Effect Of Amino-oligosaccharides On The Tertiary Nutritional Relationship Between Cucumis Sativus,Frankliniella Occidentalis And Neoseiulus Barkeri

In the three-level trophic relationship among plants,phytophagous pests and natural enemies,plants,as the first trophic level,not only directly affect the pests at the second trophic level,but also directly or indirectly affect the natural enemies at the third trophic level.Because the immune-antagonist amino-oligonucleotide causes some effects on the plant’s own nutrition and physiological biochemistry,can it affect Frankliniella occidentalis as well as Neoseiulus barkeri with the food chain?Based on this,this thesis systematically studied the effects of amino-oligonucleotide treatment on T.occidentalis and the natural enemy N.barkeri using amino-oligonucleotide-cucumber-F.occidentalis-N.barkeri as a baseline,aiming to lay the foundation for the scientific use of amino-oligonucleotide in the field and to provide a theoretical basis for revealing the effects of amino-oligonucleotide on tertiary nutritional relationships,aiming to provide a reference for the scientific use of amino-oligonucleotides in the field and to provide a theoretical basis for revealing the effects of amino-oligonucleotides on tertiary nutritional relationships.The research results are as follows:1.Effect of amino-oligonucleotides on the development and reproduction of F. occidentalisThe survival rate of F.occidentalis at all stages after feeding on amino-oligonucleotide-treated cucumber seedlings was higher than that of the control,indicating that was beneficial for the survival of F.occidentalis after root irrigation treatment with amino-oligonucleotide-treated cucumber seedlings.Moreover,the pre-oviposition period of F.occidentalis was 33.2%shorter than that of the control after feeding on cucumber seedlings treated amino-oligonucleotide,the fecundity was 40.5%higher than that of the control,and the population perimeter finite rate was 5.7%higher than that of the control,indicating that amino-oligonucleotide treated cucumber seedlings were beneficial to the development and reproduction of F.occidentalis populations.2.Effect of amino-oligonucleotides on the development and reproduction of N.barkeri F.occidentalis on cucumber seedlings treated with amino-oligonucleotide as food were able to develop from eggs to adult mites and proliferate normally by laying eggs.Although the developmental period from egg to adult mite was significantly reduced in N.barkeri treatment group,the survival rate of N.barkeri and longevity of male and female adult mites in different periods were also significantly reduced,which may be detrimental to the reproduction of the population.Although,the female to male sex ratio of the population in N.barkeri treatment population was 2.03 compared to 1.86 in the control population,intrinsic rate of natural increase（r_m）and net reproductive rate（R₀）of the population were reduced to 76.67%and 62.73%of the control population,respectively,and doubling time for population（t）increased 1.30 times of the control.At the same time,the average female production rate of N.barkeri treated group was also lower than that of the control group,indicating that the feeding of N.barkeri mites on the 1st instar F.occidentalis nematode on amino-oligonucleotide-treated cucumber seedlings would have a detrimental effect on the growth,development and reproduction of N.barkeri populations.3.Effect of amino-oligonucleotide treatment on the protective enzyme activity of cucumber seeds and leavesCompared to dried cucumber seeds,the protein concentration and superoxide dismutase （SOD）activity of cucumber seeds were significantly reduced by water soaking,and POD activity of cucumber seeds was reduced but the difference was not significant;while CAT activity of cucumber seeds was significantly increased.Compared to water-soaked treated,SOD and CAT activities of amino-oligonucleotide-treated cucumber seeds were significantly reduced,while POD activity was elevated but the difference was not significant.The sharp decrease in protective enzyme activity indicated that the antioxidant enzyme system of amino-oligonucleotide-treated cucumber seeds was at the stage of disruption and was more conducive to breaking seed dormancy.The total protein concentration and CAT activity in treatment group of the cucumber leaf was significantly higher than those in the control group,which indicated that the continuous treatment of cucumber seedlings by root irrigation with amino-oligonucleotide would be beneficial to promote the expression of total protein and CAT activity in cucumber seedlings and activate the plant’s own defense system.4.Effect of amino-oligonucleotide treatment on protective and detoxifying enzymes activities of F.occidentalis and N.barkeriThe total protein,CAT and POD activities of F.occidentalis treated with amino-oligonucleotide increased significantly in the treated group compared with those of cucumber seedlings treated with water;Meanwhile,the activities of Car E,SOD and MFO were significantly reduced in the treated group.This indicates that cucumber seedlings treated with amino-oligonucleotides indirectly stimulated the expression of total protein,protective enzymes CAT and POD,and inhibited the expression of Car E,SOD and MFO in F.occidentalis,which may have promoted the development of F.occidentalis populations.The protective enzyme SOD activity and detoxification enzymes GSTs and MFO activities of N.barkeri feeding on cucumber seedlings treated with amino-oligonucleotide were significantly reduced compared with N.barkeri control population,indicating that the expression of protective enzyme SOD and detoxification enzymes such as GSTs and MFO were indirectly inhibited with amino-oligonucleotide,which may be detrimental to the development of N.barkeri populations.