8,454 research outputs found

    A history of mole crickets (Orthoptera: Gryllotalpidae) in Puerto Rico

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    Published claims in 1887-1903 that the mole cricket Neocurtilla hexadactyla (Perty) occurs in Puerto Rico all seem to be derived from a misidentification made by Agustín Stahl, a medical practitioner and collector of natural history objects, published in 1882. That species does not seem now to occur in Puerto Rico and almost certainly never did. However, the opportunity still exists for it to colonize by wind-assisted flight from islands to the southeast just as we believe did the mole cricket Scapteriscus didactylus (Latreille) as an immigrant. Stahl evidently mistook the latter for the former. According to some subsequent authors, he also stated that it (the mole cricket now believed to be S. didactylus) arrived in the port of Mayagüez in a cargo of guano about 1850 from Peru and thus colonized Puerto Rico. We found no verification for that story, and we doubt it. The first detection of the presence of S. didactylus in Puerto Rico may have been by a French expedition in 1797, but this species may have been present much earlier. Two other species of Scapteriscus were later detected in Puerto Rico. One, S. abbreviatus Scudder, was detected in 1917 and likely arrived as a contaminant of ship ballast some time earlier, perhaps at the port of Mayagüez. The other, S. imitatus Nickle and Castner, was detected about 1940 and seems to have been introduced inadvertently, as a result of mistaken identity. In broad terms, S. didactylus, S. abbreviatus, and S. imitatus are adventive species (meaning they arrived from somewhere else and are not native) in Puerto Rico. The vernacular name changa in Puerto Rico is owned by S. didactylus, which is called West Indian mole cricket in the English-speaking Caribbean. Historical accounts suggest that populations of S. didactylus and of two pest Phyllophaga spp. (Coleoptera: Scarabaeidae) surged after 1876/1877 and declined after 1920. This coincidence suggests that the cause may have been the same. The cause of the rise might conceivably have been introduction of the mongoose Herpestes javanicus (E. Geoffroy St. Hilaire) in 1877 (because it may have destroyed vertebrate predators) and the cause of the decline might conceivably have been introduction of the toad Bufo marinus L. in 1920, because it is a predator of Phyllophaga and Scapteriscus

    Natural history of Belonuchus Nordmann spp. and allies (Coleoptera: Staphylinidae) in Heliconia L. (Zingiberales: Heliconiaceae) flower bracts

