Regulation of Juvenile Hormone on Summer Diapause of Geleruca daurica and Its Pathway Analysis

Juvenile hormone (JH) signaling plays an important role in regulation of reproductive diapause in insects. However, we have little understanding of the effect of JH on gene expression at the transcriptome level in diapause. Galeruca daurica is a new pest in the Inner Mongolia grasslands with obligatory summer diapause in the adult stage. Topical application of a JH analog methoprene at the pre-diapause stage delayed the adults entering diapause and inhibited lipid accumulation whereas it did not during diapause. Using Illumina sequencing technology and bioinformatics tools, 54 and 138 differentially expressed genes (DEGs) were detected at 1 and 2 d after treatment, respectively. The KEGG analysis showed that the DEGs were mainly enriched in the metabolism pathways. qRT-PCR analysis indicated that methoprene promoted the expression of genes encoding vitellogenin, fork head transcription factor and Krüppel homolog 1, whereas suppressed the expression of genes encoding juvenile hormone-binding protein, juvenile hormone esterase, juvenile hormone acid methyltransferase, juvenile hormone epoxide hydrolase and fatty acid synthase 2. These results indicate that JH signaling plays an important role in regulating reproductive diapause of G. daurica.

Universal and differential transcriptional regulatory pathways involved in the preparation of summer and winter diapauses in Pieris melete

Much progress has been made in understanding the environmental and hormonal systems regulating winter diapause. However, transcriptional regulation of summer diapause is still largely unknown, making it difficult to understand an all-around regulation profile of seasonal adaptation. To bridge this gap, comparison RNA-seq to profile the transcriptome and to examine differential gene expression profiles between non-diapause, summer diapause, and winter diapause groups were performed. A total number of 113 million reads were generated and assembled into 79,117 unigenes, with 37,492 unigenes categorized into 58 functional gene ontology groups, 25 clusters of orthologous group categories, and 256 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. KEGG analysis mapped 2108 differentially expressed genes to 48 and 67 pathways for summer and winter diapauses, respectively. Enrichment statistics showed that 11 identical pathways similarly overlapped in the top 20 enriched functional groups both related to summer and winter diapauses. We also identified 35 key candidate genes for universal and differential functions related to summer and winter diapause preparation. Furthermore, we identified some genes involved in the signaling and metabolic pathways that may be the key drivers to integrate environmental signals into the summer and winter diapause preparation. The current study provided valuable insights into global molecular mechanisms underpinning diapause preparation.

Biological characteristics of Сydalima perspectalis (Lepidoptera: Crambidae) in Crimea

Studies in the Crimea have shown that both on the southern coast and in the central foothill region, an adventive pest of plants of the genus Buxus - the boxwood fireweed (Cydalima perspectalis), develops in three generations. Caterpillars of the second - third instars hibernate; their emergence from diapause occurs in early April. The timing and duration of development of each of the three generations of the boxwood firefighter in the conditions of the Crimea were determined, the lifespan of the imago was determined, averaging about two weeks, with some individuals living for more than 20 days. The sex index in adults varies in different generations, depending on the living conditions. Thus, in the central foothill region in the first generation, the ratio of females and males reaches 2: 1, and in the second generation, both the proportion of males and melanistic individuals increases in comparison with typically colored butterflies. In each of the three generations, males emerged from pupae 3-5 days earlier than females. The fertility of melanistic females is higher than that of the typically colored. A spring-summer diapause was observed in caterpillars of II-III instars in the overwintered, first and second generations.

Identification and Comparative Profiling of microRNAs at Different Diapause Stages of Galeruca Daurica Adults

Background: MicroRNAs (miRNAs) are a class of small noncoding RNAs of approximately 22 nt in length, which regulate gene expression at the post-transcriptional level. Although the regulatory roles of miRNAs in various physiological processes throughout insect development have been investigated, it is almost unknown about the roles of miRNAs involved in the regulation of diapause in insects.Results: We constructed 12 small RNA libraries from Galeruca daurica adults at different diapause stages: pre-diapause (PD), diapause (D), post-diapause 1 (TD1), and post-diapause 2 (TD2). Using Illumina sequencing, a total of 95.06 million valid reads was obtained, and 230 miRNAs, including 143 conserved and 87 novel miRNAs, were identified from G. daurica. The expression profiles of these miRNAs were assessed across different diapause stages and miRNAs that were highly expressed at different diapause stages were identified. Comparative analysis of read counts indicated that both conserved and novel miRNAs were differently expressed among the four different diapause stages, and the differential expression was validated via qRT-PCR. The 25, 11, 15, 14, 26, and one miRNAs were differentially expressed in D/PD, D/TD1, D/TD2, TD1/PD, TD2/PD, and TD2/TD1, respectively. The KEGG and GO analysis of the predicted target genes suggested the essential roles of miRNAs in the regulation of summer diapause in G. daurica, especially via the juvenile hormone, ribosome, MAPK signaling, mTOR signaling, Ca2+ signaling, and G-protein coupled receptor signaling pathways.Conclusion: Our research results indicate that miRNAs may be involved in the regulation of summer diapause in G. daurica, and these results also provide an important new small RNA genomics resource for further studies on insect diapause.

