Ticks are notorious ectoparasites and transmit the greatest variety of pathogens than any other arthropods. Cold tolerance is a key determinant of tick abundance and distribution. While studies have shown that DNA methylation is one of the important epigenetic regulations found across many species and plays a significant role in their response to low-temperature stress, its role in the response of ticks to low-temperature stress remains unexplored. Herein, we explored the DNA methylation profile of the tick, Haemaphysalis longicornis, exposed to low-temperature stress (4 °C) using whole-genome bisulfite sequencing (WGBS). We found that approximately 0.95% and 0.94% of the genomic C sites were methylated in the control and low-temperature groups, respectively. Moreover, the methylation level under the CG context was about 3.86% and 3.85% in the control and low-temperature groups, respectively. In addition, a total of 6087 differentially methylated regions (DMRs) were identified between the low-temperature and control groups, including 3288 hypermethylated and 2799 hypomethylated DMRs. Further, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of differentially methylated genes revealed that most of the DMGs were significantly enriched in binding and RNA transport pathways. Taken together, this research confirmed, for the first time, the whole genome DNA methylation profile of H. longicornis and provided new insights into the DNA methylation changes relating to low-temperature stress in H. longicornis, as well as provided a foundation for future studies on the epigenetic mechanism underlying the responses of ticks to abiotic stress.

Ticks are external parasitic arthropods that can transmit a variety of pathogens by sucking blood. Low‐temperature tolerance is essential for ticks to survive during the cold winter. Exploring the protein regulation mechanism of low‐temperature tolerance of Haemaphysalis longicornis could help to explain how ticks survive in winter. In this study, the quantitative proteomics of several tissues of H. longicornis exposed to low temperature were studied by data independent acquisition technology. Totals of 3 699, 3 422, and 1 958 proteins were identified in the salivary gland, midgut, and ovary, respectively. The proteins involved in energy metabolism, cell signal transduction, protein synthesis and repair, and cytoskeleton synthesis changed under low‐temperature stress. The comprehensive analysis of the protein regulation of multiple tissues of female ticks exposed to low temperature showed that maintaining cell homeostasis, maintaining cell viability, and enhancing cell tolerance were the most important means for ticks to maintain vital signs under low temperature. The expression of proteins involved in and regulating the above cell activities was the key to the survival of ticks under low temperatures. Through the analysis of a large amount of data, we found that the expression levels of arylamine N‐acetyltransferase, inositol polyphosphate multikinase, and dual‐specificity phosphatase were up‐regulated under low temperature. We speculated that they might have important significance in low‐temperature tolerance. Then, we performed RNA interference on the mRNA of these 3 proteins, and the results showed that the ability of female ticks to tolerate low temperatures decreased significantly.

Hyalomma asiaticum is considered as the vector tick species which can carry and transmit Theileria annulata, Anaplasma marginale and Crimean-Congo hemorrhagic fever virus to humans and animals, causing a great risk to animal husbandry and posing a threat to public health as well as economic losses. In the present study, we investigated the morphology and changes of the male reproductive system for this species at different developmental stages.

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Two new species of the genus Solskyia, S. infossatasp. nov. and S. lhozhagasp. nov., are described and illustrated from Xizang, China. Solskyia lhasana is redescribed and figured based on a male, and new material of S. caporiaccoi and S. parvicollis from China is documented. The ecology and biology of adults and larvae is briefly introduced. Furthermore, photographs of habitat, and a key to Chinese species are presented.