Transcriptome of Excretory Organs Revealed Potential Targets for the Control of Nilaparvata lugens

The excretory organs of insects offer potential physiological targets for insect control. In this study, RNA-seq was utilized to identify a set of transporter and receptor genes enriched in the excretory organs of the brown planthopper (BPH), Nilaparvata lugens, which is considered the most important phloem-feeding insect pest in rice. A total of 1565 and 1084 transcripts were upregulated in the excretory organs, Malpighian tubules, and hindgut, respectively, compared to the midgut, which was enriched for transport activity and oxidoreductase activity. Eight potentially important genes were selected for the exploration of biological function, including one sodium/potassium-ATPase (NKA) subunit (ATP1A1), five aquaporins (AQPs), and two neuropeptide receptors. RNA interference (RNAi) assays showed that the knockdown of ATP1A1 and two AQP genes in BPH resulted in significant lethal phenotypes (corrected mortalities = 42.9-63.6%, 7 days after injection) and significantly reduced honeydew amounts. Our findings suggest that several genes enriched in excretory organs were important for BPH survival, which could be new insect control targets.