Factors Affecting the Distribution and Survival of Endangered American Burying Beetles, \u3ci\u3eNicrophorus americanus\u3c/i\u3e Olivier

The disappearance of the federally endangered American burying beetle (Nicrophorus americanus Olivier) over most of its range is poorly understood, which is why the identification and evaluation of conservation measures is important. The presence and distribution of all carrion beetles in Nebraska was first reported to help understand where American burying beetles (ABBs) occur to aid in creating a habitat suitability model for the Sandhills ecoregion and to locate suitable experiment areas. There are 18 Nebraska counties with records of ABB presence in the last 15 years. The final habitat suitability model performed well with an AUC value above 0.8 and will be a functional tool in implementing conservation measures. There were eight variables that best fit the presence and absence of ABBs. Loamy sand, variable soil textures, wetland, and easting as a surrogate of precipitation were found to be positively correlated with ABB presence; whereas, loam soil, agriculture, woodland, and development were negatively correlated. Experiments testing the effectiveness of bait away methods revealed that bait stations did not draw significant numbers of ABBs out of mock “construction” zones and did not successfully keep ABBs at bait stations. Even with the use of vertebrate excluder cages, there was mortality caused by northern leopard frogs (Lithobates pipiens Schreber), and without the cages, video captured opossum (Didelphis virginiana (Kerr)) consuming ABBs at a bait station. Bait away stations should no longer be used to clear areas of ABBs for habitat alteration. In Nebraska, a large portion of the known ABB distribution overlaps with distributions of economically damaging grasshoppers that are managed using Dimilin and Malathion pesticides. Dimilin was found to have some negative effects on N. orbicollis Say brood success when carcasses were exposed to the pesticide and then later used for larval development. Malathion caused direct mortality of N. marginatus Fabricius, a diurnal species, when sprayed directly, but would be unlikely to directly harm nocturnal ABBs. Indirectly, Malathion on a carcass might stress parental beetles and cause changes in brood size. Dimilin use should be restricted to periods with little ABB aboveground activity until further research can pinpoint the associated risks. Advisors: W. Wyatt Hoback and Shripat T. Kambl