524 research outputs found

    Inventory of Thysanoptera Collected from French Polynesia.

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    v. ill. 23 cm.QuarterlyA survey for Thysanoptera was conducted in the Society (Tahiti, Moorea, and Raiatea), Marquesas (Hiva Oa, Nuku Hiva, Ua Huka, and Ua Pou), and Austral islands (Rurutu and Tubuai) archipelagos in French Polynesia from September 2003 to November 2005. At least 55 thrips species in 36 genera and three families were identified from 823 slide-mounted specimens that were collected from 61 host plants in 33 families. Twelve species are considered to be important pests. The greatest diversity of species, 43 (77%), was collected from the Society Islands, with 60% being recorded from Tahiti alone. Species diversity was intermediate in the Marquesas Islands at 43% (24 species collected), with 35% or 19 species being recorded from Nuku Hiva. Lowest diversity was recorded for the Austral Islands, with 38% or 21 species being found in that archipelago. Less than 10% of collected species are likely to be native, with the majority of identified thrips (>90%) in French Polynesia representing a high diversity of exotic species (leaf, flower, and fungus feeders, and four predatory species) that have successfully infiltrated other island groups in the South Pacific.Survey results and subsequent estimates of thrips species diversity in French Polynesia should be interpreted with caution due to uncontrolled variation in sampling intensity that was affected by survey duration, time of year, and visitation frequency to islands

    Optimum timing for integrated pest management: Modelling rates of pesticide application and natural enemy releases

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    Many factors including pest natural enemy ratios, starting densities, timings of natural enemy releases, dosages and timings of insecticide applications and instantaneous killing rates of pesticides on both pests and natural enemies can affect the success of IPM control programmes. To address how such factors influence successful pest control, hybrid impulsive pest–natural enemy models with different frequencies of pesticide sprays and natural enemy releases were proposed and analyzed. With releasing both more or less frequent than the sprays, a stability threshold condition for a pest eradication periodic solution is provided. Moreover, the effects of times of spraying pesticides (or releasing natural enemies) and control tactics on the threshold condition were investigated with regard to the extent of depression or resurgence resulting from pulses of pesticide applications. Multiple attractors from which the pest population oscillates with different amplitudes can coexist for a wide range of parameters and the switch-like transitions among these attractors showed that varying dosages and frequencies of insecticide applications and the numbers of natural enemies released are crucial. To see how the pesticide applications could be reduced, we developed a model involving periodic releases of natural enemies with chemical control applied only when the densities of the pest reached the given Economic Threshold. The results indicate that the pest outbreak period or frequency largely depends on the initial densities and the control tactics

    Sex, males, and hermaphrodites in the scale insect Icerya purchasi

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    Funding: This work was supported by a number of fellowships, namely a University Research Fellowship from Royal Society of London (to AG) and a Junior Research Fellowship from Balliol College, Oxford to AG. Funding came from Independent Research Fellowships from Natural Environment Research Council (grant no. NE/K009524/1 to AG and NE/K009516/1 to LR), a Consolidator Grant from European Research Council (grant no. 771387 to AG), a European Research Countil Starting Grant (PGErepro to LR), and a Royal Society Newton fellowship (to LR).Androdioecy (the coexistence of males and hermaphrodites) is a rare mating system for which the evolutionary dynamics are poorly understood. Here we study the only presumed case of androdioecy in insects, found in the cottony cushion scale, Icerya purchasi . In this species, female-like hermaphrodites have been shown to produce sperm and self-fertilize. However, rare males are sometimes observed too. In a large population-genetic analysis, we show for the first time that although self-fertilization appears to be the primary mode of reproduction, rare outbreeding events between males and hermaphrodites do occur, and we thereby confirm androdioecy as the mating system of I. purchasi . Thus, this insect appears to have the colonization advantages of a selfing organism while also benefitting from periodic reintroduction of genetic variation through outbreeding with males.Publisher PDFPeer reviewe

