LAUSR

BACKGROUND The brown planthopper (BPH), Nilaparvata lugens (Stål), is the most severe pest attacking rice crops with sucking mouthparts. It causes significant damages to rice growth and food production worldwide. With the long-term and wide use of insecticides, the field populations of BPH have developed resistance to many insecticides. RESULTS Here, we showed that up-regulation of an ATP-binding cassette transporter gene NlMdr49-like contributes to imidacloprid resistance in the field populations of BPH. A comparative transcriptome analysis was performed to evaluate the gene expression in two field populations (JXSG18 and YNTC18). Compared with susceptible strain (Sus), 202 up-regulated genes and 170 down-regulated genes were identified in both field populations. Functional enrichment analysis revealed that the differentially expressed genes (DEGs) are mainly linked to metabolic process and transmembrane transport. Among the candidate DEGs, NlMdr49-like was significantly up-regulated in both field populations. Based on the genome and transcriptome of BPH, the full-length cDNA of NlMdr49-like was sequenced and its molecular characteristics were analyzed. The expression pattern analysis of various tissues showed that NlMdr49-like was predominantly expressed in midgut and Malpighian tubules which are important excretion organs. Knocking down NlMdr49-like reduced BPH resistance to imidacloprid, but did not affect its resistance to the other nine insecticides (chlorpyrifos, thiamethoxam, nitenpyram, dinotefuran, sulfoxaflor, triflumezopyrim, ethiprole, buprofezin and pymetrozine). Furthermore, transgenic strain of Drosophila melanogaster overexpressing NlMdr49-like was less susceptible to imidacloprid. CONCLUSIONS Our findings indicate that up-regulation of NlMdr49-like is another mechanism contributing to imidacloprid resistance in N. lugens. And this result is helpful to further understand the resistance mechanism of N. lugens to imidacloprid. This article is protected by copyright. All rights reserved.