Effects of indoxacarb on total protein, RNA, and DNA contents in the ovaries and fat bodies of Nilaparvata lugens Stål (Hemiptera: Delphacidae) adult females

• Protein and RNA contents decreased linearly with the concentration of indoxacarb.
• DNA contents did not significantly decrease except at 5 days after emergence.
• Protein and RNA were more sensitive to indoxacarb than was the DNA.
• The RNA-to-protein ratios were consistently 0.2 in all of groups.

The new insecticide indoxacarb was recently developed with high insecticidal activity in the control of lepidopteran pests, and recent findings demonstrated that indoxacarb also significantly suppressed the fecundity of Nilaparvata lugens Stål (Hemiptera: Delphacidae) populations, a serious insect pest of rice in Asia. The current study investigated the total protein, RNA, and DNA contents in the ovaries and fat bodies of N. lugens adult females after treatment with the insecticide indoxacarb. The results demonstrated that all of the tested concentrations of indoxacarb caused a significant decrease in the protein and RNA contents in the ovaries and fat bodies of the adult females that developed from nymphs fed indoxacarb-treated rice plants compared with those from nymphs fed untreated rice plants, while the DNA contents did not significantly decrease except at 5 days among all of the tested days after emergence. In general, the protein and RNA contents in both the ovaries and the fat bodies decreased linearly with the concentration of indoxacarb applied. There was a significant negative correlation between the total protein and RNA contents and the concentrations of indoxacarb, showing that the total protein and RNA were more sensitive to indoxacarb than was the DNA, and that the changes in RNA contents in turn influence protein synthesis in both the ovaries and fat bodies. The RNA-to-protein ratios in both the ovaries and fat bodies were consistently 0.2 in all of the treatment groups and in the control groups.

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