|
Oleaceae (Oleaceae) Fraxinus genus (Fraxinus L.) is a species of timber, shelter, and other scenic forest afforestation fine species. However, flower EAB (emerald ash borer, EAB) Agrilus planipennis Fairmaire trunk borer as an important, in our country, Liaoning, Shandong, Tianjin and other places serious harm ash trees, causing huge losses. Since the invasion of North America, and especially in the past 10 years, only in the lethal hazards southeast Michigan ash trees 30 million, as of February 2010 has spread to the northeastern United States 13 states and southeastern Canada, Ontario and Quebec 2 Province. Because the larvae hidden hazards, extremely difficult to detect in the early damage control difficult and expensive to control, the most effective measure is to create a mixed forest, providing pest isolated environment. Ash property of their respective insect species explore mechanisms help to reveal spend EAB between different species cause harm, so as to spend EAB regional control provides scientific reference. In this study, on the flower EAB insect resistance with varying degrees of eight kinds of ash trees, by measuring the bark, branches organizational structure differences in physical properties, bark inclusions composition differences, and leaves volatile compounds differences in types and levels, clear flower EAB preferences for eight kinds of species differences, identify the cause of species differences in resistance to the key factor. Evaluation ash tree on the flower EAB resistance mechanisms, the main findings are as follows: (a) under natural conditions, flowers EAB harmfulness of different species significantly different, and red ash Fraxinus velutina suffer very serious , the United States and Europe, ash Fraxinus suffer heavier, while cuango ash and ash less harmful, and a large ash tree Fraxinus and found no hazards. (2) the main tree species Fraxinus velutina victims in different directions is not significant, and different height difference is extremely significant ,1-2m suffer significantly more than at other heights up to 1.5m in place hazards, can be very good with a normal distribution predict emergence holes in the trunk distribution. (3) Flowers EAB bark color has nothing to do with the hazards, insect resistance and bark thickness, roughness, stomata size, degree of compaction is inversely proportional to the bark thicker, rougher, more lenticels large, bark more closely, the better to spend EAB hazards. (4) Species internal organizational structure, the catheter area, lignified cell number, cell radius of wood, wood and stone cells of the cell area number is selected stepwise regression closely associated with insect resistance factor. Among them, the catheter area and lignified cell area was negatively correlated with insect resistance; cell radius wood, stone and wood of the number of cells and insect cells was positively correlated. (5) Major inclusions polyphenols, soluble sugar, reducing sugar, flavonoids are closely associated with insect resistance factor. Among them, in different resistant species, the polyphenol content in the ash tree, a large ash Fraxinus and Europe was significantly higher than in other species, polyphenol content was negatively correlated with insect resistance; soluble sugars in various species differences and ask not significant, positive correlation with insect resistance; reducing sugar content in the ash tree was significantly higher than the big-leaf ash and red ash, while the big-leaf ash and red ash was significantly higher than the other species, and insect resistance reducing sugar content was negatively relevant; flavonoid content in ash and European ash content was significantly higher than in other species, polyphenol content was negatively correlated with insect resistance. (6) Determination of eight species in mechanical damage before and after volatile compounds, volatile matter content in each species are not the same. Normally, the species of insect resistance alcohols, terpenes and the relative content in the proportion of species are large; the sense of high content of fatty acids insects species. After suffering mechanical damage, each tree species and the release of volatile matter content were significantly increased in all kinds of different species release volatile compounds are different insect species type increased more ester ketones, alcohols increased sense of insects species larger terpenes have increased in all tree species.
|