Fig. 1

Annual life cycle of cotton aphid. Cotton aphid has three representative winged morphs in its life cycle. In spring, the overwintering egg (a) hatches and develops into the fundatrix (b), which gives birth to fundatrigena (c) on primary host plants. The fundatrigena undergoes several generations and then produces wing parthenogenetic female (d), which migrates to second hosts, such as cotton, in late spring. During summer, cotton aphid alternatively chooses morphs between wing or wingless parthenogenetic females (e) over a dozen of generations to adapt to changing conditions, such as population density or host plant quality. In autumn, exclusively winged GP (f) and male (g) are produced successively and migrate to the primary hosts. Sexual female (h) is produced by GP and oviposits overwintering fertilized eggs after mating with the male (i). All these morphs above were captured in wild field. Scale bars, 0.2 mm