烟粉虱传播植物病毒特性及机制研究进展

烟粉虱是一类小型刺吸式口器昆虫,目前被认为是一个包含数十个隐存种的隐存种复合群.近年来随着进出口贸易的增加,烟粉虱在世界范围内急速扩散.烟粉虱主要通过传播植物病毒危害植物,对世界范围内的多种作物、蔬菜以及园林植物等造成巨大危害.目前可由烟粉虱传播的植物病毒涵盖5个属400多个种,其中菜豆金黄花叶病毒属为单链DNA病毒且均由烟粉虱以持久循环型方式传播,其余4个属均为单链RNA病毒并由烟粉虱以半持久型或非持久型方式传播.明确烟粉虱传播植物病毒的生物学特性,解析烟粉虱与病毒间的互作机制将为阻断烟粉虱传播植物病毒提供新方法、新思路.本文分别对烟粉虱传播不同属病毒的特性进行了综述,并着重讨论了烟粉虱与菜豆金黄花叶病毒属病毒的互作机制.菜豆金黄花叶病毒属病毒跨越烟粉虱中肠、唾液腺和卵巢屏障的过程需要多种介体蛋白的参与.烟粉虱不同隐存种传播同一种病毒的能力往往存在差异,而这种差异性传播往往与病毒穿过不同烟粉虱体内屏障的能力有关.同时,烟粉虱免疫系统在抵御病毒侵染过程中发挥重要作用.此外,多项研究表明病毒在烟粉虱体内存在复制迹象.

Fluid Inclusion and H-O Isotope Geochemistry of the Phapon Gold Deposit, NW Laos: Implications for Fluid Source and Ore Genesis

The Phapon gold deposit, located in northern Laos, is a unique large-scale gold deposit in Luang Prabang-Loei metallogenic belt. It is hosted in the Lower Permian limestone and controlled by a NE-trending ductile-brittle fault system. There are three types of primary ore including auriferous calcite vein type, disseminated type, and breccia type, and the first two are important in the Phapon gold deposit. Based on fluid inclusion petrography and microthermometry, three types of primary fluid inclusions including type 1 liquid-rich aqueous, type 2 vapor-rich aqueous and type 3 daughter mineralbearing aqueous were identified in hydrothermal calcite grains. The ore-forming fluids are normally homogeneous, as indicated by the widespread type 1 inclusions with identical composition. The coexistence of type 1 and type 2 inclusions, showing similar final homogenization temperature but different compositions, indicate that fluid immiscibility did locally take place in both two types of ores. The results of microthermometry and H-O isotopes geochemistry indicate that there are little differences on ore-fluid geochemistry between the auriferous calcite vein-type and disseminated type ores. The oreforming fluids are characterized by medium-low temperatures(157–268 oC) and low salinity(1.6 wt.%–9.9 wt.% NaCl eq.). It is likely to have a metamorphic-dominant mixed source, which could be associated with dehydration and decarbonisation of Lower Permian limestone and Middle–Upper Triassic sandstones during the dynamic metamorphism. The fluid-wallrock interaction played a major role, and the locally occurred fluid-immiscible processes played a subordinate role in gold precipitation. Combined with the regional and ore deposit geology, and ore-fluid geochemistry, we suggest that the Phapon gold deposit is best considered to be a member of the epizonal orogenic deposit class.

Geochronology and Petrochemistry of Volcanic Rocks in the Xaignabouli Area, NW Laos

