Fig. 4.

Four-FPA induces deposition of phenolic polymers in parenchyma cells of rice and impairs the feeding capacity of WBPH female adults. (A) Fluorescence images of cross-sections of leaf sheaths of rice plants at 0 to 4.5 d after growing in nutrient solution containing 5 mg L⁻¹. (B) Fluorescence images of cross-sections of leaf sheaths of rice plants at 4.5 d after receiving the following treatments: W-NP, 4-FPA-R, 4-FPA-R+W-NP, and control (Con). Details of treatments are described in Methods. Sections were stained with safranine and fast green. High red fluorescence intensity corresponds to high phenolic polymer content. Yellow arrows indicate polymer particles. (Scale bars, 20 µm.) (C) Typical image of EPG waveforms generated by WBPH female adults showing the feeding behavior (Upper) and mean duration (+SE, n = 15 to 20) of the different feeding phases on control (Con) or 4-FPA-R (grown in nutrient solution containing 5 mg L⁻¹ 4-FPA for 4.5 d) rice plants (Lower). NP, nonpenetration; PP, pathway phase (N1 + N2 + N3), which is described in detail in Methods; N4-a, intracellular activity in the phloem region; N4-b, phloem sap ingestion; N5, xylem phase. EPGs were recorded for 6 h per insect. (D) Mean weight (+SE, n = 20) of honeydew excreted by a WBPH female adult feeding on control (Con) or 4-FPA-R (for 4.5 d) rice plants. (E) Mean number (+SE, n = 20) of eggs laid by a newly emerged female adult (Left) for 8 d or 15 gravid female adults (Right) for 12 h on control or 4-FPA-R (for 4.5 d) rice plants. Asterisks indicate significant differences between treatments and controls (*P < 0.05, **P < 0.01; Student’s t tests).