A deeper look into the morphology and receptors found in the tick (Acari: Ixodidae) chemoperception structure, the Haller's organ

The Haller's organ is a sensory structure unique to ixodid ticks that assists in host seeking behaviors. Presented here are the results of a detailed comparative study of the morphology and the chemoperception gene expression of the Haller’s organ. The morphometrics study focuses on the three important North American tick species: Ixodes scapularis, Amblyomma americanum, and Dermacentor variabilis. Possible differences in morphology between and within these species and between males and females for each species were observed using environmental scanning electron microscopy (ESEM). Analyses using geometric morphometrics resulted in low levels of intraspecific, within sex variation in the morphology of Haller’s organ and high variation between species. Differences between species may be due to different host seeking behaviors (passive versus active). The differences in Haller’s organ morphology of males and females of the same species could be attributed to post-mating behaviors. The exploration of chemoperception gene expression in the Haller’s organ focused on a single species, Ixodes scapularis. This study focused on the expression of ionotropic (IR) and gustatory receptors (GR) in the forelegs of male and female ticks. Additionally, two phylogenetic trees were created corresponding to each receptor type. The phylogenetic trees show the orthology between the tick ionotropic and gustatory receptors and the described insect chemoreceptors. There were two I. scapularis IRs expressed in the forelegs of these ticks and five GRs of interest. This research aids in providing an increase in our knowledge of the Haller’s organ. The Haller’s organ is critical to the performance ability of tick activities including host location. Therefore, improved knowledge of the Haller’s organ may facilitate tick management.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Entomology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Josek, Tanya

Contributors dc:contributor

• Robertson, Hugh M.
• Alleyne, Marianne
• Allan, Brian F.

• Haller’s organ
• ticks
• geometric morphometrics
• chemoperception expression

Statement dc:rights

• Copyright 2015 Tanya Josek

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/88299

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/88299