IMMUNOLOGICAL AND ABIOTIC EFFECTS ON ECTOPARASITE POPULATION DYNAMICS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0213165
• Project Start Date: Dec 1, 2012
• Project End Date: Nov 30, 2017
• Program Code: [(N/A)]- (N/A)

Recipient Organization
WASHINGTON STATE UNIVERSITY
240 FRENCH ADMINISTRATION BLDG
PULLMAN,WA 99164-0001

Performing Department
Entomology

Non Technical Summary
BACKGROUND / NEED The Rocky Mountain Wood Tick (RMWT) is a common tick species in the western United States. The RMWT completes development by blood feeding on multiple species of animals (e.g. mice, rabbits and cattle). The tick transmits multiple pathogens of importance to human and animal health. One example is the pathogen of cattle, Anaplasma marginale, which causes morbidity and mortality for cattle and is economically costly to cattle producers. The density and distribution of RMWTs influences the transmission of A. marginale. Areas with more ticks experience higher rates of pathogen transmission among cattle. RATIONALE It is important to understand the factors that affect RMWT density/distribution in order to predict areas of risk for pathogen transmission. Currently the factors that control RMWT populations are poorly understood. Research in other tick systems suggests that host animals can acquire immunological resistance to tick blood feeding that impairs tick survival and fecundity. This natural anti-tick resistance may be an important factor controlling tick density and distribution. METHODS Ticks will be blood fed on hosts in the lab to control the history of tick exposure among the host animals. The recovered ticks will be placed in field enclosures to develop and oviposit. The success of development and reproduction will be compared between ticks from naive versus exposed (= resistant) hosts at varying conditions of temperature and humidity. This information will be used to develop a predictive model for RMWT population dynamics in the field. Finally, tick populations will be monitored over time from field-trapped host species. This will provide data on actual tick densities that can be used to validate the predictive model. EXPECTED OUTCOMES / IMPACTS This project will produce a model that predicts RMWT densities and distributions, based on weather and host populations. This model can be used to estimate risk of RMWT exposure and pathogen transmission. Cattle producers and public health officials can use this risk assessment tool to make decisions about landscape use, or employing anti-tick measures (e.g. acaricides). In addition, this project will yield new data on the general importance of anti-vector immune defenses to pathogen transmission. This will improve a broader understanding of infectious disease. The results of this project will be reported in peer-reviewed journals. Any effective risk-prediction models for RWMT will also be reported to cattle producers, or other interested parties, through the WSU extension and outreach programs.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
311	0430	1090	20%
311	3310	1090	20%
312	0430	1070	20%
312	0430	1090	20%
312	0830	1070	20%

Knowledge Area
312 - External Parasites and Pests of Animals; 311 - Animal Diseases;

Subject Of Investigation
3310 - Beef cattle, live animal; 0430 - Climate; 0830 - Wild animals;

Field Of Science
1090 - Immunology; 1070 - Ecology;

Keywords

tick, anaplasma, pathogen transmission, host resistance, immunity,

population dynamics, weather, landscape, epidemiology, risk

assessment.

Goals / Objectives
Goals Dermacentor andersoni Stiles, the Rocky Mountain Wood tick (RMWT), is widely distributed across the inter-mountain west of North America (James et al. 2006). The RMWT is responsible for transmission of several human pathogens and is the vector of the cattle pathogen Anaplasma marginale, which is a costly pathogen for cattle producers. The prevalence of A. marginale infection and incidence of disease in cattle differ markedly across locations (Saulmon 1962; Long et al. 1974, Torioni de Echaide et al. 1998). Factors responsible for this variation are unknown, which makes it difficult to anticipate areas of disease risk. In its simplest form, arthropod-borne pathogen transmission involves a parasitic arthropod (vector) acquiring a pathogen from an infected host and then transmitting the pathogen during contact with a second, uninfected host. Transmission rates thus depend on the abundance of vectors. More vectors produce higher feeding rates and more opportunities for pathogen acquisition-transmission. The importance of vector density to pathogen transmission is underscored by the fact that most control strategies for arthropod-borne pathogens are based on reducing the size of the vector population with pesticides and/or habitat alteration (Hemingway & Ranson 2000; Otranto & Wall 2008; Enayati & Hemingway 2010; Randell et al. 2010). Thus, understanding the factors that impact vector population dynamics is vital to predicting patterns of infectious disease and ultimately controlling pathogen transmission. Objectives Objective 1: Determine the effects of host condition (vector resistance) and environmental variables on the development and fecundity of D. andersoni. Objective 2: Determine the persistence of acquired anti-tick resistance in the host population. 2.1. Determine the maximum time-interval resistance is retained between tick exposures. 2.2. Determine host replacement demographics and tick exposure in the field. Objective 3: Validate model predictions, using comparisons of tick populations among field populations. Expected Outputs These data will be used to develop a predictive model of RMWT population dynamics. The model will provide cattle producers with a tool to assess the risk of A. marginale transmission in areas where they manage herds. In the long term, this work will reveal tick control strategies that would benefit the cattle industry and other communities affected by tick-borne disease. For example, anti-tick vaccines could be deployed to enhance natural tick resistance within the host community (Trimnell et al., 2002), or herd rotation plans could be customized around the tick resistance properties of the herd and wild host community (Teel et al., 1998).

