母代性比对甜菜夜蛾实验种群繁殖潜力的影响

Effect of maternal sex ratio on the reproductive potentials of the beet armyworm, Spodoptera exigua

【目的】探明母代性比对甜菜夜蛾Spodoptera exigua(Hübner)实验种群繁殖及后代发展趋势的影响,为短期预测预报提供科学指导。【方法】在人工气候培养箱中(设置条件:温度28±1℃,光周期为16L:8D,相对湿度为70%±5%),研究甜菜夜蛾实验种群不同母代性比结构(♀:♂=1:1,1:2,1:3)对主要繁殖参数的影响。【结果】甜菜夜蛾成虫产卵历期随母代性比下降而缩短;种群产卵量随母代性比降低而减少;孵化率随母代性比降低而升高;每雌产卵量无差异,但雄蛾对卵及后代的贡献量却随着雌蛾比例的加大而显著提高;后代性比和雌蛹蛹重有随母代性比下降而上升的趋势。【结论】母代性比除对甜菜夜蛾雌蛾个体生殖能力影响较小,对雌蛾产卵历期、种群产卵量和孵化率、后代性比、后代雌蛹蛹重及母代雄蛾生殖贡献率均有显著影响。当以性诱剂诱集的雄虫数量为依据进行短期预测预报时,除了考虑雄虫的数量外,还有必要了解此时种群的性比结构,才能做出更准确的判断。

[Objectives] To understand the effects of sex ratio on the reproduction and population dynamics of Spodoptera exigua, and thereby improve our ability to forecast outbreaks of this pest. [Methods] Reproductive parameters were studied under different sex ratios （♀：♂=1：1; 1：2; 1：3） under laboratory conditions （temperature （28±1）℃, RH 70%±5%, photoperiod 16 L：8 D）. [Results] Sex ratio had an obvious impact on reproductive parameters. Although the oviposition duration of females reduced as the sex ratio declined the hatching rate increased. Although female egg production did not differ significantly among the three different sex ratio groups, the contribution of males to the next generation increased rapidly as the proportion of females increased. Offspring sex ratio and female pupa weight tended to increase with declining parental sex ratio. [Conclusion] Sex ratio had little influence on the reproductive capacity of individual female adults, but did have a significant influence on the oviposition duration of females and male reproduction. Therefore, short-term forecasts based on the number of male S. exigua lured into traps by sex attractants should also take into account the population sex ratio.