巢管内径尺寸对凹唇壁蜂(膜翅目:切叶蜂科)种群参数的影响

The inner diameter of nest tubes influences reproductive parameters of Osmia excavata Alfken(Hymenoptera:Megachilidae)

【目的】凹唇壁蜂Osmia excavata Alfken是我国北方果园重要的授粉昆虫,为明确人类管理措施对凹唇壁蜂种群动态的影响,本文主要探索人工巢管(芦苇管)的内径尺寸与凹唇壁蜂基本种群参数的关联,从而为维持凹唇壁蜂种群以传粉为目的扩繁确定最合适的巢管尺寸。【方法】通过在苹果园放置不同内径大小的巢管,收集凹唇壁蜂种群,进一步比较了3种不同内径尺寸(6、8、10 mm)的巢管中凹唇壁蜂蜂重、茧长、性比、寄生率和死亡率的差异。最后,综合以上结果评价了巢管内径尺寸对凹唇壁蜂种群参数的影响。【结果】(1)凹唇壁蜂具有雌雄体型性二型现象,雌蜂茧重是雄蜂的1.67倍,雌蜂茧长是雄蜂的1.15倍。(2)一定范围内增加巢管的内径可以显著增加凹唇壁蜂后代的性比(雌蜂比例)、蜂重和茧长。(3)凹唇壁蜂亲本对后代的投资随着巢管内径的增加而增加。【结论】凹唇壁蜂可根据外界筑巢条件的变化调整其对子代的亲本投资和性别分配比例。直径较小的巢管中,对应亲本所产后代偏向个体较小的雄性;直径较大的巢管中,对应亲本所产后代偏向个体较大的雌性。可获得的孔穴的尺寸能够通过影响凹唇壁蜂后代种群的体型和性比,进而影响当地壁蜂种群的结构和稳定性。因此,在半驯养独居蜂的繁育过程中,可以通过人工控制巢管内径尺寸,以筑巢直径8-10mm为最适合范围,来调整后代的蜂重、茧长、性比等,进而优化对半驯养独居蜂的种群管理。

[Objectives] To determine the effect of nest tube diameter on the population dynamics of Osmia excavata Alfken, an important pollinator of apple crops in northern China. [Methods] Bee weight, cocoon length, sex ratio, parasitism rate and mortality, of colonies nesting in tubes of three different internal diameters(6, 8 and 10 mm) were measured and compared by placing nest tubes of these diameters in apple orchards. [Results](1) O. excavata has marked sexual size dimorphism;adult females were 1.67 times heavier than males, and the length of female cocoons was 1.15 times that of male cocoons.(2) Increasing the internal diameter of the nest tube within a certain range can significantly increase the number of female progeny, and cocoon weight and length.(3) Parental investment of O. excavata increased with increasing nest tube diameter. [Conclusion] Nest tube diameter affects the parental investment and sex ratio of O. excavata. In smaller diameter nest tubes, offspring tend to be male, whereas in larger diameter nest tubes offspring tend to be female. The available tube diameter can therefore affect bee weight, cocoon length and the sex ratio of progeny, and thereby the structure and stability of the local population. Changing the size of nest tubes can affect the size and sex ratio of offspring, providing a relatively simple way to optimize the management of this semi-domesticated, solitary bee species. The best nest tubes had an internal diameter in the range of 8-10 mm.