Study On Population Dynamic And Transferring-shoot Mechanism Of Dioryctria Rubella

Dioryctria rubella Hampson belongs to Lepidoptera, Pyralidae, Dioryctria. The insect is one of the important boring pest in Pine tree and live in hidden. In this paper, we mainly studied the population dynamic and transferring-shoot mechanism of Dioryctria rubella from the perspective of ecology. The main results were summarized as follows:1. Dioryctria rubella occur for 3 generations each year in the seed orchards of pinus massioniana in Wuming of Guangxi. The first generation occur from late March to late May, and the two generation occur from mid-June to mid-August, and the third generation occur from early September to late October. The larvae began to overwinter since November. The insect has a phenomena of the generations overlap. The dynamic monitoring of Dioryctria rubella adult populations indicates that it has three peaks.2. There was no significant difference, which the distribution of Dioryctria rubella wormhole in different directions and different levels of pinus massioniana. But the distribution mattern of Dioryctria rubella was aggregative, and the distribution of basic component was individual group. According to the estimation by aggregation mean (λ) show that the reason of Dioryctria rubella is the gathering by its own actions or the circumstances.3. The larvae of Dioryctria rubella has a obvious behavior of transgferring-shoot. The bore-out-shoot and the bore-into-shoot have a significant difference in branch diameter, branch length, gallery diameter and gallery length, which the bore-out-shoot less than the bore-into-shoot in above parameters. It indicates that Dioryctria rubella transferring-shoot has a relationship with both the growth condition of the piney shoot and the size of gallery space.4. Transferring-shoot of Dioryctria rubella larvae has a relationship with the change of the piney shoot nutrients. The content of soluble sugar and protein in tender-shoot is higher than in mature-shoot of pinus massioniana, and the content of soluble sugar in the upper half part is higher than in the lower half part of both tender-shoot and mature-shoot; the protein of tender-shoot is in uniform distribution, but which the protein distribution is higher in the upper half part of mature-shoot; and the distribution of free amino acids is not different significantly. As the time of the feeding by Dioryctria rubella larvae goes in shoot, the content of soluber sugar, protein and free amino acid declines after the harm by Dioryctria rubella. It indicates that the transferring-shoot of Dioryctria rubella has a relationship with the reduce of nutrient.5. The content of tannin, total phenols and flavonoids in tender-shoot is higher significantly than in mature-shoot; the content of tannin and flavonoids in the upper half part is higher significantly than in the lower half part of both tender-shoot and mature-shoot; the total phenols content is in uniform distribution in tender-shoot and mature-shoot, and it is not different significantly in upper half part and in lower half part of branches.6. Transferring-shoot of Dioryctria rubella larvae has a relationship with the change of the shoot secondary compounds. When the piney shoot is infested by Dioryctria rubella lavare, the content of tannin and flavonoids increases, but with the extension of feeding time, the tannin and flavonoids content declines. Before the bore-out-shoot of larvae, the tannin and flavonoids content is higher than the bore-into-shoot of larvae and CK. With the time of the feeding by Dioryctria rubella larvae goes in shoot, the total phenols content increases, the total phenols content declines significantly in bore-out-shoot and bore-into-shoot, but it is still higher significantly than in the CK.7. The effects of the feeding by Dioryctria rubella larvae on the water content and pH vaule of gallery are significant, with the larvae bored, the pH vaule of gallery increases significantly, but the water content declines.In short, Experimental results showed that transferring-shoot of Dioryctria rubella has a relationship with the change of nutrient, secondary compounds, the piney shoot growth condition, and the water content and pH vaule of gallery.