Preliminary Studies On Main Pine Beetle Digestive Enzymes Metabolism And Nutrition Utilization Of Qinling

Chinese white pine beetle, Dendroctonus armandi Tsai et Li, is one of the most important trunk pests in the Qinling Bashan Forest Ecosystems, and it mainly damaged the health of Chinese white pine, Pinus armandi Fr., more than 30 years older. Under the cooperated with the symbiotic fungus overcomed the resinic, physiologiGal, biochemiGal, and structural resistance of Chinese white pine, thus resulting in death of large infested Chinese white pine in Qinling and Bashan, and it becoming a direct threat to the sustainable development of Qinling and Bashan Forest ecosystems. This paper has used the biochemiGal methods to reveal the differences of metabolic enzymes of three dominant bark beetles species, D. armandi, Ips acuminatus Gyllenhal and Polygraphus sinensis Eggers, in Qinling and Bashan Mountains, the influence of different temperatures on the enzyme metabolism of the larvae and adult of Chinese white pine beetle, nutrient selection of Chinese white pine beetle to the phloem of Chinese white pine, and also research on the artifiGal diet components and feeding procedure in laboratory condition of dominant Chinese white pine bark beetles, which could be used to reveal the relationship of metabolism and nutrition among Chinese white pine beetle and other secondary bark beetles. The following are the main conclusions:1. In comparison with the three kinds of digestive enzymes of bark beetles, proteinase, cellulase, lipase, amylase, the results indiGated that the proteinase activity of D. armandi is the highest among them,the next being P. sinensis and I. acuminatus, respectively. The amylase activity of the three bark beetles species are shown in the following sequence:D. armandi, I. acuminatus, and P. sinensis. The cellulase activity of I. acuminatus ranks firstly, with P. sinensis and I. acuminatus in succession.2. Temperature has a signifiGant impact on the proteinase, cellulase, lipase, and amylase. The optimum temperature for proteinase activity of Chinese white pine beetle larvae is 20℃, adults 25℃; The optimum temperature for cellulase and lipase activities of Chinese white pine beetle larvae and adult is 25℃; and that of amylase is 40℃.3. Dendroctonus armandi has a selective preference to the use of nutrients of its host. Results of absorption utilization of nutrients are shown in the following sequence, suGar > fat > total soluble suGar > crude fiber > starch> crude protein. Analysis on the free state of the amino acid in the health Chinese white pine phloem showed that the phloem Chinese white pine containing 17 amino acids, among which 8 amino acids are essential amino acids 8; five elements including Na, K, Ca, Mg, Fe in the tissue of phloem and xylem of Chinese white pine are in a greater demand; the demand for the K is the largest of the five elements while demand for Cu, Mn, Zn are smaller; symbiotic fungi of Chinese white pine beetle decompose nutrients of on Chinese white pine phloem and xylem which benefit Chinese white pine beetle the absorption of nutrients .4. Results of artificial breeding of Dendroctonus armandi in the laboratory show that: different formulations of artificial raising the bark beetles have a different survival rate. In the five kinds of artificial feedes, only on the WⅡartificial diet bark beetles has highest survival rate. On the other hand, the pollution of artificial diet is a mainly lethal factor in the laboratory feeding.Based on the data from enzyme activities and nutrient utilization for host pine of Chinese white pine beetle, results show that cellulase, lipase, amylase of Chinese white pine beetle have obvious differences. Such differences have a close relationship with effectively using of nutrition of its host in the different stages of resistance to Chinese white pine. The temperature is main influencing factors, which play main role on the activities of digestive enzymes of the Chinese white pine beetle adults and larvae. Moreover, Dendroctonus armandi has a different demand for the suGar, fat, soluble total suGar, crude fiber, starch and Na, K, Ca, Mg, Fe, Cu, Mn and Zn in the tissue of Chinese white pine phloem and xylem. All those results have a great influence on the further mechanism of host-nutrients among Dendroctonus armandi and its symbiotic fungi. These results could also be used to explore new methods for management of Chinese white pine bark beetles in Qinling and Bashan Forest ecosystem.