Research Programs and Projects at this Location : USDA ARS

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Research Project: Cattle Fever Tick Control and Eradication

Location: Livestock Arthropod Pests Research

2015 Annual Report

Objectives
Objective 1: Reduce the cost of pasture quarantine by developing new methods of treating cattle. Subobjective 1A: Evaluate the efficacy of novel long-acting (LA) acaricides for CFT control. Subobjective 1B: Detect tick infestation by non-invasive procedures. Objective 2: Evaluate efficacy of novel technologies for control of CFT and mitigation of acaricide resistance. Subobjective 2A: Evaluate natural products with acaricidal properties for tick control. Subobjective 2B: Evaluate natural products with repellent or attractant properties for tick control. Objective 3: Develop methods that decrease the impact of wildlife as CFT reservoirs. Subobjective 3A: Evaluate efficacy of anti-tick vaccine formulations for control of ticks on wildlife. Objective 4: Improve species distribution and ecological niche models of CFT species, and specify changes that may occur due to climate change. Subobjective 4A: Update and mine the historical CFT GIS database to produce maps and tools to support APHIS eradication efforts. Subobjective 4B: Assess effect of climate change predictions on recurring cycles of CFT outbreak activity.

Approach
Utilize our unique laboratory resources and infrastructure to evaluate new formulations of compounds for long-acting efficacy against strains of cattle fever ticks that are susceptible or resistant to commercially available acaricidal products. This effort will help prioritize efforts with stakeholder groups to deliver products the Cattle Fever Tick Eradication Program can use in the Permanent Quarantine Zone. Assess utility of non-invasive procedures, like near-infrared spectroscopy of livestock fecal samples, to detect cattle fever tick infestations. Finding non-invasive alternatives to hands-on inspection (scratching) offer the potential to streamline operations and enhance detection of infestations by Cattle Fever Tick Eradication Program personnel. Screen plant-derived substances to identify novel compounds that are active against cattle fever ticks. Research on natural products will enable the discovery of molecules that could be optimized for acaricidal efficacy. Determine immunogenicity in white-tailed deer of novel Bm86-based vaccine developed to vaccinate cattle in the Permanent Quarantine Zone. Confirming that the novel Bm86-based vaccine developed for cattle can also elicit a specific immune response against cattle fever ticks in white-tailed deer will provide a tool that could be used to minimize the impact of wildlife as tick reservoirs. Refine methods applied to cattle fever tick outbreaks using remote sensing technologies and models predicting habitat suitability and species distribution. The improvement of those methods could be used to develop science-based predictive tools the Cattle Fever Tick Eradication Program could use to adapt future strategies. Overall, the approaches described above aim to deliver science-based tools that the Cattle Fever Tick Eradication Program can integrate to adapt operations, mitigate the impact of global change, and keep the U.S. free of cattle fever ticks in a sustainable manner.

