Water-loss rates in Water-loss rates in Nicrophorus Nicrophorus marginatusmarginatus
and the implications for trapping ofand the implications for trapping ofN. americanusN. americanus
W. Wyatt HobackUniversity of Nebraska at Kearney
What Limits the Western Range of ABB?
• Observed mortality in traps during August– Bedick, Lincoln County
• No apparent damage• Dehydration and desiccation?
Experiments
• Tested N. marginatus – High and low humidity– Effects of temperature– Compared to other similar-sized beetles
N. marginatus• Most common burying
beetle in Nebraska• Day active• Habitat generalist • Large size range
WetWet DryDry
Measured time to 50% mortality
• Beetles in containers with drierite or with water-soaked cottonballs
• 5 temperatures tested
12 16 20 24 28
Temperature (oC)
0
10
20
30LT
50
Time to 50% Mortality for N. marginatus
aabb
c
d
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
0 2 4 6 8 10 12
Hours
0
2
4
6
8
10
12%
Wat
er L
oss
Water Loss of N. marginatus at 12 C
ExposedAway
0 2 4 6 8 10 12
Hours
0
4
8
12
16
20
24
28
32%
Wat
er L
oss
Water Loss of N. marginatus at 20 C
ExposedAway
0 2 4 6 8 10 12
Hours
05
1015202530354045
% W
ater
Los
s
Water Loss of N. marginatus at 28 C
ExposedAway
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
0 2 4 6 8 10
Hours of exposure
0
10
20
30
40%
wat
er-lo
ssN. marginatus
A. cylindriformis
O. disjunctus
N. marginatus Activity Pattern
Time (h)
Num
ber o
f N
. mar
gina
tus
020406080
100120140160180200220240260
Dawn
Dusk
0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00
Dry Traps Kill Beetles
• Burying beetles lose water at very high rates– Frogs
• Maintaining a layer of moist soil in a trap prevents desiccation
ImplicationsImplications• Soil moisture content and relative Soil moisture content and relative humidity may begin to define the humidity may begin to define the western edge of the beetle’s range.western edge of the beetle’s range.
• Reintroductions may not be possible in Reintroductions may not be possible in some states within the beetles historic some states within the beetles historic range due to severe habitat changes.range due to severe habitat changes.
