Nymphal Ixodes dammini: models of the temporal abundance patterns

Area of Science:

• Ecology
• Epidemiology
• Mathematical Biology

Background:

• Ixodes dammini nymphs are crucial vectors for diseases like Lyme disease.
• Understanding their seasonal activity patterns is vital for predicting disease transmission risk.
• Previous models have not fully explored the sensitivity of nymphal activity dynamics.

Purpose of the Study:

• To develop a difference equation model to analyze the temporal abundance of active, host-seeking Ixodes dammini nymphs.
• To investigate the sensitivity of nymphal activity patterns to variations in recruitment, mortality, and host-finding.
• To identify key factors driving the shape and timing of nymphal activity.

Main Methods:

• Developed a difference equation model simulating nymphal Ixodes dammini populations.
• Input parameters included temporal patterns and cumulative levels of nymph recruitment, mortality, and host acquisition.
• Varied input parameters to assess sensitivity of output patterns (shape and peak timing).

Main Results:

• Nymphal abundance pattern shape was insensitive to host-finding function shape.
• Peak nymphal abundance timing showed slight sensitivity to host-finding and mortality levels.
• Earlier peak activity observed with increased tick removal (higher host-finding or mortality).
• Activity pattern shape was sensitive to nymph recruitment temporal patterns, with left-skewed recruitment best matching field data.

Conclusions:

• The temporal recruitment pattern of nymphs is a critical determinant of their seasonal activity.
• While host-finding and mortality influence peak timing, their impact is less significant than recruitment.
• Further empirical research on nymphal recruitment dynamics is recommended for accurate modeling.