Genetics of tomato spotted wilt virus resistance coming from Lycopersicon peruvianum

New resistance sources coming from Lycopersicon peruvianum, especially those introgressed in UPV 32 line, are studied. UPV 32 resistance is controlled by a single gene. Resistance and dominance levels of this gene are conditioned by thrips transmission and isolate aggressiveness. A partial overcoming of resistance occurs due to the incomplete penetrance of the gene. Incomplete dominance of resistance also happens, which suggests gene dosage dependence. UPV 32 gene segregates independently of both Sw-5 gene and UPV 1 resistance gene, also coming from Lycopersicon peruvianum. It is proposed to name Sw-6 this new locus from UPV 32. Sw-5 gene and UPV 1 resistance gene show higher resistance than Sw-6. Heterozygotes for UPV 1 resistance gene were more resistant than heterozygotes for Sw-5. The lower dependence of UPV 1 resistance gene on the gene dosage effect makes it very useful for the development of commercial hybrids.     

Seasonal abundance of the western flower thripsFrankliniella occidentalis in the arava valley of Israel

Flowers of 22 plant species grown in the Arava region of Israel were sampled at periodic intervals to study the seasonal abundance ofFrankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Samples were collected from the most common cut-flower and vegetable plant species in this area during 1997 and from pepper in 1996–1998. Western flower thrips (WFT) was detected on 19 of the plant species surveyed, and it reproduced on numerous plant species. WFT counts peaked in late February–April and in October–December. The peak density of WFT during March in our survey corresponded to the peak flowering of cut-flower plants (during spring) and sweet pepper (during autumn). Thrips population was less abundant during autumn than in spring and was very low during summer. The possible reasons for fluctuations in thrips densities are abiotic factors (temperature and relative humidity), and availability of flowering plants. The high temperature (>40°C) and low humidity (∼20%) in summer caused a drastic reduction in WFT populations, although some flowering plant species were available in this season. WFT population remained low until October, when adults appeared in large numbers on flowering pepper. We assume that the thrips had survived the hottest months by aestivation and migrated to the plants when air temperature decreased. In most samples from the cut-flower fields, 84.8% were adult WFT; only during the period from the end of January to March, did the proportion of immature stages in the thrips population increase to 31.6%. Females always outnumbered males (71% females). In pepper fields during the first cropping month the thrips population included 96% adults; from November onwards, the proportions of adults and immatures were almost equal; and females outnumbered males. Organic pepper fields were not infested with thrips because of the presence of the predatory bugOrius albidipennis (Fieber). Contribution from the Agricultural Research Organization. No. 534/00, 2000 series. http://www.phytoparasitica.org posting July 16, 2002.     

The efficacy of spinosad against the western flower thrips, Frankliniella occidentalis, and its impact on associated biological control agents on greenhouse cucumbers in southern Ontario

Insecticides are the most commonly used tactic to control western flower thrips (WFT), Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), on greenhouse cucumber. However, WFT has developed resistance to several of the insecticides presently in use. In addition, some of these insecticides adversely affect greenhouse biological control agents used to control WFT, resulting in subsequent pest resurgence. Therefore, there is a need to identify novel insecticides with unique modes of action for use in integrated pest management (IPM) programs to effectively control WFT with minimal impact on associated biological control agents. In laboratory bioassays conducted in 2001, immature and adult WFT and three associated greenhouse biological control agents: Amblyseius cucumeris Oudemans (Acarina: Phytoseiidae), Orius insidiosus Say (Hemiptera: Anthocoridae) and Encarsia formosa Gahan (Hymenoptera: Aphelinidae) were exposed to direct, direct/residual, and residual contact applications of the novel biopesticide, spinosad (Conserve 120 SC), and the industry standard for whitefly control, endosulfan (Thiodan 50 WP). In all three types of assay, spinosad was effective against immature and adult WFT life stages. It showed low toxicity to A. cucumeris, moderate toxicity to O. insidiosus and high toxicity to E formosa. Greenhouse studies involving exposure of immature and adult WFT and adult biological control agents to cucumber leaves sprayed previously with spinosad supported the laboratory data. Spinosad showed low toxicity to A. cucumeris exposed to leaves 1 day after treatment (DAT), moderate toxicity to O. insidiosus 1 and 8 DAT, and high toxicity to E. formosa up to 28 DAT. These data, along with spinosad's unique mode of action, suggest it would be a valuable reduced-risk control agent for greenhouse cucumber IPM programs.     

