ROLE OF WEIGHT AND ACOUSTIC PARAMETERS, INCLUDING NATURE OF CHORUSING, IN THE MATING SUCCESS OF MALES OF THE KATYDID, AMBLYCORYPHA-PARVIPENNIS (ORTHOPTERA, TETTIGONIIDAE)

Amblycorypha parvipennis Stal males are unique chorusers; adjacent males alternate 4-5 s phrases frequently overlapping the end of a partner's phrases and where phrases overlap, phonatomes (phrase subunits) are synchronized. We explored the effect of weight and a number of sound parameters, including frequency, intensity, temporal parameters and phrase phase relationships during chorusing, on male mating success using laboratory tests in which single females were exposed to pairs of chorusing males. Females mated with males that were heavier, louder, and overlapped their partner's phrases less when in the presence of a sexually-receptive (sound-producing) female. Male spermatophore weight was correlated with male body weight; this suggests that females may choose heavier males to obtain larger spermatophores (10-20% of male's wet body weight) upon which females feed. Sound level rather than sound frequency may be important in mating success because competing males produce sounds in close proximity to competitors and females and this proximity negates the environmental degradation of sound level over greater distances. The reduction in the rate at which eventual successfully mating males overlap unsuccessful males in the presence of a female suggests that males compete to reduce the rate at which they overlap the end of a competitor's phrases. This ability, as well as weight and sound level, appears to be utilized by females or competitors in determining the "superior" male.