| Summary: | 碩士 === 國立臺南大學 === 環境生態研究所碩士班 === 99 === In pasture ecosystem, dung beetles can decompose animal’s dung and accelerate nutrient cycle, also able to control the population size of coprophagous flies, reduce the transmission of disease. This research proceeded dung beetles and of coprophagous flies investigation in the Ken-Ting and Xinhua pasture from April 2009 to October 2010. And investigated the individual morphology, life history, tunnel type, reproduction and decomposed rate of dung in Onthophagus rectecornutus, as biological control and management at pasture in the future of reference. Totally 9 species in 3 genera of dung beetles and 6 species in 6 genera of coprophagous flies were caught in Ken-Ting pasture. Totally 4 species in 8 genera of dung beetles and 5 species in 5 genera of coprophagous flies were caught in Xinhua pasture. Community structure showed no difference of dung beetles and coprophagous flies in these two pastures.
There are significant differences in body size and horn length between male and female beetles. There are significant differences in horn length and head width between gender adults of F1 generation. Whether captured from field or F1 generation have significantly positive correlation of body size with the horn length and head width, and the F1 generation of body size were significantly greater than field individuals. The life history, oviposition period is about 1.84 ± 0.60 days, egg period is 2.62 ± 0.65 days, growth period of first-instar larvae about 2.18 ± 0.43 days, 2nd-instar larvae about 2.53 ± 0.69 days, 3rd-instar larvae about 5.93 ± 0.98 days, pupa stage about 12.58 ± 1.80 days, and that the number of male individuals increased with the adult emergence number. The life span of male was about 66.54 ± 28.77 days, female was about 94.56 ± 44.24 days. There are significantly different in life span between male and female beetles. O. rectecornutus can make one entrance tunnels with branching or without branching, or with several entrance tunnels, nd different tunnels converging to the same brood mass. The brood mass average diameter is 12.88 ± 0.09 mm, average volume is 1150.84 ± 22.17 mm3. Under 2, 4, 8, 16 and 32 adults can used 34 %, 47 %, 53 %, 66 % and 87 % of 200 g dung after two weeks, and decomposed rate of dung by the five groups of the adults showed significant difference.
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