Abstract: [Objective] The present study was carried out in order to clarify the relationship between the percentage of Pinus yunnanensis shoots with beetles and trap catches of Tomicus minor (Coleoptera:Scolytidae), and furthermore, to provide technical support for population monitoring and controlling of the T. minor pest in the future.[Method]The shoot damages by Tomicus were investigated by random branch sampling method with a pruner in two different damage level sites of Pupeng and Xiazhuang, Xiangyun County, Yunnan province. The adults were trapped by aggregation pheromone of T. minor during the period from shoots transferring to trunk, in order to evaluate the population flight dynamics and analyze the relationship between the percentage of shoots infected with beetles and trap catches.[Result]T. minor and T. yunnanensis were two dominant Tomicus species in Pupeng and Xiazhuang forest sites. T. minor accounted for 49.75% with sex ratio 1.06:1, however, T. yunnanensis consisted of 50.25% with sex ratio 1.32:1 in the Pupeng forest site. In Xiazhuang forest site, it accounted for 54% of T. minor with sex ratio 1.45:1, and for 46% of T. yunnanensis with sex ratio 1.88:1, respectively. The percentage of shoots with beetles gradually reduced from top crown to bottom crown in Pupeng and Xiazhuang sampling locations, where the density of the Pupeng population was ca. 10 times higher than that of Xiazhuang population. The population flight dynamics of T. minor in Pupeng site showed the same trend as that of Xiazhuang, that is, adult flight began in mid-November and ended in late May of the next year. The peak period of adults' flight activities was from early March to late April. The number of natural enemies and the number of the pests in traps had obvious following phenomena. The traps caught more number of males than females with sex ratio ranging from 1:1.09 to 1.71 (♀:♂). There was a linear positive correlation between the percentage of insect-infected shoots (y) and the amount of the trap catches (x), the fitting function formula was y=0.002 4x + 0.060 1 (R²=0.67) in high population densities area (Pupeng), and y=0.003 2x-0.004 3 (R²=0.71) in low population densities area (Xiazhuang).[Conclusion]This study clarified the distribution patterns of T. minor in the tree crown of Yunnan pine with high and low pest population densities. Furthermore, the aggregation pheromone trapping test could be regard as an effective method to monitor the population dynamic of T. minor in the forest. The trapping amount of pests was positively and linearly correlated with percentage of shoots infected with beetles, suggesting that the number of trap catches could reveal the percentage of shoots infected with beetles.

Key words: Tomicus minor, Pinus yunnanensis, aggregate pheromone, percentage of shoots with beetles, correlation analysis