Progress Report
Objective 1. Field trial of moxidectin for use in the USDA APHIS VS Cattle Fever Tick Eradication Program (CFTEP). As a follow up of successful controlled efficacy experiments, ARS and APHIS jointly initiated a field trial on a private ranch in Texas. The premise selected was heavily infested with fever ticks (CFT), primarily the southern cattle fever tick Rhipicephalus (Boophilus) microplus. All cattle on the ranch received injections of the acaracide, or tickicide, at the start of the trial, with boosters applied at 60-day intervals. The cattle are also examined for tick infestations at the time of treatment. The trial is scheduled for one year. If this demonstration is successful the program will have an additional tool for preventing the spread of cattle fever from Mexico to the U.S. Objective 1. Completed 120-day stall test and field studies with a novel tickicide with a new mode of action in a long-acting injectable formulation to demonstrate efficacy against the southern cattle fever tick (R. microplus), the lone star tick (Amblyomma americanum), the winter tick (Dermacentor albipictus), and the cayenne tick (Amblyomma cajennense sensu lato). Results showed that this new tickicide under development by the cooperator has the potential to be used in the CFTEP against R. microplus. This proprietary novel tickicide formulation also controlled winter and cayenne tick cattle infestations. Objective 2A.1/2A.2. Laboratory studies were initiated to assess the tickicidal effects of: 1) limonene against the lone star tick; 2) jatropha oil against the southern cattle fever tick; and 3) two neem-based formulations against the southern cattle fever tick, lone star tick, and the winter tick. Proving their efficacy will advance these natural compounds to be candidates for further testing as alternatives to synthetic acaricides for sustainable tick control. Objective 2B. Laboratory studies were initiated to examine the repellent/attractive effects of: 1) limonene against the lone star tick; 2) jatropha oil against the southern cattle fever tick; 3) and two neem-based formulations against the southern cattle fever tick, lone star tick, and the winter tick. Documenting the repellency or attractiveness of these natural compounds will inform further testing for their strategic use to control ticks. Objective 2. A field study was started on two dairy farms, and one beef farm in Puerto Rico to investigate the tickicidal effect of veterinary products labeled for use in lactating cows, or beef cattle to control CFT. Products based on plant essential oils, substances derived from molecules produced by soil fungi, and a tick growth regulator were used strategically to attain high levels of CFT control on the three farms while mitigating pesticide safety risks. The products tested in this study are safer for workers to apply, and their integrated use according to label instructions promotes overall animal health and minimizes the risk for pesticide residues in animal products. Objective 3. Understanding the role of exotic nilgai antelope as CFT host is important because this situation complicates eradication efforts. The nilgai is a bovid game animal native to the Indian sub-continent that was introduced to Texas at the beginning of the 20th century and now ranges freely across the river between Mexico and the U.S. In 2014 a CFT outbreak was discovered in Cameron County Texas. It was suspected that the ticks had spread from Mexico into Texas carried by nilgai antelope. Between 9 October 2014 and 7 March 2015, we examined 200 hunter-culled nilgai. Many of the nilgai were lightly infested with Amblyomma ticks, which are common on deer and cattle in south Texas. Twelve of the 200 animals carried CFT. Ten of the twelve animals were lightly infested, with 1-8 ticks. Two of the nilgai were heavily infested. An animal taken on 24 December had 29 ticks of which 7 were replete females. An animal taken on 26 October had 71 ticks of which 62 were adults including 12 replete females. None of the nilgai were seropositive for Babesiosis. Objective 3. A knowledge gap exists on the movement of exotic nilgai antelope across the landscape affected by CFT outbreaks. A collaborative field study was initiated to study the movement of nilgai in south Texas using GPS satellite collars. Nilgai are CFT hosts and have relatively big home ranges, which could result in CFT dispersal beyond the Permanent Quarantine Zone. In partnership with Texas A&M Kingsville, the Texas Animal Health Commission, and the East Foundation, the ARS initiated a study at a ranch in Willacy County, which is north of the quarantine zone, where nilgai were fitted with a GPS collar to study their movement across the landscape. In general, most of the thirty GPS-collared nilgai have stayed near the study site in Willacy Co. Eight nilgai (7 cows and 1 bull) have moved off the property. Movements have been to the N or NW. None of the nilgai have moved into farmland, west of Highway 77, south of State Highway 186, or into the Laguna Madre. This study will continue for 2 years to document the movement of nilgai across the landscape through the seasons. Objective 3. A survey was completed at dairy farms in Puerto Rico to determine if the invasive mongoose, Herpestes javanicus, is a CFT host in that environment. Approximately 80 mongooses were captured in 2014 and examined for CFT. The external parasites collected from the mongooses were submitted to the USDA-APHIS National Veterinary Services Laboratory for identification. In 2014 no CFT were identified infesting mongooses collected at dairy farms in Puerto Rico. Another survey will be conducted in 2015. Objective 4. A geographic information system (GIS) database that incorporates location, collection, and infestation records for CFT infesting cattle and white-tailed deer (WTD) was regularly updated. This GIS CFT database was used to generate maps and other summary spatial data that is routinely utilized by the CFTEP to enforce eradication statutes.

Accomplishments

U.S. DEPARTMENT OF AGRICULTURE

Livestock Arthropod Pests Research: Kerrville, TX