To promote the pioneering development of life sciences and showcase major scientific achievements in this field, China Association for Science and Technology selected China’s Top 10 Achievements in Life Sciences in 2015 and announced the result on January 24. Findings, entitled “Two insulin receptors determine alternative wing morphs in planthoppers”, by a research team led by Prof. Zhang Chuanxi of the College of Agriculture and Biotechnology, Zhejiang University, were listed as one of these achievements.
Wing polyphenism is an evolutionarily successful feature found in a wide range of insects. Long-winged morphs can fly, which allows them to escape adverse habitats and track changing resources, whereas short-winged morphs are flightless, but usually possess higher fecundity than the winged morphs. Studies on aphids, crickets and planthoppers have revealed that alternative wing morphs develop in response to various environmental cues, and that the response to these cues may be mediated by developmental hormones, although research in this area has yielded equivocal and conflicting results about exactly which hormones are involved. As it stands, the molecular mechanism underlying wing morph determination in insects has remained elusive. Research shows that two insulin receptors in the migratory brown planthopper Nilaparvata lugens, InR1 and InR2, have opposing roles in controlling long wing versus short wing development by regulating the activity of the forkhead transcription factor Foxo. InR1, acting via the phosphatidylinositol-3-OH kinase (PI(3)K)–protein kinase B (Akt) signalling cascade, leads to the long-winged morph if active and the short-winged morph if inactive. InR2, by contrast, functions as a negative regulator of the InR1–PI(3)K–Akt pathway: suppression of InR2 results in development of the long-winged morph. The brain-secreted ligand Ilp3 triggers development of long-winged morphs. These findings provide the first evidence of a molecular basis for the regulation of wing polyphenism in insects, and they are also the first demonstration of binary control over alternative developmental outcomes, and thus deepen the understanding of the development and evolution of phenotypic plasticity.
These findings, published in the March issue of Nature in 2015, are labeled as an epoch-making achievement in molecular research into wing polyphenism in insects.