In general,crab receives copious quantities of seminal fluid during mating,and stores them in special seminal receptacles,viz.spermatheca,for a prolonged period.The spermatheca of the advanced brachyuran crabs has bee...In general,crab receives copious quantities of seminal fluid during mating,and stores them in special seminal receptacles,viz.spermatheca,for a prolonged period.The spermatheca of the advanced brachyuran crabs has been described for many species.The spermatheca is a dilation of the proximal region of the oviduct connecting it to the ovary.The vagina leads from the base of the spermatheca and opens outside the ovipore.Some crabs have the special structure,such as valve-like tissue,bursa,intermediate chamber.The seminal secretion delivered during mating has been shown to undergo a kind of solidification inside the spermatheca,giving rise to a structure called "sperm plug".In some species the sperm plug extends into the vagina and even protrudes from the vulva.The role of a sperm plug is not certain,but it has been assumed that it helps to prevent the loss of sperm after copulation.The sperm viability during prolonged storage is an interesting question,the seminal substances,together with spermathecal secretions,could provide nutrients and antibacterial substance for sperm maintenance.The anaerobic environment of spermatheca and the unmature spermatozoa for storage are also the reason for survival in spermatheca.In brachyuran crabs where multiple mating occurs,there is sperm competition for fertilization.Some study revealed the existence of another type spermatophore with smooth and thin spermatophoric walls,so differences in the morphology of the spermatophoric wall were directly related to the degree of dehiscence of spermatophores upon copulation,which supports the hypothesis of different fertilization.So the quantity of ejaculate stored in spermathecae does not necessarily correlate with the mating success of the female,but may also depend on the type of spematophores and their quantity transferred at the previous mating.In the brachyura,sperm transfer and storage mechanisms are related to the type of fertilization.Whether is internal or external needs more research on the fertilization of egg in spermathecae..展开更多
Phytoseiulus persimilis is an important biological control agent, commercially produced worldwide. To increase understandings of its reproduction, herein we provided quantitative descriptions of the inflation and defl...Phytoseiulus persimilis is an important biological control agent, commercially produced worldwide. To increase understandings of its reproduction, herein we provided quantitative descriptions of the inflation and deflation of its spermathecae as a function of time and copulation duration, and the quantitative impact of copulation termination on volume of spermatheca vesicle, fecundity, and offspring sex ratio. After mating started, at least one spermatheca started to inflate immediately, but no egg was produced until spermatheca volume reached 1 021 μm3. Beyond this size, cumulative fecundity was linearly correlated with vesicle volume. Producing one egg required 36 μm3 volume increase of the vesicle. Each spermatheca vesicle reached its peak size at the end of mating duration(ca. 2.38 h after mating started), and started to shrink immediately. In 24 h, ca. 71% individuals had one completely shriveled spermatheca, while in 72 h all individuals had at least one shriveled spermatheca. The estimated maximum cumulative fecundity per female after a single mating is(69.4±7.7) eggs. No significant impact of mating termination on offspring sex ratio was observed after mating duration reached 60 min, while higher proportion of male offspring was observed when mating duration is 15 or 30 min. This study is the first step to investigate possible male impact on offspring sex ratio in P. persimilis. Our results suggested the number of sperms received during mating be a restriction factor of P. persimilis offspring sex ratio regulation.展开更多
文摘In general,crab receives copious quantities of seminal fluid during mating,and stores them in special seminal receptacles,viz.spermatheca,for a prolonged period.The spermatheca of the advanced brachyuran crabs has been described for many species.The spermatheca is a dilation of the proximal region of the oviduct connecting it to the ovary.The vagina leads from the base of the spermatheca and opens outside the ovipore.Some crabs have the special structure,such as valve-like tissue,bursa,intermediate chamber.The seminal secretion delivered during mating has been shown to undergo a kind of solidification inside the spermatheca,giving rise to a structure called "sperm plug".In some species the sperm plug extends into the vagina and even protrudes from the vulva.The role of a sperm plug is not certain,but it has been assumed that it helps to prevent the loss of sperm after copulation.The sperm viability during prolonged storage is an interesting question,the seminal substances,together with spermathecal secretions,could provide nutrients and antibacterial substance for sperm maintenance.The anaerobic environment of spermatheca and the unmature spermatozoa for storage are also the reason for survival in spermatheca.In brachyuran crabs where multiple mating occurs,there is sperm competition for fertilization.Some study revealed the existence of another type spermatophore with smooth and thin spermatophoric walls,so differences in the morphology of the spermatophoric wall were directly related to the degree of dehiscence of spermatophores upon copulation,which supports the hypothesis of different fertilization.So the quantity of ejaculate stored in spermathecae does not necessarily correlate with the mating success of the female,but may also depend on the type of spematophores and their quantity transferred at the previous mating.In the brachyura,sperm transfer and storage mechanisms are related to the type of fertilization.Whether is internal or external needs more research on the fertilization of egg in spermathecae..
基金supported by the National Key R&D Program of China(2017YFD0200400)the National Natural Science Foundation of China(31701850)the Basal Research Fund of Chinese Academy of Agricultural Sciences(Y2016PT13)
文摘Phytoseiulus persimilis is an important biological control agent, commercially produced worldwide. To increase understandings of its reproduction, herein we provided quantitative descriptions of the inflation and deflation of its spermathecae as a function of time and copulation duration, and the quantitative impact of copulation termination on volume of spermatheca vesicle, fecundity, and offspring sex ratio. After mating started, at least one spermatheca started to inflate immediately, but no egg was produced until spermatheca volume reached 1 021 μm3. Beyond this size, cumulative fecundity was linearly correlated with vesicle volume. Producing one egg required 36 μm3 volume increase of the vesicle. Each spermatheca vesicle reached its peak size at the end of mating duration(ca. 2.38 h after mating started), and started to shrink immediately. In 24 h, ca. 71% individuals had one completely shriveled spermatheca, while in 72 h all individuals had at least one shriveled spermatheca. The estimated maximum cumulative fecundity per female after a single mating is(69.4±7.7) eggs. No significant impact of mating termination on offspring sex ratio was observed after mating duration reached 60 min, while higher proportion of male offspring was observed when mating duration is 15 or 30 min. This study is the first step to investigate possible male impact on offspring sex ratio in P. persimilis. Our results suggested the number of sperms received during mating be a restriction factor of P. persimilis offspring sex ratio regulation.
