Intrasexual Competition and Mating Behavior in Ptomascopus morio (Coleoptera:

In nicrophorine beetles, genus Nicrophorus care their larva using small ver-tebrate carrion, whereas genus Ptomaucopus reproduce with small verte-brate carrion but show no parental care. Aggression and sexual behavior were examined in Ptomascopus morio and Nicrophorus quadripunctatus. Nicrophorus quadripunctatus had intense female–female as well as male– male contests. In Ptomascopus morio, by contrast, female–female aggres-sion was rarely observed. Male–male aggression (pushing, biting, male–male mounting) in Ptomascopus morio was observed when a resource for breed-ing was present, whether or not a female was present. The lack of female– female aggression, andmale–male aggression when resources but not females are present, suggest that the mating system of Ptomascopus morio is resource defense polygyny. Large males of Ptomascopus morio were also found to exhibit mate choice, preferring large females over small females