Effects Of Sclerodermus Guani On The Nutritional Metabolism And Immune Response Of Monochamus Alternatus Larvae Of Two Body Sizes

M.alternatus bores and eats directly to death or carries a large number of pine wood nematode diseases indirectly to the death of a large number of pine trees,which has caused great difficulties for our country to implement the concept of "green water and green mountains are golden mountains and silver mountains" and promote forestry ecological construction.In recent years,S.guani has been widely used to control the young larvae of M.alternatus and has achieved certain control effects.Exploring the interaction between S.guani and its host is the basis for effective biological control.The selection of S.guani for parasitism accords with the hypothesis of "host type-quality",that is,the size of host type affects the host selection and oviposition decision of female wasps,as well as the growth and development of offspring.However,the current research mainly focuses on the developmental performance of S.guani,and it is not clear how the size of the host affects the parasitic effect.The individual size of the host means the richness of the host’s nutrition.In addition to being the main energy substance in the growth and development of parasitic wasps,nutrients are also an important feature of the host insect’s natural immune response system.Therefore,on the basis of the hypothesis of "host type-quality",we elaborated the influence of different individual sizes of M.alternatus larvae on the parasitism process of S.guani from the perspectives of nutritional metabolism and immune response,which is a scientific use of S.guani.The prevention and control of M.alternatus provides a theoretical basis,and at the same time enriches the theoretical research on the interaction between natural enemy insects and longhorn pests.The main findings are as follows:(1)The parasitic performance of S.guani on two types of M.alternatus larvae.The two body types of M.alternatus larvae did not affect the initial paralysis time and the initial paralysis rate of S.guani,indicating that the size of the host did not affect the host identification and detection process of S.guani;however,the time to paralyze the large larvae and the laying of eggs The early stage was longer than the small larvae,and the complete paralysis rate and the average number of emergence of the offspring were significantly lower than that of the small larvae,indicating that the host size has a significant impact on the energy consumption and egg laying decision of S.guani.(2)The effect of parasitism of S.guani on nutrient metabolism of M.alternatus larvae.The parasitic effect of S.guani preferentially consumes lipids in M.alternatus larvae,and then promotes the conversion of carbohydrates to proteins in large hosts,and consumes carbohydrates and proteins in small hosts.(3)The effect of parasitism on the immune response of two types of M.alternatus larvae.Five blood cell types involved in the immune response of M.alternatus larvae were observed and identified: prohemocyte,plasmatocyte,granulocyte,oenocytoide and coagulocyte.The parasitism of S.guani can obviously inhibit the blood cell extension ability,encapsulation ability,phenoloxidase activity and melanization of the two body types of M.alternatus larvae,and the inhibitory effect is more obvious in M.alternatus larvae.