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Mealybugs (Hemiptera: Pseudococcidae) are economically important agricultural pests with several compelling biological phenomena including paternal genome elimination (PGE). However, limited high-quality genome assemblies of mealybugs hinder a full understanding of this striking and unusual biological phenomenon. Here, we generated a chromosome-level genome assembly of cotton mealybug, Phenacoccus solenopsis, by combining Illumina short reads, PacBio long reads and Hi-C scaffolding. The assembled genome was 292.54 Mb with a contig N50 of 489.8 kb and a scaffold N50 of 49.0 Mb. Hi-C scaffolding assigned 84.42% of the bases to five chromosomes. A total of 110.75 Mb (37.9%) repeat sequences and 11,880 protein-coding genes were predicted. The completeness of the genome assembly was estimated to be 95.5% based on BUSCO genes. In addition, 27,086 (95.3%) full-length PacBio transcripts were uniquely mapped to the assembled scaffolds, suggesting the high quality of the genome assembly. We showed that cotton mealybugs lack differentiated sex chromosomes by analysing genome resequencing data of males and females. DAPI staining confirmed that one chromosome set in males becomes heterochromatin at an early embryo stage. Chromatin immunoprecipitation assays with sequencing analysis demonstrated that the epigenetic modifications H3K9me3 and H3K27me3 are distributed across the whole genome in males, suggesting that these two modifications might be involved in maintaining heterochromatin status. Both markers were more likely to be distributed in repeat regions, while H3K27me3 had higher overall enrichment. Our results provide a valuable genomic resource and shed new light on the genomic and epigenetic basis of PGE in cotton mealybugs.

The cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), which is native to North America, emerged as a major invasive insect pest of multiple crops in Asia at the beginning of the 21st century. Considering the economic significance of this insect and its rapid worldwide spread, we examined the possible factors driving its invasions. In this paper, we summarize the life history traits of P. solenopsis conceivably related to population development in invaded regions; these traits include its use of diverse host plants, reproductive capacity and mode, adaptation to temperature, response to food shortage, and insecticidal resistance. Then, focusing on the multiple trophic interactions that may promote or hinder invasion, we review the mutualistic relationship of this mealybug with ants and predation and parasitism by natural enemies. Finally, we suggest topics for future research and provide our perspective on the biological invasions of this mealybug. We speculate that specific biological factors associated with this mealybug, particularly its wide host range, high reproductive potential, evolved changes in life history traits, and mutualism with ants have played important roles in its invasions, allowing this pest to become established and rapidly increase its population upon its introduction into new regions.

The cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is a polyphagous insect that attacks tens of plant and causes substantial economic loss. Insect chitinases are required to remove the old cuticle to allow for continued growth and development. Though insect chitinases have been well studied in tens of insects, their functions in mealybug are still not addressed. Here, we sequenced the transcriptomes of adult males and females, from which eight chitinase genes were identified. We then used the method of rapid amplification of cDNA ends to amplify their full length. Phylogenetic analysis indicated that these genes clustered into five subgroups. Among which, group II PsCht2 had the longest transcript and was highly expressed at second instar nymph. PsCht10, PsCht3-3 and PsIDGF were highly expressed in the adult females, whereas PsCht4 and PsCht4-1 were significantly expressed at the male pupa and adult male. Next, we knocked down all eight chitinase genes by feeding the double-stranded RNA. Knockdown of PsCht4 or PsCht4-1 led to the failure of moult and, silencing PsCht5 resulted in pupation defect, while silencing PsCht10 led to small body size, suggesting these genes have essential roles in development and can be used as a potential target for pest control.

For insects, female density is closely related to reproductive output. However, little is known about the effects of female density on male mating and female postmating performances. Here, we explored the effects of female density in cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), an invasive, rapidly spreading pest in Asia damaging multiple crops and horticultural plants. Using USB digital microscopes, we investigated the frequency, duration, and intervals of mating for males that were individually supplied with 1, 5, 10, and 15 females. We also evaluated the reproduction of mated females and the sex ratio of their offspring. As the female density increased, males mated with more females while substantially shortening mating intervals. Mating occurred actively at the densities of 10 and 15 females, where males mated four times on average, and some mated 6–9 times. However, mating duration and the observed reproductive parameters of females (preoviposition period, overall period from formation of ovisacs to female death, fecundity, and offspring sex ratio) did not differ significantly with female density. A weak trade-off existed between males’ mating frequency and longevity, but there was no relationship between females’ fecundity and longevity. In conclusion, despite their short lifespan, P. solenopsis males have a high mating capacity, and their mating frequency and intervals can be significantly affected by female density. In contrast, female density has little influence on females’ postmating performance. Our findings indicate the significance of the reproductive biology and life history strategies for rapid establishment and population development of mealybugs in newly invaded regions.

