MALE MATING SUCCESS IN THE PRESENCE OF A CONSPECIFIC OPPONENT IN A MADAGASCAR HISSING COCKROACH, GROMPHADORHINA-PORTENTOSA (DICTYOPTERA, BLABERIDAE)

The influence of a conspecific competitor on male mating behavior was examined in a Madagascar hissing cockroach, Gromphadorhina portentosa. Previous studies have suggested that both male-male competition and f emale discrimination during courtship interactions may influence male mating success. Familiar pairs of males with a known social associatio n were placed in an arena with a single virgin female and observed. As expected, subordinate males mated significantly less often than their dominant opponents. In pairs in which one male mated, dominant indivi duals limited the access of subordinates to females. Dominant males di splayed an increased frequency and duration of interaction with the fe male. However, in pairs where both males remained unmated, the mating behavior of dominant and subordinate males did not differ significantl y. As interactions progressed, as in the case of males that remained u nmated, subordinate males gained increased access to the female. Mated males tended to be larger than their opponent although within a rank, males that mated were no larger than those that remained unmated. The se results are discussed in light of the possible roles of male-male c ompetition and female discrimination during courtship interactions.