Age-Related Sperm Production, Transfer, and Storage in the Sweet Potato Weevil, Cylas formicarius (Fabricius) (Coleoptera: Curculionidae)

Sperm Supply from the Testes to the Seminal Vesicle over Consecutive Matings in the Sweetpotato Weevil, <i>Cylas formicarius</i> (F<sub>ABRICIUS</sub>) (Coleoptera: Curculionidae)

“…This weevil is polyvoltine and reproduce all the year except for winter (Kohama 1990). Male adults, if given 10 virgin female adults, mate on average 4 or 5 times per night, irrespective of the male's age [4]. Mean copula duration of 10-day-old male adults (51 min) is significantly shorter than that that of 30-day-old (74 min) and that of 50-day-old (79 min) male adults [4].…”

“…Young 10-day-old males ejaculates 7636 sperms on average while 50-day-old adults ejaculates do 61720. The total number of sperm in both testes and the seminal vesicle increases with adult age [4]. As the mass of free sperm in the seminal vesicle increases with adult age (Hiroyoshi, unpublished data), the number of free sperm in the seminal vesicle appears to increase until there is no more capacity.…”

“…The length of the vas deferens differs in species, resulting in the differences of distance between the testes and the seminal vesicle. In the sweetpotato weevil, Cylas formicarius Fabricius) (Coleoptera: Curculionidae), both the testes and the seminal vesicle are very close to each other and both store free sperm [4] The vas deferens of this weevil is connected with ejaculatory duct. The positional relationship between the testes and the seminal vesicle, however, is unclear.…”

“…Male adults, if given 10 virgin female adults, mate on average 4 or 5 times per night, irrespective of the male's age [4]. Mean copula duration of 10-day-old male adults (51 min) is significantly shorter than that that of 30-day-old (74 min) and that of 50-day-old (79 min) male adults [4]. Young 10-day-old males ejaculates 7636 sperms on average while 50-day-old adults ejaculates do 61720.…”

“…As the mass of free sperm in the seminal vesicle increases with adult age (Hiroyoshi, unpublished data), the number of free sperm in the seminal vesicle appears to increase until there is no more capacity. The number of sperm ejaculated increases with adult age at first mating [4]. This suggests that old male adults transfer large numbers of sperm along with accessory gland substances to females, whereas young males transfer fewer sperm.…”