An integrated study of zircon U-Pb geochronology and petrochemistry, together with zircon Lu-Hf isotopes, has been carried out on the basaltic-andesitic tuff and volcanic breccia from the Nam Hang Formation and andesitic tuff from the Muang-Nan Formation in the Xaignabouli area, which had been mapped as the Permian–Early Triassic on the 1 : 1 000 000 geological map or Late Carboniferous on the 1 : 200 000 geological maps. Zircon U-Pb dating of three samples yielded weighted mean ages of 235±2.6, 232±1.4 and 278±2.8 Ma, respectively, suggesting a Late Triassic origin for the Nam Hang Formation and an Early Permian origin for the Muang-Nan Formation. Geochemically, they are characterized by depletions in HFSEs(e.g., Nb, Ta, Ti) and high LILE/HFSE ratios, and they have positive zircon ε_(Hf)(t) values of 8.7–15.9, which exhibits the continental arc volcanic affinity and partial melting of subducting oceanic slab in the magma source. Combined with spatial occurrence of the volcanic rock and existing geochronological and geochemical data, we suggest that the Xaignabouli-Luang Prabang volcanic belt can be linked to the Loei-Phetchabun belt. The Permian–Triassic volcanic rocks in this belt might be a product of the Nan back-arc basin eastward subduction.

New insights into the transovarial transmission of the symbiont Rickettsia in whiteflies

Endosymbiont transmission via eggs to future host generations has been recognized as the main strategy for its persistence in insect hosts;however,the mechanisms for transmission have yet to be elucidated.Here,we describe the dynamic locations of Rickettsia in the ovarioles and eggs during oogenesis and embryogenesis in a globally significant pest whitefly Bemisia tabaci.Field populations of the whitefly have a high prevalence of Rickettsia,and in all Rickettsia-infected individuals,the bacterium distributes in the body cavity of the host,especially in the midgut,fat body,hemocytes,hemolymph,and near bacteriocytes.The distribution of Rickettsia was subjected to dynamic changes in the ovary during oogenesis,and our ultrastructural observations indicated that the bacteria infect host ovarioles during early developmental stages via two routes:(i)invasion of the tropharium by endocytosis and then transmission into vitellarium via nutritive cord and(ii)entry into vitellarium by hijacking bacteriocyte translocation.Most of the Rickettsia are degraded in the oocyte cytoplasm in late-stage oogenesis.However,a few reside beneath the vitelline envelope of mature eggs,spread into the embryo,and proliferate during embryogenesis to sustain high-fidelity transmission to the next generation.Our findings provide novel insights into the maternal transmission underpinning the persistence and spread of insect symbionts.

Geology, Geochronology, and Hf Isotopic Composition of the Pha Lek Fe Deposit, Northern Laos: Implications for Early Permian Subduction-Related Skarn Fe Mineralization in the Truong Son Belt

The Truong Son metallogenic belt in central Laos and Vietnam is an important Fe-Cu-Sn-Au polymetallic ore district. The Pha Lek Fe deposit is closely related to Late Carboniferous– Early Permian I-type granitic magmatism, and contains >50 Mt @ 45% to 50% of Fe ore. Ore minerals occur mainly as magnetite and hematite in the skarn alteration zone between a granitic pluton and metamorphosed Middle–Upper Devonian carbonates. The granitic pluton comprises granodiorite and granite, with zircon U-Pb dating indicating synchronous emplacement at 288.2±1.3 and 284.9±1.2 Ma, respectively. Zircons from these granitoids have ε_(Hf)(t) values of 2.9–11.2 and relatively young TDM2 ages(<1.0 Ga), indicating an origin by partial melting of depleted mafic crust or magma mixing. Previous studies have shown that these granitoids have high Y, Yb, and K_2O contents, and low Sr and Na_2O contents, which are interpreted as the melting of mafic continental crust. Pyrite of the main mineralization stage yields an ^(187)Re/^(188)Os-^(187)Os/^(188)Os isochron age of 287±17 Ma, indicating that mineralization is associated with Pha Lek granitic magmatism. A Late Carboniferous–Early Permian subduction-related skarn-type Fe mineralization model is proposed for the Pha Lek deposit. More evidence is needed to verify a hypothesis of volcanic overprinting during Late Triassic post-collisional extension.

