The Colorado potato beetle is one of the most challenging agricultural pests to manage. It has shown a spectacular ability to adapt to a variety of solanaceaeous plants and variable climates during its global invasion, and, notably, to rapidly evolve insecticide resistance. To examine evidence of rapid evolutionary change, and to understand the genetic basis of herbivory and insecticide resistance, we tested for structural and functional genomic changes relative to other arthropod species using genome sequencing, transcriptomics, and community annotation. Two factors that might facilitate rapid evolutionary change include transposable elements, which comprise at least 17% of the genome and are rapidly evolving compared to other Coleoptera, and high levels of nucleotide diversity in rapidly growing pest populations. Adaptations to plant feeding are evident in gene expansions and differential expression of digestive enzymes in gut tissues, as well as expansions of gustatory receptors for bitter tasting. Surprisingly, the suite of genes involved in insecticide resistance is similar to other beetles. Finally, duplications in the RNAi pathway might explain why Leptinotarsa decemlineata has high sensitivity to dsRNA. The L. decemlineata genome provides opportunities to investigate a broad range of phenotypes and to develop sustainable methods to control this widely successful pest.

The genomes and transcriptomes of hundreds of insects have been sequenced. However, insect community lacks an integrated, up-to-date collection of insect gene data. Here, we introduce the first release of InsectBase, available online at http://www.insect-genome.com. The database encompasses 138 insect genomes, 116 insect transcriptomes, 61 insect gene sets, 36 gene families of 60 insects, 7544 miRNAs of 69 insects, 96 925 piRNAs of Drosophila melanogaster and Chilo suppressalis, 2439 lncRNA of Nilaparvata lugens, 22 536 pathways of 78 insects, 678 881 untranslated regions (UTR) of 84 insects and 160 905 coding sequences (CDS) of 70 insects. This release contains over 12 million sequences and provides search functionality, a BLAST server, GBrowse, insect pathway construction, a Facebook-like network for the insect community (iFacebook), and phylogenetic analysis of selected genes.

Chemosensory membrane proteins, including odorant receptors (ORs), ionotropic receptors (IRs), gustatory receptors (GRs) and sensory neurone membrane proteins (SNMPs), are supposed to be crucial macromolecules in the insect olfactory signal transduction pathway. The alfalfa plant bug Adelphocoris lineolatus (Goeze) (Hemiptera: Miridae) is highly attracted to high-nitrogen or flowering plants and destroys many important agricultural crops. We assembled the antennal transcriptome of A. lineolatus using Illumina sequencing technology and identified a total of 108 transcripts encoding chemosensory membrane proteins (88 ORs, 12 IRs, four GRs and four SNMPs), amongst which 90 candidates appeared to be full length. Subsequently, both semiquantitative reverse transcription PCR and quantitative real-time PCR experiments were performed to investigate their tissue- and sex-biased expression profiles. The results showed that nearly all of the 108 candidate chemosensory membrane protein genes were largely expressed in adult antennae, and some genes additionally displayed significant differences in the expression levels between sexes. The results of our phylogenetic analysis and the detailed tissue- and sex-biased expression characteristics given here provide an important foundation for further understanding of the complex chemoreception system of the alfalfa plant bug and other Hemiptera species, which also could help us use chemosensory membrane proteins as targets to manipulate insect olfactory behaviour and broaden the applications of available tools for insect pest control.