Software Defined Networking (SDN) is one of the hottest technology in the network field today. SDN divides the network into the data plane and control plane. The control plane needs to monitor the underlying network and provides an up-to-date global network view for the applications running on it by topology discovery. The most important one in topology discovery is link discovery. Based on the characteristics of SDN, most implementations use OpenFlow Discovery Protocol (OFDP), which is simple but wastes a lot of bandwidth resources on the control plane. In this paper, we divide link discovery into two stages and propose some modifications and extensions based on OFDP for the second stage. Our approach divides the initial network view into multiple paths, and each path contains multiple links. At the cost of sacrificing a small amount of flow table resources, our approach enables one probe packet to be responsible for the detection of a path, thereby significantly reducing the number of sent and received probe packets, and reducing the consumption of control plane’s bandwidth resources.

Identification of the role of the MC1R gene has provided major insights into variation in skin pigmentation in several organisms, including humans, but the evolutionary genetics of this variation is less well established. Variation in this gene and its relationship with degree of melanism was analyzed in one of the world’s highest-elevation lizards, Phrynocephalus theobaldi from the Qinghai–Tibetan Plateau. Individuals from the low-elevation group were shown to have darker dorsal pigmentation than individuals from a high-elevation group. The existence of climatic variation across these elevations was quantified, with lower elevations exhibiting higher air pressure, temperatures, and humidity, but less wind and insolation. Analysis of the MC1R gene in 214 individuals revealed amino acid differences at five sites between intraspecific sister lineages from different elevations, with two sites showing distinct fixed residues at low elevations. Three of the four single-nucleotide polymorphisms that underpinned these amino acid differences were highly significant outliers, relative to the generalized MC1R population structuring, suggestive of selection. Transfection of cells with an MC1R allele from a lighter high-elevation population caused a 43% reduction in agonist-induced cyclic AMP accumulation, and hence lowered melanin synthesis, relative to transfection with an allele from a darker low-elevation population. The high-elevation allele led to less efficient integration of the MC1R protein into melanocyte membranes. Our study identifies variation in the degree of melanism that can be explained by four or fewer MC1R substitutions. We establish a functional link between these substitutions and melanin synthesis and demonstrate elevation-associated shifts in their frequencies.

With the gradual increase of building energy consumption in recent years, the application of phase change energy storage materials in buildings has become the focus of researches. Phase change material (PCM) embedded in the envelope can increase the building inertia to keep the temperature stable. It can also store energy and release energy when needed. In this paper, the system of PCM radiant floor combined with PCM wall attached with sunspace was established. The thermal characteristics and the energy consumption of the building are studied through analyzing the data from the experimental investigation including the temperature and the heat flux. Two different buildings were built between the PCM room and the conventional room with the same dimension and building. The main test conditions are divided into passive and active control stages by comparing the air temperatures, envelope temperatures, phase transition temperatures, heat fluxes and power consumptions between the two rooms. It is concluded that the average room temperature of the experimental room is 7.15 °C higher than that of the conventional room in the passive energy storage stage. While the average energy-saving rate of PCM room was 54.27% compared with the conventional room in the active control stage.

Up to now, Software-defined network (SDN) has been developing for many years and various controller implementations have appeared. Most of these controllers contain the normal business logic as well as security defense function. This makes the business logic on the controller tightly coupled with the security function, which increases the burden of the controller and is not conducive to the evolution of the controller. To address this problem, we propose a proactive security framework PSA, which decouples the business logic and security function of the controller, and deploys the security function in the proactive security layer which lies between the data plane and the control plane, so as to provide a unified security defense framework for different controller implementations. Based on PSA, we design a security defense application for the data-to-control plane saturation attack, which overloads the infrastructure of SDN networks. We evaluate the prototype implementation of PSA in the software environments. The results show that PSA is effective with adding only minor overhead into the entire SDN infrastructure.

