Study On The Sequence And Mechanisms Of Willow Resistance To Longihorn Beetles

The sequence of different varieties of willows' resistance to longgihorn was determined by investigation in Peking City and parts of Hebei province and field experiments during which different willows were inoculated with Anoplophora glabripennis Motsch and Apriona germari Hope in the net room. Based on those results, a number of willow varieties were selected to measure the indices such as: water contents, biomass timber , anatomical structures % nutrient and tannin contents, activity of detoxification enzyme of longgihorn eating different willows. The relationship between the variant regulation of the indices among different willow varieties and damage degree by Anoplophora glabripennis Motsch were studied. The results are as follow:1. Willows were damaged more seriously by Anoplophora glabripennis Motsch than by Apriona germari Hope in the natural condition, Anoplophora glabripennis Motsch is the most dangerous borer to willow. The damaging rate is above 50 percent in willows whose age is above 4 years. The hazard index was calculated through the gradation of the defecation foramen number on the two-year-old willows in Baoding. According to the hazard index, the resistant sequence from high to low is: Salix. matsudana f. umbraculifera, S. babylonica L, S.matsudana, S.matsudana f. pendula .2. It was proved that Anoplophora glabripennis Motsch has different oviposit choice, different rate of hatching and different rate of overwinter larva to the different willow varieties through inoculation experiment in the net room. The analysis of variance proved that, the oviposition impression number and the overwinter surviving larva number are different at a significance level of 5%, the hatching larva numbers are different at a significance level of 10%, among different willow varieties. The above factors were analyzed, and it proved that , the willow resistance from high to low is: Salix matsudana f. umbraculifera , S. babylonica L > S.nankingensis C. Wang et Tung, >Salix aureo-pendula , S. matsudana sp > S. matsudana.3.Among the different physical characteristics of willows, those factors whose significance of difference are above 5% are : wall depth of vessel , diameter of vessel , area of vessel , radius of xylem cell wall , depth of xylem cell, wood ray tract number, length of fiber, width of fiber, rate of length to width of fiber, water contents of bark,breast diameter growth quantity, lumber elemental volume weight. The willow twig anatomy features which were significantly related to the longgihorn damage were analyzed by stepwise regression. It proved that: the oviposition impression number was affected most conspicuously by the wall depth of vessel, and was obviously by the radius of xylem cell wall. The overwinter surviving larva number was significantly affected by the depth of xylem cell and the width of fiber. The bias correlative coefficients of the 4 variables above were all positive; those features are all profitable to the longgihorn damage. The water contents of bark was negatively related to the ovum hatching rate significantly, so the high water content of bark disadvantage the longgihorn ovum hatching. The correlative coefficient between the breast diameter growth quantity and longgihorn ovum hatching rate was negative, but the significance level was less than 5%. The correlative coefficients between other willow physical features and the longgihorn damaging indices all did not reach the significance level.4. The willow chemical compositions were analyzed by analysis of variance, and the result indicated that, the dissolubility sugar contains, the dissolubility protein contains and the tannin contains in phloem and inxylem, are obviously different at a significance level above 5%.The result of linear regression analysis proved that, the phloem dissolubility sugar contains was positively related with the oviposition impression number obviously. The higher dissolubility sugars the phloem contents, the more attractive it was to the egg-laying of longgihorn. The xylem dissolubili...