DIFFERENTIAL MATING SUCCESS OF VIRGIN FEMALE KATYDIDS REQUENA-VERTICALIS (ORTHOPTERA, TETTIGONIIDAE)

Male katydids (Orthoptera: Tettigoniidae) invest in offspring through nutrients provided in a large spermatophore. Previous research with Requena verticalis had shown that almost all of the investment of males mating with recently mated (4 days previously) females is in eggs fertilized by the female's previous mate. Thus males are predicted to discriminate against such females as mates. In experiments placing males with both a virgin and a female mated 4-5 days previously, virgin females obtained almost all matings. Although male discrimination of mates was noted in the experiments, there was no evidence that such discrimination was against nonvirgins in both this experiment and one in which a single virgin or mated female was placed with a male. Instead, the results suggest that the differential mating was a result of interfemale competition. The mating advantage held by virgin females over nonvirgins appeared to be lost once the latter had oviposited. Finally, there was no evidence from both single-and paired-female experiments that males preferred larger females as mates.