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Ticks Tick Borne Dis. 2017 Aug;8(5):764-771. doi: 10.1016/j.ttbdis.2017.06.001. Epub 2017 Jun 13.

Infrared light detection by the haller's organ of adult american dog ticks, Dermacentor variabilis (Ixodida: Ixodidae).

Author information

1
Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC, 27695-7647, USA. Electronic address: rdmitche@ncsu.edu.
2
Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC, 27695-7647, USA. Electronic address: jzhu4@ncsu.edu.
3
Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC, 27695-7647, USA. Electronic address: alcarr2@ncsu.edu.
4
Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC, 27695-7647, USA. Electronic address: adhammi@ncsu.edu.
5
Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC, 27695-7647, USA. Electronic address: glcave@ncsu.edu.
6
Department of Biological Sciences, Old Dominion University, Norfolk, VA, 23529, USA. Electronic address: dsonensh@odu.edu.
7
Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC, 27695-7647, USA. Electronic address: michael_roe@ncsu.edu.

Abstract

The Haller's organ (HO), unique to ticks and mites, is found only on the first tarsus of the front pair of legs. The organ has an unusual morphology consisting of an anterior pit (AP) with protruding sensilla and a posterior capsule (Cp). The current thinking is that the HO's main function is chemosensation analogous to the insect antennae, but the functionality of its atypical structure (exclusive to the Acari) is unexplained. We provide the first evidence that the HO allows the American dog tick, Dermacentor variabilis, to respond to infrared (IR) light. Unfed D. variabilis adults with their HOs present were positively phototactic to IR. However, when the HOs were removed, no IR response was detected. Ticks in these experiments were also attracted to white light with and without the HOs, but were only positively phototactic to white light when the ocelli (primitive eyes) were unobstructed. Covering the eyes did not prevent IR attraction. A putative TRPA1 receptor was characterized from a D. variabilis-specific HO transcriptome we constructed. This receptor was homologous to transient receptor potential cation channel, subfamily A, member 1 (TRPA1) from the pit organ of the pit viper, python, and boa families of snakes, the only receptor identified so far for IR detection. HO scanning electron microscopy (SEM) studies in the American dog tick showed the AP and Cp but also novel structures not previously described; the potential role of these structures in IR detection is discussed. The ability of ticks to use IR for host finding is consistent with their obligatory hematophagy and has practical applications in tick trapping and the development of new repellents.

KEYWORDS:

American dog tick; Dermacentor variabilis; Haller’s organ; Infrared; Light; TRPA1

PMID:
28647127
PMCID:
PMC5588665
DOI:
10.1016/j.ttbdis.2017.06.001
[Indexed for MEDLINE]
Free PMC Article

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