The antigenic and genetic properties of 46 hantaviruses from China, 13 from patients, 23 from rodents, and 10 from unknown hosts, were compared with those of other hantaviruses. The viruses were classified as either Hantaan (HTN) or Seoul (SEO) viruses. A phylogenetic analysis of the partial M (300 bp) and S (around 485 bp) genomes of HTN viruses identified nine distinct genetic subtypes, one consisting of isolates from Korea. The SEO viruses were divided into five genetic subtypes, although they had less variability than the HTN subtypes. There was a correlation between the subtype and province of origin for four subtypes of HTN viruses, confirming geographical clustering. Hantaan virus NC167 isolated from Niviventer confucianus and SEO virus Gou3 isolated from Rattus rattus were the basal clades in each virus. The phylogenetic trees constructed from the entire S and M segments suggested that NC167 was introduced to N. confucianus in a host-switching event. The reactivity of a panel of 35 monoclonal antibodies was almost exactly the same in NC167 and a representative HTN virus and in Gou3 and a representative SEO virus. However, there was a one-way cross-neutralization between them. These results confirm the varied nature of Murinae-associated hantaviruses in China.

Summary 1.Most animal-pollinated flowering plants offer nectar as a reward for their pollinators. Some 20 000 species, however, offer only pollen and rely on pollen-foraging bees for pollination. This creates a dilemma since pollen grains contain the male gametes and should be protected from becoming bee food. Darwin was the first to hypothesize that a 'division-of-labour' among stamens could solve this dilemma, with some stamens providing pollen as food, others providing pollen for fertilization. This hypothesis can only be tested if pollen grains from the two sets of stamens can be distinguished and their fates determined to the point of attachment on the stigma. 2. We tested Darwin's hypothesis in Melastoma malabathricum (Melastomataceae), a pollen-only flower with conspicuously differentiated stamens, an inner set that is short and yellow and an outer set that is much longer and purple with small yellow spurs. Pollen release is through terminal anther pores. Taking advantage of different exine patterns on the pollen produced by the two sets of stamens, we carried out a series of experimental manipulations to compare pollinator foraging behaviour and pollen pathways from anthers to stigmas. 3.The results demonstrate that in spite of all 10 stamens being buzzed simultaneously by the carpenter bees that pollinate M. malabathricum , pollen from the purple 'fertilization' stamens is dramatically more likely to land on stigmas than pollen from the yellow 'feeding' stamens. Removal experiments showed that the yellow 'feeding' stamens also attracted pollinators from a distance. Flowers that had their anther pores plugged received fewer buzzing bouts per visit, indicating that bees assessed the amount of pollen received per bout. Surprisingly, there was no significant difference in pollen loads on stigmas of flowers that had their anthers plugged and stigmas of controls, demonstrating the efficiency of vector-assisted cross-pollination and the lack of vector-assisted self-pollination. 4. The unexpectedly precise placement of pollen grains even with buzz pollination, with a large proportion of the grains deposited out of the bees' grooming reach, helps explain the evolutionary persistence of pollen as a reward in spite of the bees' ability to assess the amount of pollen received during foraging bouts. Together, these results strongly support Darwin's division-of-labour hypothesis.

Flowers that have heteromorphic stamens (heterantherous flowers) have intrigued many researchers ever since the phenomenon was discovered in the 19th century. The morphological differentiation in androecia has been suggested as a reflection of "labor division" in pollination in which one type of stamens attracts pollinators and satisfies their demand for pollen as food and the other satisfies the plant's need for safe gamete dispersal. The extent and patterns of stamen differentiation differ notably among taxa with heterantherous flowers. Seven species with heteromorphic stamens in three genera were sampled from Leguminosae and Melastomataceae, and the morphological difference of androecia, pollen content, pollen histochemistry and viability, pollen micromorphology, as well as the main pollinators were examined and compared. Pollen number differs significantly between stamen sets of the same flower in most species investigated, and a correlation of pollen number and anther size was substantiated. Higher pollen viabilities were found in the long (pollinating) stamens of Senna alata (L.) Roxb. and S. bicapsularis (L.) Roxb. Dimorphic pollen exine ornamentation is reported here for the first time in Fordiophyton faberi Stapf. The height of stigma and anther tips of the long stamens in natural conditions was proved to be highly correlated, supporting the hypothesis that they contact similar areas of the pollinator's body.

No abstract

Agrilus mali Matsumara (Coleoptera: Buprestidae) is a wood‐boring beetle distributed to eastern China that occasionally injures apple species. However, this wood‐boring beetle is new to the wild apple forests (Malus sieversii) of the Tianshan Mountains (western China) and has caused extensive tree mortality. The development of a biological control program for these wild apple forests is a high priority that requires exploration of the life cycle, DNA barcoding and taxonomic status of A. mali. In this study, to determine the diversity of invasive beetles, a fragment of the mitochondrial cytochrome oxidase gene was analyzed. Based on the results, beetles from Gongliu and Xinyuan counties of Xinjiang were identical but differed from those in the apple nursery of Gongliu by a single‐nucleotide substitution. We summarize the taxonomic status, relationships, and genetic distances of A. mali among other Agrilus species using the Tajima‐Nei model in maximum likelihood phylogeny. Analysis revealed that A. mali was closely related to Agrilus mendax and both belong to the Sinuatiagrulus subgenus. The life cycle of A. mali was investigated based on a monthly regular inspection in the wild apple forests of Tianshan. Similar to congeneric species, hosts are injured by larvae of A. mali feeding on phloem tissue, resulting in serpentine galleries constructed between bark and xylem that prevent nutrient transport and leading to tree mortality. Future studies will focus on plant physiological responses to the invasive beetles and include surveys of natural enemies for a potential classical biological control program.

The complete nucleotide sequences of three sugarcane streak mosaic virus (SCSMV) isolates found in sugarcane plants imported from Japan (JP1, JP2) and Indonesia (ID) into China were determined. Sequence analysis showed that, based on the whole genome sequence and the nucleotide sequences encoding the ten mature proteins, the three SCSMV isolates shared identities of 81.62%-81.67% and 76.39%-85.93%, respectively, with a Pakistan (PAK) isolate of SCSMV. Phylogenetic analysis indicated that SCSMV-JP1, -JP2 and -ID were clustered in a subgroup separate from the previously described SCSMV-PAK and -India isolates, and may thus represent a new strain of SCSMV.

No abstract

Reproductive isolation is a fundamental requirement for speciation and includes several sequential stages. Few studies have determined the relative contributions of pre- and post-zygotic reproductive isolation in plants, especially between relative species with clear differentiation in flower form. To investigate the mechanisms responsible for reproductive isolation in sympatric Mussaenda pubescens var. alba and Mussaenda shikokiana (Rubiaceae) in Guangxi Province, China, we made observations of flowering phenology, patterns of insect visitation, and conducted pollination experiments, including artificial hybridization. The two species had overlapping flowering times and were pollinated by overlapping pollinators; however, their relative importance differed significantly with M. pubescens visited more commonly by bees and M. shikokiana more frequently by butterflies. Using vegetative and floral characters and molecular evidence based on nuclear ribosomal internal and external transcribed spacer regions we detected seven naturally occurring hybrids among a sample of approximately 125 individuals. Hybrids were characterized by morphologies that most closely resembled their maternal parents based on chloroplast evidence. Studies of artificially synthesized and natural hybrids demonstrated that hybrid seed had very low germination rates and naturally occurring hybrids exhibited pollen sterility. Post-zygotic reproductive isolating mechanisms play a primary role in limiting gene exchange between co-occurring species and maintaining species integrity in areas of sympatry.