Resistance of fall armyworm, Spodoptera frugiperda (J.E. Smith) to Bacillus thuringiensis

The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a target pest of Bacillus thuringiensis (Bt) corn in North and South America. In this study, multiple tests were conducted in the laboratory and greenhouse to 1) determine the susceptibility of two field populations of S. frugiperda collected from Florida (FL) and Puerto Rico (PR) to purified Cry1F protein and Bt corn leaf tissue and 2) evaluate larval survival of and plant injury by Cry1F-susceptible, -resistant, and –heterozygous genotypes of S. frugiperda on whole plants of transgenic corn containing single and pyramided Bt genes. Corn hybrids evaluated in this study included five non-Bt corn hybrids, two single-gene Bt corn products, Herculex®I (Cry1F corn) and YieldGard® (Cry1Ab corn), and four pyramided Bt corn traits: Genuity®VT Double ProTM, VT Triple ProTM, SmartStaxTM, and Agrisure® VipteraTM 3111. Diet-incorporated bioassays showed that FL was susceptible to Cry1F protein with a LC50 value of 0.13-0.23 µg/g, while PR was highly resistant to Cry1F (\u3e137-fold). Leaf tissue bioassays also exhibited that FL was susceptible to all Bt corn hybrids, while PR was highly resistant to Cry1F corn leaf tissue. Both FL and PR could not survive on leaf tissue of VipteraTM 3111. However, PR exhibited a significant cross-resistance to the leaf tissue of the other three pyramided Bt corn traits. In greenhouse whole plant tests, larvae of the three insect genotypes on non-Bt corn hybrids survived well and caused serious plant damage. Cry1Ab corn was ineffective against all three insect genotypes. On Cry1F corn plants, resistant larvae survived on 72.9% plants after 12-15 d and caused significant leaf injury. In contrast, no live larvae and little or no leaf injury were observed on the Cry1F corn plants that were infested with susceptible or heterozygous genotypes, or on the pyramided Bt plants infested with the three insect genotypes. The results demonstrated that the Puerto Rico population of S. frugiperda was highly resistant to both purified Cry1F protein and Cry1F corn plants and the resistance was recessive. Corn hybrids containing any one of the four pyramided Bt traits are effective for managing the Cry1F resistance in S. frugiperda

Risk Assessment of Fall Armyworm Resistance To Transgenic Corn Containing Single or Pyramided Bacillus Thuringiensis Genes

The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a target pest of Bacillus thuringiensis (Bt) crops in North and South America. However, after more than two decades of the intense use of Bt crop technology, S. frugiperda has developed resistance to Bt corn in several countries. The objectives of this study were: 1) to characterize the inheritance and fitness costs of Cry1A.105 resistance in S. frugiperda; 2) to evaluate larval survival and plant injury of Cry1A.105-susceptibile, -resistant, and -heterozygous S. frugiperda populations on transgenic corn plants containing single or pyramided Bt genes; 3) to estimate the frequency of Cry2Ab2 resistance alleles in field populations of S. frugiperda in the U.S. southern region; and 4) to evaluate the phenotypic performance of different genotypes of S. frugiperda possessing single- or dual-Cry1A.105/Cry2Ab2 resistant genes on MON 89034 corn. Cry1A.105 and Cry2Ab2 are the two Bt proteins expressed in the Bt corn event MON 89034, a common Bt corn trait. The results showed that Cry1A.105 resistance in S. frugiperda was inherited as a single autosomal and non-recessive gene with no fitness costs. Three commonly planted pyramided Bt corn traits (Genuity® VT Double ProTM, SmartStaxTM, and Agrisure® VipteraTM 3111) were highly effective against the Cry1A.105-resistant S. frugiperda. Frequency of major Cry2Ab2 resistance alleles in field S. frugiperda populations was estimated to be 0.0023 in the U.S. southern region. One F2 family from Georgia was confirmed to possess a major resistance allele to Cry2Ab2. A Cry1A.105/Cry2Ab2 dual-gene resistant S. frugiperda strain was generated by crossing the Cry1A.105-resistant and Cry2Ab2-resistant strains. Insect survival, growth, development, pupation, and reproduction of nine genotypes of S. frugiperda possessing Cry1A.105/Cry2Ab2 resistant alleles were evaluated on leaf tissue and whole plants of MON 89034. The nine insect genotypes were a Cry1A.105/Cry2Ab2-susceptible (aabb), a Cry1A.105 resistant/Cry2Ab2-susceptible (AAbb), a Cry1A.105-susceptible/Cry2Ab2-resistant (aaBB), a Cry1A.105/Cry2Ab2-resistant (AABB), and five heterozygous (AaBb, AABb, AaBB, Aabb, aaBb) genotypes that were produced from various crosses among aabb, AAbb, aaBB, and AABB. Laboratory bioassays and greenhouse tests exhibited that AABB was highly resistant to MON 89034. Genotypes containing one or two resistance alleles were overall susceptible to MON 89034, while those possessing three resistance alleles exhibited a significant level of resistant to the Bt plants. Information generated from this study should be valuable in assessing resistance risk, refining resistance management modeling, and developing resistance management strategies for the sustainable use of the Bt corn technology

