BackgroundThe oriental armyworm, Mythimna separata, is an economically important and common Lepidopteran pest of cereal crops. Chemoreception plays a key role in insect life, such as foraging, oviposition site selection, and mating partners. To better understand the chemosensory mechanisms in M. separata, transcriptomic analysis of antennae, labial palps, and proboscises were conducted using next-generation sequencing technology to identify members of the major chemosensory related genes.ResultsIn this study, 62 putative odorant receptors (OR), 20 ionotropic receptors (IR), 16 gustatory receptors (GR), 38 odorant binding proteins (OBP), 26 chemosensory proteins (CSP), and 2 sensory neuron membrane proteins (SNMP) were identified in M. separata by bioinformatics analysis. Phylogenetic analysis of these candidate proteins was performed. Differentially expressed genes (DEGs) analysis was used to determine the expressions of all candidate chemosensory genes and then the expression profiles of the three families of receptor genes were confirmed by real-time quantitative RT-PCR (qPCR).ConclusionsThe important genes for chemoreception have now been identified in M. separata. This study will provide valuable information for further functional studies of chemoreception mechanisms in this important agricultural pest.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-4898-0) contains supplementary material, which is available to authorized users.

Cucurbit chlorotic yellows virus (CCYV) (genus Crinivirus, family Closteroviridae) is an emerging plant virus, and is now spreading and causing severe economic losses to cucurbit crops in many Asian countries. CCYV is believed to be transmitted specifically by the sweetpotato whitefly, Bemisia tabaci, in a semipersistent manner. In the present study, we provide direct evidence for the semipersistent transmission of CCYV by Mediterranean (MED) cryptic species of B. tabaci complex. We investigated CCYV transmission characteristics, and immunofluorescently labeled and localized the virus retention site within the vector by laser confocal microscopy. Whiteflies required ≥1 h of acquisition access period (AAP) to successfully acquire CCYV, and the proportion of RT-PCR positive whitefly individuals reached to 100% at 48 h of AAP. CCYV virons could be retained within vectors as long as 12 d, but the proportion of RT-PCR positive whiteflies dropped to 55% by 3 d. Groups of thirty whiteflies given a 24 h of inoculation access period (IAP) to inoculate CCYV on cucumber plants showed a transmission efficiency rate of 72.73%. The retention site of CCYV virons was located in the foregut of virion-fed vectors. These results definitely indicated the semipersistent transmission mode of CCYV by B. tabaci MED.

Juvenile hormone epoxide hydrolase (JHEH) has attracted great interest because of its critical role in the regulation of juvenile hormone (JH) in insects. In this study, one JHEH gene from Apolygus lucorum (AlucJHEH) was characterized in terms of deduced amino acid sequence, phylogeny, homology modeling and docking simulation. The results reveals a conserved catalytic mechanism of AlucJHEH toward JH. Our study also demonstrates that the mRNA of AlucJHEH gene was detectable in head, thorax and abdomen from all life stages. To functionally characterize the AlucJHEH gene, three fragments of double-stranded RNAs (dsRNAs) were designed to target different regions of the sequence. Injection of 3rd nymphs with dsRNA fragments successfully knocked down the target gene expression, and a significantly decreased survival rate was observed, together with a molting block, These findings confirm the important regulatory roles of AlucJHEH in A. lucorum and indicate this gene as a promising target for future hemipterans pest control.