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Background: The white-backed planthopper (WBPH), Sogatella furcifera, causes great damage to many crops (mainly rice) by direct feeding or transmitting plant viruses. The previous genome assembly was generated by second-generation sequencing technologies, with a contig N50 of only 51.5 kb, and contained a lot of heterozygous sequences. Methods: We utilized third-generation sequencing technologies and Hi-C data to generate a highquality chromosome-level assembly. We also provide a large amount of transcriptome data for fulllength transcriptome analysis and gender differential expression analysis. Results: The final assembly comprised 56.38 Mb, with a contig N50 of 2.20 Mb and a scaffold N50 of 45.25 Mb. Fourteen autosomes and one X chromosome were identified. More than 99.5% of the assembled bases located on the 15 chromosomes. 95.9% of the complete BUSCO Hemiptera genes were detected in the final assembly and 16,880 genes were annotated. 722 genes were relatively highly expressed in males, while 60 in the females. Conclusion: The integrated genome, definite sex chromosomes, comprehensive transcriptome profiles, high efficiency of RNA interference and short life cycle substantially made WBPH an efficient research object for functional genomics.

We identified 18 distinct Fox genes in the genome of the brown planthopper, Nilaparvata lugens, and further found a novel insect-specific subfamily that we temporarily named FoxT. A total of 16 genes were highly expressed in the eggs, while NlFoxL2 and NlFoxT are female- and male-specific genes, respectively. Large scale RNAi and RNA-seq analyses were used to reveal the functions and potential targets of NlFoxs. In the eggs, NlFoxA, NlFoxN1 and NlFoxN2 are indispensable to early embryogenesis by regulating different target genes, NlFoxG and NlFoxQ co-regulate NlSix3 for brain development, and NlFoxC, NlFoxJ1 and NlFoxP have complementary effects on late embryogenesis. Moreover, NlFoxA, NlFoxNl and NlFoxQ have pleiotropism. NlFoxA and NlFoxQ regulate the expression of NlCHS1 and cuticular proteins, respectively, thereby participating in the formation of cuticles. NlFoxN1, which regulates the expression of NlKrt9 is involved in the formation of intermediate filament frameworks. Our previous studies have revealed that NlFoxL2 and NlFoxO play important roles in chorion formation and wing polyphenism. Altogether, N. lugens Fox genes exhibit functional diversity in embryonic development and organogenesis. This comprehensive study combines genomics, transcriptomics and phenomics, thereby constructing a complex genetic network that spans the entire life cycle of the brown planthopper.

Although farmers in China have grown transgenic Bt-Cry1Ac cotton to resist the major pest Helicoverpa armigera since 1997 with great success, many secondary lepidopteran pests that are tolerant to Cry1Ac are now reported to cause considerable economic damage. Vip3AcAa, a chimeric protein with the N-terminal part of Vip3Ac and the C-terminal part of Vip3Aa, has a broad insecticidal spectrum against lepidopteran pests and has no cross resistance to Cry1Ac. In the present study, we tested insecticidal activities of Vip3AcAa against Spodoptera litura, Spodoptera exigua, and Agrotis ipsilon, which are relatively tolerant to Cry1Ac proteins. The bioassay results showed that insecticidal activities of Vip3AcAa against these three pests are superior to Cry1Ac, and after an activation pretreatment, Vip3AcAa retained insecticidal activity against S. litura, S. exigua and A. ipsilon that was similar to the unprocessed protein. The putative receptor for this chimeric protein in the brush border membrane vesicle (BBMV) in the three pests was also identified using biotinylated Vip3AcAa toxin. To broaden Bt cotton activity against a wider spectrum of pests, we introduced the vip3AcAa and cry1Ac genes into cotton. Larval mortality rates for S. litura, A. ipsilon and S. exigua that had fed on this new cotton increased significantly compared with larvae fed on non-Bt cotton and Bt-Cry1Ac cotton in a laboratory experiment. These results suggested that the Vip3AcAa protein is an excellent option for a “pyramid” strategy for integrated pest management in China.

The effects of three transgenic Bacillus thuringiensis (Bt) rice lines, KMD1, KMD2, and G8-7, on biological parameters and population dynamics of nontarget insect, Rhopalosiphum maidis (Fitch) (Homoptera: Aphididae), were investigated in the laboratory and field. No significant differences were found between Bt and non-Bt rice lines for aphid survival. The developmental time of R. maidis that fed on KMD1 and KMD2 did not differ significantly from those of the individuals feeding on the parental variety Xiushui11, but significantly prolonged developmental time was observed on G8-7 as compared with its parental variety Xiushui110. Aphid fecundity was significantly higher on Bt than on parental rice. A 2-yr field survey indicated that Bt rice did not significantly affect the population dynamics of R. maidis in comparison with non-Bt rice. Additionally, guttation droplets of Bt rice and aphids feeding on Bt rice were analyzed for presence of Cry1Ab using ELISA. No Cry1Ab protein was found in aphid adults feeding on Bt rice lines both in the laboratory and field. By using the guttation droplets from the top of rice seedlings, we designed a novel method to collect phloem sap, and found that relatively low concentrations were detected in the guttation droplets from Bt rice lines. In conclusion, although the Bt rice lines tested in this study stimulate the fecundity of R. maidis , the aphid population density did not increase in Bt rice fields.

