The population dynamics of Placusa pinearum(Coleoptera, Staphylinidae) in forest
Author of the article:ZHAO Zheng-Ping 1** JI Bao-Zhong1*** LIU Shu-Wen2*** WANG Li-Ping1 ZHANG Xin-Wei1YANG Jin-J
Author's Workplace：1. Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China; 2. The Administration Bureau of Dr. Sun Yat-sen’s Mausoleum, Nanjing 210014, China
Key Words：Placusa pinearum, population distribution, population dynamics, in forest
Abstract：[Objectives] The distribution and population dynamics of Placusa pinearum in forest were investigated to provide a foundation for the further research on the use of P. pinearum to deliver natural enemies of Dioryctria rubella. [Methods] The effect of different forest stands, pine tree species, the diameter of pine shoots, D. rubella tunnel length, and D. rubella developmental stage, on the distribution of P. pinearum were investigated in 4 different pine tree forests in Jiangsu and Anhui Provinces. In addition, the population dynamics of P. pinearum were investigated from 2013 to 2014. [Results] The relative abundance of P. pinearum in different forest stands, was, in descending order: Laojiashan forestry station > Jurong forestry station > Guandian pine forest > Zhangbaling pine forest. The relative abundance of P. pinearum in different pine tree species, was, in descending order: Pinus massoniana > P. taeda > P. thunbergii. There were significant relationships between the abundance of P. pinearum and pine shoot diameter, and between the abundance of P. pinearum and D. rubella tunnel length (P＜0.01), but no significant relationship between the abundance of P. pinearum and the developmental stage of D. rubella (P＞0.05). P. pinearum was mainly found in pine shoots with a diameter between 4.22 mm and 15.36 mm, and in tunnels between 23.2 mm and 354.6 mm in length. The population density and distribution of P. pinearum increased with the diameter of pine shoots and tunnel length. P. pinearum could be collected from tunnels containing D. rubella larvae and pupae at different stages of development. The population density and distribution of P. pinearum in tunnels with 3rd instar D. rubella larvae were lower than in those containing other instar larvae and pupae. Adult P. pinearum were present in forests throughout the year, the two peaks of abundance were between May and July and between September and November. The larval population peak was between May and August. [Conclusion] The distribution and population dynamics of P. pinearum are mainly affected by the quantity and tunnel length of D. rubella. The best time to collect adults is between May and July and September to November.