Adaptive Mechanisms Of Locusta Migratoria To Four Different Plants

Insects and plants have formed a close and complex relationship over a long period of co-evolution,with plants providing nutrients for insects and influencing their growth,development and reproduction.Locusta migratoria is a major species causing locust infestation in China.Its strong feeding ability is a typical biological characteristic and one of the important factors leading to its rampant population and outbreak.In this paper,we systematically investigated the feeding and digestion of different plants of the locust through ecology,physiology and molecular biology to reveal its feeding adaptation mechanism.The results are as follows.1.By constructing the age-stage,two-sex life table and measuring biological indexes,it was found that the locusts feeding on maize leaves and goosegrass had better food intake,digestibility,utilization rate,developmental rate,fecundity,net proliferation rate,endogenous growth rate,and perimeter growth rate than those feeding on soybean leaves and pakchoi.Correlation between plant physical and chemical characteristics and the locust’s viability showed that the locust’s viability was significantly positively correlated with plant nutrient content and negatively correlated with secondary metabolite content.Plant starch,terpene,and phenolic content,were essential factors in locust nutrition.2.The study of oral secretion and gut enzyme activities of L.migratoria fed on different plants revealed that differences in the physicochemical characteristics of plant nutrients and secondary metabolites significantly affected their enzyme activities related to corresponding nutrient and detoxification metabolism,respectively.The high starch content of maize leaves and low total secondary metabolites were associated with higher amylase activity and lower concentrations of detoxifying enzymes,protective enzymes,glucose oxidase,and ROS after feeding,indicating that maize is its high-quality food resource,followed by goosegrass,and the opposite for pakchoi and soybean leaves.Differences in the physicochemical properties of the plants caused nutritional stress and thus affected the enzyme activities of the insects.3.The structure of the gut microbiota of the locusts on different plants showed significant differences in the diversity and abundance of the gut microbiota.There were 11 different taxa in soybean leaves treatment group,primarily Firmicutes;ten groups were found in pakchoi treatment group,mainly Proteobacteria;one different group was found in maize leaves treatment group,which corresponded to Firmicutes;one different group was found in goosegrass treatment group,which corresponded to Proteobacteria.At the genus level,the gut microbiota of L.migratoria fed on maize leaves,goosegrass,and pakchoi was similar in composition,in which Kluyvera,Enterobacter,and Pseudocitrobacter were the dominant genera.In contrast,Lactococcus and Weissella were the dominant genera in the gut microbiota of L.migratoria fed on soybean leaves.Combined with the COG functional prediction analysis,it is possible that the gut microbiota of L.migratoria has changed qualitatively and quantitatively to meet the functional requirements of the host to adapt to different food plants and in accordance with the influence of food plant characteristics.4.The differential expression of genes in the gut of L.migratoria fed on different plants showed that feeding on different plants significantly influenced the changes in transcript levels in the gut.The intestinal processes and pathways related to nutrient metabolism,digestion and absorption,substance synthesis,and energy metabolism were significantly higher in the maize leaf treatment group than in the other treatment groups.In contrast,the processes and pathways related to gut nutrient metabolism were significantly decreased in the pakchoi treatment group,with decreased nutrient digestion and absorption and significantly decreased substance synthesis and energy metabolism processes.At the genetic level,L.migratoria was found to be more adapted to maize and less to pakchoi.The genes involved in these differences represent the molecular basis of dietary adaptation in L.migratoria.Focusing on the relationship between locusts and plants,this study reveals that L.migratoria adapts to food plants by regulating phenotypes and gut microbiota to meet individual growth,development,and reproduction.It provides theoretical support for studying insect adaptation mechanisms and ecological management.