Male seminal fluid proteins are essential for sperm storage in Drosophila melanogaster

The seminal fluid that is transferred along with sperm during mating acts i n many ways to maximize a male's reproductive success. Here, we use transge nic Drosophila melanogaster males deficient in the seminal fluid proteins d erived from the accessory gland (Acps) to investigate the role of these pro teins in the fate of sperm transferred to females during mating. Competitiv e PCR assays were used to show that while Acps contribute to the efficiency of sperm transfer, they are not essential for the transfer of sperm to the female. In contrast, we found that Acps are essential for storage of sperm by females. Direct counts of stored sperm showed that 10% of normal levels are stored by females whose mates transfer little or no Acps along with sp erm.