Cyetpyrafen

Cyetpyrafen is a pyrazole insecticide/acaricide with broad-spectrum activity. It binds to DhelOBP4 (Ki = 4.95 μM) and DhelOBP21 (Ki = 5.51 μM) in Diabrotica beetles, thereby mediating olfactory recognition. Cyetpyrafen induces dose-dependent antennal potential responses and has a repellent effect on Diabrotica beetles. It exhibits bioaccumulation properties, being rapidly passively absorbed by lettuce and rice roots, reaching a steady state within 24 hours, primarily accumulating in the roots with limited xylem/phloem transport.

Cyetpyrafen (1.12 mg/L; 1-96 h) is rapidly absorbed by the roots of rice and lettuce, reaching a steady state within 24 hours. It predominantly accumulates in the roots, with an average root concentration factor (RCF) of 1290 mL/g for rice and 1730 mL/g for lettuce, while exhibiting limited translocation to the aerial parts. The compound is cleared more slowly from lettuce roots than from rice roots. Cyetpyrafen (5 mg/L; 3-96 h) does not participate in phloem-mediated transport in rice seedlings, as it is unable to move from the exposed roots to the non-exposed roots or above-ground parts. Exposure to 1.12 mg/L of cyetpyrafen for 24-96 hours significantly enhances the activity of enzymes such as CYP450, POD, CarE, GT, and GST in the roots of both rice and lettuce, indicating their role in the metabolic transformation of cyetpyrafen within these plants. Cyetpyrafen is predicted to be extremely toxic to fish and highly toxic to daphnia and green algae. Its Phase I metabolites (M-391, M-409-1/2, M-407) exhibit similar ecotoxic levels, whereas the toxicity of Phase II metabolites is reduced.

Cyetpyrafen (1-100 mg/L; applied locally) can induce dose-dependent repellent effects and EAG responses in adult Drosophila melanogaster by interacting with DhelOBP4 and DhelOBP21; after knockdown of these two odor-binding proteins, the olfactory sensitivity of the adults to all tested concentrations of Cyetpyrafen significantly decreased.