Study On The Diversity Of Gut Bacteria In Ectropis Obliqua And The Interaction Between The Gut Bacterial And EGCG In Tea Leave

Insect gut bacteria play an important role in host feeding,digestion,immune and fitness.Studying on the relationship between the feed,gut microbial microbiota and the fitness of Ectropis obliqua is of relatively high theoretical value for the management of E.obliqua.The main results as follows:1.Effects of feed types on gut bacterial diversity and larval survival rate of Ectropis obliqua.In this part of the experiment,we compared the effects of pure artificial diet and tea leaves on the fitness and gut microbiota of the larvae of E.obliqua.The results showed that the survival rate of larvae fed with pure artificial diet(62.86%)was significantly lower than that fed with tea leaves(100%).Using next generation sequencing technology,we assessed the diversity and richness of gut bacterial communities of E.obliqua larvae.At the phylum level,Firmicutes was the dominant phylum in both groups(Pure artificial diet:78.59%vs.Tea leaves:79.62%),followed by Proteobacteria(Pure artificial diet:10.44%vs.Tea leaves:78.44%),and Bacteroidetes(Pure artificial diet:2.88%vs.Tea leaves:3.32%).At the genus level,Enterococcus was the dominant genus in the Pure artificial diet group(74%)followed by Weissella(1.54%),and Streptococcus(0.86%).For the tea leaves group,Enterococcus was the dominant genus(75.50%),followed by Rhodococcus(0.75%)and Parabacteroides(0.67%).In addition,the diversity and richness of gut microbiota of larvae fed with pure artificial diet were significantly higher than those fed with fresh tea leaves.2.The effects of different tea components on the survival of the larvae of Ectropis obliqua.In this part of the experiment,we added different concentrations(0.5%?1%?1.5%?2%?2.5%and 3%)of EGCG and two concentrations(0.5%and 1%)Caffeine into artificial diet to observe and record the survival rate of larvae.The results showed that the survival rate of larvae fed with low concentration EGCG(0.5%,1%,1.5%and 2%)diet increased from 62.86%to more than 88%.High concentration EGCG feed(2.5%and 3%)was not conducive to the survival of larvae.When the concentration of EGCG was 3%,all larvae died.Besides,caffeine is not conducive to larval survival.3.Effects of EGCG on the fitness and gut bacterial of E.obliqua larvae.In this part of the experiment,we compared the effects of EGCG treatment and artificial feed treatment on the larvae of E.obliqua.The results showed that EGCG treatment significantly increased the pupa weight,eclosion rate and survival rate of larvae.From the perspective of gut bacteria,we found that EGCG could significantly reduce the species and quantity of gut bacteria in larvae,and inhibit the colonization of pathogenic bacteria in gut.In this study,we demonstrated that changing the feed types of the E.obliqua larvae could significantly affected the survival of the larvae and the structure of gut bacteria;And we also demonstrated that EGCG can effectively improve the fitness of E.obliqua larvae and present the reason by which EGCG promotes larval fitness.