Underwater survival in the dog tick Dermacentor variabilis (Acari:Ixodidae)

• Published in: Journal of insect physiology Vol. 57; no. 1; pp. 21 - 26
• Main Authors: Fielden, Laura J., Knolhoff, Lisa M., Villarreal, Susan M., Ryan, Philip
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 2011
• Subjects: Animals; Arthropoda; Cell Survival; Dermacentor variabilis; Ixodidae; Ixodidae - physiology; Oxygen - metabolism; Plastron; Spiracle; Underwater survival; Water - parasitology; Dermacentor variabilis; Plastron; Spiracle; Ixodidae; Underwater survival
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/j.jinsphys.2010.08.009

Ticks are blood-feeding arthropods known for their long survivability off the host. Although ticks are terrestrial, they can survive extended periods of time submerged underwater. A plastron is an alternative respiration system that can absorb oxygen from water via a thin layer of air trapped by hydrophobic hairs or other cuticular projections. The complex spiracular plate of ticks has been postulated to serve as a plastron but that function has not been verified. This study provides evidence of plastron respiration in the American dog tick, Dermacentor variabilis, and for the first time confirmed the existence of plastron respiration in Ixodidae. Longer survival rates in oxygenated water indicate that underwater respiration requires oxygen. Wetting the spiracular plate with alcohol debilitates any potential plastron function and lowers the survival rate. Survival underwater may also be enhanced by metabolic depression and possibly anaerobic respiration. This study describes the first example of plastron respiration in the Ixodidae. [Display omitted] ▶ Ixodid ticks can survive underwater for 15 days. ▶ They use plastron respiration to extract oxygen from the water. ▶ The perforated spiracular plates are the site of plastron respiration. Ticks are blood-feeding arthropods known for their long survivability off the host. Although ticks are terrestrial, they can survive extended periods of time submerged underwater. A plastron is an alternative respiration system that can absorb oxygen from water via a thin layer of air trapped by hydrophobic hairs or other cuticular projections. The complex spiracular plate of ticks has been postulated to serve as a plastron but that function has not been verified. This study provides evidence of plastron respiration in the American dog tick, Dermacentor variabilis, and for the first time confirmed the existence of plastron respiration in Ixodidae. Longer survival rates in oxygenated water indicate that underwater respiration requires oxygen. Wetting the spiracular plate with alcohol debilitates any potential plastron function and lowers the survival rate. Survival underwater may also be enhanced by metabolic depression and possibly anaerobic respiration. This study describes the first example of plastron respiration in the Ixodidae.