Effect Of Prothoracicostatic Peptide On Sperm Dimorphism In Bombyx Mori

Insects have become the largest population in the animal kingdom because of their strong reproductive capacity,in which the reproductive system plays an important role.In the field of traditional Entomology,the researches on female reproductive system are more than that of male.In recent years,the testis in the male reproductive system has attracted much attention as an organ that produces sperm and provides a place for its growth and development.Bombyx mori,the model insect of Lepidoptera in Insecta,was used in this study.On this basis of the research on the development of silkworm testis and spermatozoa,the relationship between insect brain neuropeptides and silkworm reproductive system is studied,which can not only further understand the law of insect growth and development,but also open a new way for pest control.The main research contents and results are as follows:1.Correlation analysis between the development of silkworm testis and the change of body shapeIn this study,the body length,body width,body mass and testis axis of the 4th instar to the moth stage of silkworm were measured and analyzed.The results showed that there was no correlation between the short axis of testis and the body length from the 4th instar to prepupa,but there was significant correlation between long/short axis of testis and the body length,the body width and the body mass from the 4th instar to the moth stage.This suggests that body size may affect the size of the testis of insects,which in turn affects male fecundity.2.Perfection of sperm dimorphismIn this study,the sperm development of male silkworm from the 4th instar to moth stage was observed.The results showed that in the 4th and 5th instar of male silkworm's testis,eupyrene sperm bundles mainly occurred.In pupal stage,the occur of apyrene sperm bundles and the peristalsis and extrusion of the two kinds of spermatozoa formed mature spermatozoa.Eupyrene sperm and apyrene sperm with head and tail disbanded in female spermatheca after mating.This is the place where the two sperm bundles can be completely disbanded.From the male testis to the female spermatophore,the motile sperms completely separated from the bundles were observed,which further perfected the development process of dimorphism of Bombyx mori.3.The effect of PTSP on the growth and spermatogenesis of silkwormIn this study,PTSP was injected into silkworm to observe the effects of PTSP on the growth and development of silkworm,and the sperm development was observed by indirect immunofluorescence technique.The feeding amount of silkworm injected with PTSP was significantly increased,the larval stage was prolonged by 24 hours,and the wandering stage was prolonged by 12 hours.The mortality rate was as high as56.7%,which had no significant effect on cocoon shell rate and hatching rate.The results showed that the peristalsis and extrusion of eupyrene sperm bundles and the appearance of apyrene sperm bundles were delayed,and the number of eggs laid by male mating with wild female decreased in the treatment group.The results showed that PTSP injection into the silkworm could increase the mortality and decrease the number of eggs laid,but it would not affect the cocoon production significantly.In this way,it could not only kill Lepidoptera pests,but also not affect the economic value of the silkworm.PTSP has the potential to become a new non-toxic biological pesticide.