45 research outputs found

    The effect of temperature on the development of Nephus includens (Kirsch) and Nephus bisignatus (Boheman) (Coleoptera: Coccinellidae), predators of Planococcus citri Risso (Hemiptera: Pseudococcidae)

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    The effect of temperature οη the development of the predators Nephus includens (Kirsch) and Ν. bisignatus (Boheman) (Coleoptera: Coccinellidae), was studied. The development time of immature stages and the pre-oviposition period of adult females for the two predators was recorded at eight constant temperatures (10, 15, 20, 25, 30, 32.5, 35 and 37.5°C). The beetles were reared on eggs, nymphs and female adults of Planococcus citri (Risso) (Homoptera: Pseudococcidae) that had developed on squash (Cucurbita pepo) and on sour orange leaves (CΊtrus aurantium). Using the linear model for the biological cycle of Ν. includens on squash and on sour orange leaves, the developmental zeros (lower temperature thresholds) were estimated to be 10.9 and 11.0°C respectively and the thermal constants, 490.5 and 472.8 day-degrees respectively. Using the Lactin model the lower thresholds were estimated to be 11.1 and 11.2°C respectively and the upper thresholds 36.1 and 36.0°C respectively. For the biological cycle of Ν. bisignatus, using the linear model, the lower thresholds were estimated to be 9.4°C on squash and 9.3°C on sour orange leaves and the thermal constants were 614.3 and 647.9 day-degrees respectively. Using the Lactin model the lower thresholds were estimated to be 9.9 and 1O.0°C respectively and the upper thresholds, 34.7 and 35.0°C respectively. The survival rate of Ν. includens in­stars at 10, 15, 20, 25, 30, 32.5, 35 and 37.5°C on squash and on sour orange leaves was respectively 0.0, 34.9, 63.2, 70.6, 63.3, 54.5, 19.8, 0.0, and 0.0, 32.2, 61.0, 68.0, 68.3, 56.6, 17.6, 0.0%. The survival rate of Ν. bisignatus instars at 10, 15, 20, 25, 30, 32.5 and 35°C on squash and on sour orange leaves was respectively, 0.0, 39.9, 61.1, 60.7, 47.2, 26.4, 0.0 and 0.0, 35.7, 65.7, 68.0, 44.2, 29.1, 0.0%. The results show that Ν. includens has a shorter biological cycle than Ν. bisignatus, whereas the latter species has lower temperature thresholds

    Use of Lichen and Moss in Assessment of Forest Contamination with Heavy Metals in Praded and Glacensis Euroregions (Poland and Czech Republic)

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    The concentrations of selected metals—Cr, Ni, Cu, Zn, Cd, and Pb—were determined in the samples of Hypogymnia physodes lichen and Pleurozium schreberi moss collected in Polish and Czech Euroregions Praded and Glacensis. More specifically, the samples were collected in Bory Stobrawskie, Bory NiemodliƄskie, and Kotlina KƂodzka (Poland) and in Jeseniki (Czech Republic). The concentration of metals in the samples was measured using the atomic absorption spectrometry (flame AAS technique and electrothermal atomization AAS technique). The results were used to calculate the comparison factor (CF) that quantifies the difference in concentration of a given bioavailable analyte × accumulated in lichens and mosses: CF = 2 (cx,lichen − cx,moss) (cx,lichen + cx,moss)−1. The values of CF greater than 0.62 indicate the most probable location of heavy metals deposited in the considered area. In this work, the method was used to show a significant contribution of urban emissions to the deposition of heavy metals in the area of Bory Stobrawskie and in the vicinity of KƂodzko City

    Photochemical air pollutant levels and ozone phytotoxicity in the region of Mesogia-Attica, Greece