Wide planting of transgenic Bt cotton in China since 1997 to control cotton bollworm (Helicoverpa armigera) has increased yields and decreased insecticide use, but the evolution of resistance to Bt cotton by H. armigera remains a challenge. Toward developing a new generation of insect-resistant transgenic crops, a chimeric protein of Vip3Aa1 and Vip3Ac1, named Vip3AcAa, having a broader insecticidal spectrum, was specifically created previously in our laboratory. In this study, we investigated cross resistance and interactions between Vip3AcAa and Cry1Ac with three H. armigera strains, one that is susceptible and two that are Cry1Ac-resistant, to determine if Vip3AcAa is a good candidate for development the pyramid cotton with Cry1Ac toxin. Our results showed that evolution of insect resistance to Cry1Ac toxin did not influence the sensitivity of Cry1Ac-resistant strains to Vip3AcAa. For the strains examined, observed mortality was equivalent to the expected mortality for all the combinations of Vip3AcAa and Cry1Ac tested, reflecting independent activity between these two toxins. When this chimeric vip3AcAa gene and the cry1Ac gene were introduced into cotton, mortality rates of Cry1Ac resistant H. armigera larvae strains that fed on this new cotton increased significantly compared with larvae fed on non-Bt cotton and cotton producing only Cry1Ac. These results suggest that the Vip3AcAa protein is an excellent option for a “pyramid” strategy for pest resistance management in China.

Summary 1. Rice is one of the most important crops in the world. Several transgenic varieties of rice have been developed, and some have recently entered pre-production trials. One concern with genetically modified (GM) crops is transgene escape, but prior studies suggest this risk is low for rice because it is self-pollinated and the dispersal of pollen by wind is limited. 2. Little is known about the impact of pollen transport by insects. We characterized the insects visiting rice plants during anthesis and considered the effects of insect pollination on gene flow. 3. We conducted a 2-year nationwide survey in China and identified more than 510 insect species that visited rice flowers. Honeybees, hoverflies and several other species carried large amounts of pollen. The European honeybee Apis mellifera visited rice flowers regularly with daily foraging activity peaking between 12.00 and 13.00 h. 4. We monitored 20 European honeybee colonies located 100–1000 metres away from rice fields in mixed agricultural landscapes and found the honeybees carried viable pollen at least 500 m away from the rice pollen source. 5. We used four GM rice lines as pollen donors, their non-GM parental varieties as pollen recipients and the European honeybee as the pollinator in field-cage experiments to assess whether honeybees increase the frequency of gene flow in rice. Results from screening over 15 million germinated offspring seeds over a 3-year study period showed that honeybees significantly increase transgene flow in rice. 6. Synthesis and applications. Our results indicate that a remarkably high diversity of insects visit rice flowers in China and that hundreds of species including honeybees carry large amounts of rice pollen. European honeybees carry viable pollen over long distances, forage on rice flowers regularly and increase the frequency of transgene flow. Insects mediate gene flow in rice more than previously assumed, and this should be taken into consideration during the ecological risk assessment of transgene flow in self-pollinated and/or anemophilous crops.

The brown planthopper ( Nilaparvata lugens , BPH) is the most serious rice plant pests in Asia. In this study, we performed transcriptome-wide analysis on BPH intestine. We obtained more than 26 million sequencing reads that were then assembled into 53,553 unigenes with a mean size of 388 bp. Based on similarity search with the nucleotide sequences available at NCBI, BPH intestine-specific transcriptome analysis identified 21,405 sequences. Assembled sequences were annotated with gene description, gene ontology and clusters of orthologous group terms. The digestion-, defense- and xenobiotic metabolism-related genes were abundantly detected in the transcripts from BPH intestine. Many novel genes including 33 digestion-related genes, 25 immune responsive genes and 27 detoxification-related genes are first reported here. We investigated the gene expression patterns at the transcript levels in different tissues by quantitative real-time PCR analysis, which revealed that some genes had intestine-specific expression, implicating their potential significance for BPH management.

Effects of copper (Cu) accumulation by the flesh fly Boettcherisca peregrina (R.- D.) (Diptera: Sarcophagidae) on the ectoparasitic wasp Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae) were investigated experimentally by exposing host larvae to contaminated diets with final Cu concentrations of 400 � g/g and 800 � g/g diet fresh weight (DFW), respectively. Results showed that Cu can be transferred along food chains to secondary consumers (parasitoids) in small amounts, resulting in negative effects on parasitoid growth and development (body weight and developmental duration) as well as fecundity (number of offspring per female). Copper exposure also inhibited vitellogenesis of parasitoids from Cu-contaminated host pupae. It is suggested that the decreased fecundity and inhibition of vitellogenesis of N. vitripennis resulted from poor host nutritional state rather than from direct effects of Cu stress.

