48 Genetic study of horn fly abundance in beef cattle

Abstract Disturbing the non-symbiotic relationship between horn flies and cattle is of economic, health, and animal welfare importance. Reliance on management and insecticides has proven inadequate. In the United States, horn flies are estimated to cause more than $1 billion in economic losses on pastured cattle annually. Although insecticides provide temporary control, their efficacy is hampered by several factors. Intensive insecticide use has led to horn fly resistance and decreased predation on horn flies by other insects. Due to the cost and logistic complexity of measuring fly resistance traits under commercial conditions, the genetic basis of these traits remains largely unknown. Only a few heritability estimates are available based on small-scale studies. Currently, the economic injury threshold (EIT) due to horn fly abundance (onset of production decay) is set at around 200 flies for beef cattle. This threshold is largely heuristically set. Additionally, the rate of decay in performance as a function of fly abundance after injury onset is unknown. It is also likely that EIT is breed and animal specific. Data used in this study was collected during the summer of 2019. Animals were not treated or managed in any way to control horn flies prior to data collection. Animals were assessed subjectively and based on image counts for horn fly abundance. Estimates of heritability of horn fly abundance ranged between 0.14 and 0.22 for subjective and image-based phenotypes. The lowest heritability was for the subjective assessment, likely due to the excessive variation between evaluators. Changepoint model-based analysis showed that EIT is variable between sire families, ranging from 265 to 413 flies. Furthermore, there was significant difference in the decay of performance after the onset of injury. The rate of decay ranged between -0.0003 and -0.00018. Collectively, these results indicate the potential to improve horn fly resistance/tolerance using genetic tools.

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PSVIII-5 Genetic parameters of thrombin as a proxy for horn fly abundance in beef cattle

Journal of Animal Science ◽

10.1093/jas/skab235.435 ◽

2021 ◽

Vol 99 (Supplement_3) ◽

pp. 239-239

Author(s):

Ashley S Ling ◽

Taylor Krause ◽

Amanda Warner ◽

Jason Duggin ◽

Bradley Heins ◽

...

Keyword(s):

Beef Cattle ◽

Fixed Effects ◽

Large Scale ◽

Genetic Basis ◽

Threshold Model ◽

Economic Losses ◽

Small Data ◽

Horn Fly ◽

Improvement Programs ◽

Highest Posterior Density

Abstract Horn flies (Haematobia irritans) are a major nuisance to cattle, especially in warm, humid regions, and are estimated to cause economic losses in excess of $1 billion annually to the U.S. beef cattle industry. Variation in horn fly tolerance has been reported within and across breeds, and heritability estimates ranging between 10 and 80% show a clear genetic basis. However, collecting fly abundance phenotypes is costly and logistically demanding, which precludes large-scale implementation. Consequently, finding correlated phenotypes and endo-phenotypes that are heritable and relatively easy to measure would facilitate implementation of horn fly tolerance genetic improvement programs. Thrombin (TH), a blood coagulation precursor, has a reported association with horn fly count variation within and across cattle breeds. In this study, the genetic basis of thrombin in beef cattle was investigated. Blood samples and horn fly count were collected on 360 cows and heifers twice during the summer of 2019 (June and August). Due to uncertainty associated with assessment of horn fly abundance and thrombin and the fact that economic losses occur only when fly abundance exceeds a certain threshold, thrombin was categorized into 4 classes (1=TH > 500 ng/ml; 2=250< TH< 500 ng/ml; 3=100< TH< 250 ng/ml; and 4=TH< 100 ng/ml). The trait was analyzed using linear (continuous) and threshold (discrete) mixed models. Both models included farm, pregnancy status, and cow age as fixed effects and additive and permanent environment random effects. The pedigree included 642 animals. Estimates of heritability were 0.24 and 0.29 using linear and threshold models, respectively. Estimates of repeatability were slightly higher using the threshold model (0.21 vs 0.19). Despite the small data size, all estimates were non-zero based on their respective highest posterior density intervals. These results indicate reasonable genetic variation for thrombin that could be harnessed for improvement of horn fly tolerance in cattle.

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Wolbachia Endosymbiont of the Horn Fly (Haematobia irritans irritans): a Supergroup A Strain with Multiple Horizontally Acquired Cytoplasmic Incompatibility Genes

Applied and Environmental Microbiology ◽

10.1128/aem.02589-19 ◽

2020 ◽

Vol 86 (6) ◽

Cited By ~ 6

Author(s):

Mukund Madhav ◽

Rhys Parry ◽

Jess A. T. Morgan ◽

Peter James ◽

Sassan Asgari

Keyword(s):

