Low temperature exposure (20 °C) during the sealed brood stage induces abnormal venation of honey bee wings

All insects are influenced by low temperature. However, as a typical stenothermic insect, the honey bee is perhaps the most severely affected. Low temperature exposure during the capped brood stages leads to high mortality and shortened worker longevity. The impact of low temperature stress on vein development has not, however, been investigated. In this study, the eight different developmental stages of capped brood (Apis mellifera) were exposed to 20 °C for 12, 24, 36, 48, 60, 72, 84, and 96 h, and then incubated at 35 °C (the optimum temperature for brood development) until emergence. We found a total of 21 abnormal vein types, consisting of 16 types of supernumerary veins and five types of lost veins. The abnormal phenomena in the brood occurred mainly 1–4 days after capping, when the metamorphosis process from larvae to pupa occurs. Our results suggest that this metamorphosis process is critical for the development of veins, indicating it as the most sensitive period to low-temperature. In addition, we found a cross vein “rs-m” between Rs and M in the hind wing of the honey bee, which has previously been ignored due to its very short length. This study on the effects of temperature on wing venation in stenothermic insects adds to our understanding of the thermal requirements for shaping the wing vein pattern, and for predicting wing venation deformation. This also adds a new research route for the investigation of the evolutionary relationship between honey bees and other hymenopteran insects.

所有昆虫均受低温影响。然而作为典型的狭温性昆虫（stenothermic insect），蜜蜂受其影响可能最为严重。封盖幼虫期暴露于低温会导致高死亡率以及工蜂寿命缩短，但此前尚未有研究探讨低温胁迫对翅脉发育的影响。本研究将西方蜜蜂（Apis mellifera）的8个不同封盖幼虫发育阶段分别置于20℃环境中暴露12、24、36、48、60、72、84及96小时，随后置于35℃（蜂群幼虫发育的最适温度）环境中培养至羽化。本研究共发现21种翅脉异常类型，其中16种为额外翅脉，5种为翅脉缺失。幼虫封盖后1~4天（即幼虫向蛹变态的阶段）主要出现翅脉异常现象。研究结果表明，该变态过程对翅脉发育至关重要，同时也是蜜蜂对低温胁迫最为敏感的时期。此外，本研究在蜜蜂后翅Rs与M脉之间发现了一条名为"rs-m"的横脉，该横脉因长度极短此前被学界忽略。这项针对狭温性昆虫温度对翅脉影响的研究，增进了我们对塑造翅脉模式所需温度条件的认知，同时也为翅脉变形预测提供了理论支撑，还为蜜蜂与其他膜翅目昆虫（hymenopteran insects）的演化关系研究开辟了全新的研究路径。