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ARS Home » Plains Area » Kerrville, Texas » Knipling-Bushland U.S. Livestock Insects Research Laboratory » LAPRU » Research » Research Project #437205

Research Project: Year 2 CFTEP Funding - Modeling Treatment Strategies for Cattle-Nilgai-White-tailed Deer Interactions on South Texas Rangelands

Location: Livestock Arthropod Pests Research

Project Number: 3094-32000-042-40-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Jul 15, 2019
End Date: Jun 30, 2021

Objective:
Eradication of Cattle Fever Ticks (CFT) from infested rangelands in Texas has been made more complicated by involvement of alternate hosts including white-tailed deer (WTD) and nilgai antelope. In previous work, including the 2018 Omnibus Project Nilgai Modeling, we integrated a 3rd host, nilgai antelope, into a spatially explicit, individual based model previously designed with cattle and white-tailed deer and applied to CFT-infested south Texas rangeland landscape systems. The model was applied to evaluate the roles of nilagi antelope and white-tailed deer in distributing and sustaining CFT populations. The model has been vetted by peer review and now provides the platform to evaluate a number of critical system elements driving the spread of CFT, the population dynamics of CFT, and treatment options for tick suppression under a variety of multiple host species situations. This approach to assessing CFT eradication scenarios is expected to provide essential a priori guidance to optimal tactics, strategies, and operational decisions to the Cattle Fever Tick Eradication Program. Objectives include: 1) To determine the threshold efficacy of a product/delivery system needed within different population densities of nilgai antelope and/or white-tailed deer to achieve CFT eradication with and without cattle in the system, 2) To evaluate spatial distribution of treatment stations on product/treatment efficacy, 3) To evaluate the impact of wildlife population regulation on the dispersal and population dynamics of CFT eradication strategies, 4) To compare the influence of different spatial distributions of habitat types for cattle, WTD, nilgai and CFT on the risks of developing refuge populations of CFT, and 5) To identify strategies for CFT refuge identification and elimination.

Approach:
This project team will utilize previous treatment and efficacy data for products and delivery methods currently used and hypothetically considered for cattle fever tick (CFT) suppression on cattle and white-tailed deer (WTD), as well as data from ongoing studies of products/treatments for nilgai, but will apply these to spatial, temporal and species specific applications. The modeling efforts will be further informed by data being collected from the ongoing field project entitled Multi-source Data Collection to Enhance Predictive Modeling for the Control of Cattle Fever Ticks, other ongoing projects developing specific biological and chemical treatments of nilgai, and additional data on telemetry of nilgai movement. Our goal is to provide a meaningful tool and methods for a priori evaluations of treatment scenarios and information meaningful for operational assessments of current and future technological applications. The existing modeling platform will be used to integrate spatial data for landscape characteristics, host-animal movement and tick population dynamics. Model performance will be evaluated by comparing simulated population dynamics, movement patterns, and CFT loads on each host-type with independent sets of analogous field observations. The impacts of each host-type independently and collectively will be assessed by simulating the daily spatial/temporal dynamics of off-host larval CFT populations and the temporal dynamics of adult CFT on each host species over a time period of up to 4 years under a variety of tick suppression protocols and tactics. Each protocol will be simulated under a variety of assumptions regarding cattle stocking rates, WTD densities, nilgai densities, and environmental conditions of temperature, humidity and precipitation. The following data will provide the basis to analyze hypotheses under project objectives 1-4: 1) post-treatment off-host larval tick densities and distribution within the landscape to establish the threshold of suppression necessary at each ratio of host species, 2) cumulative number of days of co-occurrence among the 3 host species in each habitat cell within the landscape.