A1 Refereed original research article in a scientific journal
One out of ten: low sampling efficiency of cloth dragging challenges abundance estimates of questing ticks
Authors: Nyrhilä Siiri, Sormunen Jani J, Mäkelä Satu, Sippola Ella, Vesterinen Eero J, Klemola Tero
Publisher: SPRINGER
Publication year: 2020
Journal: Experimental and Applied Acarology
Journal name in source: EXPERIMENTAL AND APPLIED ACAROLOGY
Journal acronym: EXP APPL ACAROL
Volume: 82
Issue: 4
First page : 571
Last page: 585
Number of pages: 15
ISSN: 0168-8162
eISSN: 1572-9702
DOI: https://doi.org/10.1007/s10493-020-00564-5
Web address : https://doi.org/10.1007/s10493-020-00564-5
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/50295862
Hard ticks (Acari: Ixodidae) act as important vectors of zoonotic pathogens. For instance, Borrelia burgdorferi s.l. spirochetes pose a severe health risk as aetiological agents of Lyme borreliosis. Commonly, to study the abundance of questing (host-seeking) ticks, a 1 m(2) piece of cloth is dragged over vegetation for a determined distance. Here, we designed a tick-sampling study to estimate the sampling efficiency of this standard method. We established 10 m dragging transects in a hemiboreal mixed forest patch in SW Finland for a 5-day monitoring period. Five of the transects were cloth-dragged 3x a day, whereas another five transects were dragged 6x a day in a manner that after each morning, midday and afternoon dragging, a second dragging was conducted on the same transect immediately. Captured Ixodes ricinus ticks were subsequently analysed for tick-borne pathogens. The initial population size of nymphal ticks on a transect was approximated by the accumulated nymph catch from the dragging sessions. The sampling efficiency of the cloth dragging was low, as a single dragging in a previously untouched vegetation strip always caught less than 12% (mean 6%) of the estimated population of active nymphs that were assumed to be questing during the study. Clear results were not found for daily activity rhythm, as ticks were caught in all daily dragging sessions. Approximately every third nymph and every second adult carried a pathogen, but nothing indicated that the occurrence of a pathogen affected the likelihood of the tick being caught by cloth dragging. Our results suggest that only a minority of active ticks can be caught by a single cloth dragging. The abundance estimates in many tick investigations might thus be downward biased.
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