Influences Of Stand Types On The Induced Resistance Of Pinus Tabulaeformis

The effect of mixed forests and pure forest on the population parameters of two color morph pine caterpillar (Dendrolimus punctatus tabulaeformis) and its utilization and consumption characteristics to the pine (Pinus tabulaeformis) were studied by feeding on the larva with pine needle. In order to reveal the influences of stand types on the induced resistance of the pine and define the defense structure and mechanism of the pine under the effect of stand conditions and insects feeding, the biochemical substances in the pines which were damaged by differential number caterpillars in different stand types were analyzed. The main results are as follows.1. The survival rate, feeding amount, food digest coefficient, pupa weight, fertility, mean development period and ability of resistance to hunger of the pine caterpillar larvae fed with pine needle in mixed forest were lower than that fed with pine needle in pure forest. The results show that the pine needle in mixed forests goes against the growth and development of pine caterpillar.2. The nutrient substance content of the pine needle which was in damaged in different stand types was various. Compared with the each treatment of pure forests, the polysaccharide content was higher and reducing sugar and protein content were lower when the pine damaged by 5 pine caterpillars, the polysaccharide content was lower and reducing sugar and protein content were higher when the pine damaged by 15 pine caterpillars, and the polysaccharide content was higher and reducing sugar and protein content were lower when the pine damaged by 30 pine caterpillars in mixed forest. The results indicated that nutrients substance content was related to stand type. The change range of nutrient substance content in damaged pine needles was greater in mixed forests. And the polysaccharide content increased and reducing sugar and protein decreased in the pine needle under the slight and serious feeding stimulation.3.The reducing sugar and protein content were lower and the polysaccharide content was higher in damaged pine needles than that in undamaged pine needles. The polysaccharide content increased and reducing sugar and protein decreased in the pine needle damaged by 5 or 15 pine caterpillars. And the polysaccharide content increased to maximum and reducing sugar and protein reduced to minimum in the pine needle damaged by 30 pine caterpillars. These indicated that nutrient substance content was related to feeding stimulation degree. The feeding stimulation degree was greater and the change range of nutrients substance content was greater in the needles. Feeding stimulation could enhance the polysaccharide content and reduce the sugar and protein content.4. The secondary chemicals content in the pine needle which was in damaged in different stand types was various. Compared with the each treatment of pure forests, the content of tannin, total phenol and crude fat in the ping needle were higher when the pine damaged by 5 or 30 pine caterpillars and lower when the pine damaged by 15 pine caterpillars in the mixed forests. These indicated that secondary chemicals content was related to stand types. The change of secondary chemicals content was greater in the mixed forests when the pine was in slight and serious feeding stimulation.5. The content of tannin, total phenol and crude fat were higher in damaged pine needles than that in undamaged pine needles in differential stands types. The content of tannin, total phenol and crude fat increased in the pine needle which damaged by 5 or 15 pine caterpillars. And the content of tannin, total phenol and crude fat increased to maximum in the pine needle which damaged by 30 pine caterpillars. These indicated that secondary chemicals content was related to feeding stimulation degree. The feeding stimulation degree was greater and the change range of secondary chemicals content was greater in the needles. The secondary chemicals content in the pine needles increased with the increasing of feeding stimulation degree.