{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T10:49:39Z","timestamp":1785408579113,"version":"3.56.0"},"reference-count":15,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,5,22]],"date-time":"2026-05-22T00:00:00Z","timestamp":1779408000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["32460671"],"award-info":[{"award-number":["32460671"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"award":["32460671"],"award-info":[{"award-number":["32460671"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Special Basic Cooperative Research Programs of Yunnan Provincial Undergraduate Universities Association","award":["202301BA070001-088"],"award-info":[{"award-number":["202301BA070001-088"]}]},{"name":"Yuxi Normal University College Student Innovation and Entrepreneurship Training Program","award":["S202411390021"],"award-info":[{"award-number":["S202411390021"]}]},{"name":"Yuxi Normal University College Student Innovation and Entrepreneurship Training Program","award":["S202411390003"],"award-info":[{"award-number":["S202411390003"]}]},{"award":["S202411390021"],"award-info":[{"award-number":["S202411390021"]}],"id":[{"id":"https:\/\/ror.org\/048fp0x47","id-type":"ROR","asserted-by":"publisher"}]},{"award":["S202411390003"],"award-info":[{"award-number":["S202411390003"]}],"id":[{"id":"https:\/\/ror.org\/048fp0x47","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Yunnan Technological Innovation Talent Training Object Project","award":["202305AD160037"],"award-info":[{"award-number":["202305AD160037"]}]},{"name":"Yunnan Provincial First-Class Discipline Construction Project\u2014New Discipline Cultivation Program for Plateau Agricultural Ecological Protection and Restoration"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Insects"],"abstract":"<jats:p>The invasive plant Tithonia diversifolia is a promising source of botanical insecticides, yet the mechanisms by which its active compounds impair insect physiology remain incompletely characterized. This study investigated the effects of 6-methoxyluteolin (6-ML), a flavonoid isolated from T. diversifolia, on melanization and cuticle integrity in Spodoptera litura larvae. Cuticle melanization, mediated by tyrosinase-catalyzed oxidation of tyrosine-derived substrates, is essential for cuticle sclerotization and immune defense in insects. Whether 6-ML directly targets this pathway has not been previously examined at the biochemical and histological level. Tyrosinase activity and melanin content were measured across 3rd\u20136th-instar larvae exposed to a concentration gradient of 6-ML (1.625\u2013100 \u03bcg\/mL). Histological sections of 4th- and 5th-instar larvae were prepared by paraffin embedding and hematoxylin and eosin (H&amp;E) staining. 6-ML significantly reduced tyrosinase activity and melanin content in a concentration-dependent manner across all instars examined. Histological analysis revealed progressive cuticle thinning and loss of pigmentation granules with increasing 6-ML concentration. These findings provide the first biochemical and histological evidence that 6-ML targets the melanization pathway in S. litura, supporting its potential as a melanization-inhibiting botanical insecticide.<\/jats:p>","DOI":"10.3390\/insects17060535","type":"journal-article","created":{"date-parts":[[2026,5,22]],"date-time":"2026-05-22T10:07:47Z","timestamp":1779444467000},"page":"535","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["6-Methoxyluteolin from the Invasive Plant Tithonia diversifolia Suppresses Melanization and Impairs Epidermal Integrity in Spodoptera litura Larvae"],"prefix":"10.3390","volume":"17","author":[{"given":"Zhandi","family":"Wang","sequence":"first","affiliation":[{"name":"School of Agronomy and Biological Science, Yuxi Normal University, Yuxi 653100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Junying","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Agronomy and Biological Science, Yuxi Normal University, Yuxi 653100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yandan","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Agronomy and Biological Science, Yuxi Normal University, Yuxi 653100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Weili","family":"Dai","sequence":"additional","affiliation":[{"name":"School of Agronomy and Biological Science, Yuxi Normal University, Yuxi 653100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-4885-6388","authenticated-orcid":false,"given":"Yinglan","family":"Dai","sequence":"additional","affiliation":[{"name":"School of Agronomy and Biological Science, Yuxi Normal University, Yuxi 653100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lin","family":"Jia","sequence":"additional","affiliation":[{"name":"School of Agronomy and Biological Science, Yuxi Normal University, Yuxi 653100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2471-8071","authenticated-orcid":false,"given":"Weifeng","family":"Ding","sequence":"additional","affiliation":[{"name":"School of Biological and Chemical Science, Pu\u2019er University, Pu\u2019er 665000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,22]]},"reference":[{"key":"ref_1","first-page":"e05765","article-title":"Pest categorisation of Spodoptera litura","volume":"17","author":"Bragard","year":"2019","journal-title":"EFSA J."},{"key":"ref_2","first-page":"192","article-title":"Insect pest Spodoptera litura (Fabricius) and its resistance against the chemical insecticides: A review","volume":"11","author":"Thakur","year":"2024","journal-title":"Plant Sci. 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