Influence of photoperiod on Population Occurrence of Dendrolimus punctutas (Lepidoptera: Lasiocampidae) at Highlands: basing on age-stage, two-sex life tables
Author of the article:Zeng Ju-ping1,2**，OUYANG Fang2，WANG Yong3，LIU XingPing1
Author's Workplace：1.College of Forestry, Jiangxi Agriculture University，Nanchang330045, China；2.Institute of Zoology,Chinese Academy of Sciences, Beijing100101, China；3.Plant Protection and Quarantine Station, Hunan Province Agricultural Department, Changsha410005, China
Key Words：Dendrolimus punctutas Walker, highland, age-stage two-sex life tables, population parameter
Abstract：Dendrolimus punctutas Walker is a key forest-pest in South China, its population occurrence at highlands （>700m) is still unknown. This study took samples of D. punctutas at the highland of Suining (26.35°N, 110.09°E). These samples were treated by five successive photoperiods in laboratory, aiming to investigate the influence of photoperiod on the population parameters, which were computed by the method of age-stage, two-sex life tables. Results showed that the population occurrence finished completely at L:D = 15.5:8.5(15.5h) and L:D = 14.5:9.5(14.5h), but partly at L:D = 11.5:12.5(11.5h), L:D = 12.5:11.5(12.5h) and L:D = 13.5:10.5(13.5h). The population parameters were counted as 0.057d-1 of intrinsic rate of increase(r), 55.73 of net reproductive rate (R0), 241.5/female of fecundity and 71.05d of mean generation time (T) at 15.5h, and the r and R0 were significantly higher than 0.018 d-1 and 6.29 at 14.5h. The dispersive breeding behavior was observed at 14.5h because reproduction distributed at two separate times, with the second time lagging almost one month. Adults at 14.5h showed a shorter longevity compared with those at 15.5h. It suggested that the response to photoperiod change was intensified in the highland population, and D. punctutas was early induced into diapause by the decrease of photoperiod since the end of July in Suining, thus it could be produced just one generation there annually.