|Allan, Sandra - Sandy|
Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2003
Publication Date: 10/15/2003
Citation: Sonenshine, D.E., Adams, T., Allan, S.A., Mclaughlin, J., Webster, F.X. 2003. Chemical composition of some components of the arrestment pheromone of the black-legged tick, ixodes scapularis (acari: ixodidae) and their use in tick control. Journal of Medical Entomology.
Interpretive Summary: Ixodes scapularis is one of the most important tick species in North America due to its status as a vector of Lyme disease, ehrlichiosis and babesiosis. Relatively little is known of pheromones of this species and their potential for use in developing control strategies. In this study, which was conducted by a scientist at the Center for Medical, Agricultural, and Veterinary Entomology in Gainesville in cooperation with scientists at Old Dominion University, IPM Technologies, and the State University of New York, the potential use of pheromones in conjunction with a pesticide was examined for this species. Various compounds including guanine, xanthine, 8-azaguanine and hematin were identified from extracts and found to elicit strong arrestant responses in several stages of ticks. When these compounds were incorporated in a controlled-release matrix with permethrin, mortality of ticks was significantly greater that those exposed to the permethrin-impregnated matrix only. This information provides the basis for development of a pheromone-based control strategy for this tick species.
Technical Abstract: Chemical analysis and bioassays demonstrated the presence of compounds that appear to be components of the I. scapularis arrestment pheromone. Two purines, guanine and xanthine were found in saline extracts of cast skins following molting and fecal/excretory exudates deposited by unfed adults. Guanine and xanthine were the only purines found in the cast skin extracts. Guanine, xanthine and traces of 8-azaguanine, were found in extracts made from filter paper strips or washings from glass vials contaminated with tick feces and excreta. 8-azaguanine may be a product of microbial degradation of the other purines rather than a natural product from the ticks. Low concentrations of ammonia were detected in saline extracts and found in NH4OH extracts of exudate. A strong positive arrestment response was seen in bioassays to cast skins found to contain a mixture of guanine and xanthine and to black fecal/excretory exudates containing guanine, xanthine, 8-azaquanine and hematin. Video tracking analysis showed statistically significant increases in the frequency of visits to the treated zone versus the control. Ticks were significantly more likely to assemble in response to the tick exudates within as little as 3 hours as compared to the controls. When combined with a permethrin-impregnated matrix, Last CallTM, inclusion of pheromone components increased the lethal activity to 95% compared to 65% in the formulation with permethrin alone. More detailed knowledge of I. scapularis arrestment pheromone may be useful for improving the efficacy of this tick-killing technology even further.