Electroantennogram Response Of Nilaparvata Lugens (Stal)to Rice Volatiles And Cloning Odorant Binding Protein Genes

Brown planthopper (BPH), Nilaparvata lugens (Stal)(Homoptera: Delphacidae) is a major pest of rice in China and various other countries in Asia. The adults and nymphs prefer a damp environment, often clustered at the base of the rice plexus, and with the resistance constantly enhance and which bring some difficulties to traditional chemical control methods. With the development of chemical ecology and molecular biology, studying the relationship between herbivorous insects and host plant and the behavioral response and molecular mechanisms of insect olfactory has become a new way to study insect olfactory mechanism and biological control strategies. Now the studies on the electrophysiological behavior responses of N. lugens to rice volatiles and its odorant binding proteins are rare. Therefore, this study applies EAG responseto rice volatiles to choose substances which lead electrophysiological activity to N.lugens. At the same time building the antennae transcription group library and cloning odorant binding protein genes to further choose rice volatileswhich lead behavioral activity to the N. lugens and explore their sense of smell mechanism to provide a theoretical basis. The main findings are as follows:1. EAG responses of N. lugens to different rice volatilesThe EAG responses are measured to8classes,35kinds of rice volatiles. The results showed that, the average of EAG response is4-8mV to10μg/μl rice volatiles, EAG responses of N. lugens which were emergence Id, emergence5d (unmated) and emergence5d (mated), long-winged females, long-winged male, short-winged female and short-winged male has difference strength to35kinds of rice volatiles. But in P<0.05level, most of ther EAG have no significant difference. The EAG response of N. lugens to different classes of compounds no significant difference too.2. Information analysis of the N. lugens antennae transcriptomeClipped the antennae of the nymphs and adults and constructed N. lugens antennae transcriptome library, one of the EST conducted a preliminart analysis. The results showed that the transcriptome library contains70239unigenes. By GO classification analysis,60686unigenes involves biological processes, cellular components and molecular functions, accounting for86.4%of the total number of unigenes. By KEGG annotation information analysis,11785(16.8%) unigenes has commented the function, involved in219metabolic pathways metabolism pathway, which contains neuroactive ligand-receptor interactionpathway and chemokine signaling pathway. By reference COG database, predict the function of unigenes and functional classification statistics,13629unigenes can determine the function, accounting for19.4%of the entire unigenes.3. Cloning N. lugens odorant binding protein genesSelected two odorant-binding protein genes fragments from the N. lugens antennae transcriptome library, named NlugOBP4and NlugOBP5, cloned and obtained the full sequence. The open reading-fragment of NlugOBP4is591bp, encoding194amino acid residues, and the open reading-fragment of NlugOBP5is426bp, encoding141amino acid residues. Both of odorant-binding protein genes contain six conserved cysteines and a signal peptide with24amino acids in the N-terminal sequence, which comply with the typical characteristics of the insect odorant-binding proteins. The amino acids sequence analysis of NlugOBP4and NlugOBP5indicated that, NlugOBP4has low homology with29odorant-binding protein genes of other insects. NlugOBP5has high homology with LstrOBPl and LstrOBP3of Laodelphaxstriatellus, and low homology between NlugOBP4andNlugOBP5.