AGGRESSIVE INTERACTIONS AND FEEDING SUCCESS OF SCAVENGING GRASSHOPPERS (ORTHOPTERA, ACRIDIDAE)

Scavenging of arthropod tissue by grasshoppers has been hypothesized t o be an important aspect of their diet selection and an important rout e of pathogen transmission. By placing grasshopper cadavers in the fie ld, we determined that the frequency distributions of nymphs and adult s of different species observed scavenging differed from that in the l ocal grasshopper community. Only four of the 10 species present in swe ep samples were observed scavenging grasshopper cadavers. The largest species, Melanoplus packardii Scudder tended t be present among scaven gers in proportions much greater than its representation in the commun ity. The most abundant species at the two research sites, Melanoplus s anguinipes F. and Aulocara elliotti (Thomas) tended either to be under represented in the scavenger samples or to be present in proportions e qual to those in the community. Access to the cadavers was strongly re lated to success in aggressive interactions among grasshoppers congreg ating at feeding sites. We observed both intra- and interspecific comp etitive interactions among grasshoppers. Using a logistic regression m odel that took into account the size differences among contestants and the species involved in each interaction, we found a good match betwe en the observed and expected number of fights won by each species/sex/ developmental stage class. M. packardii and M. sanguinipes tended to w in fights when they were matched against smaller opponents, but A. ell iotti lost more fights than expected from their size alone. Neither se x nor status of the contestants as resident and intruder at a cadaver had a significant effect on the outcome of interactions.