Seasonal variation of spider species composition in Volgograd agglomeration

The article addresses changes in the species composition of spiders during the warm season. The qualitative and quantitative characteristics of the spider community were analyzed during the most important periods of their activity in the main biotopes of the Volgograd agglomeration. The Cluster Analysis application, based on the Jaccard index, was used. The material was collected using 10 mm Barber soil traps with a fixing liquid (6% acetic acid solution). In total, 235 species of spiders belonging to 26 families were identified, including 195 species belonging to 23 families on the territory of Volgograd. Notably, 155 species were new to the fauna of the Volgograd region. Species Trichoncus villius Tanasevitch et Piterkina was found in the Russian Federation for the first time. The species composition was analyzed during critical periods of spider life: the end of winter diapause, the time before the summer diapause, the termination of summer diapause, and the period of before winter the diapause. In each case a set of traps were exposed for seven days. The spring period was characterized by the maximum number of species, and the maximum similarity in species composition was observed between the moment when spiders leave the winter diapause and the period before the summer diapause. During the warm season, the species composition changed almost completely twice: before the end of the summer diapause and at the end of the warm season, approaching the spring values. These changes were significantly less relevant to near-water biotopes, where environmental conditions were more stable compared to the other studied biotopes.

Differential transcriptome profiling of the diapause and cold-responsive genes in unfed adult Dermacentor silvarum Olenev (Acari: Ixodidae)

The tick Dermacentor silvarum mainly overwinters in northern China as an unfed adult entering diapause; however, little is known about the involvement of genes and pathways in summer diapause and overwintering adults of this species. Hence, we investigated the differential transcriptome profile of D. silvarum ticks’ diapause and cold-responsive genes and pathways during its summer diapause, overwintering, and questing/active stages. Through transcriptomic sequencing, a total of 136,740 unigenes were assembled, and 1,549, 2,196, and 2,125 differentially expressed genes (DEG) were identified in active and diapause, diapause and overwintering, and active and overwintering ticks, respectively. Between active and diapause ticks, 875 genes were up-regulated, while 674 genes were found down-regulated in diapause ticks. When compared with active ticks, overwintering ticks had 993 up-regulated genes and 1,132 down-regulated genes. Comparison between diapause and overwintering ticks revealed 745 up-regulated and 1,451 down-regulated genes in overwintering ticks. Gene Ontology analysis revealed that, among the active, diapause, and overwintering ticks, most of the DEGs in molecular function were enriched in catalytic activity and hydrolase activity. In the cellular component, most DEGs were assigned to the integral component of the cell membrane , whereas the oxidation-reduction process was the most enriched among biological processes. In addition, the lysosome pathway was the most enriched pathway identified in KEGG pathway analysis. The above results deepened our understanding of the mechanism underlying diapause and overwintering adaptation of ticks, which is important for integrative prevention and control of ticks and tick-borne diseases.

PERIODS OF ACTIVITY DERMACENTOR RETICULATUS IN THE TAIGA ZONE

The range of D. reticulatus ticks mainly covers forest-steppe and steppe, where they occupy open spaces. The discovery of high-abundance populations of this tick in the taiga zone is a rare phenomenon. On the outskirts of the city of Tomsk, on the coastal slope of the Tom River of the south-southwestern exposure, such a population was found in 2015. In 2018, this species was also found on the slope of the southern exposure, on the outskirts of the city, which has a very rare young stand. In contrast to the coastal slope, people practically did not appear here, which made it possible to trace the natural dynamics of the population and, using marks, determine the duration of their life. Here, mites appeared on the surface immediately after the snow melted. The spring period of activity lasted until the end of June, then during July there was a summer diapause, and in the beginning of August the autumn period of activity began. The number in spring was higher than in autumn. The life span, as shown by the tagging, in this area, is no more than 1 year.