Mortality of two beetles, Araecerus levipennis Jordan and Mimosestes sallaei (Sharp) in field populations

Abstract

The anthribid, Araecerus levipennis Jordan, has been the subject of a comprehensive investigation by Sherman and Tamashiro (1956), who considered starvation on dry seeds and "predation" by a mite to be the most important causes of death. Cushman (1911) and Bridwell (1919 & 1920) made some observations on the bionomics of the bruch1d, Mimosestes sallaei (Sharp), but their records of mortality were limited to parasite rearings. Although neither A. levipennis nor M. sallaei have been subjects of detailed mortality studies, research similar to that which is described in this dissertation was conducted by Varley (1947) and Harville (1955) on fly and moth populations respectively. Preliminary work in the present study included descriptions of the climate and vegetation in ten research areas on leeward Oahu. In addition, notes were made on the systematics, bionomics, and competitors of A. levipennis and M. sallaei. There were also several phases in the actual mortality studies. It was first necessary to identify and categorize the causes of death. Then, appropriate sampling and autopsy techniques were developed, these techniques being used in collections and experiments. The collections were of two kinds; sequential, in which pods were gathered at one location as a crop matured; and periodic, in which samples were taken at regular intervals from four of the research areas. Finally, mortality was measured not only in undisturbed populations but also in those which had been experimentally reduced below the normal infestation levels.