Abstract: 【Aim】 The aim of this study is to investigate the role of spalt major, a regulator of wing development, in wing differentiation of the pea aphid, Acyrthosiphon pisum, and to further reveal the molecular mechanism of non-genetic wing polyphenism in insects. 【Methods】 A high ratio of winged offspring was induced by density in the parthenogenetic wingless A. pisum under the laboratory conditions and the expression level of Apsal was detected by qRT-PCR. dsRNAs were synthesized, including dsApsal targeting spalt major gene (Apsal), dsApWnt2 targeting Wnt-2 (ApWnt2) and dsApdpp targeting decapentaplegic (Apdpp) in A. pisum. ApWnt2 and Apdpp are upstream of Apsal in the Wg/Wnt and Dpp pathways, respectively. Nanocarrier-mediated body wall penetration was used to interfere with Apsal, ApWnt2 and Apdpp in wingless female adults and their newly born nymphs, and then the ratio of winged morph was recorded, and the gene expression levels were analyzed by qRT-PCR. 【Results】 More than 80% of winged offspring of A. pisum could be stably induced by high density treatment on the female adults. The expression level of Apsal, a key gene in wing development, was increased in the winged offspring aphid induced by density as compared with that in the wingless solitarily bred aphid. Interfering the expression of Apsal by dsApsal resulted in a significant decrease of the ratio of winged morph compared with the control group (dseGFP). When the expression of upstream gene ApWnt2 or Apdpp was interfered, the expression level of Apsal decreased as compared with that in the control group (dseGFP). 【Conclusion】 Apsal regulates wing differentiation of A. pisum and is activated by both Wg/Wnt and Dpp signaling pathways. This study further reveals the molecular mechanism of aphid wing differentiation, providing theoretical and technical bases for RNAi-based pest management to prevent aphids from migrating to new hosts.

Key words: Acyrthosiphon pisum, wing differentiation, Wg/Wnt signaling pathway, Spalt, RNAi