I. Team members
Chief Scientist: Prof. XU Xuenong
Key members: Profs. CHEN Hongyin, ZHANG Lisheng, WANG Endong
Assistants: Assoc. Profs. WANG Mengqing, LIU Chenxi, MAO Jianjun.
Adjunct professors: Prof. LI Dunsong, Assoc. Prof. DANG Xiangli

Ⅱ. Team leader
Dr. XU Xuenong got his Ph.D. from University of Hanover, Germany. He has been engaged in Institute of Plant Protection, CAAS since 2004. He is the PI of the Research Group for Predatory Mites, and Deputy Director of Department of Biological Control, IPP-CAAS.Dr. XU has been working on biological control of small insect pests for years. He carried out multiple research on predatory mites and Orius spp., focusing on resource screening, biology, ecology, mass production, release techniques and field applications, etc. Key projects led by Dr. XU included the Special Fund for Agro-scientific Research in the Public Interest: Mass rearing and field application techniques of predatory mites; Beijing Leafy Vegetables Innovation Team of Modern Agro-industry Technology Research System: Bureau of pest and disease management and product safety, National Basic Long-Term Work in Agriculture: Big data center of insect natural enemies and edible insects. Being a research group PI and innovation team leader, Dr. XU always kept his own research consistent with the team's direction, and carried out technological innovation around the global aims of the team.
He has published more than 80 research papers, and 25 national patents for invention. He has won 4 provincial and ministerial-level science and technology awards and 4 outstanding paper awards. In 2014, Dr. XU convened the Predatory Mites as Biological Control Agents working group, IOBC-APRS. This is the first IOBC working group in China. In 2016, he organized the 1st work shop of this working group, which significantly enhanced the international influence of his team and predatory mite research in China.

III. Research fields
The major objective of the team is to control important pest insects and mites on vegetables and fruit trees using insect and mite natural enemies. Our research interests include exploring resources of potential biological control agents, investigating patterns and mechanisms of development regulation, nutrition and reproduction physiology, innovating mass production techniques, and performing highly efficient release and applications in protected environments such as greenhouses.
IV. Research progress1. Genome sequencing of Phytoseiulus persimilis
We completed the whole genome sequencing and assembly of Phytoseiulus persimilis, and annotated more than 20,000 genes based on genome and transcriptome sequences. The total size of its genome was about 200 Mb. The four longest contigs added up to a total length of 111.71 Mb, accounting for 57.2% of the total length. We speculated the 4 contigs may correspond to 4 chromosomes. This assembly was much better than Galendromus occidentalis, the only phytoseiid species with its genome published.

2. Reproduction process and regulation of Phytoseiulus persimilis
Being tiny in size, many ultrastructure and physiological processes in phytoseiid mites have not been clearly described. We described the producing process of spermatophore in Phytoseiulus persimilis in details. Its shape, and the number and shape of sperms inside were also analyzed, each as affected by coupling time. Based on our results, the spermatophore of P. persimilis was pyriform, and produced from male genital opening within 3 mins since mating started. When produced, the spermatophore was transferred along the capitular groove to the cheliceral base, where it was adhered to one of the two small holes at the bases of the chelicerae. Seminal fluid passed through the hole, the hollow spermatodactyl, the opening on spermatodactyl tip, and enter the insemination pore to reach the spermatheca of the female. No sperm was observed in spermatophores obtained 5 mins after mating started. The number of sperms inside increased in the next 10 mins, reached its maximum (ca. 52 sperms per spermatophore), and then decreased. All sperms were released in 75 mins after mating started. Sperms were slender in shape with the mean length being 3.9±0.3 μm. This study added new information to knowledge regarding mating in phytoseiid mites and provided chances to further investigate mechanisms of reproduction through analyzing the transcriptome and proteome of spermatophores.
Regarding mechanisms of reproduction, potential orthologs to insect genes that regulate reproduction and sex determination were blasted in P. persimilis based on genome sequencing data. RNA interference of three genes, ribosomal protein L11 (RpL11), ribosomal protein S2 (RpS2), and transformer-2 (tra-2) to newly emerged females were performed through oral delivery of double-stranded RNA. Knockdown of target genes was verified using qRT-PCR analysis, and the impact of each target gene on reproduction were evaluated. Our results verified the possibility of RNA interference in Phytoseiidae through oral delivery, and indicated RpL11 or RpS2 that are involved in egg formation, while tra-2 is involved in embryo development in P. persimilis. No impact of tra-2 (one of the conservative genes that regulates sex determination in insects) on sex determination was observed in P. persimilis, suggesting phytoseiid mites might have different sex determination pathways comparing to insects.

