Infection with Babesia bovis alters metabolic rates of Rhipicephalus microplus ticks across life stages

Authors: EARLS, KAYLA - Washington State University; Poh, Karen; Ueti, Massaro; Oyen, Kennan

Submitted to: Parasites & Vectors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2024
Publication Date: 3/1/2025
Citation: Earls, K., Poh, K.C., Ueti, M.W., Oyen, K.J. 2025. Infection with Babesia bovis alters metabolic rates of Rhipicephalus microplus ticks across life stages . Parasites & Vectors. 18(1):81. https://doi.org/10.1186/s13071-024-06645-3.
DOI: https://doi.org/10.1186/s13071-024-06645-3

Interpretive Summary: Metabolic rates can be used to tell how much energy an organism is consuming. Ticks must conserve energetic resources because they have long lifespans and only feed three times. We tested how infection with a pathogen (Babesia bovis) influences the metabolic rate of ticks. We found that ticks carrying a pathogen had different metabolic rates from ticks that were not infected. Our study shows that infection can increase the energetic reserves ticks require to persist which might drive shorter lifespans and higher levels of activity. If infected ticks have higher activity levels, it may result in earlier infection of animals and help to facilitate the persistence of cattle fever within a population.

Technical Abstract: Metabolic responses to infection differ depending on both arthropod and pathogen. Increased metabolic rate can result in faster depletion of energetic resources and decreases may allow for energy conservation. Babesia bovis is a protozoan pathogen transmitted by the cattle fever tick, Rhipicephalus microplus. Adult female ticks acquire the B. bovis by feeding on an infected animal. Babesia bovis undergoes development and invades the ovaries where it is transmitted transovarially to tick offspring. The effects of infection on R. microplus metabolic rate are understudied. We tested the hypothesis that R. microplus infected with B. bovis would have altered metabolic rates (VCO2) across life stages using flow-through respirometry. Results show that infected replete females have decreased VCO2 while their offspring have increased VCO2 at egg and larval stages. Interestingly, replete females that fed on an infected calf had a 25% reduction in body mass compared to uninfected tick controls. Uninfected larvae were twice as likely to hatch than larvae from infected replete female ticks. The larval VCO2 may promote earlier questing and shorter lifespans. Changes in metabolic and hatch rate have implications regarding disease spread.