Project Methods
Objective 1: Cohorts of ticks will be split into two groups reflecting the condition of hosts that ticks will use through the life cycle: (i) "naive hosts" (no prior tick exposure) or (ii) "resistant hosts" (single prior tick exposure). After dropping from the host animal, the ticks at each stage will be transferred to a small, soil-core enclosure and placed outside to complete development under ambient weather conditions. Ticks that successfully complete development will be recovered from the enclosures and placed onto a host at each successive feeding stage. Host animals will include Deer mice and Holstein cattle. Objective 2.1 (Years 2-3): For each host species, we will expose a cohort of hosts to a fixed tick burden. We will re-expose host animals at set time intervals and determine tick feeding/molting success relative to ticks feeding on naive hosts (age-matched). We will detect if resistance is lost in previously exposed hosts at 2 time points: 12-weeks and 32-weeks. The 12-week interval reflects tick activity of each stage. Objective 2.2 (Years 1-4): We will we determine how long resistance persists in hosts, relative to host turnover, using a combination of mark-recapture of juvenile hosts (mice), census of tick densities over time and testing for tick exposure in host animals using ELISA screening for anti-RMWT antibodies in trapped hosts. Blood samples will be collected from cattle in the spring and fall, during regular health checks conducted by ranchers. Objective 3: For validation of the model we will select cooperating ranches that are expected to have different levels of tick activity and which practice different cattle management strategies. The questing adult RMWT population will be sampled at each site and weather data will be collected. The cattle will be bled at the beginning and end of the tick season to assess A. marginale infection prevalence (overall infection rate), as well as tick exposure using the anti-tick ELISA. The model will be parameterized based on the data from Objectives 1-3. We will use maximum likelihood methods to fit equations for tick infestation rates and abiotic mortality to observed data in the field.

Progress 12/01/12 to 11/30/17

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Two peer-reviewed papers were published and a third paper is being revised after review.

Publications

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:The target audience for this work includes researchers interested in parasitic disease, ecology, animal agriculture, and conservation. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?The results of this research have been published in peer-review journals. What do you plan to do during the next reporting period to accomplish the goals?Complete analysis of data from experiments that were finished in 2017 and prepare manuscripts for publication.

Impacts
What was accomplished under these goals? Two peer-reviewed papers were published and a third paper is being revised after review.

Publications

• Type: Journal Articles Status: Published Year Published: 2017 Citation: Knutie, S.A., Herman, J.M., Owen, J.P., Clayton, D.H. (2017) Tri-trophic ecology of native parasitic nest flies of birds in Tobago. Ecosphere 8: e01670.
• Type: Journal Articles Status: Awaiting Publication Year Published: 2017 Citation: Meadows, A., Owen, J.P., Snyder, W.E. (2017) Keystone non-consumptive effects within a diverse predator community. Ecology and Evolution.
• Type: Journal Articles Status: Under Review Year Published: 2018 Citation: Jones, C.R., Scoles, G.A., Snyder, W.E., Owen, J.P. (2017) Host Diet Affects Resistance and Tolerance Responses to Parasitism. Journal of Medical Entomology.

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Researchers in medicine, immunology and infectious disease. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Three peer-reviewed publications.

