THE EFFECT OF REPEATED MATINGS ON SPERM NUMBERS IN SUCCESSIVE EJACULATES OF THE CABBAGE WHITE BUTTERFLY PIERIS-RAPAE (LEPIDOPTERA, PIERIDAE)

The effect of repeated matings on sperm numbers in successive ejaculat es of the cabbage white butterfly, Pieris rapae, was examined. First e jaculates were larger than successive ones, which did not differ among themselves. Moreover, the cumulative mass of previous spermatophores was not correlated with that of the last mating. The number of eupyren e sperm bundles in the ejaculate did not differ between first and succ essive matings. Multiplying by 256 a male transfers about 11,000 eupyr ene sperm at every mating. First ejaculates contained about 46,000 apy rene sperm, whereas successive ejaculates contained higher numbers. Th e sperm density increased after the first mating, though the spermatop hore mass decreased. The significance of change in sperm quantity with mating number is discussed from the viewpoint of male investment.