Cytoplasmic Incompatibility ◽

The United States ◽

Whole Genome ◽

Evolutionary Analysis ◽

Content Type ◽

Wolbachia Pipientis ◽

Haematobia Irritans ◽

Horn Fly ◽

Horn Flies ◽

Horizontal Acquisition

ABSTRACT The horn fly, Haematobia irritans irritans, is a hematophagous parasite of livestock distributed throughout Europe, Africa, Asia, and the Americas. Welfare losses on livestock due to horn fly infestation are estimated to cost between $1 billion and $2.5 billion (U.S. dollars) annually in North America and Brazil. The endosymbiotic bacterium Wolbachia pipientis is a maternally inherited manipulator of reproductive biology in arthropods and naturally infects laboratory colonies of horn flies from Kerrville, TX, and Alberta, Canada, but it has also been identified in wild-caught samples from Canada, the United States, Mexico, and Hungary. Reassembly of PacBio long-read and Illumina genomic DNA libraries from the Kerrville H. i. irritans genome project allowed for a complete and circularized 1.3-Mb Wolbachia genome (wIrr). Annotation of wIrr yielded 1,249 coding genes, 34 tRNAs, 3 rRNAs, and 5 prophage regions. Comparative genomics and whole-genome Bayesian evolutionary analysis of wIrr compared to published Wolbachia genomes suggested that wIrr is most closely related to and diverged from Wolbachia supergroup A strains known to infect Drosophila spp. Whole-genome synteny analyses between wIrr and closely related genomes indicated that wIrr has undergone significant genome rearrangements while maintaining high nucleotide identity. Comparative analysis of the cytoplasmic incompatibility (CI) genes of wIrr suggested two phylogenetically distinct CI loci and acquisition of another cifB homolog from phylogenetically distant supergroup A Wolbachia strains, suggesting horizontal acquisition of these loci. The wIrr genome provides a resource for future examination of the impact Wolbachia may have in both biocontrol and potential insecticide resistance of horn flies. IMPORTANCE Horn flies, Haematobia irritans irritans, are obligate hematophagous parasites of cattle having significant effects on production and animal welfare. Control of horn flies mainly relies on the use of insecticides, but issues with resistance have increased interest in development of alternative means of control. Wolbachia pipientis is an endosymbiont bacterium known to have a range of effects on host reproduction, such as induction of cytoplasmic incompatibility, feminization, male killing, and also impacts vector transmission. These characteristics of Wolbachia have been exploited in biological control approaches for a range of insect pests. Here we report the assembly and annotation of the circular genome of the Wolbachia strain of the Kerrville, TX, horn fly (wIrr). Annotation of wIrr suggests its unique features, including the horizontal acquisition of additional transcriptionally active cytoplasmic incompatibility loci. This study provides the foundation for future studies of Wolbachia-induced biological effects for control of horn flies.

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Chemosensory-Related Gene Family Members of the Horn Fly, Haematobia irritans irritans (Diptera: Muscidae), Identified by Transcriptome Analysis

Insects ◽

10.3390/insects11110816 ◽

2020 ◽

Vol 11 (11) ◽

pp. 816

Author(s):

Pia Untalan Olafson ◽

Christopher A. Saski

Keyword(s):

Gene Family ◽

Binding Proteins ◽

Control Strategies ◽

Family Members ◽

Blood Feeding ◽

The United States ◽

Horn Fly ◽

Differential Gene ◽

Horn Flies ◽

Species Specific

Horn flies are one of the most significant economic pests of cattle in the United States and worldwide. Chemical control methods have been routinely utilized to reduce populations of this pest, but the steady development of insecticide resistance has prompted evaluation of alternative control strategies. Behavior modifying compounds from natural products have shown some success in impacting horn fly populations, and a more thorough understanding of the horn fly chemosensory system would enable improvements in the development of species-specific compounds. Using an RNA-seq approach, we assembled a transcriptome representing genes expressed in adult female and male horn fly head appendages (antennae, maxillary palps, and proboscides) and adult fly bodies from which heads were removed. Differential gene expression analysis identified chemosensory gene family members that were enriched in head appendage tissues compared with headless bodies. Candidate members included 43 odorant binding proteins (OBP) and 5 chemosensory binding proteins (CSP), as well as 44 odorant receptors (OR), 27 gustatory receptors (GR), and 34 ionotropic receptors (IR). Sex-biased expression of these genes was not observed. These findings provide a resource to enable future studies targeting horn fly chemosensation as part of an integrated strategy to control this blood-feeding pest.

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Efficacy of Insecticide Ear Tags on Cattle in Central Kentucky, 1995

Arthropod Management Tests ◽

10.1093/amt/21.1.397 ◽

1996 ◽

Vol 21 (1) ◽

pp. 397-397

Author(s):

J. D. Webb ◽

F. W. Knapp

Keyword(s):

Beef Cattle ◽

Horn Fly ◽

Cattle Herds ◽

Horn Flies

Abstract Tests were conducted on 5 beef cattle herds in central Kentucky using insecticide ear tags against horn flies and face flies. Ear tags were applied 1/ear in all tests during a 5-day period starting 10 Jun 1995. All tags were applied 1 per ear on all adults and weaned animals in each group. Using binoculars, horn fly estimates were taken on one side of 10 animals while face flies were counted on the head and face of the same animals at weekly intervals.