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    The levels of photochemical air pollutants: O-3, NO and NO2, were monitored in Athens and in the neighbouring region of the Mesogia plain (Spata, Artemis and Markopoulo) from 1 May-31 August 2000. Phytodetection of ozone was also conducted using bioindicator plants of Bel-W3 and Zichnomirodata (KK6/5) tobacco varieties. The average maximum daily O-3 concentration was 60-75 ppb, while the 24 hour average ranged from 40-65 ppb. The AOT40 (ppb hours) index was very high in Athens (16 679 over 121 days), Spata (16325 over 110 days), Artemis (8093 over 22 days) and Markopoulo (18 646 over 113 days), suggesting potentially phytotoxic ozone levels. The ozone bioindicator plants of Bel-W3 and KK6/5 tobacco varieties were highly injured in all regions confirming the phytotoxicity of those ozone levels. The levels of NO and NO2 recorded at the three stations, in the Mesogia plain, were considerably lower than those occurring in Athens. The data presented here provide important background information concerning pollution levels in the Mesogia plain shortly before the operation of the new international airport 'Eleftherios Venizelos' in this region (March 2001)

    New Species Of Paranthrene (Lepidoptera, Sesiidae)

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    Volume: 81Start Page: 499End Page: 50

    Effects of Short- and Long-Day Photoperiods on Growth and Development of Sesamia nonagrioides (Lepidoptera: Noctuidae)

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    The effects of 2 photoperiods, a diapause-inducing (10:14 [L:D] h) and a non-diapause inducing one (16:8 [L:D] h) at 25°C on the growth and development of larvae of the corn stalk borer, Sesamia nonagrioides, were investigated. Under a long-day photoperiod, larvae completed their development and pupated after 6 molts, whereas under a diapause-inducing short-day photoperiod, several additional molts and considerable delay of pupation were recorded. Duration of 1st to 5th instars was about the same in diapause and nondiapause destined insects, but the duration of the 6th instar was significantly longer in diapause larvae. Similarly, head capsule widths of the larvae were about the same under both photoperiods until the 5th instar. The head capsule width of all instars, under both photoperiods, is described by the logistic model. Dyar's rule, implying a geometric model, was not found appropriate for our data. Larval weights were greater under long-day photoperiod up to 5th instar, but the reverse was true for 6th instar. Only 36% of the initial number of larvae reached pupation under short-day photoperiod, whereas 74% reached pupation under long-day photoperiod. Larval mortality gradually increased, for ≈ about 150 d under short-day photoperiod, whereas under long-day photoperiod, larval mortality occurred mainly during the first few days. Mean pupal weights for diapause and nondiapause insects were 202.8 mg and 168.1 mg, respectively. Under both photoperiods, female larvae tended to pupate later and the pupae were heavier

    Diapause Termination in Sesamia nonagrioides (Lepidoptera: Noctuidae) under Laboratory and Field Conditions

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    The influence of photoperiod and temperature on the termination of diapause of Sesamia nonagrioides (Levebvre) was evaluated under laboratory and field conditions. Long-day photoperiod enhanced termination of diapause. Larvae held under a short-day photoperiod (10:14 [L:D] h) for various times and then transferred to a long-day photoperiod (16:8 [L:D] h) proceeded to pupate in ≈14 d, indicating that regardless of the state of diapause intensity, diapause completion and postdiapause development lasted similar lengths of time. Larval diapause termination was not hastened when diapausing larvae kept at a photoperiod of 10:14 (L:D) h and 25°C were exposed for short periods at 30, 35, and 40°C, whereas it was shortened when diapausing larvae were transferred from 25 to 30°C and kept continuously at this temperature. At higher temperatures (35 and 40°C), all transferred larvae died. It was also shown that exposure of diapausing larvae to low temperature (5°C) simply accelerated diapause development but termination of diapause did not require a period of chilling. Moreover, after low temperature treatment, diapausing larvae showed a faster diapause development when transferred to a long-day photoperiod than those kept in a short-day photoperiod. In the latter case, the longer the exposure the faster the termination occurred. Diapause termination of field-collected larvae was practically spontaneous. After transfer to laboratory conditions, 25°C and a photoperiod of 16:8 (L:D) h, they quickly proceeded to pupate. Field-diapausing larvae terminated diapause in January but exhibited a postdiapause development; the 1st record of pupation was observed in the field at the end of March

    The Textures of Heroin: User Perspectives on “Black Tar” and Powder Heroin in Two U.S. Cities

