Grasshopper egg mortality mediated by oviposition tactics and fire intensity |
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Authors: | DAVID H BRANSON LANCE T VERMEIRE |
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Institution: | U.S. Department of Agriculture, Agricultural Research Service, Northern Plains Agricultural Research Laboratory, U.S.A.;and U.S. Department of Agriculture, Agricultural Research Service, Livestock and Range Research Laboratory, U.S.A. |
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Abstract: | Abstract. 1. It is commonly assumed that arthropod species living or hibernating in the soil would not be affected by grassland fires, even though burning results in elevated surface and below-ground soil temperatures. The importance of elevated below-ground soil temperatures during fires on the survival of grasshopper eggs had not been examined. 2. The effects of simulated autumn grassland fires of varying intensities on below-ground egg mortality were examined with grasshopper species laying shallow egg pods ( Ageneotettix deorum ) and deeper egg pods ( Melanoplus sanguinipes ) to test the hypothesis that exposure to heat during fires was the mechanism responsible for population reductions in A. deorum following fire. 3. Species-specific oviposition characteristics mediated the effects of fire intensity on below-ground egg mortality. The results indicate that fires occurring in areas with at least 3100 kg ha?1 standing crop biomass would be expected to significantly reduce populations of A. deorum , but not M. sanguinipes . No A. deorum eggs hatched in 12 of the 14 oviposition containers subjected to simulated fires approximating a standing crop biomass of 4500 kg ha?1. This is the first study to link field observations of rangeland insect populations following fire to mechanisms related to below-ground egg mortality. |
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Keywords: | Ageneotettix deorum burning egg mortality fire grasshopper Melanoplus sanguinipes Orthoptera |
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