低温导致中华蜜蜂后翅翅脉的新变异

New mutations in hind wing vein of Apis cerana cerana(Hymenoptera:Apidae) induced by lower developmental temperature

在封盖发育期,将中华蜜蜂Apis cerana cerana封盖子放入24℃低温环境中分别处理24、48、72 h,再恢复到正常的发育温度35℃至羽化,或将封盖子放在30℃低温中培养至羽化,发现羽化后的蜜蜂后翅翅脉发生明显变异。发现翅脉变异有3种类型,翅脉增加、翅脉突出和翅脉缺失。后翅翅脉增加的变异只发现一种,基室、缘室共有的径分脉与基室、盘室共有的中脉之间,新增径中横脉。新增的径中横脉发生的程度不同,有的在径分脉和中脉相对的位置相向伸出,有的形成完整的新脉,新增的径中横脉与原径中横脉相似,在末端均有"弱化点"。由于原有径中横脉较短,一直忽略其存在,这次径中横脉的确定,可以判定原来公认的"中脉分叉"应分别是径分脉和中脉延伸出来的两条翅脉。后翅突出的变异有2种,中脉向基室突出,径分脉向基室突出。翅脉突出的程度不同,有的略突出,有的明显突出,有的伸出翅脉较长。中脉突出均发生在中脉的转折点上,且此类翅脉变异,仅发生在雄蜂样本中,在工蜂样本中还未见。后翅翅脉缺失的变异有2种,发生在肘臀横脉和中脉。肘臀横脉"弱化点"处缺失。将中华蜜蜂雄蜂封盖子放入低温30℃恒温培养箱中发育,发现2个羽化的雄蜂样本发生肘臀横脉在"弱化点"处缺失。中脉向盘室伸出的部分发生缺失。翅脉缺失的程度不同,有的明显缩短,有的仅存痕迹,有的缺失大部分或完全缺失。中脉向盘室伸出的部分是东方蜜蜂Apis cerana区别于西方蜜蜂Apis mellifera的主要形态特征之一,如果东方蜜蜂这段翅脉全部缺失,此部位的形态与西方蜜蜂完全相同。这意味着这个翅脉作为区分东方蜜蜂和西方蜜蜂的翅脉特征将面临挑战。对蜜蜂种质资源鉴定,蜜蜂的系统发育和进化生物学等领域的研究将具有重要影响。温度影响翅脉发育的深入研究,为研究蜜蜂翅脉发育过程,揭示翅脉发育调控机制,以及蜜蜂发育的温度适应生理机制提供一个新思路。

The capped broods of Apis cerana cerana were incubated at constant lower temperature of 30℃ or treated at 24℃ for 24,48,72 h and then incubated at 35℃（the optimum temperature for brood development） until emergence.Three dominant mutation types,including newborn vein,protrusion vein and missing vein,were observed in hind wing vein after lower temperature treatment.Only one newborn vein was found,which was a new radiomedial crossvein generated between radial sector shared by basal cell and marginal cell,and mediae shared by basal cell and discal cell.The new radiomedial crossvein was developed to different degrees.Some only had two protuberances protruding towards each other,some almost or completely connected forming a new vein.This new radiomedial crossvein,which was similar to the original radiomedial crossvein,often had a ＂feeble point＂ at its bottom.Since the original radiomedial crossvein is short,its existence has long been ignored and just looks like a ＂point＂ connecting two veins.Now we are sure that the radiomedial crossvein is existent connecting radial sector and mediae.Therefore,the two veins at the back of radiomedial crossvein protruding towards wing′s outer margin were not the branches of mediae as generally accepted,but the extensions of radial sector and mediae.Two positions were found with protrusion mutations,the mediae and the radial sector,the mediae protruded towards basal cell and the radial sector protruded towards basal cell.There were different degrees of the protrusions.Some of protrusion veins protruded slightly,some protruded visibly and some protruded significantly forming a long vein.The protrusion veins of mediae were all observed at the ＂turning point＂.In addition,the protrusion veins of mediae were only found in drones instead of workers.Two kinds of missing vein were discovered in cubito-anal crossvein and mediae vein.The broken cubito-anal crossveins were found at the ＂feeble point＂ in both two capped broods of drones,which were incubated at constant lower developmental temperature of 30℃ until emergence.The part of mediae protruding towards discal cell was missing in different degrees.Some of the veins were obviously shorten,some only had vestige left and some were mostly or completely missing.The part of mediae protruding towards discal cell was one of the main morphological features to discriminate A.mellifera and A.cerana.If this feature of A.cerana disappeared completely,it will made the mediae looks exactly the same as that of A.mellifera.This means that it provokes a challenge to the traditional method of honeybee taxonomy based on the vein morphological feature.These discoveries of new mutations in hind wing vein of A.cerana will have a significant influence on the study of germplasm resources evaluation,evolutional biology and phylogenetics of honeybee.A further study of the effect of temperature on the development of honeybee wing vein may provide new ideas to research vein′s developmental process,to reveal regulatory mechanism and physiological mechanisms of temperature adaptation of honeybee.