The Effect Of Mulberry Leaf Surface Dust On The Intestinal Flora And Digestion Of Silkworm

Xinjiang is an important channel of the "Silk Road".The silkworm industry was introduced into Xinjiang before the 7th century.It has a long history of sericulture.The unique natural and geographical conditions have created a unique way of sericulture in Xinjiang.It needs water to wash away the dust on the surface of mulberry leaves in order to feed silkworm normally.However,the impact of dust on the surface of mulberry leaves on silkworm is limited to experience,There is no clear related discussion.In order to investigate the effects of dust and moisture in mulberry leaves on silkworm in southern Xinjiang,three controllable experimental designs,namely feeding mulberry leaves directly,washing and drying mulberry leaves and washing and high humidity mulberry leaves,were used to study the diversity of intestinal microorganisms,morphological structure of midgut and peritrophic membrane of silkworm by 16S rDNA high-throughput sequencing and paraffin section,and analyze the effects on feed utilization rate and cocoon quality.The results are as follows:(1)Taking Huakang No.3 and Suyou No.1 as test objects,it was found that Proteobacteria was dominant in intestinal flora at phylum level;At the family level,Enterobacteriaceae and Burkholderiaceae are the dominant families;Erwinia,Aquabacterium and Tyzzerella-3 are the dominant genera in genus classification.Compared with the control group,the content of Erwinia was the highest in the high humidity mulberry leaf feeding group and the lowest in the sandy mulberry leaf feeding group;Enterococcus widely existed in the group fed with sandy mulberry leaves,but hardly existed in the group fed with high humidity mulberry leaves.Compared with the control group,the content of Aquabacterium in suyou-1 was significantly higher than that in the other two groups;Enterococcus only existed in the group fed with mulberry leaves,but not in the other two groups;Acinetobacter was only found in the normal mulberry leaf feeding group,but not in the other two groups.(2)Taking the midgut and peritrophic membrane of silkworm Huakang No.3 and Suyou No.1 as the observation samples,it was found that the secretory activity of the midgut of silkworm was the strongest under the condition of clean mulberry leaves feeding,and the midgut morphology was different under the condition of sandy mulberry leaves feeding,even no peritrophic membrane was observed.Under the condition of washed mulberry leaves,the peri feeding membrane of silkworm variety Huakang No.3 was multilayer and dense,and the midgut secretion activity was strong;The morphology of midgut was different under the condition of high humidity mulberry leaf feeding,but the peritrophic membrane was close to the epithelial cells of midgut;Under the condition of feeding with mulberry leaves,the midgut cells were dense and formed three cavities,and there were almost no mulberry leaves in the peritrophic membrane;Therefore,fine sand has the greatest effect on the midgut of silkworm;Suyou No.1,a silkworm variety,had the highest level of digestive activity under the condition of clean mulberry leaves feeding.The morphology of midgut cells was different under the condition of sandy mulberry leaves feeding.The thickness of midgut digestive tract wall was thicker than the other two groups,and the peritrophic membrane was discontinuous.(3)Both Huakang No.3 and Suyou No.1 are suitable for rearing in Xinjiang silkworm area under high humidity mulberry leaves in summer,and the dust on mulberry leaves has a great influence on their feed efficiency.There was no significant difference in the adaptability of Huakang No.3 between the two seasons,indicating that the climate of summer and autumn in Xinjiang had little effect on Huakang No.3,but the high humidity mulberry leaf feeding effectively improved the conversion efficiency of cocoon weight in autumn and the amount of food consumed in summer.The fine sand mulberry leaf feeding had a greater impact on the feed efficiency of silkworm,and the feed efficiency was reduced by half compared with the control group.Suyou No.1 was reared in summer.It was found that the variety had the largest amount of mulberry leaves,the highest digestibility,and higher cocoon weight conversion efficiency and cocoon layer production efficiency than the control group.