Differential efficiency of a begomovirus to cross the midgut of different species of whiteflies results in variation of virus transmission by the vectors

Begomoviruses are important crop viral disease agents, and they are transmitted by whiteflies of the Bemisia tabaci complex.Although the transmission of begomoviruses by whiteflies has been studied for many years, the mechanisms governing differential transmission of begomoviruses by different species of the Bemisia tabaci complex remain largely unknown. Here we firstly compared the transmission efficiency of tobacco curly shoot virus(TbCSV) by four species of the B. tabaci complex and found that Asia II 1 transmitted this virus with the highest efficiency, whereas MEAM1 transmitted it with the lowest. Next, by performing quantitative analysis of virus and immune-fluorescence detection, we found that the efficiency of TbCSV to cross the midgut wall was higher in Asia II 1 than in MEAM1. Finally, we set the quantities of virions in the haemolymph to the same level in Asia II 1 and MEAM1 via injection and then compared their capacity in TbCSV transmission, and found that the difference in TbCSV transmission between them became smaller. Taken together, our findings suggest that the efficiency of a begomovirus to cross the midgut wall of a whitefly to reach the vector's haemolymph plays a significant role in determining transmission of the virus.

Spatial Distribution Prediction of Laterite Bauxite in Bolaven Plateau Using GIS

Mineral resources are the most important natural resources for developing countries. Bauxite is an indispensable mineral resource for industrial production. Potential assessment of bauxite is an important issue in Indochina Peninsula. In this paper, the factors affecting the mineralization of the lateritic bauxite are analyzed. The collected spatial data are processed and the information is extracted to obtain the spatial extent of favorable constraints. Then, the spatial distribution of potential bauxites on the Bolaven Plateau has been investigated with a Boolean modeling process in GIS environment on the basis of some constraints such as rock, elevation, topographical features and vegetation coverage. Finally, based on the hydrogeological conditions and alteration information of Fe3+ and OH-, the bauxite mapping has been carried out. There are twenty bauxite metallogenic areas delineated, with a total area of 750 km2, which is 5% of the entire study area. This has greatly reduced the scope of the field investigation. Seven of the twenty predicted areas were validated in the field and six of them were found to have bauxite mineralization. Using the methods proposed in this study, the potential bauxite for the entire Bolaven Plateau could be achieved much more cheaply than the traditional methods. This study also provides a good idea for the prediction of laterite bauxite in the other regions of the Indochina Peninsula.

GPIBase:A comprehensive resource for geminivirus-plant-insect research

Dear Editor,As one of the most widespread and destructive families of plant viruses,Geminiviridae,named for the twinned icosahedral particles of virus members in the family,poses a serious threat to agricultural production worldwide.Transmitted by various homopterans insects such as whiteflies,leafhoppers,aphids,and treehoppers,geminiviruses infect,in addition to wild plants,vegetable,root,and fiber crops,thus causing important losses around the globe(Hanley-Bowdoin et al.,2013;Li et al.,2022).

Differences in mating behavior lead to asymmetric mating interactions and consequential changes in sex ratio between an invasive and an indigenous whitefly

The invasive B whitefly and the indigenous ZHJ2 whitefly in China of the Bemisia tabaci complex represent two previously allopatric cryptic species.Laboratory experiments have shown that the invasive B can displace the indigenous ZHJ2.Here,we observed the mating behavior and mating interactions between B and ZHJ2 to elucidate the behavioral mechanisms underlying their competition.The 2 species are able to mate with each oth-er,although at a significantly lower frequency than that between males and females within the same species.Heterospecifically-mated females produce only male progeny,indicating reproductive isolation.Heterospecific mating had only a marginal effect on reproduction of females in either species.Detailed observations on mating interactions between the 2 species showed that B had higher sexual activity than ZHJ2.B males were more like-ly to interrupt courtships initiated by rival males than ZHJ2 males.Compared with ZHJ2 males,B males were also more likely to successfully interrupt courtships initiated by rival heterospecific males than by males of the same species.In addition,B males guarded B females post-copulation,whereas ZHJ2 males did not.When the 2 species co-occurred,the behavioral differences and interactions between them resulted in an increased propor-tion of females produced in the offspring of B but reduced proportion of females in the progeny of ZHJ2.These asymmetric mating interactions might be an important mechanism underlying the displacement of ZHJ2 by B.Our study shows that reproductive interference might contribute to the competitive exclusion between closely related species during biological invasions.