| The cholesterol,part of constructive components of cell membrane and precursor of ecdysone biosynthesis,is important in development of insects.Insects cannot synthesize cholesterol,and must acquire it from their diets.The phytophagous insects can convert the phytosterol into cholesterol,and the carnivorous insects acquire the cholesterol directly from their prey.Decreasing of sterol content in plant negatively affect development of phytophagous insects.So it is a potential method to control pests by regulating sterol content in plant.However,little is known about the influence of sterol content in plants on suitability of natural enemies.Arma chinensis is one of the most important predatory natural enemies and prey on more than 40 important pests in China.The M.separata is a worldwide pest,and for a common prey of A.chinensis.This study focused on artificial diet-M.separata-A.chinensis,and tested(1)the species and contents of sterols in four kinds of artificial diets that made of wheat germ powder and corn seed powder sterol-eluted for 0,1,2,5 times;(2)the effects of sterol elution in artificial diet on sterol content and development of M.separata;(3)the effects of sterol elution in artificial diet on sterol content,development and metabolism of A.chinensis.Results showed that:1.Contents of sterols in artificial diets,M.separata and A.chinensis.Four species of sterols but not cholesterol were found in artificial diets that made of sterol-eluted wheat germ powder and corn seed powder.The contents of four species sterols were decreased with the sterol elution times increased.M.separata could convert phytosterol into cholesterol,and the content of cholesterol significantly decreased with the decreasing of the sterol content in artificial diets.However,cholesterol in A.chinensis was not significantly affected by contents of sterol in M.separata.Content of cholesterol in A.chinensis is significantly lower than that in M.separata.2.The development of M.separata was significantly affected by sterol content in artificial diets.The weight of M.separata larva fed on 2 and 5 times sterol elution artificial diets was significantly lower than those fed on 1 time sterol elution artificial diet and CK,besides,all of them fail to pupate;same result was found in the weight of M.separata pupae.The contents of sterol in M.separata did not significantly affect the life history parameters of A.chinensis,such as weight of nymphs and adults,longevity,fencundity,egg hatchability,egg period.The results suggested that content of cholesterol in M.separata treated could satisfy development of A.chinensis.3.In respect of physiological and biochemical indexes,total 53 types of metabolites in 7 categories are detected in A.chinensis.Only 8 of them including alanine,betaine and dimethylamine etc.,are significantly different from contrast in different treatments.Metanolic profile analysis showed that distinct separation generates between 5 times sterol-elution and CK.Maltose,glucose,tyrosine and proline greatly contribute to separation.Result of metabolic pathway analysis indicated that two metabolic pathways in 2 and 5 times sterol-elution reach significant difference from control,but the impact value is 0.In conclusion,decreasing of sterol content in plants significantly and negatively affected on development of pest M.separata,but not affected natural enemy A.chinensis.The results provide basis for control of pests by regulation sterol content in plant. |
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