Stimulation of attachment in a camel tick, Hyalomma dromedarii (Acari: Ixodidae): the unintended result of sublethal exposure to permethrin-impregnated fabric.
The susceptibility of a camel tick, Hyalomma dromedarii (Koch), to permethrin-impregnated military uniform fabric was studied to determine the effects of laundering and contact time. Separate contact toxicity tests were conducted with laboratory-colonized male and female ticks of uniform age. Unfed, unmated ticks were exposed for periods of 5, 10, 30, and 60 min to each of five fabrics: unwashed-untreated, unwashed-treated, and 1, 2, or 3 times washed after treatment (1-, 2-, 3-wash-treated). Treated fabric was impregnated with permethrin at 0.125 mg (AI)/cm2. Laundering was by machine washing with detergent followed by hot air machine drying. Intoxication immediately after exposure was assessed by activity response: the proportion of ticks attaching to a host (rabbit) within 60 min and the average time elapsed between contact and insertion of mouthparts. Unexpectedly, permethrin exposure activated an attachment response in both sexes. At all contact times, and in each wash-treated group, a greater proportion of ticks attached, and did so more rapidly, than in controls. Mortality assessment 24 h after exposure showed that females were more tolerant than males and experienced light mortality even after 60 min of contact. Both natural and acquired factors may account for permethrin tolerance in this species. Consistent with pyrethroid mode of action and pheromone function in ticks, it is hypothesized that sublethal levels of permethrin may act on H. dromedarii to induce premature or excess release of a neurosecretory substance that elicits attachment.
Fryauff
D J
DJ
Medical Zoology Branch, U.S. Naval Medical Research Unit No. 3, PSC 452, FPO, AE 09835-0007.
Shoukry
M A
MA
Schreck
C E
CE
D000818:Animals; D003020:Clothing; D005069:Evaluation Studies as Topic; D005260:Female; D007299:Insect Bites and Stings / Q000453:epidemiology; D007846:Laundering; D008297:Male; D026023:Permethrin; D011722:Pyrethrins; D011817:Rabbits; D013987:Ticks / Q000502:physiology*
D011722:Pyrethrins; D026023:Permethrin