鞭角华扁叶蜂自然种群消长规律初步研究

A Study on the Regularity of the Fluctuation of the Natural Population of Chinolyda flagellicornis

鞭角华扁叶蜂是柏木、柳杉林中的重要食叶害虫，自１９９８年以来在浙江、四川、湖北、福建等省柏木、柳杉产区成灾，导致中幼林乃至上百年大树被害致死。自１９９１～１９９７年间进行了鞭角华扁叶蜂自然种群消长规律研究，结果表明：林间幼虫期逐期残存率占其总和的６０．４％ ，回归系数ｒ 值０．９６２ ９，ｂ 值０．６５５ ９，其中，危害期幼虫回归系数ｂ 值０．５６７ ３，滞育幼虫ｂ 值０．３４０ ９；卵期ｂ 值０．３０２ ７，ｒ值０．７９８ ９。幼虫期和卵期分别为第１、第２关键消亡因子；经野猪拱掘的滞育幼虫林地，其虫口减少量与对照比为１ｖ１．９４～３．０，其它种群天敌种寡量低，抑制能力弱。冬季－ ２ ℃霜冻天气，３ｃｍ 内土层滞育幼虫死亡率４３．８％ ～９７．１％ ，冰雹等灾害性天气对发生期各虫态影响明显。该虫自然种群消长指数Ｉ＝ １０．２２，明显大于１，表明种群呈现现快速上升与发展趋势。

The webspinning sawfly (Chinolyda flagellicornis (F.Smith)) is an important forest pest insect injuring Cupressus funebris and Cryptomeria fortunei. It started to cause disastrous damage in Zhejiang, Sichuan, Hubei and Fujian provinces in 1988. A study on the regularity of the fluctuation of the natural population of the sawfly was carried out from 1991 to 1997. The results showed that in the forest, the survival rate of the larvae was 60.4%,the regression coefficient r=0.962 9, b=0.655 9, in which the regression coefficient value ( b ) for the larvae at feeding stage was 0.567 3, that for diapausing larvae was 0.340 9,that for egg stage was 0.798 9. The mortality of the larvae and the eggs were the first key lethal factor and the second one, respectively. The number of the diapausing prepupae in the forest excavated by wild boar to that in the forest not excavated by wild boar was 1∶1.94～3.0. Other natural enemies had only a little effect. The mortality of the diapausing prepupae within 3 cm belowtop soil in frost weather in winter at -2 ℃ was 43.8%～97.1%. The disastrous weather with hail significantly influence the survival of the sawfly. The index of the fluctuation of the natural population I=10.22 , indicating the population had a tendency of rapid increase.