A Comparative Study Of The Amino Acids And Defensive Substances Of The Gall And Host Plants Of Andricus Mukaigawae

Insect galls are abnormal tissues of host plants induced by gall-inducing insects.The main monoid of gall insects are 6 orders and 20 families,Gall wasps is the second largest gall-forming group after gall mosquitoes.Andricus mukaigawae(Cynipidae,Cynipini)is a gall-making insect which forms galls on the twigs of Quercus fabri et al.In terms of the adaptability of galls,Price et al.drew up six main hypotheses: nutrition,microenvironment,natural enemies,mutual benefit,defense and non-adaptability hypothesis.The nutritional hypothesis holds that galls induced gall-inducing insects that have higher content of nutrients and lower defensive substances than non-gall-inducing tissues,to meet their own needs.At present,it is not clear whether the gall of A.mukaigawae supports the nutritional hypothesis.The contents of 20 free amino acids in galls,galls and ungalled twigs of A.mukaigawae larvae and host plants were determined for the first time by high performance liquid chromatography,and the monotony of different structure layers and twigs of host plants was determined by spectrophotometer.The content or activity of defensive substances such as flavonoids,lignin,polyphenol oxidase and phenylalanine ammonia lyase.The main achievements are as follows:1.As far as the total amount of free amino acids is concerned,gall in larval stage is significantly higher than gall twigs and non-gall twigs,but,in adult stage,it is opposite,and gall in larval stage is significantly higher than gall in adult stage.As far as essential amino acids are concerned,galls of larvae and adults are significantly lower than gall twigs and non-gall twigs,there is no significant difference between galls of larvae and adults.There was no significant difference in total free amino acids and essential amino acids between gall twig and non-gall twig in larval and adult stages.2.As far as the content of different amino acids is concerned,there is only one proline in adult stage and 12 amino acids in gall in larval stage are significantly higher than that in gall twig and non-gall twig.Among them,asparagine and tryptophan were the most abundant non-essential and essential amino acids in larval stage.3.Principal component analysis showed that the amino acid composition of gall was different from that of gall twig and non-gall twig in larval and adult stages,and the components of gall twig and non-gall twig were similar.4.The distribution of defense-related substances in galls of larvae is uneven.Among them,tannin and flavonoids content and polyphenol oxidase activity in the outer gall layer were the highest,and significantly higher than those in the inner gall layer and gall twigs.As far as gall inner layer is concerned,only phenylalanine aminolytic enzyme activity is significantly lower than gall twig.There was no significant difference in lignin content among gall layers,but it was significantly higher than gall twigs.This study showed that the amino acid content of gall of A.mukaigawae supports the nutritional hypothesis.The larvae of A.mukaigawae may induce higher free and most amino acid contents than those of plant tissues by feeding,which is conducive to satisfying the nutritional needs of larvae and gall formation.Some defense-related substances in larval galls do not support the nutritional hypothesis.