13种杀虫剂对荔枝蛀蒂虫成虫触杀效果测定

【目的】筛选对荔枝蛀蒂虫成虫有较好触杀作用的杀虫剂,为荔枝蛀蒂虫防治提供技术支持。【方法】以2日龄荔枝蛀蒂虫成虫为对象,用13种杀虫剂以不同稀释倍数设37个处理,采用室内喷雾法进行不同处理对荔枝蛀蒂虫成虫触杀效果测定。【结果】60 g/L乙基多杀菌素SC 5000倍、5%多杀霉素SC 4000倍、480 g/L毒死蜱EC 4000倍、35%硫丹EC 4000倍、1.8%阿维菌素EC＋480 g/L毒死蜱EC（1∶1）4000倍、10%联苯菊酯EC和20%甲氰菊酯EC 2000倍及4.5%高效氯氰菊酯EC 1000倍处理对荔枝蛀蒂虫成虫的24 h触杀死亡率均可达100.0%;2.5%高效氯氟氰菊酯EC、10%虫螨腈SC、20%氯虫苯甲酰胺SC和240 g/L氰氟虫腙SC等4种杀虫剂对荔枝蛀蒂虫成虫的防效则低于60.0%。【结论】60 g/L乙基多杀菌素SC、10%联苯菊酯EC、480 g/L毒死蜱EC及1.8%阿维菌素EC＋480 g/L毒死蜱EC混配剂对荔枝蛀蒂虫成虫有较好的防效,可作为荔枝、龙眼产区防治荔枝蛀蒂虫成虫的首选药剂;10%联苯菊酯EC、20%甲氰菊酯EC和4.5%高效氯氰菊酯EC可作为备选药剂使用。     

A mail survey to estimate the fishery dynamics of southern Florida's bonefish charter fleet

Abstract Bonefish, Albula vulpes (L.), support an economically important recreational fishery in southern Florida, USA that has received little scientific study and has never been adequately assessed. A mail survey of 322 captains that comprise the southern Florida bonefish charter fleet was conducted to acquire a baseline understanding of the primary fishery statistics. The response rate was 59% and a follow‐up telephone survey of non‐respondents indicated no non‐response bias. Experience in the fishery ranged from 3 to 61 years. The annual fishing effort was 30 875 boat days. The majority of the fleet fishing effort occurred in the northern Florida Keys and is presumed to reflect bonefish abundance. The instantaneous mortality rate of released fish was 0.11 year^?1. The majority of the respondents indicated that the bonefish stock had declined over the past decade.     

哲罗鱼的产卵量和亲鱼死亡分析

统计分析了2008—2012年期间哲罗鱼雌亲鱼产前、产后体质量和产卵量及人工繁殖中产后亲鱼死亡的原因。结果表明,在繁殖期雌性亲鱼的体长与产前体质量相关性符合幂函数方程W=0．003L3326,R2=0．926;产前个体之间体质量与实际的产卵量关系差异性较大,有的产前体质量较小,产卵量却较高,有的产前体质量较大,产卵量却较少,但整体趋势随着产前体质量的增大,产卵量增多。初次性成熟的个体产卵量一般在3116±1054粒,随着年龄和体质量的增加,产卵量逐渐增多,10kg的个体产卵量可达到17361±5304粒。人工繁殖过程中,亲鱼死亡的原因多数是人工操作不当,体表受伤水霉滋生而致死,少数个体是由于背部注射药物造成肌肉腐烂及体内血管破裂造成大出血而死亡,并针对亲鱼产后死亡的情况提出了预防措施。     

基于灰色关联和BP神经网络的汽车保有量预测

极端死亡率债券是票息或面值与极端死亡概率相关的债券,能够将寿险公司所面临的极端死亡率风险转移到资本市场。本文阐述了极端死亡率债券的市场发展,包括发行规模、触发机制、债券期限、债券分层、债券评级等,分析了以Tartan债券为代表的本金赔付累积型极端死亡率债券的运行机制,并给出了考虑极端死亡率风险的跳跃性特征下的本金赔付累积型极端死亡率债券Wang转换定价的解析式。     

17种云南乡土树种对不同程度水涝胁迫的忍耐性调查

以17种苗木为研究对象,调查了其在人工模拟根系全部淹没、1/2淹没和间隙性淹没等3种不同程度水涝胁迫下的死亡率及危害症状情况等,并对其耐水湿性进行了评价。结果表明:在根系全部淹没水涝胁迫14d时,毛果冬青、云南金钱槭出现死亡,死亡率分别为3.33%、13.33%;42d时,云南金钱槭死亡率达100%;56d时,毛果冬青、云南木樨榄、灯台树、水马桑的死亡率分别为86.67%、56.67%、80.00%、86.67%,这些树种均表现出耐水湿性弱。而肋果茶、香油果、红河榕、榉树、多果槭、金丝桃、厚皮香等树种,在根系全部淹没水涝胁迫56d时,虽然成活率高,但危害症状较重,在实际应用中只能作为稍耐水湿树种。而鳞斑荚迷、川滇桤木、连香树、枫杨在根系全部淹没63d时,均未出现植株死亡,尤其川滇桤木、连香树在根系全部淹没77d的水涝胁迫下,未出现植株死亡,表现出具有较好的耐水湿性。     

