Similar to Ixodes scapularis and Amblyomma americanum ticks, female D. occidentalis ticks harbored a less diverse array of bacteria than males (Fig. 2) (Ponnusamy et al., 2014; Van Treuren et al., 2015). Endosymbionts belonging to Rickettsia, Coxiella, Francisella and Arsenophous genera have been found in different tick species and are thought to interfere with and partially exclude other bacteria and pathogenic forms of closely related organisms from transovarial transmission leading to lower alpha diversity in female ticks than males (Burgdorfer & Brinton, 1975; Macaluso et al., 2002; Niebylski, Peacock & Schwan, 1999; Noda, Munderloh & Kurtti, 1997; Reinhardt, Aeschlimann & Hecker, 1972; Telford III, 2009). In D. occidentalis, a higher percentage of Rickettsia and Francisella in the microbiomes of female ticks than male ticks may have similarly decreased species richness in female ticks compared to males (Fig. 2).