Pyrokinin receptor silencing in females of the southern cattle tick Rhipicephalus (Boophilus) microplus is associated with a reproductive fitness cost

On-Demand

Presenting Author(s)

Juan Wulff

Postdoc
Texas A&M University
College Station, Texas

Co-author(s)

KT

Kevin B. Temeyer

Research Molecular Biologist
USDA-ARS
Kerrville, Texas

Co-Author(s)

Jason Tidwell

Microbiologist
USDA-ARS
Edinburg, Texas
KS

Kristie G. Schlechte

USDA-ARS
Kerrville, Texas
Caixing Xiong

Postdoctoral Research Associate
Texas A&M University
College Station, Texas
Kimberly H. Lohmeyer

Research Entomologist
USDA-ARS
Kerrville, Texas
Patricia V. Pietrantonio

Professor
Texas A&M University
College Station, Texas

Rhipicephalus microplus is the vector of deadly cattle pathogens, especially Babesia spp., for which recombinant vaccines are not available. Therefore, disease control depends on tick vector control. However, R. microplus populations worldwide, and especially in Central and South America, have developed resistance to most available acaricides, prompting the need for novel acaricide targets. G protein-coupled receptors (GPCRs) are involved in the regulation of many physiological processes and were suggested as druggable targets for the control of arthropod vectors. The pyrokinin receptor (PKR) is a GPCR previously functionally characterized in ticks. Pyrokinins myotropic activity in feeding-related tissues of Rhipicephalus sanguineus and Ixodes scapularis was recently reported. We now silenced the R. microplus pyrokinin receptor (Rhimi-PKR) through RNA interference in unfed females. Two dsRNAs previously validated in tick cell culture with high in vitro PKR silencing efficiency were injected. Rhimi-PKR silencing was associated with increased mortality, decreased weight of surviving females and egg masses (P <0.05); delays in repletion, pre-oviposition and incubation periods were observed (P <0.05). Overall, Rhimi-PKR silencing negatively affected the female reproductive fitness. The PKR appears to be directly or indirectly associated with the regulation of female feeding and/or reproductive output in R. microplus. Antagonists of the pyrokinin signaling system could be explored for tick control. The presentation will include striking pictures of tick females at different time points while on animals, and which phenotypes support the results of qRT-PCR, that demonstrated in vivo receptor silencing efficiencies from 68-92%, in whole females and dissected tissues.