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    Adults, and in some species larvae, of several members of Belonuchus Nordmann (Coleoptera: Staphylinidae: Staphylininae) and a few related genera seem to be to various degrees consistently associated with flower bracts of the genus Heliconia (Zingiberales: Heliconiaceae). They are predators and eat various dipterous and lepidopterous larvae in that habitat. Adults of at least Belonuchus cephalotes (Sharp) and Odontolinus fasciatus Sharp are able to immerse completely in water to capture larvae and/or pupae of mosquitoes (Culicidae). Adults and larvae of Belonuchus satyrus Erichson, and adults of B. cacao Blackwelder and B. rufipennis (F.) were found in water-filled flower bracts of Heliconia bihai (L.) L. in northern, lowland Venezuela. The bracts also contained mosquito larvae and semiaquatic coleopterous (Chrysomelidae: Hispinae), lepidopterous (Crambidae: Pyraustinae) and dipterous (Syrphidae, Stratiomyidae, Psychodidae, Richardiidae) larvae, and Annelida. In feeding trials, B. satyrus adults and larvae did not feed on hispine larvae or annelids, but did feed on all the lepidopterous and dipterous larvae available to them; adults dragged larvae and pupae of the mosquito genus Toxorhynchites Theobald from shallow water and thus seemed to be the top predators of the food pyramid within bracts. Records are compiled of association of Belonuchus and relatives with Heliconia bracts in the neotropics. We correct the names used for Heliconia spp. by earlier entomological authors working in Venezuela. Their ‘Heliconia caribaea Lamarck’ is H. bihai (L.) L. and their ‘H. aurea Rodríguez’ is H. bihai cv. Aurea.Los adultos y en algunos casos también las larvas de varias especies de Belonuchus spp. (Coleoptera: Staphylinidae: Staphylininae) y algunos géneros relacionados están consistentemente asociados con las espatas florales del género Heliconia (Zingiberales: Heliconiaceae). Estos coleópteros son depredadores y comen larvas de varios tipos de dípteros y lepidópteros en ese hábitat. Los adultos de Belonuchus cephalotes (Sharp) y Odontolinus fasciatus Sharp pueden sumergirse completamente en el agua para capturar las larvas y pupas de mosquitos (Culicidae). Larvas y adultos de Belonuchus satyrus Erichson, así como adultos de B. cacao Blackwelder y B. rufipennis (F.) fueron encontrados en las brácteas florales de Heliconia bihai (L.) L. de las partes bajas del norte de Venezuela. Las brácteas también contenían larvas de mosquitos y coleópteros semi-acuáticos (Chrysomelidae: Hispinae), larvas de lepidópteros (Crambidae: Pyraustinae) y de dípteros (Syrphidae, Stratiomyidae, Psychodidae, Richardiidae), y anélidos. En experimentos de alimentación, las larvas y los adultos de B. satyrus no se alimentaron de larvas de Hispinae ni de anélidos, sin embargo todas las larvas de lepidópteros y de dípteros que se les ofrecieron fueron ingeridas; los adultos de B. satyrus también extraen larvas de mosquitos del género Toxorhynchites Theobald del agua, por lo cual parecen ser los depredadores del tope de la pirámide alimentaria en las brácteas. Los registros de asociaciones de Belonuchus y géneros afines con las brácteas de Heliconia en el Neotrópico fueron recopiladas. Corregimos los nombres de Heliconia spp.utilizados anteriormente por entomólogos que trabajaron en Venezuela. Su ‘Heliconia caribaea Lamarck’ corresponde a H. bihai (L.) L. y su ‘H. aurea Rodríguez’ corresponde a H. bihai cv. Aurea

    Natural history of four species of Platydracus Thomson (Coleoptera: Staphylinidae) in Heliconia bourgaeana Petersen (Zingiberales: Heliconiaceae) flower bracts

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    The insect fauna within inflorescences of Heliconia bourgaeana Petersen (Zingiberales: Heliconiaceae) was evaluated in Parque Metlac, Fortín de las Flores, Veracruz, Mexico between May and October 1995. Floral bracts were present in May and some persisted to October, despite much destruction in August by a grackle, Quiscalus mexicanus (JF Gmelin) (Icteridae). Flowers were abundant in the bracts in May-June, after which their number declined as fruits matured. Insects that fed on the flowers were most abundant in May-June; several of them could be pollinators; the immature stages of most of these insects were absent from Heliconia Linnaeus. The floral bracts contained water enriched by decomposition of the flowers, and this provided nutrition for aquatic organisms. Syrphid larvae (Diptera) contributed the largest biomass among the aquatic insects, and their distribution among bracts was more uniform in time than that of other aquatic insects. Larvae of Culicidae and Psychodidae (Diptera) were more variable in density and were more abundant after decomposition of the flowers. The most abundant aquatic predators of culicid larvae were larvae of Toxorhynchites Theobald (Culicidae). The most abundant amphibious predators of dipterous larvae were adults of four species of Platydracus Thomson (Staphylinidae), one of them yet undescribed. To capture its prey, the Platydracus adult would immerse its head and thorax, with open mandibles, to snap at passing dipterous larvae.La fauna insectil asociada con las inflorescencias de Heliconia bourgaeana Petersen (Zingiberales: Heliconiaceae) fue evaluada en el Parque Metlac, Fortín de las Flores, Ver., México entre mayo y octubre de 1995. Las brácteas florales estuvieron presentes en mayo y persistieron hasta octubre, aunque con mucha destrucción a partir de agosto debido a la acción del zanate mexicano (Quiscalus mexicanus (JF Gmelin), Icteridae). Las flores en las brácteas fueron abundantes en mayo y junio, después de lo cual su número se redujo conforme aumento el tamaño de los frutos, los cuales maduraron en octubre. Los insectos adultos que se alimentaron en las flores fueron más abundantes en mayo y julio; varios de ellos podrían actuar como polinizadores. Los estados inmaduros de la mayoría de estos insectos no fueron encontrados en Heliconia Linnaeus. Las brácteas florales contuvieron agua enriquecida por la descomposición de las flores, lo cual provey de nutrimentos para algunos de los organismos acuáticos. Las larvas de la familia Syrphidae (Diptera) constituyeron la mayor biomasa de las larvas de insectos y su distribución fue notablemente uniforme entre las brácteas en cada espiga floral y a lo largo del periodo de observación. Las larvas de las familias Culicidae y Psychodidae (Diptera) fueron más variables en su densidad, y más abundantes después de la descomposición de las flores. Los depredadores acuáticos de las larvas de Culicidae más abundantes fueron larvas de Toxorhynchites Theobald (Culicidae). Los depredadores anfibios más abundantes de las larvas de dípteros fueron cuatro especies de Platydracus Thomson (Staphylinidae), una de ellas aun no descrita. Para capturar su presa, un estafilínido sumerge su cabeza y su tórax, con mandíbulas abiertas, en el agua e intenta capturar las larvas de dípteros

