Submitted to: Journal of Medical Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/6/2003
Publication Date: 2/18/2003
Citation: Carroll, J.F., Solberg, V.B., Klun, J.A., Kramer, M., Debboun, M. 2003. Comparative activity of deet and AI3-37220 repellents against the tick ixodes scapularis and amblyomma americanum (acari:ixodidae) in laboratory bioassays. Journal of Medical Entomology. 41:249-254. Interpretive Summary: The blacklegged tick, Ixodes scapularis, is the principal vector of Lyme disease in the eastern half of the U. S., and the lone star tick, Amblyomma americanum, can transmit monocytic ehrlichiosis. Most recommendations for personal protection against tick bite, include the use of repellents. Deet is the most widely used repellent approved for use on human skin, but relatively little is known about its efficacy against ticks. We evaluated the effectiveness of deet and AI3-37220, a promising ARS-developed repellent, against nymphs of I. scapularis and A. americanum. We used 2 laboratory behavioral tests with ticks on horizontal and vertical filter paper treated with repellent. Both repellents were more effective against I. scapularis than A. americanum. Deet was more effective than AI3-37220 against I. scapularis in both the horizontal and vertical tests, but AI3-37220 was more effective than deet against A. americanum in the vertical tests. These tests provide baseline data, against which novel repellents can be compared and selected for field testing. The public and Department of Defense will ultimately benefit from this study, because it will lead to the development of new and more effective tick repellents.
Technical Abstract: The repellents N,N-diethyl-3-methylbenzamide (deet) and 2-methylpiperidinyl-3-cyclohexene-1-carboxamide (AI3-37220) were evaluated using 2 different laboratory bioassays to determine their relative effectiveness against host-seeking nymphs of the blacklegged tick, Ixodes scapularis Say, and the lone star tick, Amblyomma americanum L. In a petri dish bioassay, ticks were released within a ring of repellent on a horizontal filter paper disk. In the second bioassay, ticks were allowed to climb a vertical strip of filter paper whose central portion was treated with a repellent. Deet and AI3-37220 were more effective against I. scapularis than A. americanum nymphs. In the petri dish bioassay, none of the concentrations of deet or AI3-37220 tested confined A. americanum within the treated ring. However, in the vertical bioassay, both species exhibited avoidance of the repellents, and I. scapularis was repelled by much lower doses than A. americanum. Ixodes scapularis were repelled by lower doses in the vertical bioassay than in the petri dish bioassay. Deet was slightly more effective against I. scapularis than AI3-37220 in both bioasays, but AI3-37220 was significantly more effective than deet against A. americanum in the vertical bioassay.