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Commingled black and white cows (Bos taurus; Angus and Charolais) in high-elevation rangeland are differentially parasitised by Haematobia irritans

Animal Production Science ◽

10.1071/an18400 ◽

2019 ◽

Vol 59 (9) ◽

pp. 1727

Author(s):

John D. Scasta ◽

Travis Smith

Keyword(s):

Management Strategies ◽

Blood Feeding ◽

High Elevation ◽

Haematobia Irritans ◽

Horn Fly ◽

Economic Thresholds ◽

Significant Difference ◽

White Cattle ◽

Performance Development ◽

Horn Flies

Globally horn flies (Haematobia irritans) are one of the most economically damaging parasites of beef cattle. These obligate blood-feeding external parasites take blood meals from cattle leading to blood loss, annoyance avoidance behaviours, and reductions in animal performance. Development of chemical resistance by horn flies suggests that novel management strategies are needed. More in-depth understanding of parasitism relative to hide colour and temperature, especially in a changing climate, may enhance animal production. In peak parasitism periods of 2016 and 2017, we measured horn fly loads on commingled black Angus and white Charolais cows in a cold high-elevation rangeland in Wyoming, USA. We tested how breed, year, and interactions explained horn fly parasitism and economic thresholds. In 2016 we also measured ambient and external cow temperatures to further elucidate thermal ecology mechanisms explaining horn fly hide colour preferences. Mean annual horn fly infestations were always four times greater or more on black cows than white cattle both years, but not all cattle reached economic thresholds all years and the breed by year interaction was not significant. Difference in horn fly preference for black cattle over white cattle in our cold high-elevation environment may be explained by greater absolute and relative external surface temperatures of black hided cows. Host colour and thermal preferences of horn flies could be incorporated into integrated pest management strategies that only treat darker hided cattle and producers in cold high-elevation environments conduct real-time monitoring to determine if treatments are even needed on a year-by-year basis.

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Optimal Collection Methods for Asian Longhorned Ticks (Ixodida: Ixodidae) in the Northeast United States

Journal of Medical Entomology ◽

10.1093/jme/tjab083 ◽

2021 ◽

Author(s):

Phurchhoki Sherpa ◽

Laura C Harrington ◽

Nicholas P Piedmonte ◽

Kathryn Wunderlin ◽

Richard C Falco

Keyword(s):

United States ◽

Disease Risk ◽

Life Stage ◽

The United States ◽

Economic Losses ◽

Haemaphysalis Longicornis ◽

Significant Difference ◽

And Control ◽

Collection Methods ◽

Tick Check

Abstract The Asian longhorned tick, Haemaphysalis longicornis Neumann, is an invasive species in the United States. Since its earliest recorded presence in West Virginia in 2010, H. longicornis has been reported from 15 states. While its public health significance in the United States is unclear, globally it transmits pathogens that infect livestock and humans, causing economic losses and substantial morbidity. Management and control of H. longicornis requires knowledge of its biology, ecology, and distribution. Here, we address the need for effective collection methods for host-seeking H. longicornis as an important step for accurately assessing tick abundance and potential disease risk. The number of H. longicornis collected were compared across three collection methods (dragging, sweeping, CO2 traps) and three tick check distances (5 m, 10 m, and 20 m) were compared for dragging and sweeping. Field collections were conducted from June through August 2019 in Westchester County, New York, and ticks were grouped by life stage to assess collection method efficiency. Results indicated that implementing shorter (5 m) tick check distance was ideal for adult and nymphal collections. The dragging method proved better than sweeping for adult collections; however, there was no significant difference between the methods for nymphal collections, at any tick check distance evaluated. CO2 traps attracted H. longicornis, but additional research is necessary to devise an effective tick retaining method before the traps can be implemented in the field. The results are presented to inform and support H. longicornis surveillance and control programs across the nation.

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PSIX-16 Association between Thrombin and horn fly abundance in beef cattle

Journal of Animal Science ◽

10.1093/jas/skab235.490 ◽

2021 ◽

Vol 99 (Supplement_3) ◽

pp. 267-268

Author(s):

Taylor Krause ◽

Ashley S Ling ◽

Amanda Warner ◽

Jason Duggin ◽

Bradley Heins ◽

...

