Novel low-dose neonicotinoid mode of action targeting ecdysone signaling in Lepidoptera
Research partnership opportunity to advance the discovery of a new mode of action for neonicotinoid insecticides. At sub-symptomatic doses, three neonicotinoids cause arrested development during larval-to-pupal molting in Lepidoptera, likely by disrupting the ecdysone signaling pathway. This finding could enable pest control at significantly lower application rates, reducing environmental impact and risks to beneficial insects.
Overview
Researchers at Iowa State University have identified a previously unrecognized mode of action for neonicotinoid insecticides. At doses well below those that produce typical intoxication symptoms, three neonicotinoids — imidacloprid, clothianidin, and thiamethoxam — cause arrested development (arrested ecdysis) in larval Lepidoptera as they attempt to transition into the pupal stage. The research team hypothesizes that this effect results from interference with the ecdysone signaling pathway, a neuroendocrine process that governs molting and metamorphosis. Because the effect occurs at efficacious exposure levels far below current agricultural application rates, this discovery has the potential to reduce environmental loading of neonicotinoids and minimize harm to beneficial insects such as pollinators.
Technical specifications
- Observed effect: Final instar monarch larvae exposed to low doses of imidacloprid, clothianidin, or thiamethoxam die during pupation with no prior signs of intoxication. Larval-to-pupal molts are disrupted while larval-to-larval molts remain unaffected, suggesting a pathway specific to pupal development.
- Effective doses: Topical imidacloprid exposure at 0.9–9.0 µg/g and dietary exposure at 0.78 µg/g leaf tissue produced 82–100% mortality due to arrested ecdysis.
- Routes of exposure: Both topical and dietary exposure routes are effective.
- Species range: Arrested ecdysis has been confirmed in monarch larvae and documented in preliminary bioassays with corn earworm and red admiral butterfly, indicating potential relevance across multiple Lepidoptera pest species.
- Proposed mechanism: Interference with the ecdysone signaling pathway, a neuroendocrine hormone cascade that triggers pupal development.
Technology readiness level
The discovery is supported by published and preliminary bioassay data demonstrating arrested ecdysis across multiple Lepidoptera species and exposure routes. Next-stage validation will determine the critical timing window in the last instar for the effect to occur, test dietary exposure at concentrations relevant to aerial or systemic field applications, evaluate additional insect species including both holo- and hemimetabolous insects to assess broader applicability, and explore whether registered neonicotinoids could be reformulated into bait products for pest Lepidoptera. The research team is seeking a partner to support insect bioassays, bait testing, and mode-of-action identification studies.
About Iowa State University
Iowa State University is a large, comprehensive public land‑grant research university based in Ames, known for combining fundamental discovery with translational, industry‑relevant work. Companies collaborate through a research and technology park that co‑locates corporate R&D with faculty labs and startups, creating steady talent pipelines. Pilot‑scale facilities, field test sites, and a statewide extension network support prototyping, validation, and deployment with partners across the region. Research is supported by competitive federal funding, including awards from NSF, USDA, and DOE. A dedicated technology transfer office and affiliated research foundation streamline IP, licensing, and startup formation, with incubator space on site.
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