|Allan, Sandra - Sandy|
Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2001
Publication Date: 1/1/2002
Citation: ALLAN, S.A., SONENSHINE, D.E. EVIDENCE OF AN ASSEMBLY PHEROMONE IN THE BLACK-LEGGED DEER TICK, IXODES SCAPULARIS. JOURNAL OF CHEMICAL ECOLOGY. 2002. v. 28(1).p. 15-27. Interpretive Summary: The tick, Ixodes scapularis, is the most predominant vector of Lyme disease in North America. Despite its importance, relatively little is known about various aspects of its behavior, including chemicals used for attracting other ticks. Such chemicals can be used in conjunction with other control strategies to develop alternative methods for control, possibly even methods that do not rely on conventional insecticides. This study was conducted by Sandra Allan, currently a USDA Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, Florida employee. An assembly pheromone was discovered in this species. This pheromone results in the assembly of unfed nymphs and adults in the area where the pheromone is present. The pheromone was present in hexane extracts of molted skins of ticks. Chemicals that elicited the same response included guanine, inosine, xanthine, uric acid, hypoxanthine and hematin. This study provides the first evidence of an assembly pheromone in Ixodes scapularis which may provide the basis for alternative control methods of this tick.
Technical Abstract: The responses of Ixodes scapularis nymphs and adults to extracts of cast larval skins were tested in a petri dish bioassay. Assembly was elicited in nymphs and adults in the presence of skins, exudate from ticks and filter paper exposed to ticks compared to untreated controls. Assembly was noted by one hour after exposure with little change between 1 and 24 hours. .The assembly response increased in the presence of an increased number of skins. Similar assembly was elicited in nymphs and adults in the presence of cast larval skins and a saline (0.95 percent NaCl) skin extract. Methanol and hexane extracts were not attractive. When chemical standards were tested against nymphs, they responded to guanine, uric acid, hypoxanthine, xanthine, inosine and hematin. Adults were tested against guanine, inosine and xanthine and all elicited significant assembly. Responses of nymphs increased significantly with increase in dose of uric acid and guanine. Responses of nymphs to a mixture of guanine: xanthine and adenine (25:1:1 ratio) were similar to responses to cast skins. This study provides the first evidence of an assembly pheromone in I. scapularis. These pheromones in conjunction with acaricide may provide the basis for development of targeted control strategies for I. scapularis.