3. Regulation and mechanisms of diapause in natural enemy insects
Knowledge of environmental regulation of diapause in natural enemy insects is essential for understanding seasonal adaptations of insects and for increasing the shelf-life and shipment of natural enemies used in biological control programs. We have identified environmental factors responsible for diapause regulation in several natural enemy insects, including Aphidius gifuensis, Nasonia vitripennis, Coccinella septempunctata and Chrysopa formosa. Our results indicated that photoperiod and temperature are the main factors that govern diapause. We also investigated physiological and molecular adaptations enabling natural enemy insects to survive during diapause. Transcriptomes, proteomes and metabolomes were compared between diapausing and nondiapausing insects with significant differences detected. A total of 443 genes of interest that involved in metabolism, signal transduction and hormonal control of development were identified during diapause in C. septempunctata. A unique set of diapause-associated genes and proteins, including genes involved in trehalose synthesis and immunity system, were also identified in the aphid parasitoid A. gifuensis by iTRAQ and transcriptomic analysis. Decreased energy metabolism, accumulation of cryoprotectants, amimo acids and carbohydrates were observed during diapause of N. virtipennis. These physiological and molecular changes are expected to account for increased stress resistance and survival in the diapausing insects.

4. Summary of the pathways involved in metabolite accumulation in Aphidius gifuensis diapause Breakthroughs in mass rearing techniques and extensive applications
We have developed series of techniques in mass production of parasitoids and predators, including multiple predatory mites, Aphidius gifuensis, Trichogramma sp., Diglyphus isaea, Coccinella septempunctata, Arma chinensis, Chrysopa formosa and C. pallens, Phytoseiulus persimilis, Neoseiulus californicus, N. barkeri, Amblyseius oritentalis etc. for biological control. According to biological, metabolomics, and nutrigenomics studies, we succeeded in continuous rearing of predators, such as A. chinensis, C. pallens and ladybirds, with semi-artificial diets. Alternative hosts for mass production of predatory mites and insect parasitoids were also selected.
We developed more than 15 insect natural enemy products and 8 predatory mite products. More than 10 production lines have been developed. We also developed techniques of mass rearing parasitoids, predators, hosts and host plants. Particularly, we have established mass rearing centers for predatory mites, predacious bugs, ladybirds, lacewings and parasitoids in Beijing, Zunyi, Guizhou Province and Langfang, Hebei Province. Now, our natural enemy products have been applied in greenhouse and other crops for pest biological control in multiple provinces in China. Million-yuan economic benefit has been achieved annually.

