Ecological Adaptability Of Schlechtendalia Chinensis Bell

Insects are the most abundant in species and population among all organisms. They are themost prosperous creature distributed all over the world, and play important roles in theecosystem. Along with the evolutionary history, the genetic recombination accomplished bygene mutation, chromosomal aberration and sexual reproduction resulted in the evolution ofinheritance strategy with certain ability and reaction that are in adaptation to variousenvironmental conditions, and then the consequent evolution of anatomical structure and lifestyle adaptative to environments in insects, which enable their better survival and reproductionin natural condition.The horned gall aphid, Schlechtendalia chinensis Bell is one of the gall-making aphidsthat produce most of the Chinese gallnuts, with the fundatrix feeding on the winged rachis orthe leaflet of the compound leaf of sumac tree Rhus chinensis Mill and producing galls.In this thesis, horned gall aphid was used as a main studyed object. Five facets werestudied for the investigation of adaptation of S. chinensis to environment and of influence onthe biologic characteristic of S. chinensis from environmental factors. These were themorphological characteristic of each developmental stages, the relationship between thefeeding behavior and the morphological characteristic of the galls, the environmental contextof the two host relationships, the comparison of the genetic diversity of the two type of S.chinensis on two hosts, and the influence from environment temperature on the reproductionbehavior of S. chinensis. All results provide a foundation for the study on the co-evolutionbetween the S. chinensis and their host plants, as well as proof for the study on the evolutionand genetic origin of S. chinensis. The main results are as follows:(1) Morphological characteristics including the measurements generally used in taxonomy,and the features related to feeding behavior and parasite status on the host were studied for themorphological variations among the ten stages of S. chinensis. Results showed that during the historic adaptation, S. chinensis had evolved characteristics that were basically in accordance tothe theory of use and disuse. The migrants have strong characteristics such as strong legs,segmented claw, long antennae, and well developed sensilla; whereas, the immobilized aphidshave undeveloped legs, leg spike, and mouthparts; and the non-feeding aphids (male andfemale) have no mouthparts.(2) Histological section of the infected winged rachis and galls in the formation of hornedgalls revealed that in the early feeding phase the fundatrix penetrated their stylets into thepalisade tissue, which induced its reorganization and substitution by parenchymatous tissue inthe winged rachis. With the development of horned galls, the inner and outer walls changedinto2~3epidermal layers and single epidermal layers from single cell layer, respectively;unicellular hairs and multicellular glandular hairs on the outer surface and the opening of thehorned gall were diminishing with the development of galls; the gall wall histocytesproliferated irregularly, most of the latex canal and vascular bundle were distributed near theinner chamber of galls. Relations between the aphid feeding behavior and the characteristicmodifications of galls were discussed.(3) The dynamics of the temperature, humidity and illumination intensity in and out of thegall during the fast growing stage and dehiscent stage of gall development and in theenvironment of in and out of the moss layer were analyzed. Results showed that, irrespective toweather and the development of galls, the temperature inside galls were well buffered withsmaller amplitude of variation than outside galls, with the temperature inside galls is below theenvironmental temperature when environmental temperature is higher in the daytime andtemperature inside galls is above the environmental temperature when environmentaltemperature is lower at night. The relative humidity inside galls was steadily saturated at99.9%~100%, regardless of the weather and the development of galls. The illumination inside galllswas slightly. Dynamics of environmental temperature and humidity in the moss layer were inaccordance with that of galls, which indicated that both the gall habitats for virginoparae onhost plant R. chenesis during summer and the wax bead habitats for over-winter larvae in moss layer during winter could provide the HGAs with comfortable environment be of steadytemperature and humidity.(4) The genetic sequence of CO I gene were amplified and compared for the investigationof DNA polymorphism between the virginoparae and larvae. Results showed that the two typesof aphids were genetically differentiated. The haplotype diversity (Hd) and nucleotide diversity(π) of virginoparae S. chinensis (G group) were all higher than those of winter larvae, whichindicated that the virginoparaes had better adaptive capacity to environment than overwinteringlarvae. According to the inheritance richness and network, the genetic distance between the twotypes of aphids was calculated and the haplotype over-winter larvae were postulated to be earlybranched.(5) The overwintering larvae were cultivated under different temperature to change theirreproduction types, larvae from different reproduction types were subscribed to transcriptomesequencing for reproduction related genes in S. chinensis. Results showed that84,280unigeneswere obtained. There were623differentially expressed genes with164up-regulate genes and459down-regulate genes. GO function annotation for these genes revealed476annotatedgenes and147not annotated genes. The147unknown genes might be related to thereproductive responses to temperature. GO function concentration revealed13items correlatedto reproduction. A total of27unigenes were concentrated with21highly expressed in lowtemperature treated groups and6in high temperature treated groups. Meanwhile, we analyzedthe transcription of the51known genes in the two types of S. chinensis, revealing that42geneswere high in homology with the transcriptome of S. chinensis, among these genes,8wereexpressed differently between the two types. Thus, the total69unigenes were postulated to berelated with the decision of reproduction type.