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# Immersion Tolerance in Rangeland Grasshoppers (Orthoptera: Acrididae)

Mathew L. Brust, W. W. Hoback and R. J. Wright
Journal of Orthoptera Research
Vol. 16, No. 2 (2007), pp. 135-138
Stable URL: http://www.jstor.org/stable/20066576
Page Count: 4
Population fluctuations of short-horned grasshoppers have been linked to the interactions of numerous factors including precipitation, temperature, vegetative growth, latitude, and timing of rainfall events. In some areas, grasshopper populations decline with increased moisture, potentially as a result of direct mortality from raindrops, or from indirect factors including the increase of fungal pathogens. Grasshoppers may also become submerged by flooding events and suffer mortality from drowning. However grasshopper survival of immersion has not been quantified in controlled experiments. We tested nymph and adult survival of immersion of seven species of rangeland grasshoppers. Under laboratory conditions, the $\text{LT}_{50}$ of adult grasshoppers ranged between 7.5 and 21 h, while nymphs had an $\text{LT}_{50}$ of between 3 and 13 h. Survival times indicate that mortality associated with seasonal rainfall is rarely caused by immersion. The significant resistance to hypoxia by these grasshoppers is not strongly correlated with habitat association and may instead be correlated with life history traits associated with overwintering.