Term of Award

Spring 2010

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Biology

Committee Chair

Lance A. Durden

Committee Member 1

Oscar Pung

Committee Member 2

Edward Mondor


Ectoparasite size can be influenced by many factors; one is host size. Harrison's rule states that larger hosts typically have larger parasites. In this study, sucking lice (Insecta: Anoplura) were used to test this rule. Sucking lice should provide a good test for this rule because they are generally host-specific and because, as a group, they parasitize hosts of different sizes. Also, sucking lice use their tibio-tarsal claws to grasp host hairs, therefore, correlations between claw size and host hair diameters were also tested. Raw analyses including 206 species of slide-mounted sucking lice from throughout the world, followed by analyses of phylogenetically subtracted data, were used to test the hypotheses that sucking louse body size is correlated with host body size and that sucking louse claw size is correlated with host hair diameters. Data from 3 separate louse families, Hoplopleuridae, Linognathidae and Polyplacidae, were also analyzed. Lice, their claws, and hairs were measured using a calibrated graticule fitted into the eyepiece of a compound microscope. The combined raw data showed that louse body and claw size were positively correlated with host body and hair size, respectively. However, after phylogenetic subtraction, the overall data showed that another indicator of louse size, female louse second tarsal segment length, was positively correlated to host body mass and length. However, male louse thorax width was negatively correlated to host body length. Within the family Hoplopleuridae, both male and female louse thorax width were significantly correlated with host body mass and length, as well as, second tarsal segment length and host body length. Within the family Polyplacidae, male and female thorax width was positively correlated to host body length. Phylogenetically subtracted data revealed significant positive correlations for the families Hoplopleuridae and Polyplacidae between indicators of host and louse size but not between host hair diameters and louse claw measurements. Overall, the data show sucking lice have adapted morphologically to their hosts and conform to Harrison's rule.

Research Data and Supplementary Material