1. Dispersal flight, a well-known strategy for aphids to locate suitable plants, was studied for its possible role in disseminating fungal pathogens and parasitoids as natural control agents of aphids by air captures in Hangzhou, China during 2001–2005. Up to 3183 migratory alates of green peach aphid Myzus persicae were captured from air using a yellow-plus-plant trap on the top platform of a six-storey building in an urbanised area, and individually reared in a laboratory for ≥ 7 days. 2. Among the captured alates, 28.9% survived on average for 2.5 days and then died from mycoses attributed to 10 species of obligate or non-obligate aphid pathogens. These were predominated by Pandora neoaphidis, which was causative of 80% of the mycosed alates. Another 4.4% survived for an average of 3.7 days, followed by mummification of Aphidius gifuensis (52.9%) and Diaeretella rapae (47.1%). 3. Numerous progeny colonies individually initiated by infected, parasitised, or healthy alates were monitored daily for 12 days, and fitted well to a logistic equation depicting the potential of their post-flight colonisation and fecundity. Both infected and parasitised alates from air were highly capable of initiating progeny colonies independently, although their potential fecundity was greatly reduced compared with that of healthy counterparts. 4. Our results confirmed that both obligate and non-obligate pathogens can be widespread with aphid dispersal flight, and demonstrated that parasitoids also took advantage of the host flight for their dispersal. This study provides new insights into aphid dispersal biology.

In 2003 and 2004, field studies were conducted at three sites in Zhejiang Province in China to assess the impacts of Bacillus thuringiensis (Bt) Berliner rice expressing a fused gene of cry1Ab and cry1Ac on nontarget planthoppers and leafhoppers. Populations in Bt plots were sampled with yellow sticky card traps, Malaise traps, and a vacuum-suction machine, and compared with samples from non-Bt control (IR72) plots. The results from yellow sticky card trap samplings indicated no significant differences between Bt and non-Bt plots in the species composition or densities of each species of planthopper and leafhopper. Three species of planthoppers, Sogatella furcifera (Horvath), Nilaparvata lugens (Stal), and Laodelphax striatellus (Fallen), were collected at all sites, and three species of leafhoppers, Nephotettix cincticeps (Uhler), Thaia subrufa (Motschulsky), and Recilia dorsalis (Motschulsky), were collected at Hangzhou. Another species of leafhopper, N. virescens (Distant), was collected at Anji and Jiande instead of T. subrufa. The results from the Malaise trap and vacuum-suction samples revealed no significant differences between Bt and non-Bt plots in species structure of planthoppers and leafhoppers or in population changes of the predominant planthopper species, S. furcifera, the predominant leafhopper species, N. cincticeps, or N. virescens throughout most sampling dates. Densities of planthoppers and leafhoppers were significantly affected by year and site but not by Bt rice. In general, our results suggest that the Bt rice line tested did not adversely affect nontarget planthopper and leafhopper populations and will not lead to higher populations or damage by planthoppers and leafhoppers.

Background The brown planthopper, Nilaparvata lugens, the most destructive pest of rice, is a typical monophagous herbivore that feeds exclusively on rice sap, which migrates over long distances. Outbreaks of it have re-occurred approximately every three years in Asia. It has also been used as a model system for ecological studies and for developing effective pest management. To better understand how a monophagous sap-sucking arthropod herbivore has adapted to its exclusive host selection and to provide insights to improve pest control, we analyzed the genomes of the brown planthopper and its two endosymbionts. Results We describe the 1.14 gigabase planthopper draft genome and the genomes of two microbial endosymbionts that permit the planthopper to forage exclusively on rice fields. Only 40.8% of the 27,571 identified Nilaparvata protein coding genes have detectable shared homology with the proteomes of the other 14 arthropods included in this study, reflecting large-scale gene losses including in evolutionarily conserved gene families and biochemical pathways. These unique genomic features are functionally associated with the animal’s exclusive plant host selection. Genes missing from the insect in conserved biochemical pathways that are essential for its survival on the nutritionally imbalanced sap diet are present in the genomes of its microbial endosymbionts, which have evolved to complement the mutualistic nutritional needs of the host. Conclusions Our study reveals a series of complex adaptations of the brown planthopper involving a variety of biological processes, that result in its highly destructive impact on the exclusive host rice. All these findings highlight potential directions for effective pest control of the planthopper. Electronic supplementary material The online version of this article (doi:10.1186/s13059-014-0521-0) contains supplementary material, which is available to authorized users.