53 research outputs found

    Temperature-dependent development of the two-spotted ladybeetle, Adalia bipunctata, on the green peach aphid, Myzus persicae, and a factitious food under constant temperatures

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    The ability of a natural enemy to tolerate a wide temperature range is a critical factor in the evaluation of its suitability as a biological control agent. In the current study, temperature-dependent development of the two-spotted ladybeetle A. bipunctata L. (Coleoptera: Coccinellidae) was evaluated on Myzus persicae (Sulzer) (Hemiptera: Aphididae) and a factitious food consisting of moist bee pollen and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs under six constant temperatures ranging from 15 to 35 degrees C. On both diets, the developmental rate of A. bipunctata showed a positive linear relationship with temperature in the range of 15-30 degrees C, but the ladybird failed to develop to the adult stage at 35 degrees C. Total immature mortality in the temperature range of 15-30 degrees C ranged from 24.30-69.40% and 40.47-76.15% on the aphid prey and factitious food, respectively. One linear and two nonlinear models were fitted to the data. The linear model successfully predicted the lower developmental thresholds and thermal constants of the predator. The non-linear models of Lactin and Briere overestimated the upper developmental thresholds of A. bipunctata on both diets. Furthermore, in some cases, there were marked differences among models in estimates of the lower developmental threshold (t(min)). Depending on the model, t(min) values for total development ranged from 10.06 to 10.47 degrees C and from 9.39 to 11.31 degrees C on M. persicae and factitious food, respectively. Similar thermal constants of 267.9DD (on the aphid diet) and 266.3DD (on the factitious food) were calculated for the total development of A. bipunctata, indicating the nutritional value of the factitious food

    Effect of temperature on the functional response of Adalia bipunctata to Myzus persicae

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    The effect of temperature on the functional response of female adults of the two-spot ladybird, Adalia bipunctata L. (Coleoptera: Coccinellidae) was examined in petri dish arenas containing sweet pepper leaves infested with different densities of the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). The predator showed a type II functional response at three tested temperatures ranging from 19A degrees C to 27A degrees C. The theoretical maximum number of prey captured by the predator increased with temperature. Based on the random predator equation, the estimated attack rates ranged from 0.13 h(-1) at 19A degrees C to 0.35 h(-1) at 27A degrees C on a leaf area of 20-25 cm(2). There was no significant difference between the attack rates of the predator at 23A degrees C and 27A degrees C. Handling time significantly decreased as temperature increased from 19A degrees C (0.39 h) to 27A degrees C (0.24 h). This study shows that A. bipunctata displays high predation rates on M. persicae for a wide range of temperatures, indicating its potential for augmentative releases against this aphid pest. The limitations of the predictions generated by functional response experiments are discussed

    Temperature-Dependent Development of the Two-Spotted Ladybeetle, Adalia bipunctata, on the Green Peach Aphid, Myzus persicae, and a Factitious Food Under Constant Temperatures

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    The ability of a natural enemy to tolerate a wide temperature range is a critical factor in the evaluation of its suitability as a biological control agent. In the current study, temperature-dependent development of the two-spotted ladybeetle A. bipunctata L. (Coleoptera: Coccinellidae) was evaluated on Myzus persicae (Sulzer) (Hemiptera: Aphididae) and a factitious food consisting of moist bee pollen and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs under six constant temperatures ranging from 15 to 35° C. On both diets, the developmental rate of A. bipunctata showed a positive linear relationship with temperature in the range of 15–30° C, but the ladybird failed to develop to the adult stage at 35° C. Total immature mortality in the temperature range of 15–30° C ranged from 24.30–69.40% and 40.47–76.15% on the aphid prey and factitious food, respectively. One linear and two nonlinear models were fitted to the data. The linear model successfully predicted the lower developmental thresholds and thermal constants of the predator. The non-linear models of Lactin and Brière overestimated the upper developmental thresholds of A. bipunctata on both diets. Furthermore, in some cases, there were marked differences among models in estimates of the lower developmental threshold (tmin). Depending on the model, tmin values for total development ranged from 10.06 to 10.47° C and from 9.39 to 11.31° C on M. persicae and factitious food, respectively. Similar thermal constants of 267.9DD (on the aphid diet) and 266.3DD (on the factitious food) were calculated for the total development of A. bipunctata, indicating the nutritional value of the factitious food

    Financial Vulnerability and Stabilization Policy in Commodity Exporting Emerging Economies

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    This paper develops a new Keynesian DSGE model compatible with the structural characteristics of commodity exporting developing economies (financial vulnerability, relatively high pass-through rates, procyclical fiscal policy, and high terms of trade volatility) to compare the performance of alternative policy regimes, namely flexible domestic inflation targeting, flexible consumer price index inflation targeting, and the real exchange rate targeting. Evaluation of the above alternative policy regimes and relative stability of key macroeconomic variables are conducted through an optimal Ramsey policy method. The policy evaluation results based both on stabilization and welfare measures obtained for the case of Iran imply that for the developing commodity (oil) exporting economies stabilization with a broader inflation targeting framework in which the real exchange rate is also targeted is the superior policy regime. Optimality of the alternative policy regimes and their rank are sensitive to the degree of financial vulnerability. Financial vulnerability in this model explains why departure from floating exchange rate in an inflation targeting framework is the appropriate policy and not merely a “fear”. As the degree of financial development increases sufficiently, the standard flexible inflation targeting becomes the superior policy regime. A policy rule to weaken procyclicality of fiscal policy further enhances the welfare performance of this regime

