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Chilo suppressalis Walker is a devastating pest of rice in Asia and exhibits facultative diapause in the larval stage. Most prior experiments on diapausing and non-diapausing C. suppressalis were conducted in the laboratory. In this study, transcriptome analyses were performed on pre-diapausing larvae collected from field populations of C. suppressalis and compared to laboratory populations. Among 2674 differentially expressed genes (DEGs), 32 DEGs related to pre-diapause and 239 universally expressed genes were screened; these were primarily enriched in "neuroactive ligand-receptor interaction", "lysosome" and "glycerolipid metabolism" in KEGG pathway analysis. With respect to clusters of orthologous genes (COG), DEGs were assigned to "posttranslational modification, protein turnover, chaperones", "carbohydrate transport and metabolism", and "secondary metabolite biosynthesis, transport and catabolism" categories. Further analysis also revealed that a key "circadian clock-controlled protein" gene is sensitive to photoperiod and significantly decreased during the pre-diapause phase. Genes encoding two small heat shock proteins, hsp21.4 and hsp27.2 , were significantly expressed on August 15 as compared to three other sampling times in August 2018. Eight DEGs were randomly chosen and evaluated by real-time quantitative PCR (RT-qPCR) to validate the accuracy of the transcriptome data. The expression of six DEGs (gene-evm_000752, gene-evm_006486, gene-evm_008626, gene-evm_002485, gene-evm_011981 and Chilo_suppressalis_newGene_18103) showed significant same patterns of differential expression in both the RT-qPCR and RNA-Seq analyses. This study increases our understanding of the complex physiological and molecular mechanisms involved in C. suppressalis at the pre-diapause phase. [Display omitted] • Transcriptomic analysis of pre-diapause larvae of C. suppressalis in field populations • Circadian clock is involved in pre-diapause induction in C. suppressalis. • Heat shock proteins showed distinct expression patterns during pre-diapause. • The pre-diapause phase is a critical time of energy accumulation in C. suppressalis. [ABSTRACT FROM AUTHOR]

Heat shock 70kDa proteins (HSP70s) and their cochaperones DNAJs are ubiquitous molecular chaperones, which function as the "HSP70/DNAJ machinery" in a myriad of biological processes. At present, a number of HSP70s have been classified in many species, but studies on DNAJs, especially in insects, are lacking. Here, we first systematically identified and characterized the HSP70 and DNAJ family members in the brown planthopper (BPH), Nilaparvata lugens, a destructive rice pest in Asia. A total of nine HSP70 and 31 DNAJ genes were identified in the BPH genome. Sequence and phylogenetic analyses revealed the high diversity of the NlDNAJ family. Additionally, spatio-temporal expression analysis showed that most NlHSP70 and NlDNAJ genes were highly expressed in the adult stage and gonads. Furthermore, RNA interference (RNAi) revealed that seven NlHSP70s and 10 NlDNAJs play indispensable roles in the nymphal development, oogenesis, and female fertility of N. lugens under physiological growth conditions; in addition, one HSP70 (NlHSP68) was found to be important in the thermal tolerance of eggs. Together, our results in this study shed more light on the biological roles of HSP70/DNAJ in regulating life cycle, coping with environmental stresses, and mediating the interactions within, or between, the two gene families in insects. [ABSTRACT FROM AUTHOR]

Aquaporins (AQPs), which are members of the major intrinsic protein (MIP) family, play an important role in the transport of water and other small, uncharged solutes across membranes. In this study, we identified gene encoding two aquaporin 12-like (AQP12L) proteins, CsAqp12L_v1 and CsAqp12L_v2, from Chilo suppressalis, a serious rice pest in Asia. Phylogenetic analysis indicated that CsAQP12L_V1 and CsAQP12L_V2 were grouped in a well-supported cluster that included other members of Lepidoptera. The two proteins are almost identical, except that CsAQP12L_V1 lacks 34 amino acids that are present in CsAQP12L_V2 at site 217. The qRT-PCR indicated that both CsAqp12L and CsAqp12L_v2 were expressed in heads, epidermis, foregut, midgut, and hindguts, with the highest level of expression in hindguts, heads, and epidermis. Expression of CsAqp12L and CsAqp12L_v2 was detected in all life stages and both sexes and was highest in first instar larvae and lowest in eggs. Expression of CsAqp12L and CsAqp12L_v2 was not significantly altered by exposure to brief changes in temperature. There were no significant differences in the third instar larvae, male and female pupae, and female adults in response to adverse humidity. However, the mRNA level of CsAqp12L in the fifth instar larvae and CsAqp12L_v2 in male adults was induced significantly by low humidity, respectively. Moreover, Xenopus oocytes injected with cRNAs of CsAQP12L_V1 and CsAQP12L_V2 showed no significant changes in permeability to water, glycerol, trehalose, or urea. The two CsAQP12L variants likely localize to an intracellular location in C. suppressalis and may respond to novel stimuli. [ABSTRACT FROM AUTHOR]