幼虫密度对二点委夜蛾生长发育及繁殖的影响

【目的】在不同幼虫密度饲养条件下,研究二点委夜蛾Athetis lepigone生长发育及繁殖的情况,明确幼虫密度对该害虫的室内种群增长的影响。【方法】本实验设置5个幼虫饲养密度即1,5,10,20和30头/瓶(750 mL),分别观察5个饲养密度下该虫的各个龄期及整个幼虫发育历期及存活率、蛹重、蛹期以及成虫生殖情况。【结果】幼虫密度对该虫幼虫各龄期及整个幼虫发育历期及存活率、蛹重、蛹期以及成虫生殖情况均有显著性影响。整个幼虫发育历期随着密度的增加而缩短,10头/瓶达到最短(18.27 d),之后随着幼虫密度的增加而显著延长;幼虫至蛹的存活率随着密度增高而显著下降,30头/瓶最低(39.37%)。蛹期随着密度的增加而延长(10头/瓶除外)。蛹重和每雌产卵量均以1头/瓶最高,随着幼虫密度的增加而显著下降。雌雄蛾寿命均以10头/瓶最长,与1和5头/瓶没有显著性差异。生命表分析显示:二点委夜蛾的种群增长指数以5头/瓶最高,幼虫密度过低或者过高均不利于种群增长。【结论】幼虫密度是影响二点委夜蛾种群增长的重要因子之一。

Effects of larval density on the development and reproduction of Athetis lepigone

[Objectives] To investigate the effects of larval density on the development, reproduction, and population growth ofAthetis lepigone. [Methods] The growth, development, and reproduction ofA. lepigone were examined by rearing larvae at densities of 1, 5, 10, 20, and 30 larvae/750 mL. ]Results] The developmental duration of different instars, all larvae, pupae, survival rate from larvae to pupae, pupal weight and adult reproduction of A. lepigone were significantly affected by larval density. The duration of larval development was lowest at a density of 10 larvae/750 mL （18.27 d） but significantly increased with increasing larval density. The survival rate from larvae to pupae decreased with larval density and was only 39.37 % at a density of 30 larvae/750 mL. Pupal developmental duration was prolonged with increasing larval density, except at a density of 10 larvae/750 mL. Pupal weight and the number of eggs laid per female significantly reduced with increasing larval density. The longevity of both sexes was greatest at 10 larvae/750 mL, but less at either lower or higher density. Life table analysis suggested that larval density significantly affected the population growth index, being highest at a density of 5 larvae/750mL and significantly lower when the larval density was too high. [Conclusion] The results suggest that larval density is one of the major ecological factors influencing the population dynamics in A. lepigone.