| Summary: | 碩士 === 國立臺灣大學 === 昆蟲學研究所 === 94 === The Chinese-fir (Cunninghamia lanceolata) belongs to the needle plant with economical significance for the usage of construction lumber. The scolytids (Curculionidae: Scolytinae), that are key pests in the forest and some are also quarantine pests, are likely to cause the dying of Chinese-fir in central Taiwan, 2002. The scolytids are attracted by volatile chemicals released from trees or woods, therefore in this study two lures, α-pinene and ethanol, were used with 12-units of Lindgren multiple funnel traps to investigate the species of scolytids in Chinese-fir plantation. From June 2004 to May 2005 in Nei-Mou-Pu Tract of NTU Experimental Forest, 3, 3, 7 and 12 traps were set in the no. 64-7, 65-7, 69-5 and 70-3 lots, respectively. During the investigation period, the beetles in the 25 traps were collected every other week and the lures were replaced every 60 days. The result showed that 40,366 scolytid individuls belonging to 73 species (including 9 species with only one specimen in the investigation period), 30 genera, and 9 tribes were collected and the number was 53.7% of that of total beetles (75,153 beetles belonging to 59 familes were collected). These 73 scolytid species included 2 endemic species, 18 recorded species, 5 near species, 27 new recorded species and 21 possible-new species (8 species had one specimen only) in Taiwan. The numbers of Hypothenemus eruditus Westwood, Phloeosinus pertuberculatus Eggers, Scolytoplatypus pubescens Hagedorn, Xyleborus affinis Eichhoff, and Xylosandrus mancus (Blandford) were 37%, 24.4%, 7.8%, 7.6%, and 6.4%, respectively, and they were the top five species of attracted scolytids in the collection. Three1.5-meter-length dead woods were collected in each lot, and each wood was cut into 3 lumbers to breed the insects which were collected in these woods. This experiment was repeated three times and it was for the comparison of the beetles in the traps. Finally 6 families of beetles were collected. Phloeosinus pertuberculatus Eggers was the third rich species in the traps; however, it was the most abundant one (accounted for 42.6% of beetles) in the woods. The microclimate changes little in pine forest, but heavy rain or typhoon influences the release rate of lures and the flight ability of scolytids. Therefore, after a typhoon hit Taiwan the numbers of scolytid species and their populations were the least in the investigation. The correlation between the numbers of total scolytids and their natural enemies that belong to 12 families and between the numbers of 5 dominant scolytids and these natural enemies were studied. In the collection, the numbers of Staphylinidae and Nitidulidae were the most abundant ones of these natural enemies. In these four areas the correlation between Staphylinidae and total scolytids is the most significant one (r = 0.73). Among 5 dominant scolytids, the correlations between H. eruditus and Nitidulidae is the most significant one (r = 0.87) and between X. affinis and Cleridae (r = 0.88) are the most two significant ones. In the pure pine forest the species richness of beetles and scolytids are 5.04 and 5.1, respectively, and the Simpson’s indices are 0.62 and 0.72, respectively. These data might be the good reference for the study on ecological conservation.
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