Feeding density influences acquisition of Borrelia burgdorferi in larval Ixodes scapularis (Acari: Ixodidae).

The intensity of Borrelia burgdorferi transmission in nature is dependent upon the efficiency of acquisition of spirochetes by larval Ixodes scapularis Say (= I. dammini Spielman, Clifford, Piesman & Corwin). White-footed mice infected with B. burgdorferi were infested weekly for 5 consecutive weeks with 25 or 250 larval I. scapularis. Prevalence of infection in nymphs derived from larvae fed at high density (25.0-38.9%) was consistently higher than in nymphs derived from larvae fed at low density (6.7-23.5%). Spirochete prevalence in nymphal I. scapularis populations in nature may be influenced by larval population density.