Scavenging Behavior of Rangeland Grasshoppers (Orthoptera: Acrididae): Rubidium-Label Studies

Abstract

Scavenging on grasshopper cadavers by other grasshoppers is a common phenomenon that might provide an efficient mechanism for disease transmission. Field-cage studies were conducted in Montana to quantify the consumption of cadaver tissues by various members of the grasshopper community. Caged grasshoppers were exposed to Rb-enriched cadavers for 24-32 h. Atomic absorption spectrophotometry was used to quantify the concentration of Rb in tissues of the feeding grasshoppers. The probability of feeding on cadavers, the average amount of Rb assimilated (micrograms), and the resultant tissue concentrations of Rb (parts per million) among feeders, increased with the weight of the live grasshoppers. The increase in Rb concentrations indicates that larger grasshoppers consumed more Rb per gram of body weight. These results are consistent with behavioral observations that larger grasshoppers were more likely to find cadavers and defend them against intruders. The implications of these competitive interactions for pathogen epizootiology in grasshopper communities are discussed.