A quantitative comparison of two sample methods for collecting Amblyomma americanum and Dermacentor variabilis (Acari: Ixodidae) in Missouri.

In studies of tick communities, sampling methodology may influence observed patterns. The objective of this study was to compare two sampling methods, dragging and dry ice baiting, in two habitats to assess abundance of off-host ticks. Tick communities were monitored from March to December in a forested and an old-field habitat in northeast Missouri. In each habitat, eight drag and eight dry ice bait samples were collected every 2 weeks on a permanent grid. The most common ticks collected were all life stages of Amblyomma americanum L. and adult and larval Dermacentor variabilis Say. Capture data was analyzed to determine if there were differences due to sampling method, habitat or an interaction for each life stage of each species across the entire monitoring period. Data indicate that there were differences in the methods. Significantly more A. americanum nymphs were captured by bait sampling. Dragging captured significantly more larval A. americanum. Significantly more larval and nymphal A. americanum and larval D. variabilis were caught in the forest, whereas significantly more adult D. variabilis were collected in the field. Significant interaction between site and method was found for A. americanum adults and D. variabilis larvae. These differences are likely due to differences in behavior among species and developmental age that interact with microclimate. These data indicate that community monitoring studies should use multiple sampling methodologies to avoid bias. While comparing these methods, the first documented collection of off-host Ixodes scapularis Say in Adair County, Missouri was made.