玫烟色棒束孢对小菜蛾的致病力

在室内条件下,测定了玫烟色棒束孢对小菜蛾的生物活性,结果表明:玫烟色棒束孢对小菜蛾具有较强的致病力,当孢子浓度较高时(>1×107个孢子/mL),小菜蛾第2天便出现死亡高峰,第3天左右试虫基本全部死亡。此外,孢子浓度和温度越高,玫烟色棒束孢的毒力越强,对小菜蛾2龄幼虫的毒力大于3龄幼虫,这说明玫烟色棒束孢具有防治小菜蛾的潜力。     

基于伪刚体因子的LEMs设计

伪刚体模型是柔性机构运动、动力学性能分析及综合的基础,梁和铰链的组合是基本的柔性片段,用柔性片段代替刚性构件设计柔性机构是刚体替代综合法的基本思路。传统伪刚体模型不考虑几何非线性影响和梁的变形,使伪刚体模型和设计的实际柔性机构存在较大误差,为了减小误差,建立了几何非线性影响下的修正伪刚体模型;为了确定伪刚体模型的可用条件,提出了伪刚体因子的概念,通过分析得出伪刚体因子在一定范围可以用柔性片段直接代替刚性构件,从而得到柔性机构。最后在该条件下基于蚁群连续空间优化算法给出了用于细胞工程的LEMs机构的优化实例,结果表明该伪刚体因子可应用于LEMs的设计。     

Influence of different phosphorus levels and phytase supplementation in gestation diets on sow performance

A total of 104 sows of different parities were studied. They were fed four diets with different phosphorus (P) levels during gestation for two reproductive cycles, while the same diet was fed during lactation. The aim was to decrease the total P level in the diet during gestation and to evaluate the effect on sow performance. The gestation treatments were low P (LP-; 3.7 g P/kg feed), low P with phytase (LP+, Ronozyme P; 765 FTU/kg feed), medium P (MP; 4.5 g P/kg feed) and high P (HP; 6.0 g P/kg feed). Daily feed allowances were 2.6 kg during gestation and 9.2 kg during lactation. Number of born piglets and piglet mortality were higher (p < 0.05) in the LP treatments than in the MP and HP treatments. No difference (p > 0.05) in the numbers of live-born piglets, piglet birthweights, sow weights or piglet weight gains was found between the treatments. Phosphorus level in sow milk was the highest (p < 0.05) in the MP treatment, while no effects (p > 0.05) of treatment were found on milk Ca levels, P and Ca levels in serum of sows and piglets, nor on the analysed mineral, fat and protein contents of piglets. The estimated average requirement of P for the entire gestation period was 4.4-4.5 g/day. In conclusion, a reduction of dietary total P content during gestation did not result in negative effects on sow or piglet performance. This suggests that it should be possible to lower the dietary P content for gestating sows, compared with earlier recommendations, and thereby reduce the environmental P pollution.     

Spatial estimation of the density and carbon content of host populations for Phytophthora ramorum in California and Oregon

Outbreak of the emerging infectious disease sudden oak death continues to threaten California and Oregon forests following introduction of the exotic plant pathogen Phytophthora ramorum. Identifying areas at risk and forecasting changes in forest carbon following disease outbreak requires an understanding of the geographical distribution of host populations, which is unknown. In this study, we quantify and map the population density and carbon contents of five key host species for P. ramorum in California and Oregon, including four hosts killed by the pathogen (Notholithocarpus densiflorus, Quercus agrifolia, Quercus kelloggii and Quercus chrysolepis) and the foliar host Umbellularia californica which supports high sporulation rates. We integrate multiple sources of vegetation data, assembled from sparsely distributed (regional-scale) forest inventory and analysis (FIA) plots and more densely distributed (landscape-scale) plots for monitoring sudden oak death, and develop spatial prediction models based on correlation with environmental variables and spatial dependencies in host abundance. We estimate that 1.8 billion N. densiflorus trees (68 Tg C) and 2.6 billion Quercus host trees (227 Tg C) occur across 3.9 and 17.7 million ha of their respective habitat. A total of 436 million U.californica trees (14 Tg C) occur across 4.2 million ha which frequently overlap with Quercus and N. densiflorus host populations. Combination of landscape-scale data with FIA data resulted in more accurate estimation of host populations and their carbon contents. Forests of northern California and southwest Oregon have the highest concentration of the most susceptible hosts along with climatic conditions that favor pathogen spread. This study represents the first spatially-explicit estimate of P. ramorum host populations and their carbon contents which exceed previously published estimates. Our results will inform landscape- to regional-scale models of disease dynamics and guide management decisions regarding ecosystem impacts including risk of C release following widespread tree mortality.