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Heat shock proteins (HSPs) play essential roles in stress tolerance in insects, such as the cigarette beetle, Lasioderma serricorne, which is an important pest of stored products. However, the function of HSPs in environmental stress response in L. serricorne is poorly understood. In this study, six cDNAs encoding putative HSP70s were identified in L. serricorne (LsHSP70-1 to LsHSP70-6). The LsHSP70 proteins identified have signature motifs of insect HSP70s and exhibit high amino-acid identity with their respective orthologs from other insect species. Phylogenetic analysis showed that these LsHSP70s fall into three major clans: HSP70 in the cytosol (four genes), endoplasmic reticulum (one gene), and mitochondria (one gene). LsHSP70 genes are differentially expressed in different developmental stages. LsHSP70-4 and LsHSP70-5 are mainly expressed at the larval stage, while LsHSP70-3 shows the highest level at the pupal stage. The other genes are ubiquitously expressed. Furthermore, the expression levels of LsHSP70-1 and LsHSP70-4 are significantly upregulated upon exposure to temperatures of both 0 and 15 °C, while LsHSP70-3 is inducible at 15 °C and LsHSP70-6 at 0 °C. In addition, treatment at 0 °C causes significant downregulation of LsHSP70-2 and LsHSP70-3. Exposure to a temperature of 30 °C upregulates LsHSP70-1 expression, while 35 and 40 °C treatments result in significantly enhanced transcription of all the LsHSP70 genes. To the best of the authors’ knowledge, this is the first report on the sequence characteristics, phylogenetic relationships, and expression profiles of HSP70 genes in L. serricorne. The cold- and heat-inducible regulation of LsHSP70s suggests that these genes are related to tolerance of abnormal temperatures.

Chemosensory proteins (CSPs) play a crucial role in olfactory recognition in insects. The small white butterfly Pieris rapae—a major pest of Brassicaceae vegetables, which causes enormous economic losses—uses olfaction to locate its host plants. However, the molecular mechanism of olfaction in this species remains unknown. Herein, we performed a genome-wide and transcriptome-wide analysis of CSP genes in P. rapae and identified 21 CSPs (PrapCSP1 to PrapCSP21). Proteins encoded by these genes showed typical characteristics of CSPs—an N-terminal signal peptide and four positionally conserved cysteine residues. BLASTX analysis indicated that most P. rapae CSPs showed high amino acid identity with their respective orthologs in other lepidopterans. Phylogenetic analysis showed that most P. rapae CSPs were well segregated and were clustered into different branches. The 21 genes were located on six genomic scaffolds, and most genes were tandemly arrayed. Quantitative reverse transcription-PCR showed that PrapCSP3, 4, 16 and 21 had the highest expression level in the antennae; PrapCSP7 and PrapCSP18 were mainly expressed in the ovaries, and PrapCSP9 and PrapCSP17 were leg-enriched. PrapCSP11 and PrapCSP20 were found mainly in the heads and testes, respectively. Our findings provide a solid foundation for studying the function of these genes.

In insects, odorant-degrading enzymes (ODEs) play essential roles in the degradation of volatile odorants and maintenance of olfactory sensitivity. ODEs include several enzyme families with detoxification functions, such as carboxylesterases (CXEs) and aldehyde oxidases (AOXs). The rice leaffolder, Cnaphalocrocis medinalis (Lepidoptera: Pyralidae), is a serious rice insect pest in Asia. In this study, 18 putative CXE genes and four AOX genes were identified from the antennae of C. medinalis by retrieving a previously released transcriptome dataset. BLASTX searching and phylogenetic analyses showed that these genes are closely related to their respective orthologs in other lepidopteran species. Expression patterns of these genes were determined by reverse transcription-quantitative PCR (RT-qPCR). Four candidate genes, including three CmedCXEs (CmedCXE17, CmedCXE20 and CmedCXE24) and one CmedAOX (CmedAOX2) were antenna-enriched and considered potentially involved in odorant degradation. Our findings provide a comprehensive sequence resource and expression profiles of CXE and AOX genes in C. medinalis antennae, which may facilitate further studies of the odorant degradation mechanisms in this insect species.