In this study, a new two-dimensional model of CPRF was developed in TRNSYS. Its accuracy was validated by a full-scale experiment. The effects of key parameters of CPRF coupled with solar water heating system on indoor temperature was analyzed. The single factor analysis revealed that reducing tube pitch and solidification temperature, increasing PCM layer thickness and solar collector area could increase indoor temperature. The orthogonal test analysis indicated that tube pitch has the greatest impact on the average indoor temperature. The CPRF heating system coupled to solar energy and an electric boiler operating on valley electricity (CSSEBV) was proposed to ensure stable heating. It was optimized by GENOPT. The optimal parameters are that the tube pitch is 0.28 m, the PCM layer thickness is 0.02 m, the solar collector area is 12.5 m2 and the operating time of the electric boiler is 2h. The economy, energy saving property and environmental benefits of four systems were also compared and analyzed.

Geographical variation of body color is widely present in reptile populations that survive in different substrate habitats, multiple potential mechanisms can account for this color variation. Phrynocephalus versicolor and P. frontalis, close genetic relatives, constitute a phylogenetic species group together with P. przewalskii. In this study, a fiber spectrophotometer (AvaSpec-2048) was used to record the skin luminous reflectivity of 12 sites across the lizard’s body, and we quantitatively compared the natural color variation of dark P. versicolor and light P. frontalis that lived in “melanistic” and “non-melanistic” habitats, respectively. We aimed to determine whether the color variations of both populations were time reversible, and further discuss potential mechanisms that substrate color may have on color variation of Phrynocephalus lizards. Our results showed that the body color of P. versicolor in “melanistic” habitat was significantly darker than P. frontalis in the “non-melanistic” withered yellow habitat. We also conducted a reciprocal transplantation experiments (i.e. “non-melanistic” withered yellow P. frontalis individuals were transplanted and fed in “melanistic” substrate environment, while “melanistic” P. versicolor individuals were transplanted and fed in withered yellow substrate environment). For “melanistic” P. versicolor, the skin reflectivity of six sites increased significantly after one week, while no significant changes were detected in other sites. For “non-melanistic” P. frontalis, except the skin reflectivity of two sites (left hind limb and top right on the •研究报告• 1040 生 物 多 样 性 Biodiversity Science 第 24 卷 back) significantly changed, compared to corresponding values one week previously, other sites showed no significant changes. Our results suggest that P. versicolor possesses stronger color variation ability than P. frontalis, and the color phenotypes are likely inherited in both species. Short-term changes of substrate color can cause slightly color variations that are difficult to distinguish by naked eyes, suggesting ontogeny related hereditary factors may also play a controlling role.

Voucher specimen and mitogenome used in selection analyses. (DOC 49 kb)

ML tree for Phrynocephalus inferred from 15,417Â bp of mtDNA (6 partitions; GTRGAMMA model for each). Values on nodes are bootstrap proportions (2000 bootstraps). (DOCX 172 kb)

The complete mitochondrial genome was sequenced from the toad-headed viviparous lizard, Phrynocephalus putjatia. The mitogenome was 16,283 bp in length; it contained 13 protein coding, 22 tRNA, 2 rRNA genes and 2 control regions. The gene order and compositions were identical with all published congeneric mitogenomes for the fragment between 12 s RNA and tRNA-Thr, but with some differences for the remaining sequences including CR, tRNA-Pro and tRNA-Phe. The characteristics of the mitogenome was analyzed and discussed in detail.

The complete mitochondrial genome was sequenced from the toad-headed viviparous lizard subspecies, Phrynocephalus erythrurus parva, which occupies the highest regions of any reptile on the earth. The mitogenome sequence was 16,431 bp in size, with the overall base composition of H-strand is T: 26.06%, C: 25.14%, A: 36.45%, G: 12.35%. It consists of 13 protein coding, 22 tRNA, 2 rRNA genes and 3 control regions, and its gene order and gene content were identical with the published congeneric mitogenomes of other Phrynocephalus, except for the small protion between tRNA-Pro and tRNA-Phe.