Despite the fact that sap-feeding hemipterans are major agricultural pests, little is known about the pea aphid's (Acyrthosiphon pisum) nymphal development, compared to other insect models. Given our limited understanding of A. pisum nymphal development and variability in the naming/timing of its developmental events between different environmental conditions and studies, here, we address developmental knowledge gaps by elucidating how diet impacts A. pisum nymphal development for the LSR1 strain when it develops on its universal host plant (Vicia faba), isolated leaves, and artificial diet. Moreover, we test how plant age and transgenerational stressors, such as overcrowding and low plant vigor, can affect nymphal development. We also validate a morphological method to quickly confirm the life stage of each nymphal instar within a mixed population. Overall, we found extremely high variation in the timing of developmental events and a significant delay in nymphal (~5-25-h/instar) and pre-reproductive adult (~40-h) development when reared on isolated leaves and artificial diets, compared to intact host plants. Also, delays in development were observed when reared on older host plants (~9-17-h/event, post 2nd instar) or when previous generations were exposed to overcrowding on host plants (~20-h delay in nymph laying) compared to controls.
Keywords: Acyrthosiphon pisum; artificial liquid diet; developmental delay; nymphal development; nymphal instars; pea aphid; plant-rearing; siphunculus; transgenerational stressors.