SOMATIC CONDITION DETERMINES FEMALE MATING FREQUENCY IN A FIELD POPULATION OF THE GRASSHOPPER EYPREPOCNEMIS-PLORANS

Mating pairs and nonmating individuals of the grasshopper Eyprepocnemi s plorans were collected in a natural population during the 1992 seaso n, in order to determine whether sexual preferences of males and femal es are correlated with various morphological and physiological charact ers. These included condition based on body size and somatic and gonad al weight. A comparison of frequency distributions for these character s between the two types of individuals showed that mating frequency (t he probability of being sampled while mating) was independent of the c haracters measured in males but was highly significantly dependent on somatic condition in females. Mating females showed a better somatic c ondition (defined as the residuals of the regression of somatic weight on body size) than nonmating ones. The implications of this finding i n shaping the polygynandrous mating system of this species are discuss ed.