De facto currency baskets of China and East Asian economies: The rising weights

We employ Bayesian method to estimate a time-varying coefficient version of the de facto currency basket model of Frankel and Wei (2007) for the RMB of China, using daily data from February 2005 to July 2011. We estimate jointly the implicit time-varying weights of all 11 currencies in the reference basket announced by the Chinese government. We find the dollar weight has been reduced and sometimes significantly smaller than one, but there is no evidence of systematic operation of a currency basket with discernable pattern of significant weights on other currencies. During specific periods, the reduced dollar weight has not been switched to other major international currencies, but to some East Asian currencies, which is hard to explain by trade importance to or trade competition with China. We examine currency baskets of these East Asian Economies, including major international currencies and the RMB in their baskets. We find an evident tendency of Malaysia and Singapore to increase the weights of RMB in their own currency baskets, and a steadily and significantly positive weight of RMB in the basket of Thailand. These evidences suggest that, the positive weights of some East Asian currencies in RMB currency basket during specific periods largely reflect the fact that these East Asia economies have been systematically placing greater weights on RMB under the new regime of RMB exchange rate.RMB currency basket; time-varying regressions; East Asia; China; US

Design of the Control System of 2-DOF Parallel Manipulator Based on CoDeSys

The 2-DOF parallel manipulator takes a parallelogram construction which can make its workbench always remain stable. Now it is widely used in various industrial sites. In consideration of the construction features and the control demands of 2-DOF parallel manipulator, this paper mainly introduces the motion control scheme and man-machine interface design of the manipulator. Based on the motion control programming platform of CoDeSys, the motion control and simulation debugging of the 2-DOF parallel manipulator are realized

Hankel determinants, Pad\'e approximations, and irrationality exponents

The irrationality exponent of an irrational number $\xi$, which measures the approximation rate of $\xi$ by rationals, is in general extremely difficult to compute explicitly, unless we know the continued fraction expansion of $\xi$. Results obtained so far are rather fragmentary, and often treated case by case. In this work, we shall unify all the known results on the subject by showing that the irrationality exponents of large classes of automatic numbers and Mahler numbers (which are transcendental) are exactly equal to $2$. Our classes contain the Thue--Morse--Mahler numbers, the sum of the reciprocals of the Fermat numbers, the regular paperfolding numbers, which have been previously considered respectively by Bugeaud, Coons, and Guo, Wu and Wen, but also new classes such as the Stern numbers and so on. Among other ingredients, our proofs use results on Hankel determinants obtained recently by Han.Comment: International Mathematics Research Notices 201

Immediate Attention Please! What Matters To Customers Using A Social Network To Complain: Empirical Evidence From The Airline Industry

The popularity of social networks and smart mobile devices makes it convenient for customers to complain about unsatisfied service experiences by posting messages online, which needs immediate attention from service providers. Since the airline industry is one of the industries with lowest customer satisfaction and some airlines have been trying to use social networks for customer service, we collected tweets from five major airlines\u27 Twitter accounts to uncover the critical failure points complained by customers and to explore the missing links that cause the mismatches between airlines\u27 strategic intent and customers\u27 needs and expectations. Our findings revealed that customers\u27 complains mainly center on unsatisfied primary needs in five broad categories: explicit services, supporting facilities, implicit services, facilitating goods, and facilitating information. The top three most complained broad categories are explicit services, supporting facilities, and facilitating information. In addition, we identified that customers\u27 dissatisfaction is mainly due to the mismatch in three operation areas in the airline industry: (a) airlines\u27 emphasis on cost financial performance doesn\u27t match customers\u27 expectation on best values, (b) airlines\u27 focus on process-centered approach doesn\u27t match customers\u27 preferences on customer-centered approach, and (c) lack of information and unsynchronized communication doesn\u27t meet customers\u27 real time information and communication needs. Our findings can provide valuable insights for airline executives to improve their service operations