施肥对洞庭湖平原水稻土团聚体特征及其有机碳分布的影响

【目的】团聚体是土壤重要的物理属性,也是土壤有机碳的主要固存场所。研究长期不同施肥对洞庭湖平原红壤性水稻土团聚体数量、稳定性、分形特征及其有机碳含量及分布的影响,为区域双季稻田施肥管理提供理论依据。【方法】以国家稻田土壤肥力与施肥效应长期试验为平台（1986—2013）,运用湿筛法获得不同粒级水稳性团聚体,分析对照（不施肥,CK）、单施氮磷钾肥（NPK）、低量有机肥与氮磷钾肥配施（LOM,有机肥氮比例为30%）和高量有机肥与氮磷钾肥配施（HOM,有机肥氮比例为60%）4种处理影响下耕作层（0—20 cm）土壤粒径＞0.25 mm的水稳性团聚体数量（WR_0.25）、平均重量直径（MWD）、几何平均直径（GMD）、分形维数（D）及其有机碳含量与分布的变化特征。【结果】除粒径＞5 mm的土壤团聚体外,水稳性团聚体含量和团聚体对土壤有机碳的贡献率均随团聚体粒径减小呈现逐渐增加的趋势,而团聚体有机碳含量则呈现逐渐降低的变化趋势,其变化特征在不同处理间表现一致。长期不同施肥对2—5 mm和0.5—2 mm团聚体含量影响最大,与对照相比,施肥处理中上述两粒级团聚体含量分别增加35.5%—64.5%和6.2%—14.7%。施肥后团聚体的WR_0.25、MWD、GMD分别增加8.6%—12.5%、7.1%—15.1%、13.7%—28.4%,而D值降低2.3%—3.5%,说明长期施肥增强团聚体稳定性,改善团聚体结构。单施氮磷钾肥和氮磷钾肥配施有机肥均可显著提高各粒级团聚体中有机碳含量（P＜0.05）,并始终表现出HOM强于LOM、LOM强于NPK的处理效应,与对照相比,HOM处理各级团聚体中有机碳含量较对照提高了22.1%—36.6%。水稳性大团聚体是土壤有机碳的主要载体,不同处理间＞0.25 mm团聚体中有机碳的分量占土壤有机碳的比例表现出HOM（83.5%）＞LOM（81.6%）＞NPK（79.2%）＞CK（69.9%）的顺序。施肥各处理均可显著提高＞5 mm、2—5 mm、0.5—2 mm三级团聚体中有机碳对土壤有机碳的贡献率,且主要影响土壤有机碳在2—5 mm和0.5—2 mm两级团聚体中的分配率。＞0.5 mm的各级团聚体含量与土壤有机碳含量呈极显著正相关（P＜0.01）,说明施肥后土壤新增有机碳主要向＞0.5 mm的水稳性团聚体中富集。【结论】长期实行NPK平衡施肥及与有机肥配施有利于洞庭湖平原红壤性水稻土水稳性团粒结构的形成及大团聚体中有机碳的积累,与单施氮磷钾肥处理相比较,施用有机肥特别是高量有机肥与化学氮磷钾肥配施更有利于土壤良好结构体的形成和固碳能力的增强,是更优的稻田施肥模式。     

The mRNA Expression Profiles of Five Heat Shock Protein Genes from Frankliniella occidentalis at Different Stages and Their Responses to Temperatures and Insecticides

The westem flower thrips, Frankliniella occidental＆ （Pergande） is a highly invasive pest that is able to exploit many crops across a wide range of environmental conditions. Five full-length cDNAs of heat shock protein （HSP） genes （Fo-HSP90, Fo-HSP70, Fo-HSP60, Fo-HSP40 and Fo-HSP28.9） were cloned from F. occidentalis, and their expression profiles were investigated under conditions of thermal stress and insecticide exposure, and at different stages during development, using real-time quantitative PCR. All five gene sequences showed high similarity to homologs in other species, indicating the conserved fimction of this gene family. HSP60 represents an informative phylogenetic marker at the ordinal taxonomic level within Insecta, but HSP90, which has two homologous copies in Hymenoptera, was not informative. The expression of Fo-HSPs under thermal stress suggests that Fo-HSP90, Fo-HSP70, and Fo-HSP28.9 are inducible by both cold and heat stress, Fo-HSP40 is only heat-inducible, and Fo-HSP60 is thermally insensitive. There were two patterns of cold induction of Fo-HSPs： one is from 0 to 4℃ and the other is around -8℃. All five Fo-HSPs genes were induced by exposure to sublethal concentrations of the insecticide avermectin. The expression of the five Fo-HSPs during different developmental stages suggests that they all play a role in development of F. occidentalis.     

