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Water-loss rates in Nicrophorus marginatus and the implications for trapping of N. americanus

Water-loss rates in Nicrophorus marginatus and the implications for trapping of N. americanus. W. Wyatt Hoback University of Nebraska at Kearney. What Limits the Western Range of ABB?. Observed mortality in traps during August Bedick, Lincoln County No apparent damage

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Water-loss rates in Nicrophorus marginatus and the implications for trapping of N. americanus

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  1. Water-loss rates in Nicrophorus marginatusand the implications for trapping ofN. americanus W. Wyatt Hoback University of Nebraska at Kearney

  2. What Limits the Western Range of ABB? • Observed mortality in traps during August • Bedick, Lincoln County • No apparent damage • Dehydration and desiccation?

  3. Experiments • Tested N. marginatus • High and low humidity • Effects of temperature • Compared to other similar-sized beetles

  4. N. marginatus • Most common burying beetle in Nebraska • Day active • Habitat generalist • Large size range

  5. Wet Dry

  6. Measured time to 50% mortality • Beetles in containers with drierite or with water-soaked cottonballs • 5 temperatures tested

  7. Time to 50% Mortality for N. marginatus 30 d 20 c 50 LT b ab 10 a 0 12 16 20 24 28 Temperature (oC)

  8. Exposed beetles to direct contact with drying agent • Tested the effects on water loss rates • Also tested beetles that were killed with cyanide • Also tested beetles which had openings sealed with wax

  9. Water Loss of N. marginatus at 12 C 12 Exposed 10 Away 8 % Water Loss 6 4 2 0 0 2 4 6 8 10 12 Hours

  10. Water Loss of N. marginatus at 20 C 32 28 Exposed 24 Away 20 % Water Loss 16 12 8 4 0 0 2 4 6 8 10 12 Hours

  11. Water Loss of N. marginatus at 28 C 45 40 Exposed 35 Away 30 25 % Water Loss 20 15 10 5 0 0 2 4 6 8 10 12 Hours

  12. N. marginatus compared to other beetles • Pasalidae (Bess beetle) • Moist wood-dwelling large beetle • Predicted high water loss rates • Giant tiger beetle (Amblycheila) • Nocturnally active tiger beetle • Inhabitant of dry areas

  13. 40 N. marginatus O. disjunctus 30 A. cylindriformis % water-loss 20 10 0 0 2 4 6 8 10 Hours of exposure

  14. N. marginatus Activity Pattern

  15. Dry Traps Kill Beetles • Burying beetles lose water at very high rates • Frogs • Maintaining a layer of moist soil in a trap prevents desiccation

  16. Implications • Soil moisture content and relative humidity may begin to define the western edge of the beetle’s range. • Reintroductions may not be possible in some states within the beetles historic range due to severe habitat changes.

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