    Stepper motor control that adjusts to motor loading

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    A system and method are provided for controlling a stepper motor having a rotor and a multi-phase stator. Sinusoidal command signals define a commanded position of the motor's rotor. An actual position of the rotor is sensed as a function of an electrical angle between the actual position and the commanded position. The actual position is defined by sinusoidal position signals. An adjustment signal is generated using the sinusoidal command signals and sinusoidal position signals. The adjustment signal is defined as a function of the cosine of the electrical angle. The adjustment signal is multiplied by each sinusoidal command signal to generate a corresponding set of excitation signals, each of which is applied to a corresponding phase of the multi-phase stator

    Larra bicolor Fabricius (Hymenoptera: Crabronidae): its distribution throughout Florida

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    We document the presence of Larra bicolor Fabricius (Hymenoptera: Crabronidae) in 46 of Florida's 67 counties. The species is represented by two stocks. The first (released in 1981) originated in Pará, Brazil, but was obtained from Puerto Rico, and became established in Broward County in southern Florida. The second (released in 1988) originated in Santa Cruz de la Sierra, Bolivia, and became established in Alachua County in northern Florida. The Bolivian stock, aided by additional satellite releases from Alachua County, is now widely distributed. The species probably occupies all counties in central and northern Florida, but may yet be absent from some southern counties. Introduction was made for classical biological control of invasive mole crickets

    Elucidation of the anaerobic pathway for the corrin component of cobalamin (vitamin B12)

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    It has been known for the past 20 years that two pathways exist in nature for the de novo biosynthesis of the coenzyme form of vitamin B12, adenosylcobalamin, representing aerobic and anaerobic routes. In contrast to the aerobic pathway, the anaerobic route has remained enigmatic because many of its intermediates have proven technically challenging to isolate, because of their inherent instability. However, by studying the anaerobic cobalamin biosynthetic pathway in Bacillus megaterium and using homologously overproduced enzymes, it has been possible to isolate all of the intermediates between uroporphyrinogen III and cobyrinic acid. Consequently, it has been possible to detail the activities of purified cobinamide biosynthesis (Cbi) proteins CbiF, CbiG, CbiD, CbiJ, CbiET, and CbiC, as well as show the direct in vitro conversion of 5-aminolevulinic acid into cobyrinic acid using a mixture of 14 purified enzymes. This approach has resulted in the isolation of the long sought intermediates, cobalt-precorrin-6A and -6B and cobalt-precorrin-8. EPR, in particular, has proven an effective technique in following these transformations with the cobalt(II) paramagnetic electron in the dyz orbital, rather than the typical dz2. This result has allowed us to speculate that the metal ion plays an unexpected role in assisting the interconversion of pathway intermediates. By determining a function for all of the pathway enzymes, we complete the tool set for cobalamin biosynthesis and pave the way for not only enhancing cobalamin production, but also design of cobalamin derivatives through their combinatorial use and modification

    Calibration of optical tweezers with positional detection in the back-focal-plane

