The transcriptomic responses of small brown planthopper, Laodelphax striatellus upon juvenile hormone agonist and antagonist treatment

The small brown planthopper, Loadelphax striatellus is one of the serious pest insects of rice plants because it can transmit the rice strip virus which often causes significant reduction of yield in the field. Insect growth regulators (IGRs) are insecticides which disrupt the normal development of target insects by inducing symptoms such as premature molting or supernumerary larval stages as the results of hormonal disruption. One of the most important insect hormones, juvenile hormone (JH) becomes the target of two types of IGRs: JH agonists (JHAs) and antagonists (JHANs). Pyriproxyfen is one of the popular IGR insecticides which acts as JHA to control many kinds of insects while kanakugiol is a plant-originated chemical which recently revealed its function as JHAN. In order to study the responses of L sulatellus to JHA and JHAN treatments, pyriproxyfen and kanakugiol were sprayed on 4th instar nymphs, and each total RNA sample was extracted for RNA-Seq by using Illumina sequencing platform. For differential gene expression study, the in silico cDNA library was constructed by Tirinity de novo assembler. The expression levels of each gene were quantified by Bowtie2 and eXpress programs, and then subjected to gene ontology (GO) enrichment analysis to study the changes of gene expression profile. Total of 33 GO terms showed differential expression upon JHA or JHAN treatment, and the genes related to insect hormone biosynthesis were identified. These results will provide important information for future studies of molecular biology and physiology of L stiatellus. (C) 2017 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society. Published by Elsevier B.V. All rights reserved.