Publications

• Type: Journal Articles Status: Accepted Year Published: 2016 Citation: Knutie, S.A., Herman, J.M., Owen, J.P., Clayton, D.H. (2016) Tri-trophic ecology of native parasitic nest flies of birds in Tobago. Ecosphere. In press.
• Type: Journal Articles Status: Accepted Year Published: 2016 Citation: Knutie, S.A., Owen, J.P., NcNew, S.M., Bartlow, A.W., Arriero, E., Herman, J.M., DiBlasi, E., Thompson, M., Koop, J.A.H., Clayton, D.H. (2016) Galapagos mockingbirds tolerate introduced parasites that affect Darwins finches. Ecology 97: 940-950.
• Type: Journal Articles Status: Accepted Year Published: 2016 Citation: Murillo, A.C., Chappell, M.A., Owen, J.P., Mullens, B.A. (2016) Northern Fowl Mite (Ornithonyssus sylviarum) Effects on Metabolism, Body Temperatures, Skin Condition, and Egg Production as a Function of Hen MHC Haplotype. Poultry Science. 95:25362546.

Progress 10/01/14 to 09/30/15

Outputs
Target Audience:The target audience includes researchers, health practitioners and public health officials working with infectious diseases related to arthropod-borne pathogen transmission. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project has supported research that trained a Ph.D. medical entomologist for the U.S. Navy (Dr. Adam Strong). In addition, three women were trained (Dr. Cami Jones, Ph.D.; Ms. Samantha Whiteside, M.S.; Ms. Kathryn Holden, M.S.), which helps increase the representation of women in the sciences How have the results been disseminated to communities of interest?Through peer-reviewed publications. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Two papers were published that report new information about the interactions between climate, pathogens and tick-borne pathogen transmission. One paper was published that reports how different bird species respond to ectoparasitism through "tolerance". Tolerance responses are an active area of research in disease ecology and the published paper describes the first robust study of tolerance in the field. Two Ph.D. students and two M.S. students were graduated this year after completing research in this project area.

Publications

• Type: Journal Articles Status: Published Year Published: 2015 Citation: Jones, C.R., Brunner, J.L., Scoles, G.A., Owen, J.P. (2015) Factors affecting larval tick feeding success: host, density and time. Parasites & Vectors 8: 340-350.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Rogovskyy, A.S., Casselli, T., Tourand, Y., Jones, C.R., Owen, J.P., Mason, L. K., Scoles, G.A., Bankhead, T. (2015) Evaluation of the Importance of VlsE Antigenic Variation for the Enzootic Cycle of Borrelia burgdorferi. PLoS One. 10 (4): e0124268.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Knutie, S.A., Owen, J.P., McNew, S.M., Bartlow, A.W., Arriero, E., Herman, J.M., DiBlasi, E., Thompson, M., Koop, J.A.H., Clayton, D.H. (2015) Gal�pagos mockingbirds are tolerant hosts of introduced parasites that threaten Darwins finches. Ecology. 10.1890/15-0119.1

Progress 10/01/13 to 09/30/14

Outputs
Target Audience: The target audience for this research project includes scientists working in immunogenetics, animal health and disease. In addition, the data from this project are relevant to stakeholders in animal agriculture (e.g., cattle and poultry producers). Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? This project has provided graduate training for 2 Ph.D. students and 2 M.S. students. How have the results been disseminated to communities of interest? Results from this project have been disseminated through peer-reviewed journal articles (3) and presentations at professional meetings (2). What do you plan to do during the next reporting period to accomplish the goals? During the next reporting period we will continue ongoing experiments that involve the effects of host diet on defenses against ectoparasites.

Impacts
What was accomplished under these goals? Three key accomplishments were made in the last reporting period: 1. Our work provided new evidence of defensive effects of innate antibodies (immunoglobulins) in host defense against parasites. 2. Our work has shown additive effects of immunological and behavioral defenses of hosts in the regulation of ectoparasite populations. 3. Our work has provided new evidence that diet of animals will affect the physiological response to ectoparasites and the capacity to develop immune defenses against ectoparasites.

Publications

• Type: Journal Articles Status: Published Year Published: 2014 Citation: Waite, J.L., Henry, A.R., Owen, J.P., Clayton, D.H. (2014) An experimental test of the effects of behavioral and immunological defenses against vectors: do they interact to protect birds from blood parasites? Parasites & Vectors 7: 104.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Owen, J.P., Vander Vliet, A., Scoles, G.A. (2014) Comparative Off-Host Survival of Larval Rocky Mountain Wood Ticks (Dermacentor andersoni) Collected from Ecologically Distinct Field Populations. Medical and Veterinary Entomology. 28: 341-344.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Owen, J.P., Waite, J., Clayton., D. (2014) Does antibody binding to novel proteins predict future infection? Parasite Immunology. 36: 571-582.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Crowder, D., Dykstra, E., Owen, J.P. Tradeoffs between agricultural intensification and insect-transmitted disease. Annual Meeting of Entomological Society of America. Nov. 16, 2014. Portland, OR.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Jones, C.J. and Owen, J.P. Diet and the demands of defense: Testing resource tradeoffs with deer mice and Rocky Mountain wood ticks. Annual Meeting of Entomological Society of America. Nov. 16, 2014. Portland, OR.

