Structural Anatomy And Internal Regulation Mechanism Related To The Regulation Of Diapause By The Gypsy Moth

Lymantria dispar Linnaeus,a gypsy moth,is widely distributed and has a large feeding capacity.The gypsy moth has one generation a year,and its egg phase diapause lasts for up to 9 months,accounting for three-quarters of its life history.For gypsy moths in the egg stage,they are more likely to spread with the means of transportation and human carriers.Therefore,it is of great importance to explore the diapause mechanism of gypsy moths,understand the biological process of diapause and develop prevention and control strategies.For gypsy moths,the diapause hormones that regulate diapause eggs,the brain and subpharyngeal ganglion that control and secrete diapause hormones,or the chemical informants associated with diapause,such as ascarosides,have not yet been reported.Based on this,the key factors affecting the diapause of gypsy moth are analyzed from two aspects: diapause hormones and ascarosides.In this study,from the perspective of diapause hormones,the central nervous system of gypsy moth larvae was dissected,and the brain and subpharyngeal ganglion,which controlled and secreted diapause hormones,were morphometrically measured and 3D reconstructed from the outside to the inside.The dynamic changes of diapause hormone content in Asian and European gypsy moth larvae at different ages were analyzed by double antibody sandwich method.To determine the presence,species,and content of ascarosides in gypsy moth eggs,and to explore the biological role of ascarosides in the development of gypsy moth eggs.The main results are as follows:(1)In vitro anatomy showed that the central nervous system of gypsy moth larvae was mainly composed of 12 ganglion,including cranial ganglion,subpharyngeal ganglion,3thoracic ganglion(prothoracic,mesothoracic and retrothoracic)ganglion and 7 abdominal ganglion.The central nervous system of gypsy moth larva was dissected,and the positions of brain and subpharyngeal ganglion of gypsy moth were determined,which laid a morphological basis for further study of brain and subpharyngeal ganglion in the later period.(2)The study on the external morphological structure of the inferior pharyngeal ganglion of gypsy moth larvae showed that there was no significant difference in appearance morphology of the inferior pharyngeal ganglion of gypsy moth larvae of different ages,but the color of the ganglion would change from jujube red to light pink with the increase of insect age.External measurements of the subpharyngeal ganglion showed that the length,width and area increased with the increase of insect age.The brain of gypsy moth was composed of forebrain,midbrain and hindbrain by immunostaining and3 D reconstruction of the inner nerve pulp of brain and subpharyngeal ganglion.The outermost layer of the brain is the cell body layer,the forebrain in the upper end of the brain,the main distribution of the central body,mushroom body,optic lobe.The midbrain is mainly distributed with antennal lobes,and the posterior brain is located on the ventral side of the brain and below the antennal lobes.The inferior pharyngeal ganglion is mainly composed of the mandibular,mandibular and lower labial ganglion.(3)The diapause hormones in Asian and European gypsy moth larvae of different ages were detected.The content of diapause hormones in Asian gypsy moth larvae was always lower than that in European gypsy moth larvae.The diapause hormone content in both types of gypsy moth larvae increased from the first to the second instar and decreased from the second instar.The diapause hormone content of the second instar larvae of Asian gypsum moth was the highest(1150 pg/m L),and the diapause hormone content of the sixth instar larvae was the lowest(930pg/m L).The diapause hormone content of the second instar larvae of the European gypsum moth was the highest,reaching 1330pg/m L,while the diapause hormone content of the sixth instar larvae was the lowest,only 1090pg/m L.(4)By detecting the type and content of chemical informational ascarosides in gypsy moth eggs of different geographical populations and diapause states in China,the results show that ascarosides are present in gypsy moth eggs of different geographical populations and diapause states,but the type and content of ascarosides may vary.In terms of ascarosides species,each of the standard species is found in gypsy moth eggs,but only asc-C7 species is found to be stable in gypsy moth eggs.In addition,the ascarosides content in gypsy moth eggs is very low,with most ascarosides content ranging from 0.03 to 1.6ng/m L.In this study,the biological function of asc-△C6 and asc-△C7,which are ascarosides,on the development of gypsy moth eggs was further explored.The results showed that asc-△C6 and asc-△C7 may have a promoting effect on the development of gypsy moth eggs,and the promoting effect of asc-△C7 is more obvious.The effect of asc-C9 on egg development of gypsy moth was also studied.It is preliminarily believed that asc-C9 may play a role in delaying egg development.