    Age Determination of the Glassy-Winged Sharpshooter, Homalodisca vitripennis, using Wing Pigmentation

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    A red pigment is contained in the wing veins of the glassy-winged sharpshooter, Homalodisca vitripennis (Hemiptera: Cicadellidae). This insect is the main vector of the plant-pathogenic bacterium Xylella fastidiosa Wells (Xanthomonadales: Xanthomonadaceae), the causal agent of Pierce's disease of grapevines. Over the course of the H. vitripennis lifespan, the red pigment darkens and eventually becomes brown/black in color. These pigments are believed to be pheomelanin and eumelanin, respectively. The age of H. vitripennis can be determined by calculating the amount of red pigment found in the wings by analyzing high resolution wing photographs with image analysis software. In this study, a standard curve for the age determination of H. vitripennis was developed using laboratory—reared insects of known ages varying from 1 to 60 days. The impact of three environmental conditions on these readings was also investigated and found to have little effect on the age determination, and could be easily accounted for. Finally, field collected insects from several Central Texas vineyards were successfully analyzed for age determination suggesting that the annually reported influx of H. vitripennis was composed almost entirely of older insects

    Development of an attract-and-infect system to control Rhynchophorus ferrugineus with the entomopathogenic fungus Beauveria bassiana

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    This is the peer reviewed version of the following article: Dembilio, Ó. , Moya, P. , Vacas, S. , Ortega‐García, L. , Quesada‐Moraga, E. , Jaques, J. A. and Navarro‐Llopis, V. (2018), Development of an attract‐and‐infect system to control Rhynchophorus ferrugineus with the entomopathogenic fungus Beauveria bassiana. Pest. Manag. Sci, 74: 1861-1869., which has been published in final form at http://doi.org/10.1002/ps.4888. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving[EN] BACKGROUNDA new Beauveria bassiana-based attract and infect device (AID) to control Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) was developed. The virulence and persistence of the fungal formulation used in the AID were evaluated in the laboratory. Semi-field and field trials were carried out to validate the results and establish the potential of this device as a control tool. RESULTSIn laboratory conditions, a 50% lethal time (LT50) of 4.33 days was obtained when adults (7-10 days old) were exposed to the inoculation tunnel (IT) containing 1 x 10(10) conidia g(-1) in an oil-based fungal formulation. This formulation maintained conidium viability at 50% for up to 2 months. Moreover, when adults were exposed to 2.5-month field-aged ITs, mortality still reached 50% 40 days after exposure. In addition, no differences were observed between ITs aged in early spring and those aged in summer, suggesting that the fungal formulation is not strongly affected by environmental factors in Mediterranean basin conditions. Semi-field assays showed that the device allowed an easy transit of weevils through the IT, which were effectively attracted and infected. Using the AIDs in 4-ha plot field trials, a reduction of >50% in the percentage of infested sentinel palms was obtained. CONCLUSIONBased on the results obtained in terms of the efficacy and persistence of this new AID in the field and its potential in reducing R. ferrugineus populations and palm infestation, this device could become a key tool for the management of R. ferrugineus. (c) 2018 Society of Chemical IndustryWe wish to thank Manuel Piquer, Juan Argente and Carlos Campos for their assistance with many parts of this work, Cuca Orero for providing the trial field at Sagunt, and Jose Sancho from Sansan Prodesing SL for providing prototype solutions for the infective trap. The research that has led to these results received funding from the 7th European Union Framework Programme with Grant Agreement no. FP7 KBBE 2011-5-289566 (PALM PROTECT).Dembilio, O.; Moya Sanz, MDP.; Vacas, S.; Ortega-García, L.; Quesada-Moraga, E.; Jaques, J.; Navarro-Llopis, V. (2018). Development of an attract-and-infect system to control Rhynchophorus ferrugineus with the entomopathogenic fungus Beauveria bassiana. Pest Management Science. 74(8):1861-1869. https://doi.org/10.1002/ps.4888S1861186974
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