Progress 01/01/13 to 09/30/13

Outputs
Target Audience: Researchers interested in arthropod-borne pathogen transmission and agencies associated with public health. Changes/Problems: Continued data collection. What opportunities for training and professional development has the project provided? Two Ph.D. students have initiated dissertation research in this project area. Three undergraduate research projects have been initiated in this project area. How have the results been disseminated to communities of interest? Results have been published, accepted and submitted to peer-reviewed journals (see Products above). What do you plan to do during the next reporting period to accomplish the goals? Continued data collection.

Impacts
What was accomplished under these goals? New data have been gathered that link host (biotic) and environment (abiotic) effects on blood feeding arthropods. This has been accomplished for 3 systems: (1) Deer mouse and Wood tick; (2) House sparrow and House mosquito (Culex pipiens); and (3) Ground squirrel flea and Yersinia pestis.

Publications

• Type: Journal Articles Status: Published Year Published: 2013 Citation: Crowder, D.W., Dykstra, E., Brauner, J.M., Duffy, A., Reed, C., Martin, E., Peterson, W., Carriere, Y., Dutilleul, P., & Owen, J. (2013). West Nile virus prevalence across landscapes is mediated by local effects of agriculture on vector and host communities. PLoS One. 8, e55006.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Koop, J.A., Owen, J., Knutie, S.A., Aguilar, M.A., & Clayton, D.H. (2013). Experimental demonstration of a parasite-induced immune response in wild birds: Darwin's finches and introduced nest flies. Ecology and Evolution. 3(8), 2514-2523.
• Type: Journal Articles Status: Accepted Year Published: 2014 Citation: Scoles, G.A., Vander Vliet, A., & Owen, J. (in press). Comparative Off-Host Survival of Larval Rocky Mountain Wood Ticks (Dermacentor andersoni) Collected from Ecologically Distinct Field Populations. Medical and Veterinary Entomology.
• Type: Journal Articles Status: Accepted Year Published: 2014 Citation: Waite, J.L., Henry, A.R., Owen, J., & Clayton, D.H. (submitted). An experimental test of the effects of behavioral and immunological defenses against vectors: do they interact to protect birds from blood parasites?. Parasites & Vectors.

Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: The publications resulting from this project have provided key empirical evidence to the scientific community that vertebrate immune responses play an important role in the population dynamics of blood feeding arthropods. This work is relevant to researchers interested in disease ecology and ecological immunology. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: This work is relevant to researchers interested in disease ecology and ecological immunology. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
This work has led to the development of several collaborative relationships. These include: 1.Dr. Marcia Miller, City of Hope Cancer Research Center. (Collaborative Project - role of immunogenetics in parasite resistance, using poultry as a model system). 2.Dr. Rebecca Safran, University of Colorado. (Collaborative Project - testing the role of parasitic mites in sexual selection among songbirds). 3.Dr. Carol Fassbinder-Orth (Creighton University). (Collaborative Project - testing impact of mosquitoes on immune function and virus resistance in birds).

Publications

• Olds C., S. Mwaura, D.W. Crowder, D. Odongo, M.van Oers, J. Owen, R.Bishop, C.Daubenberge. 2012. Immunization of cattle with Ra86 impedes Rhipicephalus appendiculatus nymphal-to-adult molting. Acarologia. 3:170-178.

Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: In 2011 I published 1 peer-reviewed article that discussed work linked to this CRIS Research Project (King, M.O., Owen, J.P., Schawbl, H. (2011) Injecting the mite into ecological immunology: measuring the antibody response of House Sparrows (Passer domesticus) challenged with hematophagous mites. The Auk. 128 (2): 340-345.). I mentored 1 postdoctoral researcher (Dr. Marisa King), who completed experiments that have provided the first empirical evidence that wild song birds (House Sparrows) will acquire immune resistance to mosquitoes responsible for transmitting West Nile Virus. I developed a collaborative relationship with Dr. Jesse Brunner (WSU School of Biological Sciences) that is focused on characterizing the effects of host immunity on the ecology of the Rocky Mountain Wood Tick. This collaborative relationship produced a recently submitted grant proposal to the National Science Foundation program "Ecology and Evolution of Infectious Disease". I presented 1 invited talk to peers at the Society for Vector Ecology (SOVE) meeting (Flagstaff, AZ) in the symposium "Recent Advances and Issues with Vectors of Animal Diseases/Zoonoses". The talk covered research results from this CRIS project. PARTICIPANTS: Dr. Jeb P. Owen (PI) TARGET AUDIENCES: Geneticists, Ecologists, Parasitologists and Public Health Officials PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The outcomes/impacts within the last year involve a change in knowledge. This work has helped to determine that wild birds can develop immune resistance to mosquitoes that impairs the ability of the mosquito to reproduce and shortens the mosquito life-span. These are critical facets to pathogen transmission by mosquitoes. Additionally, this work was conducted with bird and mosquito species that are responsible for West Nile Virus (WNV) transmission in the United States. These insights will be valuable to future work on predicting the population dynamics of mosquitoes and the potential for pathogen (WNV) transmission.

Publications

• King, M.O., J.Owen, and H.G.Schwabl. 2011. INJECTING THE MITE INTO ECOLOGICAL IMMUNOLOGY: MEASURING THE ANTIBODY RESPONSE OF HOUSE SPARROWS (PASSER DOMESTICUS) CHALLENGED WITH HEMATOPHAGOUS MITES.. The Auk. 128(2):340-345.

Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: In 2010 I published 4 peer-reviewed articles that discussed work linked to this CRIS Research Project. In addition, I presented two talks to peers (Gonzaga University, invited; Annual Meeting, Entomological Society of America) covering research results from this work. Data from the host anti-tick resistance work has been incorporated into a predictive mathematical model illustrating the potential for host resistance to strongly impact tick population dynamics. This model will enable more accurate predictions of tick population densities in the field and the associated risk for tick-transmission of pathogens. PARTICIPANTS: Collaborators: Dr. Dale Clayton (University of Utah, Dept. of Biology) - Project director for NSF-funded project investigating the impacts of invasive parasites on Darwin's finches in the Galapagos islands. Dr. Clayton provided serum samples from birds, which the Owen lab used to develop novel immunological assays for avian antibody production. Dr. Glen Scoles (USDA, Agricultural Research Service) - Helped to facilitate experiments on the development of resistance by natural host animals to the Rocky Mountain Wood Tick. Training: Dr. Marisa King (postdoctoral researcher) is engaged in experiments to determine immunological interactions between bird species and mosquitoes. Cami Jones (M.S. student) is studying the development of antibody responses of host animals to Rocky Mountain Wood Tick. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Research from this project has provided the first concrete evidence that natural host species of a 3-host tick (Dermacentor andersoni) are capable of acquiring resistance to ticks after a single exposure. These insights will contribute to future development of anti-tick vaccines. Collaborative work from this project demonstrated that wild populations of birds are capable of developing immune responses to novel, exotic parasites (see Huber et al. PLoS One). This is the first work to illustrate that a wild bird species can immunologically respond to multiple, diverse classes of parasites. In addition, this work illustrates how immunological markers can be used to reveal impacts of invasive parasites on fragile, endemic species of animals. This is valuable to monitoring disease in wild animal populations.

Publications

• Owen JP, Nelson AC, Clayton DH (2010) Ecological immunology of bird-ectoparasite systems Ecological immunology of bird-ectoparasite systems. TRENDS IN PARASITOLOGY 26 (11): 530-539.
• King MO, Owen JP, Schwabl HG (2010) Are Maternal Antibodies Really That Important Patterns in the Immunologic Development of Altricial Passerine House Sparrows (Passer domesticus). PLOS ONE 5 (3): e9639
• Huber SK, Owen JP, Koop JAH, et al. (2010) Ecoimmunity in Darwin's Finches: Invasive Parasites Trigger Acquired Immunity in the Medium Ground Finch (Geospiza fortis). PLOS ONE 5 (1): e8605
• Author(s): Mullens BA, Chen BL, Owen JP (2010) Beak condition and cage density determine abundance and spatial distribution of northern fowl mites, Ornithonyssus sylviarum, and chicken body lice, Menacanthus stramineus, on caged laying hens. POULTRY SCIENCE 89 (12):2565-2572

Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: Three peer-reviewed research papers were published using data resulting from this project (see below). PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The published papers (Vet Parasitol. and Immunogenetics) have provided novel information to poultry producers on the ability of poultry to develop resistance to a common poultry pest - the northern fowl mite. This information may be used to develop control strategies that include breeding resistant chicken strains, and timing pesticide control to take advantage of immunological resistance. In addition, this project has contributed to novel insights regarding the interactions between the immune systems of wild birds and exotic parasites that are threatening island species (PLoS One).

