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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICAL, CHEMICAL AND MOLECULAR APPROACHES TO REDUCING TICK BITES AND TICK-BORNE DISEASES Title: An increasing presence: the lone star tick, Amblyomma americanum

Author
item Carroll, John

Submitted to: The Maryland Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 16, 2011
Publication Date: October 8, 2011
Citation: Carroll, J.F. 2011. An increasing presence: the lone star tick, Amblyomma americanum. The Maryland Entomologist. 5:66-76.

Interpretive Summary: Because of its expanding range and capacity to transmit the pathogen causing human monocytic ehrlichiosis, the lone star tick, Amblyomma americanum, is a serious human health problem. In the course of flagging for the purpose of collecting large numbers of A. americanum nymphs, some relatively small areas (less than 5 by 5 meters) were found to yield 300-500 nymphs. One or two denser concentrations of ticks were found within the 5 by 5 meter areas. A possible explanation for such high concentrations of host-seeking A. americanum nymphs may lie in the tendency of larvae to stay in clusters of hundreds of individuals allowing large numbers of ticks to infest a large host (deer) simultaneously. Although all these larvae do not complete feeding and drop off the host in perfect synchrony, hundreds can drop off in a period of hours. Thus, if peak drop off coincided with a time when a deer was bedding or stationary for a while, a large concentration of fed larvae of limited mobility would be deposited in a small area, where they develop into nymphs. These findings are of interest to scientists researching tick ecology and control.

Technical Abstract: In June and July, 2006 and 2007, flagging with the purpose of collecting large numbers of lone star tick, Amblyomma americanum, nymphs revealed hyper-dense foci of host-seeking nymphs occupying areas =5 by 5 m. Nymphs were concentrated in one or two core areas within the 5 by 5 m. It is unlikely that standard flag/drag sampling protocols would reveal the magnitude and dimensions of such foci. A possible explanation for such high concentrations of host-seeking A. americanum nymphs may lie in the tendency of larvae to remain in clusters of hundreds of individuals, so that large numbers of ticks may infest a large host simultaneously. Although all these larvae do not complete feeding and drop off the host in perfect synchrony, hundreds can drop off in a period of hours. Thus, if peak drop off coincided with a time when a large host, such as a deer, was bedding or stationary for a while, a large concentration of fed larvae of limited mobility would be situated in a small area, where they develop into nymphs.

Last Modified: 4/19/2014