Evidence for the Role of Ecdysteroids in the Genital Sex Pheromone of Two species of Hard Ticks, <i>Dermacentor variabilis</i> (Say) and <i>Dermacentor andersoni</i> Stiles

<p>Neutering of part-fed females virtually eliminated copulatory behavior in <em>Dermacentor variabilis</em> and<em> D. andersoni</em> males. Extracts from the anterior reproductive tracts (ART) of part-fed (7 days) females restored the male copulatory behavior in conspecific neutered females, suggesting the presence of a genital sex pheromone (GSP). Similar extracts from unfed females did not restore the behavior, suggesting that the pheromone was produced during feeding. Perception of the GSP by sensillae on the male cheliceral digits was confirmed by electrophysiological techniques.</p> <p>Ecdysteroids, specifically ecdysone and 20-OH-ecdysone were shown to be present in the anterior reproductive tracts in excess of amounts that could be explained by mere hemolymph contamination. Ecdysteroids were also found in washings of the vaginal lumen of these two species. <em>D. andersoni</em> females contained larger amounts of ecdysteroids than <em>D. variabilis</em> females. Males of <em>D. variabilis</em> and <em>D. andersoni</em> responded positively to authentic ecdysone, and 20-OH-ecdysone in neutered female bioassays and electrophysiological assays. The strongest responses were to 20-OH-ecdysone in both species. No response was found with sterols. 20-OH-ecdysone and possibly ecdysone appear to be components of the genital sex pheromone (GSP) of <em>D. variabilis</em> and <em>D. andersoni</em>. Species recognition is facilitated by these components, but the complete mechanism is not yet fully understood. The importance of ecdysteroids in the evolutionary development of chemical communication systems in Arthropoda is also discussed.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biological Sciences

Year dc:date.available

1989

Author dc:creator

• Taylor, DeMar

Contributors dc:contributor

• Daniel E. Sonenshine
• Keith A. Carson
• Roy L. Williams

• Pheromones
• Dermacentor
• Ticks
• Ecology and Evolutionary Biology
• Entomology

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).</p>

Repository record dc:identifier

https://digitalcommons.odu.edu/biology_etds/104

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:biology_etds-1103