Testing resistance to TSWV introgressed from Lycopersicon peruvianum by artificial transmission techniques

Three lines of Lycopersicon esculentum (RDD, UPV 1 and UPV 32) with resistance to TSWV introgressed from L. peruvianum have been tested. RDD is a carrier of the SW5 gene and the other two lines have been developed at the Universidad Politécnica de Valencia (UPV) from accessions collected in the Andean region. Two methods of artificial inoculation, mechanical and by Frankliniella occidentalis populations, and three highly virulent Spanish isolates of TSWV have been used. Inoculation by populations of thrips proved to be more efficient than mechanical transmission independently of the considered isolate. The three lines were completely resistant when mechanical transmission was used. Also RDD and UPV 1 showed high resistance levels by thrips inoculation method; the isolates had the same effect on these two genotypes. Nevertheless, UPV 32 shows a partial resistance depending on the isolate utilized. The inoculation of virulent isolates by thrips under a high pressure of inoculum caused infection in a few plants of the three genotypes tested. In spite of being the most efficient at present for their unspecificity to isolates (and so the most used by breeders), resistance conferred by SW5 does not guarantee the absence of infection depending on the prevailing crop conditions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Resistance to western flower thrips in greenhouse cucumber: effect of leaf position and plant age on thrips reproduction

Three greenhouse cucumber (Cucumis sativus L.) accessions, previously selected for low levels of damage after infestation with Frankliniella occidentalis (Pergande), were tested for resistance against F. occidentalis in a no-choice greenhouse experiment at the mature plant stage. The three accessions showed a strong reduction in thrips damage compared to the susceptible control. The effects of leaf position and plant age of the four cucumber accessions on the reproduction of F. occidentalis were determined in a leaf disc assay. Leaf position had a significant effect on thrips reproduction, whereas plant age, within the test range, had not. In general, reproduction was higher on young leaves. Reproduction as measured on leaf discs from certain leaf positions was strongly correlated with resistance of mature plants in the greenhouse, and can therefore be used as a quick test to screen cucumber accessions for resistance against thrips. This revised version was published online in July 2006 with corrections to the Cover Date.     

重要外来入侵害虫西花蓟马在吉林省部分地区的首次发现

记述了外来入侵害虫西花蓟马在吉林省的首次发现,并对玻片的制作方法和西花蓟马形态特征进行了描述,对该虫在吉林省的发生和分布进行了记述。     

四季豆西花蓟马种群的密度及空间分布

本试验通过对云南省弥渡县四季豆西花蓟马的危害情况进行研究,为四季豆西花蓟马的防治提供依据。为了更加了解西花蓟马在四季豆叶片上的空间分布格局,通过8种聚集度指标以及Iwao回归方程对四季豆叶片上的西花蓟马进行了分析,同时,比较了花期和成熟期以及叶片在绿色和浅绿色两种生长情况时,西花蓟马的空间分布情况。结果显示在四季豆叶片上西花蓟马的空间分布型为聚集分布型;成虫主要分布在四季豆上部,若虫分布在下部;若虫数量在各个时期均多于成虫数量,成熟期西花蓟马的种群数量普遍高于开花期叶片上的种群;绿色叶片上的种群数量要多于浅绿色叶片上的种群数量。四季豆西花蓟马呈聚集分布,在田间防治四季豆西花蓟马时,应该注意对若虫以及绿色叶片上的蓟马进行重点防治。     

Esterase inhibition by synergists in the western flower thrips Frankliniella occidentalis

BACKGROUND: Western flower thrips (WFT), Frankliniella occidentalis (Pergande), is among the most important crop pests in the south‐eastern region of Spain. Its increasing resistance to insecticides constitutes a serious problem, and understanding the mechanisms involved is therefore of great interest. Use of synergists to inhibit the enzymes involved in insecticide detoxification is widely used to determine their responsibility for insecticide resistance. However, they do not always act as intended or expected, and caution must be exercised when interpreting synergist results. RESULTS: Laboratory‐selected strains of WFT were used to analyse the effects of the synergists piperonyl butoxide (PBO), S,S,S‐tributyl phosphorotrithioate (DEF) and methiocarb on total esterase activity. Significant differences were found, indicating esterase activity inhibition by DEF, a lower effect for methiocarb and a small inhibition of the activity by PBO. Esterase isoenzyme inhibition by these compounds showed a similar result; this assay revealed an extreme sensitivity of Triplet A (resistance‐associated esterases) to DEF. In an in vivo assay carried out with these compounds at different incubation times, only DEF caused posterior in vitro esterase activity inhibition, with a maximum effect 1 h after treatment. CONCLUSION: In this work, only DEF shows true synergistic inhibition of WFT esterases. Copyright © 2011 Society of Chemical Industry