Study On The Harmfulness Between Distylium Racemosum And Distylium Myricoides By Neothoracaphis Hangzhouensis

The experiment selects Distylium racemosum and Distylium myricoides as the testedmaterial which are located near ShuShan of Hefei in Anhui Province to discuss thedifferent damage degree from Neothoracaphis hangzhouensis. Compare the differences ofdamage degree between Distylium racemosum and Distylium myricoides by mensuratingthe numbers and the diameter of cecidums. Find out the possible reasons for the differencesof damage degree by mensurating and analysing the inclusions of leaves from thesedifferent trees. Use the LI6400portable photosynthetic apparatus produced by theAmerican LICOR to measure the net photosynthetic rate and chlorophyll fluorescenceparameters of Distylium racemosum and Distylium myricoides in different seasons, and thechanges of photosynthesis characteristics of Distylium racemosum and Distyliummyricoides infested by Neothoracaphis hangzhouensis were studied in this paper. Theresults were as follows.1. The total number of cecidum on Distylium racemosum leaves is far more than it onDistylium myricoides leaves; the number of cecidum on a single leaf of Distyliumracemosum is up to twelve, while the maximum number is two on a Distylium myricoidesleaf; For the same number of cecidum on a leaf, the average diameter of cecidum onDistylium racemosum leaf is significantly larger than it on Distylium myricoides leaf. It isshowen that the area and the degree of damage on Distylium racemosum leaves is moreserious than it on Distylium myricoides leaves.2. Sixteen kinds of amino acids were measured from the leaves of Distyliumracemosum and Distylium myricoides, and there are significant differences were appearedin nine kinds of amino acids; the regression equation between the damage degree（Y） andthe relational amino acid （X） isY=0.27x₁+0.34x₂+0.21x₃-0.12x₄-0.11x₅+0.23x₆+0.17x₇+0.18x₈-0.15x₉, and the mostrelational amino acid is glycine among the all relational amino acids; the significantpositive correlations were founded between the damage degree with glycine, glutamic,leucine, alanine, phenylalanine and tyrosine, there was a significant negative correlationbetween the damage degree and arginine, cysteine and methionine. Meanwhile, there aresix kinds of phenolic acids were measured from the leaves, but there was no significantcorrelation among them.3. The overall trend of the net photosynthetic rate graphs between Distylium racemosum and Distylium myricoides are similar in different seasons because of thedamage caused by Neothoracaphis hangzhouensis. The diurnal variation of netphotosynthetic rate of the two trees shows a singlepeak curve in spring and autumn and adoublepeak curve in summer, the net photosynthetic rate in summer is higher than it inspring and autumn obviously. In the meantime, there is a significant difference between thenet photosynthetic rate of healthy leaf and infested leaf which from the same tree, nomatter it is Distylium racemosum or Distylium myricoides. The accumulation ofphotosynthetic products was reduced by the effect of insect pest. Because of the differentdamage degree from Neothoracaphis hangzhouensis, there was no stress effect on thephotosynthetic tissues of two trees in spring and autumn and reversible stress effect onthree kinds of leaves except Distylium myricoides leaves without cecidums in summer,however, there was irreversible stress effect on the photosynthetic tissues of Distyliumracemosum leaves with cecidums, it shows that the resistance of Distylium racemosum wasdecreased by the infested of Neothoracaphis hangzhouensis.