Entomology, Department of


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Published in Journal of Orthoptera Research 2007, 16(2): 135-138. Copyright 2007. Used by permission.


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 LT50 of adult grasshoppers ranged between 7.5 and 21 h, while nymphs had an LT50 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.

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