Study On The Interaction Between Cotton,Aphis Gossypii And Lysiphlebia Japonica On The Content Change Of Free Amino Acid

Aphis gossypii is one of the important stinging pests,which directly or indirectly reduces the yield and quality of cotton by competing with host nutrients and transmitting pathogens,and thus poses a great threat to cotton production.As a dominant parasitic natural enemy of A.gossypii in the cotton field,Lysiphlebia japonica(Ashmead)can effectively control the population of cotton aphid and reduce its harm to the cotton field.Free amino acids are important nitrogen nutrients,which mainly function in the synthesis of proteins and a variety of bioactive substances,and participate in the metabolism of material energy and a variety of physiological activities.In this study,the content of free amino acids in A.gossypii at different development stages were studied,and the changes of the content of free amino acids in different cotton tissues after being damaged by cotton aphid were illustrated,what’s more,we studied the effects of parasitization on the content of free amino acids in cotton aphid.The relationship of the free amino acids among cotton,cotton aphid and parasitiods was clarified and provided a basis for the relationship of nutrients between plants,pests and natural enemies.The main results are as follows.1.The difference of free amino acid content in different developmental stages of cotton aphid was clarified.The identification results of 21 kinds of free amino acids showed that the total amount of free amino acids was the lowest in the 4th instar nymph of cotton aphid,and the highest in the 5th day of adult,but there was no significant difference.At different development stages of aphids,the amino acids with the highest content were aspartic,glutamic,alanine,tyrosine and arginine,and the amino acids with the lowest content were tryptophan phosphate,methionine and ornithine,the contents of amino acids varied significantly in different development stages of cotton aphid.2.The changes of the content free amino acid contents in different cotton tissues of different damage levels were identified after being damaged by cotton aphid.The results showed that the total amount of free amino acids in cotton hypocotyl,root and cotyledon increased significantly.The total amount of essential amino acids increased significantly in the hypocotyl,while the non-essential amino acids increased significantly in different tissues.Among them,glutamic acid and aspartic acid increased significantly in all tissues with the level of damage.3.The effects of parasitization on the free amino acid content of cotton aphid were studied.The results showed that the total content of free amino acids increased after parasitism,and reached a significant difference level after parasitism for 16 h and 24 h.Among them,the contents of valine,isoleucine,aspartic acid and ornithine were significantly higher than that of non-parasitized cotton aphid.The contents of proline,tyrosine,histidine and arginine increased significantly at different time after the parasitization of cotton aphid.