A Preliminary Study on the Abundance, Seasonality, and Sampling Patterns of Amblyomma americanum (Acari: Ixodidae) in Central Missouri

Abstract

Amblyomma americanum (Ixodida: Ixodidae) is Missouri's most common tick species and a carrier of bacterial pathogens. The objectives of this study were to analyze tick abundance and seasonality in two locations in central Missouri, to compare the effectiveness of dragging and dry ice trap sampling methods for collecting A. americanum in the field, and to analyze tick developmental stage collection pattern. We collected ticks from Knob Noster State Park, in Johnson County, Missouri and Mark Twain National Forest, in Boone County, Missouri. On eight dates from May to November, we collected ticks simultaneously at both locations, using dry ice traps and drag sampling. Of the 7,475 collected ticks, 99.7% were A. americanum. We found the most larvae in August and September, the most nymphs in June and July, and the most adults in June. Drag sampling collected more nymphs at Columbia than Knob Noster on one sampling date in the late summer. Abundance did not differ between locations at any other time point, regardless of developmental stage or sampling method. Compared to the drag method, significantly more nymphs and adults were identified using the dry ice trap sampling method. Additionally, we found that nymphs and adults were more likely to be found in the same areas of the sampling locations, but neither larvae and adults nor nymphs and larvae followed this relationship. Our findings demonstrate a strong seasonality of A. americanum in Missouri and support dry ice trapping as an effective sampling method for collecting all of its life stages.