The future of tick control: Identifying genetic tools to control cattle fever ticks

by

Editors' notes

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:

fact-checked

peer-reviewed publication

trusted source

proofread

A female Rhipicephalus (Boophilus) microplus, Southern cattle fever tick. The USDA-Texas A&M Department of Entomology study identified chromosomes that determine whether ticks develop as male or female. The discovery could lead to novel control methods of these and other disease-spreading ticks. Credit: Sam Craft/Texas A&M AgriLife

Research collaboration by the Texas A&M Department of Entomology and the U.S. Department of Agriculture, USDA, creates potential for genetic tools to control disease-spreading ticks.

A recently published study by Jason Tidwell, a part-time graduate student in the Texas A&M College of Agricultural and Life Sciences Department of Entomology and full-time microbiologist with the USDA's Agricultural Research Service Cattle Fever Tick Research Unit at Edinburg, lays the foundation for potential new control methods against cattle fever ticks, the vectors of pathogens causing bovine babesiosis, historically known as Texas cattle fever.

The work is published in the journal G3: Genes, Genomes, Genetics.

Tidwell primarily conducts genetic research in arthropods, specifically cattle fever ticks. The publication is based on a foundational research project that identified the genetic markers for sex determination in the tick species Rhipicephalus microplus, one of two invasive cattle fever tick species found in northern Mexico that constantly threaten re-establishment in the U.S.

Collaboration could aid tick control

Kimberly Lohmeyer, Ph.D., center director at the Knipling-Bushland U.S. Livestock Insects Research Laboratory, Kerrville, said Tidwell's findings are a great example of a researcher identifying an unknown aspect of a pest's biology that could be leveraged and used as a novel control tool.

Lohmeyer said Tidwell was hooked by the idea of using genetic control methods of an important pest and that his study's discovery now opens the door for innovative solutions against disease-carrying ticks.

"This study sets the stage for advancements in how we protect U.S. livestock from cattle fever ticks," she said. "It answers a basic biological mystery about these ticks, but it is also a big step toward novel tools for the eradication program."

Pete Teel, Ph.D., a Texas A&M AgriLife Research scientist in the Department of Entomology and one of Tidwell's co-advisors, said Tidwell's work identifying the mechanisms of sex determination is critical to understanding genetic control of tick reproduction.

"It lays the foundation for potential genetic pest control methods that have been applied to other arthropods including the primary screwworm and several mosquito species," Teel said.

A dendrogram using hierarchical clustering of the R. (B.) microplus larva estimated genome sizes by flow cytometry. The AU (left) and BP (right) values are percentages. The AU (left) is the P-value generated by multiscale bootstrap resampling. The BP value is the bootstrap probability. The 2 dotted rectangles are clusters with an AU ≥ 95%. Samples V1–V27 were larvae (sex unknown), samples V28–32 were adult females (+), and samples V33–37 were adult males (*). Larval samples V1–V9, V17–V20, V23, and V26 clustered with the adult female samples and samples V10–V16, V21, V22, V24, V25, and V27 clustered with the adult male samples. Credit: G3: Genes, Genomes, Genetics (2024). DOI: 10.1093/g3journal/jkae234

Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. Sign up for our free newsletter and get updates on breakthroughs, innovations, and research that matter—daily or weekly.

Subscribe

Research provides foundation for potential weapon against ticks

The Cattle Fever Tick Eradication Program is a joint effort of USDA Animal and Plant Health Inspection Service Veterinary Services and the Texas Animal Health Commission to prevent the two species of cattle fever ticks from reestablishing in the U.S., Tidwell said. The program started in 1906 and eradicated the ticks in all 13 southern states and California, aside from a permanent quarantine zone in South Texas.

"These ticks are the only vectors of pathogens causing bovine babesiosis, thus eliminate the ticks and you eliminate the risk of disease," Teel said.

There are no approved anti-babesia vaccines, nor therapeutic drugs to treat the disease. The program has depended on chemical control with acaricides, pesticides for controlling ticks and mites. Discovery of genetic control tactics would be a novel approach, Teel said. New tactics are increasingly necessary because cattle fever ticks are showing increased resistance to acaricides.

"One idea is to genetically manipulate sex ratios in the environment in ways that prevent reproduction and crash populations of the pest," Tidwell said.

That genetic method has already shown promise to control Aedes aegypti mosquitoes, which vector diseases like West Nile virus, Dengue, yellow fever and Zika to humans. In that way, Tidwell's discovery could lead to similar control methods for other tick-borne diseases like Lyme disease in humans.

Aaron Tarone, Ph.D., an AgriLife Research scientist and professor in the Department of Entomology, and co-advisor to Tidwell, said any new control tool will need to be logistically, environmentally and economically sustainable, but agreed the study has opened the door for innovative advancements.

"The next step will be building genomes of ticks of local reference from both here in Texas and Mexico to examine their genetic variation," Tarone said. "The whole genomics arena and technology associated with it has opened the door to so many possibilities when it comes to dealing with vectors that pose serious threats to human and animal health."

More information: Jason P Tidwell et al, Identifying the sex chromosome and sex determination genes in the cattle tick, Rhipicephalus (Boophilus) microplus, G3: Genes, Genomes, Genetics (2024). DOI: 10.1093/g3journal/jkae234

Journal information: G3 Genes|Genomes|Genetics

Provided by Texas A&M University