Entomology, Department of
Date of this Version
Four studies were conducted on dung beetles (Coleoptera: Scarabaeidae), which are insects of great ecological and economic importance. Range management practices were found to impact dung beetle diversity and abundance. While sampling on organic and conventionally managed ranches in Nebraska, 93% (5,767) of total dung beetle capture was from the organically managed ranch. Only 480 dung beetles (7% of total) were collected from the conventionally managed ranch. Results indicated that organic ranching had increased numbers and diversity of dung beetles.
Comparison of the attractiveness of native and exotic herbivore, carnivore, and omnivore dung yielded 9,089 dung beetles from 15 species. Significant differences were observed in mean dung beetle capture and individual species preference among the dung of omnivores, herbivores, and carnivores. Omnivore dung and carrion were most attractive; however, preference for a specific dung type was not correlated with dung quality or mammalian diet.
Dung beetles are exposed to hypoxic conditions throughout much of their life cycle. Data on hypoxia tolerance of five species of adult dung beetle (Aphodius haemorrhoidalis, Canthon pilularius, Melanocanthon nigricornis, Onthophagus hecate, and Phanaeus vindex) yielded no differences in mean survival time (LT50) among behavioral groups, which ranged from 7-37 hours.
Digitonthophagus gazella (F.) has been intentionally released in numerous areas around the world. Using amplified fragment length polymorphism (AFLP) analysis, genetic variation was examined between two populations of D. gazella from South Africa and Vieques, Puerto Rico. Analysis of molecular variance (AMOVA) revealed 69% of genetic diversity to be within populations, while 31% of genetic diversity was between the populations indicating little gene flow. Genetic diversity was high in both South Africa and Vieques with no evidence of inbreeding depression on Vieques. These data are helpful in understanding the population dynamics of dung beetles through knowledge of the effects of agricultural practices, niche separation, and genetics.
A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree Doctor of Philosophy, Major: Entomology, Under the Supervision of Professors W. Wyatt Hoback and John E. Foster. Lincoln, Nebraska: December, 2011
Copyright (c) 2011 Sean Doyle Whipple