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    We explain and demonstrate a new method of force- and position-calibration for optical tweezers with back-focal-plane photo detection. The method combines power spectral measurements of thermal motion and the response to a sinusoidal motion of a translation stage. It consequently does not use the drag coefficient of the trapped ob ject as an input. Thus, neither the viscosity, nor the size of the trapped ob ject, nor its distance to nearby surfaces need to be known. The method requires only a low level of instrumentation and can be applied in situ in all spatial dimensions. It is both accurate and precise: true values are returned, with small error-bars. We tested this experimentally, near and far from surfaces. Both position- and force-calibration were accurate to within 3%. To calibrate, we moved the sample with a piezo-electric translation stage, but the laser beam could be moved instead, e.g. by acousto-optic deflectors. Near surfaces, this precision requires an improved formula for the hydrodynamical interaction between an infinite plane and a micro-sphere in non-constant motion parallel to it. We give such a formula.Comment: Submitted to: Review of Scientific Instruments. 13 pages, 5 figures. Appendix added (hydrodynamically correct calibration

    Solution structure of a bacterial microcompartment targeting peptide and its application in the construction of an ethanol bioreactor

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    Targeting of proteins to bacterial microcompartments (BMCs) is mediated by an 18-amino-acid peptide sequence. Herein, we report the solution structure of the N-terminal targeting peptide (P18) of PduP, the aldehyde dehydrogenase associated with the 1,2-propanediol utilization metabolosome from Citrobacter freundii. The solution structure reveals the peptide to have a well-defined helical conformation along its whole length. Saturation transfer difference and transferred NOE NMR has highlighted the observed interaction surface on the peptide with its main interacting shell protein, PduK. By tagging both a pyruvate decarboxylase and an alcohol dehydrogenase with targeting peptides, it has been possible to direct these enzymes to empty BMCs in vivo and to generate an ethanol bioreactor. Not only are the purified, redesigned BMCs able to transform pyruvate into ethanol efficiently, but the strains containing the modified BMCs produce elevated levels of alcohol

    Long-term yogurt consumption and risk of incident hypertension in adults

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    The Nurses' Health Study and Health Professionals Follow-up Study cohorts are supported by grants UM1 CA186107, UM1 CA176726, and UM1 CA167552 from the National Institutes of Health. The current analyses were supported by small grants from the National Dairy Council, the General Mills Bell Institute for Health and Nutrition, and the Boston Nutrition and Obesity Research Center. The Boston Nutrition Obesity Research Center is administratively based at Boston Medical Center and is funded by the National Institutes of Health (NIH/NIDDK) grant P30DK046200. (UM1 CA186107 - National Institutes of Health; UM1 CA176726 - National Institutes of Health; UM1 CA167552 - National Institutes of Health; small grants from the National Dairy Council; General Mills Bell Institute for Health and Nutrition; Boston Nutrition and Obesity Research Center; P30DK046200 - National Institutes of Health (NIH/NIDDK))Accepted manuscrip

    Refinement of the Spitzer Space Telescope Pointing History Based on Image Registration Corrections from Multiple Data Channels

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    Position reconstruction for images acquired by the Infrared Array Camera (IRAC), one of the science instruments onboard the Spitzer Space Telescope, is a multistep procedure that is part of the routine processing done at the Spitzer Science Center (SSC). The IRAC instrument simultaneously images two different sky footprints, each with two independent infrared passbands (channels). The accuracy of the initial Spitzer pointing reconstruction is typically slightly better than 1". The well‐known technique of position matching imaged point sources to even more accurate star catalogs to refine the pointing further is implemented for SSC processing of IRAC data as well. Beyond that, the optimal processing of redundant pointing information from multiple instrument channels to yield an even better solution is also performed at the SSC. Our multichannel data processing approach is particularly beneficial when the star‐catalog matches are sparse in one channel but copious in others. A thorough review of the algorithm as implemented for the Spitzer mission reveals that the mathematical formalism can be fairly easily generalized for application to other astronomy missions. The computation of pointing uncertainties, the interpolation of pointing corrections and their uncertainties between measurements, and the estimation of random‐walk deviations from linearity are special areas of importance when implementing the method. After performing the operations described in this paper on the initial Spitzer pointing, the uncertainty in the observatory pointing history file is reduced 10–15 fold
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