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Small heat shock proteins (sHSPs) are a very complex protein superfamily that increase insect temperature tolerance. In order to deeply understand the function and role of sHSPs in Chilo suppressalis (Walker), this study isolated and identified two CsHSP genes lacking introns from C. suppressalis, Cshsp23.9 and Cshsp27.3. The cDNA full-length of Cshsp23.9 and Cshsp27.3 were 909 and 1 036 bp encoding 220 and 242 amino acids, respectively. Alignment with homologs and phylogenetic analysis indicated Cshsp23.9 and Cshsp27.3 were two new types of Cshsps in C. suppressalis. Real-time quantitative PCR (qPCR) revealed that Cshsp23.9 had the highest relative expression in hindgut compared with other tissues (head, epidermis, foregut, midgut, fat body, Malpighian tubules, and hemocytes), while Cshsp27.3 expressed the highest in fat body content. When exposed to thermal stress from −11 to 43°C for 2 h, two genes showed different expression patterns. Cshsp23.9 did not respond to low temperature, but could be up-regulated by high temperature and the highest expression temperature was at 36°C. Cshsp27.3 could only be induced by mild temperature, with the highest expression at 15 and 30°C. In conclusion, Cshsp23.9 and Cshsp27.3 existed in different tissues/organs of C. suppressalis, and played different important roles in C. suppressalis to resist temperature stress and regulate physiological activities.

Wolbachia are widespread maternally-inherited endosymbiotic bacteria that infect numerous arthropods. This study represents a thorough survey of the Wolbachia infection patterns in the pink stem borer, Sesamia inferens (Walker), an important rice pest in China, based on nucleotide comparisons for the surface protein (wsp) and cell division protein (ftsZ) genes. The effects of Wolbachia on mtDNA variation and evolution of S. inferens were also investigated. Although we identified six genetically diverse strains, we found infections to be infrequent, with only 7.8% of hosts infected, and identified geographical differences in infection rates between southern and northern populations. Nucleotide indexes (haplotype diversity (Hd), nucleotide diversity (Π) and number of variable sites (S) of mtDNA in infected populations were not significantly lower or higher than that in the uninfected populations. Furthermore, there was no association between Wolbachia infection status and phylogeny of mtDNA haplotypes. Analysis of molecular variance (AMOVA) showed that significant differentiation mainly existed within groups rather than among the groups. Additionally, using Tajima's D and Fu's F values, the mtDNA genes did not deviate significantly from neutral evolution. Taken together these results indicate that currently there were no effects of Wolbachia infection on host mtDNA variation and evolution in S. inferens.

Heat shock protein 70 (HSP70) is one of the most important members in the heat shock protein family, and plays important roles in the thermotolerance of insect. To explore the molecular mechanism of thermotolerance of Frankliniella occidentalis adults, the difference in the expression of HSP70s in F. occidentalis male or female adults under the thermal stress was studied under the laboratory conditions. Two full length cDNAs of HSP70s gene (Fohsc704 and Fohsc705) were cloned from F. occidentalis by using RT-PCR and RACE. The genomic sequence was demonstrated by genomic validation, and the position and size of the intron were analyzed by sequence analysis of cDNA. Real-time PCR was used to analyze the HSP70 expression patterns. The cDNA of Fohsc704 and Fohsc705 possessed 2 073 and 1 476 bp which encoded 690 and 491 amino acids (aa) with a calculated molecular weight of 75 and 54 kDa, respectively. Four introns in Fohsc704 and six introns in Fohsc705 protein were found. However, the HSP70 protein sequences in our study were ended with EKKN and GIFL, which were different from the reported FoHSP70s. Various expression patterns of Fohsc704 and Fohsc705 were found in both genders of F. occidentalis under thermal stress. The expression of Fohsc704 and Fohsc705 reached to the highest level at –12 and –8°C in male adults, respectively, and Fohsc705 expressed the highest level at 33°C in female adults. In conclusion, HSP70s of F. occidentalis in our study are novel heat shock proteins. There were difference in expression patterns of the two hsc70s in genders of F. occidentalis, and the two HSP70s play important roles in the thermotolerance of F. occidentalis.

Five genes encoding heat shock proteins (HSPs), Cchsp40, Cchsp60, Cchsp70, Cchsc70 and Cchsp90, were cloned and sequenced from Cotesia chilonis using RT-PCR and RACE. The cDNA sequences of Cchsp40, Cchsp60, Cchsp70, Cchsc70 and Cchsp90 were 1 265, 2 551, 2 094, 2 297 and 2 635 bp in length, respectively, with a molecular weight (MW) of 39.1, 60.6, 71.45, 70.19 and 82.92 kDa, respectively. The predicted amino acid sequences of these proteins showed high similarities with published HSPs of other insects in Hymenoptera. Analysis of genomic DNAs indicated that Cchsp40, Cchsp60, Cchsp70 and Cchsp90 lacked introns, but Cchsc70 contained an intron. The results also suggested that CcHSP40 in C. chilonis was the Type II HSP40, CcHSP60 was a member of the mitochondrial HSP60 family, and CcHSP90 was a part of cytoplasmic HSP90A family. Expression patterns varied in the five Cchsps in response to temperature. Expression of Cchsp40 and Cchsp60 was induced significantly by cold but not heat stress. Cchsp70 and Cchsc70 showed similar response to the thermal stress and could be induced by both cold and heat, but their expression levels were consistently lower than that of Cchsp40 and Cchsp60. Cchsp90 could be induced by heat stress and mild cold, but not cold stress. In addition, the results demonstrated Cchsc70 might be constitutive and inducible protein that was expressed during normal cell functioning and also up-regulated in response to stressful stimuli while Cchsp70 was solely inducible protein induced by temperature changes. Overall, results generated from this study could significantly advance the understanding of Cchsps in response to temperature and provide important biological information for C. chilonis insects that reared under different temperatures.

Many proteins require assistance from molecular chaperones at various stages to attain correctly folded states and functional conformations during protein synthesis. In this study, the gene encoding T-complex polypeptide 1 (TCP-1), which belongs to the heat shock protein 60 (HSP60) family, was isolated and characterized from the rice stem borer, Chilo suppressalis, by RACE and qPCR, respectively. The full-length cDNA of Tcp-1 was 2 144 bp and encoded a 1 635-bp ORF; the deduced translational product contained 545 amino acids with 5'- and 3'-UTRs and an isoelectric point of 5.29. Cluster analysis confirmed that the deduced amino acid sequence shared high identity (60–99%) with TCP-1 from other insects. To investigate Tcp-1 expression in response to abiotic stress, qPCR was used to analyze expression levels of Tcp-1 mRNA in C. suppressalis larvae exposed to temperatures ranging from –11 to 43°C. With respect to heat shock, Tcp-1 expression was higher than the control after a 2-h exposure to 30 and 36°C and declined at 39 and 43°C. Difference in Tcp-1 expression was observed at temperatures ranging from –11 to 27°C. qPCR analyses revealed that Tcp-1 expression was the highest in hindgut tissue as compared to heads, epidermis, fat body, foregut, midgut, and malpighian tubules. Our results indicated that Tcp-1 expression was differentially expressed in C. suppressalis tissues, and was impacted by temperature stress.