V. Selected papers since 2015
Jiang X, Lv J, Wang E, Xu X, 2018. Spermatophore producing process and sperm transfer in Phytoseiulus persimilis. Experimental and Applied Acarology, 1-15.
Lv J, Zhang B, Jiang X, Wang E, Xu X, 2018, Quantitative impact of mating duration on reproduction and offspring sex ratio of Phytoseiulus persimilis (Acari: Phytoseiidae). Journal of Integrative Agriculture, 17(0): 60345-7
Zhang H-Z, Li Y-Y, An T, Huang F-X, Wang M-Q, Liu C-X, Mao J-J, Zhang L-S, 2018. Comparative transcriptome and iTRAQ proteome analyses reveal the mechanisms of diapause in Aphidius gifuensis Ashmead (Hymenoptera: Aphidiidae). Frontiers in physiology 9 (1697).
Li Y, Wang M, Gao F, Zhang H, Chen H, Wang M, Liu C, Lisheng Zhang. Exploiting diapause and cold tolerance to enhance the use of the green lacewing Chrysopa formosa Brauer in biological control. Biological Control, 2018, 127: 116-126.
Wu SY, Xing ZL, Sun WN, Xu XN, Meng RX, Lei ZR, 2018. Effects of Beauveria bassiana on predation and behavior of the predatory mite Phytoseiulus persimilis. Journal of Invertebrate Pathology, 153: 51–56.
Liu S, Lv JL, Wang ED & Xu XN, 2017. Life-style classification of some Phytoseiidae (Acari: Mesostigmata) species based on gnathosoma morphometric. Systematic & Applied Acarology 22(5): 629–639.
Guo Y, Liu CX, Zhang LS, Wang MQ, Chen HY, 2017. Sterol content in the artificial diet of Mythimna separata affects the metabolomics of Arma chinensis (Fallou) as determined by proton nuclear magnetic resonance spectroscopy. Arch Insect Biochem Physiol. 96:e21426.
Han B, Zhang S, Zeng F, Mao J, 2017. Nutritional and reproductive signaling revealed by comparative gene expression analysis in Chrysopa pallens (Rambur) at different nutritional statuses. PLOS ONE 12(7): e0180373.
Wang J, Chen HY, Wang MQ, Liu CX, Zhang HP, Zhang LS, 2017. Scanning electron microscopy observations of antennal sensilla of Chrysopa pallens. Plant Disease and Pests, 8: 1-4.
Zhang TT, Zhang GC, Zeng FR, Liu CY, Mao JJ, 2017. Insulin-like peptides regulate vitellogenesis and oviposition in the green lacewing, Chrysopa septempunctata. Bulletin of Entomological Research, 107: 148-154.
Zhang T, Zhang G, Zeng F, Mao J, Liang H & Liu F, 2017. Molecular Cloning of the Vitellogenin Gene and the Effects of Vitellogenin Protein Expression on the Physiology of Harmonia axyridis (Coleoptera: Coccinellidae). Scientific Reports, 7: 13926. doi: 10.1038/s41598-017-14339-3.
Guo YW, Lv JL, Jiang XH, Wang BM, Gao YL, Wang ED & Xu XN, 2016. Intraguild predation between Amblyseius swirskii and two native Chinese predatory mite species and their development on intraguild prey. Scientific Reports, 6, 22292. doi:10.1038/srep22992
Lv JL, Li FQ, Wu CY, Zhang J, Wang GR, Wang ED, Xu XN, 2016. Molecular and biological characterization of Neoseiulus species from China. Systematic & Applied Acarology, 21(3): 356–366.
Lv JL, Yang K, Wang ED & Xu XN, 2016. Prey diet quality affects predation, oviposition and conversion rate of the predatory mite Neoseiulus barkeri (Acari: Phytoseiidae). Systematic & Applied Acarology, 21(3): 279-287.
Du WX, Zeng F, 2016. Identification of development-related genes in the ovaries of adult Harmonia axyridis (Pallas) lady beetles using a time- series analysis by RNA-seq. Scientific Reports, 6, 39109.
Ren XY, Zhang LS, Han YH, An T, Liu Y, Li YY, Chen HY, 2016. Proteomic research on diapause-related proteins in the female ladybird, Coccinella septempunctata L, Bulletin of Entomological Research, 106(2): 168-174.
Zhang X, Lv J, Hu Y, Wang B, Chen X, Xu X, Wang E, 2015, Prey preference and life table of Amblyseius orientalis on Bemisia tabaci and Tetranychus cinnabarinus. PloS one, 10.10 (2015): e0138820.Qi X, Zhang L, Han Y, Ren X, Huang J, Chen H, 2015. De novo transcriptome sequencing and analysis of Coccinella septempunctata L. in non-diapause, diapause and diapause-terminated states to identify diapause-associated genes. BMC Genomics 16, 1086.
Li YY, Zhang LS, Chen HY, Kostal V, Simek P, Moos M, Denlinger DL, 2015. Shifts in metabolomic profiles of the parasitoid Nasonia vitripennis associated with elevated cold tolerance induced by the parasitoid's diapause, host diapause and host diet augmented with proline. Insect Biochem Mol Biol 63, 34-46.