Keyword(s):

Beef Cattle ◽

Pearson Correlation ◽

Coagulation Factors ◽

Subjective Assessment ◽

Research Unit ◽

Horn Fly ◽

University Of Georgia ◽

Feeding Process ◽

Selection For ◽

The Impact

Abstract It has been reported that differences in horn fly tolerance in beef cattle could be associated with variation in blood enzymes. Thrombin (TH), a major enzyme for hemostasis that plays an important role in the activation of several pro-coagulation factors through the conversion of fibrinogen to fibrin, has been associated with horn fly prevalence on cattle. Although this assumption is reasonable, as fast-coagulating blood tends to complicate the feeding process for flies, there is little meaningful field data that clearly supports this hypothesis. Therefore, the objective of this study was to assess TH levels in relation to horn fly abundance using 360 cows at two University of Georgia farms (Northwest Georgia REC, 34.5°N, 85.0°W and Eatonton Beef Research Unit, 33.4°N, 83.5°W). Horn fly counts were taken twice by trained evaluators during the summer of 2019 (June and August). Additionally, blood samples were collected twice on each cow to quantify serum TH levels using an ELISA assay (MyBioSource, San Diego, CA). The Pearson correlation between serum TH level and horn fly count was -0.19, indicating a decrease in the number of flies with increasing TH in the blood. In order to reduce the impact of the uncertainty associated with the subjective assessment of horn fly abundance and the potential nonlinear relationship between both parameters, TH was categorized into four classes (1=TH >500 ng/mL; 2=250< TH< 500 ng/mL; 3=100< TH< 250 ng/mL; 4=< 100 ng/mL). Average fly counts were 336, 353, 391, and 464 for the four classes, respectively. Between the first (high TH) and fourth (low TH) classes, there was a 38% reduction in fly abundance. Across sire families, fly abundance ranged between 190 and 650. Collectively, these results indicate that selection for higher serum TH levels could be used as a proxy for improving horn fly tolerance in beef cattle.

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Evaluation of Insecticide Ear Tags on Horn Flies in West Central Nebraska, 1993

Arthropod Management Tests ◽

10.1093/amt/19.1.364 ◽

1994 ◽

Vol 19 (1) ◽

pp. 364-364

Author(s):

D. J. Boxler ◽

J. B. Campbell

Keyword(s):

Beef Cattle ◽

Central Research ◽

Native Range ◽

The West ◽

Treatment Groups ◽

Horn Fly ◽

West Central ◽

Horn Flies ◽

Fly Control ◽

Extension Center

Abstract Y-Tex experimental ear tags (YT-615) were compared with PYthon® 10% ear tags for horn fly control on beef cattle. The study was initiated 17 Jun at the West Central Research and Extension Center, North Platte, NE. Cattle used in the trial were randomly selected from a herd of 200 heifers. Ear tags were applied as follows: YT-615 applied to 25 heifers (one tag per heifer), PYthon applied to 30 heifers (two tags per heifer) and PYthon applied to 120 heifers (one tag per heifer). An untreated group of 10 heifers served as a comparison. The three treatment groups were maintained in separate native range pastures throughout the study period. Horn fly counts were recorded at weekly intervals by counting flies on both sides of a minimum of 15 heifers during each fly counting session.

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An insight into the sialome, mialome and virome of the horn fly, Haematobia irritans

10.21203/rs.2.9877/v2 ◽

2019 ◽

Author(s):

Jose M. Ribeiro ◽

Humberto Julio Debat ◽

M. Boiani ◽

X. Ures ◽

S Rocha ◽

...

Keyword(s):

Biological Effects ◽

Life Cycles ◽

Economic Losses ◽

Comprehensive Description ◽

Haematobia Irritans ◽

Horn Fly ◽

Horn Flies ◽

Available Information ◽

Insight Into ◽

Alternative Control Methods

Abstract Background The horn fly (Haematobia irritans) is an obligate blood feeder that causes considerable economic losses in livestock industries worldwide. The control of this cattle pest is mainly based on insecticides; unfortunately in many regions, horn flies have developed resistance. Vaccines or biological control have been proposed as alternative control methods, but the available information about the biology or physiology of this parasite is rather scarce. Results We present a comprehensive description of the salivary and midgut transcriptomes of the horn fly (Haematobia irritans), using deep sequencing achieved by the Illumina protocol, as well as exploring the virome of this fly. Comparison of the two transcriptomes allow for identification of uniquely salivary or uniquely midgut transcripts, as identified by statistically differential transcript expression at a level of 16 x or more. In addition, we provide genomic highlights and phylogenetic insights of Haematobia irritans Nora virus and present evidence of a novel densovirus, both associated to midgut libraries of H. irritans. Conclusions We provide a catalog of protein sequences associated with the salivary glands and midgut of the horn fly that will be useful for vaccine design. Additionally, we discover two midgut-associated viruses that infect these flies in nature. Future studies should address the prevalence, biological effects and life cycles of these viruses, which could eventually lead to translational work oriented to the control of this economically important cattle pest.

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