The blacklegged tick, Ixodes scapularis (Ixodida, Ixodidae), is one of the major disease vectors in the United States, and due to multiple human impact factors, such as decreasing forest size for land development and climate change, it has expanded its range and established across the United States. Throughout the life cycle, ticks locate hosts for their blood-meal, and although the ecologies of this tick and their hosts have been studied in depth, the sensory physiology behind host location largely remains unexplored. Here, we report establishing a robust paradigm to isolate and identify odors from the natural milieu for I. scapularis. We performed single sensillum recordings (SSR) from the olfactory sensilla on the tick tarsi, and used the SSR system as a biological detector to isolate natural compounds that elicited biological activity. The SSR setup was further tested in tandem with gas chromatography (GC) wherein the ticks’ olfactory sensillum activity served as a biological detector. The GC-SSR recordings from the wall pore sensilla in the Haller's organ, and further identification of the biologically active deer gland constituents by GC-mass spectrometry (GC–MS) revealed methyl substituted phenols as strong chemostimuli, as compared to ethyl or propyl substitutions. The strongest electrophysiological activity was elicited by m- cresol followed by p- cresol. Ethyl- and propylphenols with any of the three substitutions (ortho, meta or para), did not induce any neurophysiological activity. Finally, a behavioral analysis in a dual-choice olfactometer of all these phenols at three different doses revealed no significant behavioral response, except for p- cresol at −3 dilution. Overall, this study contributes to our understanding of I. scapularis tick's neurophysiology and provides a robust platform to isolate and identify natural attractants and repellents.
|Journal||Journal of Insect Physiology|
|State||Published - Jan 2021|
Bibliographical noteFunding Information:
We thank all of the members of the Allan laboratory and members of the Syed laboratory (Drs. Paul Hickner, Omprakash Mittapalli and Ms. Pritika Pande) for their comments on the early draft of this manuscript. We would also like to thank Drs. Chris Stone, Holly Tuten and Lloyd Hall for providing ticks, laboratory space, and equipment for conducting the choice-test assays. This research work was supported by funding from the National Institute of Food and Agriculture , US Department of Agriculture to ZS (under HATCH Project 2353077000) and the University of Illinois at Urbana-Champaign School of Integrative Biology’s Harley J. Van Cleave Research Award and Philip W. Smith Memorial Fund to TJ.
© 2020 The Author(s)
- Dual-choice assay
- GC-Mass spectrometry
- GC-linked single sensillum recordings
- Ixodes scapularis
- Single sensillum recordings
ASJC Scopus subject areas
- Insect Science