Two distinct aphid diapause strategies: slow development or development arrest.

Aphids adapt to unfavourable environmental conditions, such as low temperatures in winter, by laying diapausing eggs that overwinter. Diapause is a stress-resistant and developmentally arrested stage that can be adopted in order to increase the chance of survival in adverse environmental conditions. The diapause process of aphids is still very poorly understood. We followed the development of two species of aphids, Brachycorynella asparagi and Appendiseta robiniae, using the immunostained embryos of the aphids to identify mitotic cell divisions. Two different models of aphid diapause were demonstrated for the first time. In the first strategy, the embryo developed continuously during winter diapause, while in the second case, there was an embryonic arrest. The possibility of slow development of the whole body during diapause is a characteristic feature of aphids. The link to the plant's phenology appears to be a key factor in determining the diapause strategy in aphids.