centrifuged at 16,000g for 20 minutes. 500 microliters of supernatant produced will be transferred to a clean tube and speedvac'd to dryness. It will then reconstituted with 50 microliters of reconstitute solvent (0.5 mm ammonium formate, 0.1% formic acid in 50% methanol) and centrifuged at 16,000g for 20 minutes. Five microliters will then be used for high performance liquid chromatography (HPLC) and mass spectrometry (MS). A Thermo Scientific TSQ Quantum Ultra with HESI-II probe will be used, using ESI positive ionization mode, spray voltage of 3000V, capillary temperature of 200°C, vaporizer temperature of 300, sheath gas pressure of 40, Aux gas pressure 10, skimmer offset 10 V, SRM set up: Q1: 0.7 FWHM; Q3: 0.7 FWHM; Q2: 1.5 mTorr (Ar); scan width: 0.002 m/z, scan time at 0.02s for analysis of the reconstituted supernatant. Statistical data will be recorded as a numerical health rating system, tracking impact to the insects. The numerical interpretation of health will be (4) healthy - alert and active; (3) reactive - cognizant to stimuli without response; (2) immobile - not cognizant and lying on back with partial limb paralysis; (1) paralysis - not cognizant, on back with slight muscle twitch, and slow gut pulse; (0) dead or torpid. Chi-square analyses will be performed to examine morbidity and mortality efficacy of ivermectin against C. lectularius populations. Each time treated cohort will be compared to controls. There will be two sets of data. The first will be morbidity of each time treated cohort e. g. 1h, 6h, 12h etc. as "sick or healthy" compared to controls and the second, mortality, "dead or alive" compared to controls. The analysis takes into account the impact of Ivermectin against all stages of C. lectularius identifying peak efficacy periods of ivermectin against treated specimens in both experiments. Non-lethal effects will also be recorded.