Effects Of Nutrients And Secondary Metabolites Of Hippophae Rhamnoidea On The Transfer Damage Of Eogystia Hippophaecolus Larvae

Eogystia hippophaecolus(Hua,Chou,Fang&Chen)is the most serious pest of the Hippophae rhamnoidea forest in China.It mainly harms the H.rhamnoidea trunk by the newly hatched larvae,and transfers to the roots before wintering in the same year.In order to clarify the reasons for the transfer hazard of the larvae of E.hippophaecolus,this paper studied the digestive tract structure of the larvae,determined the difference of nutrients and secondary metabolites in the roots and stems of H.rhamnoidea,combined with the data of digestive enzymes,detoxification enzymes and protective enzymes of the larvae feeding roots and stems of H.rhamnoidea for analysis,explored the effects of differences in nutrients and secondary metabolites of H.rhamnoidea roots and stems on larvae transfer hazard.The main research findings are as follows:1.The digestive tract structure of the E.hippophaecolus larvae was clarified.The digestive tract as a whole pale yellow membranous straight tube composed of the mouth,esophagus,crop,proventriculus,midgut,ileum,rectum,anus and malpighian tube.The foregut and midgut are connected by cardiac valve.The midgut and hindgut are connected by pyloric valves.There is no gastric caecum in foregut.Degeneration of the foregut is mainly used to grind and push the food back.There are some barbs on inner membrane of the esophagus to prevent food from flowing backwards.The tops of the columnar cells of the midgut are densely covered with microvilli,which increases the secretion and absorption area of cells.The secretion of columnar cells is merocrine and holocrune;the degradation mode of epithelial cells is continuous degradation.The hindgut is short,the muscle layer is developed to facilitate the food residue to move backward;the inner membrane layer is very thin,the rectum has 6 membranous rectal mats,which can promote the absorption of water and inorganic salts.Malpighian tube is divided into six small tubules by the two main tubules,and there is no obvious cryptorchid structure in hindgut.2.The nutritional adaptation of E.hippophaecolus larvae to the roots and cadres of H.rhamnoidea was clarified.The contents of water and reducing sugar in the roots of H.rhamnoidea were higher than that in the stems and the activities of amylase in the roots of H.rhamnoidea roots was significantly higher than that in the stems.It indicated that the higher content of water and reducing sugar in roots could induce the feeding of larvae,and the larvae tend to feed on the roots with more water and reducing sugar content.The content of fat in H.rhamnoidea roots and stems is low(about 1.0%)and the difference between them is little.The larval lipase activities of is very low which has little impact on the transfer hazard behavior of E.hippophaecolus larvae.The activities of larval trypsin(F=0.372,P=0.047)of the stem larvae was significantly higher than that of the larvae feeding at the roots,indicating that the content of available protein in the stems is higher than that of the roots,which can resist the larvae transferring to roots.The activities of cellulase of the larvae feeding at the roots was higher than that of the larvae feeding at the stems,indicating that the higher content of cellulose in the roots induced the larvae feeding at the roots.The contents of alanine and tyrosine in the roots of H.rhamnoidea is 4 times higher than that in the stems,the contents of arginine and threonine is 2 times higher than that in the stems.The contents of K,Mg,P,Mn,Zn and Fe are higher than that of the stems.It has an inducing effect on the feeding behavior of larvae.3.Through the LC/MS analysis of non-targeted secondary metabolites of H.rhamnoidea roots and stems,combined with the activities of detoxification enzymes and protective enzymes in the larvae feeding on two parts of H.rhamnoidea,the detoxification strategy of E.hippophaecolus larvae feeding on H.rhamnoidea were clarified.There are 345 differential metabolites in the roots and stems of the damaged H.rhamnoidea,and 174 species belong to 28 classes are insect resistance,accounting for 50.43%of the total number of differential metabolites.The content and type of secondary metabolites related to insect resistance in the stems are much higher than the roots,which is not conducive to larvae feeding.Pregnenol ketone lipids,benzene and its substituted derivatives,flavonoids,coumarins and their derivatives have higher stem content and VIP value and have stronger evasion effects on larvae.Among them,triterpenoids have a significant contribution rate to the group,and the related metabolic pathways are extremely high,which is an important secondary metabolite of insect-resistant in H.rhamnoidea.The high level of secondary metabolites of cadres can induce the synthesis of GSTs and CYP450 in larval detoxification enzymes and stimulate the anti-defense mechanism of larvae.There is no significant difference between SOD,POD and CAT enzymes in living roots and stems.It can be speculated that stimulate the larvae to produce protective enzymes are not much different.The research results will provide basic data for the study of digestive physiology of E.hippophaecolus and provide scientific basis and new strategies for prevention and treatment of digestive system.