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    Since the 1990s, U.S. heroin consumers have been divided from the full range of available products: east of the Mississippi River, Colombian-sourced powder heroin (PH) dominates the market while, to the west, Mexican-sourced "black tar" (BTH) is the main heroin available. By conducting qualitative research in two exemplar cities, Philadelphia (PH) and San Francisco (BTH), we compare users' experiences of heroin source-types, markets, health consequences, and consumption preferences. The strict division of heroin markets may be changing with novel forms of powder heroin appearing in San Francisco. Our researchers and interviewees perceived vein loss stemming from the injection of heroin alone to be a particular problem of BTH while, among the Philadelphia sample, those who avoided the temptations of nearby cocaine sales displayed healthier injecting sites and reported few vein problems. Abscesses were common across both sites, the Philadelphia sample generally blaming missing a vein when injecting cocaine and the San Francisco group finding several explanations, including the properties of BTH. Consumption preferences revealed a "connoisseurship of potency," with knowledge amassed and deployed to obtain the strongest heroin available. We discuss the reasons that their tastes take this narrow form and its relationship to the structural constraints of the heroin market

    Heroin-related overdose: The unexplored influences of markets, marketing and source-types in the United States.

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    Heroin overdose, more accurately termed 'heroin-related overdose' due to the frequent involvement of other drugs, is the leading cause of mortality among regular heroin users. (Degenhardt et al., 2010) Heroin injectors are at greater risk of hospital admission for heroin-related overdose (HOD) in the eastern United States where Colombian-sourced powder heroin is sold than in the western US where black 'tar' heroin predominates. (Unick et al., 2014) This paper examines under-researched influences on HOD, both fatal and non-fatal, using data from a qualitative study of injecting drug users of black tar heroin in San Francisco and powder heroin in Philadelphia Data were collected through in-depth, semi-structured interviews carried out in 2012 that were conducted against a background of longer-term participant-observation, ethnographic studies of drug users and dealers in Philadelphia (2007-12) and of users in San Francisco (1994-2007, 2012). Our findings suggest three types of previously unconsidered influences on overdose risk that arise both from structural socio-economic factors and from the physical properties of the heroin source-types: 1) retail market structure including information flow between users; 2) marketing techniques such as branding, free samples and pricing and 3) differences in the physical characteristics of the two major heroin source forms and how they affect injecting techniques and vascular health. Although chosen for their contrasting source-forms, we found that the two cities have contrasting dominant models of drug retailing: San Francisco respondents tended to buy through private dealers and Philadelphia respondents frequented an open-air street market where heroin is branded and free samples are distributed, although each city included both types of drug sales. These market structures and marketing techniques shape the availability of information regarding heroin potency and its dissemination among users who tend to seek out the strongest heroin available on a given day. The physical characteristics of these two source-types, the way they are prepared for injecting and their effects on vein health also differ markedly. The purpose of this paper is to examine some of the unexplored factors that may lead to heroin-related overdose in the United States and to generate hypotheses for further study

    Seasonal abundance, spatial distribution and sampling indices of thrip populations on cotton; a 4-year survey from central Greece

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    Field studies were carried out in order to assess the populations of thrips on cotton leaves, by developing a sampling program to estimate the density with an acceptable level of precision. Thus, in a cotton field (1.1 ha) in central Greece, 45 leaves were collected (one leaf per cotton plant) at 10-day intervals from May to September, for four consecutive growing seasons (1995-98). Five species of thrips were found: Frankliniella intonsa was the most abundant species followed by Thrips angusticeps , Thrips tabaci , Frankliniella occidentalis and Aeolothrips intermedius . Although considerable differences were observed in the population fluctuations among species, the highest population densities, for all species found, were recorded in July and August. As indicated by Taylor's power law estimates, all species presented aggregated distribution among sampling units. As this type of spatial pattern indicates, the accuracy obtained in estimating mean population density increased with the increase of the mean. Furthermore, the increase of the mean caused an exponential decrease in sample size. However, the precision level is acceptable only in high mean values, while at the same time the benefit from an increase in sample size is of no practical value
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