Effect Of Diallyl Trisulfide On Sperm Quality Of Sitotroga Cerealella(Olivier)

Sitotroga cerealella Olivier（Lepidoptera:Gelechiidae）,is one of the three majors stored product pests in China（Sitophilus zeamais Motschulsky,S.cereallela Olivier,Rhizopertha dominica）,which causes serious economic loss of stored products globally.Previous studies proved that diallyl trisulfide（DAT）,an active substance from garlic essential oil(LC₁₀=0.01μL/L),effectively inhibits the oviposition of female moth without affecting the mating behavior,however,the actual mechanism is still unknown.Here,we reported the regulation of DAT at the dose of LC₁₀on the spermatophore morphology,sperm quantity and sperm vitality of the male by fumigation in glass bottle.Also,the transcriptome data from males treated with DAT were analyzed,and the lipid drop,triglyceride and cholesterol content were measured according to the results of differentially expressed genes.The main results are as follows:1)Effect of DAT on the sperm quality of the male mothsThe spermatophore in a virgin female transferred from DAT-treated males was significantly smaller than that from controls（CK）.The rate of effective spermatophore and the diameter of spermatophore were decreased significantly compared with those of controls.Meanwhile,the number of sperm bundles in spermatophore was decreased significantly according to paraffin section.Additionally,the number and vitality of sperm of a double ejaculatory tube from treated males and the spermatophore in females transferred from treated males were significantly reduced.There were no significant difference observed in sperm morphology,however,the length of sperm in the double ejaculatory tube was significantly longer than that in the spermatophore.Besides,the dynamic changes of sperm number in spermatophore also showed that the number of eusperm and apyrene were significantly less after DAT treatment than CK groups at any time,and sperm in DAT group were utilized by females earlier post-mating compared with CK groups.In post-mating,the amount of sperm in the double ejaculatory tube of male could recover continuously,but the total number of sperm in DAT groups was always more than that of CK groups and the number of eusperm in the double ejaculatory tubules of males,either CK or treated groups,was decreased significantly at the first post-mating,which was less than pre-mating one.2)Analysis of transcriptome dataThe transcriptome data of males treated with DAT showed that the differentially expressed genes（DEGs）were mainly enriched in the pathway of protein catabolic process,regulation of DNA/RNA metabolic process,Circadian rhythm,Fatty acid biosynthesis,MAPK signaling pathway and so on.Four up-regulated target genes（TGL,HSL,TIM,CRY）were chosen,respectively.The results showed that TGL and HSL were expressed in larval and adult stage,reproductive tissues（accessory gland and testis）and fat body of adult,but relatively higher expressed in adult fat body.After DAT treatment,the expression of TGL and HSL were significantly upregulated（2-4 times）,which showed that these genes might have an important role in the lipid metabolism pathway.Meanwhile,the results showed that TIM and CRY functioning in circadian rhythm pathway are expressed not only in larval and adult stage,but also in the head,testis and accessory gland of the male,suggesting that there may be a circadian rhythm regulatory network in the head and reproductive tissues to regulate the growth and development of insects.Several indexes of lipid metabolism were also tested in the study.The results showed that DAT could accelerate the process of lipid metabolism,the lipid drop was significantly empty in the fat body,and the content of triglyceride were significantly decreased,but no significant change was observed in cholesterol contents.In conclusion,DAT could reduce the sperm quality in the double ejaculatory tube of the male by accelerating the lipid metabolism rate and disturbing the circadian rhythm network,and affect the“mating content”transported to the female by mating,decrease the sperm quality of spermatophore,and finally decline the fertility of the moth.The above results provide a theoretical basis for the regulation mechanism of DAT against the reproduction of male.