室内饲养的小菜蛾种群近交衰退分析
Inbreeding depression in captive-raised diamondback moths
蒲宇辰** 黄 斌 侯有明***
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DOI：10.7679/j.issn.2095-1353.2015.149
作者单位：福建农林大学植物保护学院，福建省昆虫生态重点实验室，农业部闽台作物有害生物综合治理重点实验室，福州 350002
中文关键词：小菜蛾，近交系，交配行为，繁殖，衰退
英文关键词：diamondback moth, inbred lines, mating behavior, production, depression
中文摘要：
【目的】 分析近交繁殖对小菜蛾Plutella xylostella种群的影响，为室内繁殖小菜蛾种群提供依据。【方法】 在室内条件下，连续饲养6代小菜蛾种群，比较近交种群和杂交种群在交配行为、繁殖能力、蛹重、成虫寿命及形态等方面的差异。【结果】 近交繁殖各代蛹重达极显著差异，尤其第3代后，蛹重显著下降；近交各代的雌雄成虫在交配次数和交配持续时间上显著减小，尤其是第4代后，下降幅度极其明显，F6代雌（雄）成虫的交配次数和交配持续时间分别是F0代的12.9%（13.8%）和8.3%（8.9%），表明自F4代后，近交小菜蛾种群已呈现出明显的衰退现象。同样，F4代后近交种群的产卵前期、产卵期、产卵量、卵孵化率、成虫寿命等均极显著下降，但世代历期显著延长。同时，近交对雌雄成虫体长有显著影响，F6代雌雄成虫体长是F0代的60%左右。【结论】 自近交繁殖3代始，会导致小菜蛾种群交配行为、繁殖及形态的变化，尤其是近交繁殖4代以后变化更为明显，使种群出现明显的衰退现象。因此，在小菜蛾室内繁殖时，隔一段时间（至多3代）采集远源虫源，避免种群衰退。
英文摘要： [Objectives] To investigate the effects of inbreeding on the diamondback moth (DBM) in order to improve the captive rearing of DBM. [Methods] DBM were continuously reared for 6 generations under laboratory conditions, and differences in mating behavior, reproductive capacity, pupal weight, adult longevity and morphology etc. between inbred and outbred populations compared. [Results] The pupal weight of inbred populations decreased significantly, especially after the third generation. Mating frequency and mating duration of inbred generations of male and female adults also markedly decreased, especially after the fourth generation. These decreases were very obvious; the mating frequency and mating duration of females of the F6 generation were, respectively, 12.9% and 8.3% those of the F0 generation, whereas the corresponding data for males were 13.8% and 8.9% those of the F0 generation. This indicates that the fitness of the inbred population had undergone a significant decline since the F4 generation. Similarly, the preoviposition period, oviposition period, fecundity, hatching rate and adult longevity etc. all significantly decreased in the post-F4 inbred population, but the developmental period significantly increased. Inbreeding also had significant effects on the size of male and female adults, the body length of male and female adults in the F6 generation being only about 60% of that of the F0 generation. [Conclusion] Changes in reproductive behavior and morphology were apparent in DBM after just 3 generations of inbreeding. These changes became more obvious after 4 generations, after which they became sufficient to cause populations to decline. Wild-caught moths should be incorporated into captive DBM breeding populations at least every 3 generations to avoid the deleterious effects of inbreeding.