The Physiological Mechanism Of The Brown Planthoppers, Nilaparvata Lugens (St(?)l) Resurgence: Changes Of The Contents Of Protein, RNA And DNA In Ovary And Fat Body

This study investigated insecticide-induced changes in protein, RNA and DNA contents in ovary and fat body of female brown planthoppers (Nilaparvata lugens St?l) (Homoptera:Delphacidae). Experimental results are as follows:Our investigations were specifically targeted at the dynamics of protein content in the fat body and ovary of adult females developed from the nymphs on rice plants of shenyou 1 at the tillering stage and at the yellow maturity stage treated with imidacloprid, triazophos and deltamethrin, separately. The results showed that protein contents in the fat body and ovary increased significantly in insects from rice plants which were subjected to insecticide foliar sprays at both tillering and yellow maturation stages, as compared to the controls from untreated plants. However, the level of increase in protein contents varied with insecticide, treatment concentrations and adult age. In general, both in fat body and ovary, the percent increase induced by triazophos and deltamethrin was generally greater than that induced by imidacloprid, and the higher concentration induced a greater increase than did the lower concentration. Protein contents of both fat body and ovary linearly increased with adult age.The present study investigated insecticide-induced changes in protein, RNA and DNA levels in the ovary and fat body of female adults. Potted rice plants were sprayed with different concentrations of imidacloprid, triazophos and detamethrin. The results showed that all three insecticides caused a significant increase in protein and RNA contents in the ovary and fat body of female adults developed from nymphs fed on treated plants compared to those from on untreated plants, though there was no significant effect on DNA content. In general, protein and RNA contents in both ovary and fat body linearly increased with insecticide concentrations or days after emergence (DAEs) when they were applied. There was a significant correlation between protein content and RNA content in both ovary and fat body. In addition, the relationship between ratios of RNA to DNA in ovary and fat body of adult female of N. lugens and insecticide concentrations showed a significant positive correlation for most DAEs of imidacloprid and several DAEs of triazophos and deltamethrin treatments. These findings suggest that RNA in both ovary and fat body was more sensitive to insecticides, and the insecticide-induced changes in RNA content in turn influence protein synthesis in ovary and fat body. Consistently, RNA to protein ratios in ovary and fat body were ca 0.42 in all treatments and controls. Differences in protein, RNA and DNA contents between the experiment of foliar spray before insects release and the experiment of foliar spray after insects release. (i.e. insecticide concentration and DAEs)...