The linkage between a phase change in cuticular lipids and accelerated water loss is defined as critical transition temperature (CTT), a characteristic in ticks reputed for implying habitat preference and serving as a cue to regulate water levels during feeding. The CTT is based on activation energy (Ea) describing the effect of temperature (T) change on the rate of water loss (k) by the Arrhenius equation, k = A exp — Ea/RT. Typical CTT expression in American dog tick, Dermacentor variabilis, and lone star tick, Amblyomma americanum, occurs at 35–40 °C in the adult and 30–35°C in the larva (used for their lack of spiracles). Removing cuticular lipids from ticks produced higher evaporative losses, but this did not ablate or modify CTT or corresponding values of Ea. What changed was frequency (steric) factor A, simply as an integrated measure of increased water loss from the delipidizing treatment. This first analysis of the actual animal, rather than a cuticular lipid extract, demonstrates the failure of Ea to respond to artificially increased water loss rates, allowing for the role of cuticular lipids in tick water-proofing to be separated from CTT and the Ea.
|Number of pages||7|
|Journal||International Journal of Acarology|
|State||Published - 2005|
Bibliographical noteFunding Information:
Funding for this research was provided, in part, by competitive undergraduate research grants from Wittenberg University.
- Activation energy
- Critical transition temperature
- Water balance
ASJC Scopus subject areas
- Insect Science