Date of Graduation


Document Type


Degree Name

Doctor of Philosophy in Entomology (PhD)

Degree Level





Ashley P.G. Dowling

Committee Member

Robert Wiedenmann

Second Committee Member

Marlis R. Douglas

Third Committee Member

David Krementz


Host specificity, Molothrus ater, Nasal mites, Phylogeny, Ptilonyssus, Rhinonyssidae


Nasal mites are endoparasites that spend their entire life cycle inside the nasal cavities and respiratory passages of birds. The Brown-Headed cowbird (Molothrus ater) (BHCO) is an icterid bird that uses brood parasitism as a reproductive strategy in which it lays an egg in the nest of a different bird species and allows the host to raise its young. Interestingly, nasal mites reported from cowbirds represent the same species found infesting other icterids and other common host groups. In the first study, I examined how diversity and host prevalence might change in a large sample size of BHCO associated with three of the four migratory flyways of North America. I could identify 11 different species of nasal mites and there was an overall prevalence of 89% of infestation from 856 birds. Moreover, prevalence was not different by location or by bird sex, suggesting that patterns of nasal mite infestation in BHCO occur similarly in all locations.

The second study included questions of genetic differentiation in BHCO hosts that are isolated by geographical locations. For this, a phylogenetic analysis was conducted for the two most common nasal mites (Ptilonyssus icteridius and P. agelaii) that infest BHCO using the mitochondrial 16S, ITS, and COI. We showed that location did not affect the genetic composition of the nasal mites, which suggests a constant movement and mixing of BHCO by which they could be acquiring their nasal mites when socializing in large flocks either during winter or breeding season.

The third study focused on a phylogenetic analysis of the nasal mites from the genus Ptilonyssus (Rhinonyssidae). The analysis included different nasal mite species infesting passerine hosts in the US. Sequences from the 16S gene were amplified and relationships showed species of mites with different levels of host specificity with their host and also some variation in species with similar morphology. In conclusion, more studies on these parasites infesting bird populations are required to understand the biology, taxonomy, and relationships of these nasal mites.