Publications

• Owen, J., M.E.Delany, C.J.Cardona, A.Bickford, and B.A.Mullens. 2009. Host Inflammatory Response Governs Fitness in an Avian Ectoparasite, the Northern Fowl Mite (Ornithonyssus sylviarum). International Journal for Parasitology. 39(7):789-799.
• Mullens, B.A., J.Owen, D.R.Kuney, C.E.Szijj, and K.A.Klingler. 2009. Temporal changes in distribution, prevalence, intensity of northern fowl mite (Ornithonyssus sylviarum) parasitism in commercial caged laying hens, with a comprehensive economic analysis of parasite impact. Veterinary Parasitology. 160(1-2):116-133.
• Huber, S.K., J.Owen, J.A.Koop, M.O.King, P.R.Grant, R.Grant, and D.H.Clayton. 2009. Ecoimmunity in Darwin's Finches: Invasive Parasites Trigger Acquired Immunity in the Medium Ground Finch (Geospiza fortis). PloS one 5(1):e8605.

Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: In 2008 I initiated two new research projects exploring vertebrate immunological interactions with blood feeding arthropods. The first project is a collaborative effort with colleagues in the Washington State University (WSU) School of Veterinary Medicine (Dr. Susan Noh and Dr. Wendy Brown) and the U.S. Department of Agriculture (Dr. Glen Scoles). This project involves testing the ability of Holstein cattle to develop immunological resistance to the Rocky Mountain Wood Tick (RMWT; Dermacentor andersoni). The RMWT is a critical vector of the cattle pathogen, Anaplasma marginale, which costs the U.S. cattle industry an estimated $300 million in losses due to morbidity and mortality. We are characterizing the development of anti-tick resistance and documenting the impacts on tick survival, development and reproduction. This information is expected to contribute to our understanding of tick population dynamics in the field, where levels of tick exposure among cattle vary over time. In addition, this information may be used in future development of breeding and vaccine strategies to enhance tick resistance in cattle. The second project involves exploration of bird immunological responses to blood feeding arthropods. Specifically, we are using the domestic chicken as an avian immunological model to test the possible interaction between immunosuppressive properties of mosquito saliva and transmission of a mosquito-borne virus (Avian Pox Virus). The goal is to determine if mosquito feeding enhances the infectiveness of a mosquito-transmitted virus by suppressing immunological function in the host bird. This is important to understanding the transmission dynamics for a variety of mosquito-transmitted pathogens, such as West Nile Virus. These two projects were initiated in 2008 and will be completed in 2009. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: This project broadly targets researchers in medical entomology, parasitology and evolutionary ecologists interested in host-parasite interactions. Specifically, this work is of immediate interest and use to poultry scientists (e.g. breeders and geneticists) involved in the U.S. poultry industry. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The publication in Immunogenetics reports the first experimental evidence for a relationship between genetic variation at the major histocompatibility complex (MHC) and immunological resistance to an ectoparasitic arthropod. The practical impact of this information is the identification of a critical set of immunological genes that contribute to natural resistance to blood-feeding arthropods. This will enable livestock breeders to target these genes in breeding efforts to enhance ectoparasite resistance. Additionally, genes in the MHC may be considered in assessments of ectoparasite susceptibility among populations of wildlife. From a basic science perspective, this information may help researchers to understand the genetic underpinnings of vertebrate-ectoparasite coadaptation. The publication in the International Journal for Parasitology reports the first detailed mechanisms for the effects of host inflammation on the population dynamics of an ectoparasite. Details on the specific effects of vertebrate immunity on ectoparasites have been coarse and limited to specific life stages. This paper provides a mechanism for interacting effects on multiple life stages within an ectoparasite population, which contributes to the cessation and reversal of population growth. This improved understanding of the mechanism of immunological interactions between a vertebrate and ectoparasite will contribute to the development of immunological control strategies for ectoparasites (e.g. vaccine development and breeding for parasite resistance).

Publications

• Owen, J., M.E.Delany, and B.A.Mullens. 2008. MHC haplotype involvement in avian resistance to an ectoparasite. Immunogenetics. 60(10):621-631.