    Financial Vulnerability and Stabilization Policy in Commodity Exporting Emerging Economies

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    This paper develops a new Keynesian DSGE model compatible with the structural characteristics of commodity exporting developing economies (financial vulnerability, relatively high pass-through rates, procyclical fiscal policy, and high terms of trade volatility) to compare the performance of alternative policy regimes, namely flexible domestic inflation targeting, flexible consumer price index inflation targeting, and the real exchange rate targeting. Evaluation of the above alternative policy regimes and relative stability of key macroeconomic variables are conducted through an optimal Ramsey policy method. The policy evaluation results based both on stabilization and welfare measures obtained for the case of Iran imply that for the developing commodity (oil) exporting economies stabilization with a broader inflation targeting framework in which the real exchange rate is also targeted is the superior policy regime. Optimality of the alternative policy regimes and their rank are sensitive to the degree of financial vulnerability. Financial vulnerability in this model explains why departure from floating exchange rate in an inflation targeting framework is the appropriate policy and not merely a “fear”. As the degree of financial development increases sufficiently, the standard flexible inflation targeting becomes the superior policy regime. A policy rule to weaken procyclicality of fiscal policy further enhances the welfare performance of this regime

    Oil Price Cycles, Fiscal Dominance and Counter-cyclical Monetary Policy in Iran

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    Impulse for business cycles in Iran are largely generated from oil price (terms of trade) shocks and propagated through fiscal policies. The classic mission of monetary policy is to conduct countercyclical policy, however, this is not a universal norm. Pro-cyclical fiscal and monetary policies during boom periods has been observed in a number of developing countries. Such policies tend to amplify the impact of positive oil price (terms of trade) shocks through aggregated demand expansion. The consequence has been strengthening of domestic inflationary pressures and appreciation of the real exchange rate. This paper attempts to examine if monetary policy in Iran is countercyclical and what is the impact of fiscal policy in this regard. It will be argued that the stance of fiscal policy and how government expenditures are financed can have a significant effect on how monetary policy is conducted. Our empirical observations regarding the experience of the Iranian economy indicates that, in a fiscally dominated structure, fiscal and monetary policies are generally expansionary, particularly during economic booms. This entails subsequent very large managed depreciation of the exchange rate, higher inflation rates, and an economic downturn. Under fiscal dominance monetary policy will be ineffective and both targets and instruments of monetary policy making will not be under the control of monetary authority. The policy package of a structural balanced fiscal rule combined with smoothing of quasi-fiscal operations is the appropriate policy measure that enhances the ability of central bank to conduct more effective countercyclical monetary policies

    The roles of RFamide-related peptides (RFRPs), mammalian gonadotropin-inhibitory hormone (GnIH) orthologues in female reproduction

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    Objective(s): To benefit from reproduction and deal with challenges in the environmental conditions, animals must adapt internal physiology to maximize the reproduction rate. Maladaptive variations in the neurochemical systems and reproductive system can lead to manifestation of several significant mammalian reprocesses, including mammalian ovarian lifespan. RFamide-related peptide (RFRP, Rfrp), mammalian orthologues of gonadotropin-inhibitory hormone (GnIH), which is a regulator to prevent the gonadotropin-releasing hormone (GnRH) neural activity, is known to be related to reproductive traits. This review aimed to summarize recent five-year observations to outline historic insights and novel perspectives into the functions of RFRPs in coding the mammalian reproductive physiology, especially highlight recent advances in the impact on RFRPs in regulating mammalian ovary lifespan.Materials and Methods: We reviewed the recent five-year important findings of RFRP system involved in mammalian ovary development. Data for this review were collected from Google Scholar and PubMed using the RFRP keyword combined with the keywords related to physiological or pathological reproductive functions.Results: Recent discoveries are focused on three major fronts in research on RFRP role in female reproduction including reproductive functions, energy balance, and stress regulation. The roles of RFRPs in various development phases of mammal reproduction including prepuberty, puberty, estrous cycle, pregnancy, milking, menopause, and/or ovarian diseases have been shown.Conclusion: Overall, these recent advances demonstrate that RFRPs serve as critical mediators in mammalian ovarian development

    Association Between Metabolic Syndrome and Stroke: A Population Based Cohort Study

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    Both metabolic syndrome (MetS) and stroke are associated with increased risk of mortality. Here, we aimed to assess the prevalence of MetS among adults using three definitions (Adult Treatment Panel III (ATP-III), International Diabetes Federation (IDF) and IDF ethnic specific cut-off for Iranian criteria) and its association with stroke. We performed a cross-sectional study of a total of 9991 adult participants of Rafsanjan Cohort Study (RCS), as part of the Prospective epidemiological research studies in Iran (PERSIAN cohort study). The MetS prevalence was evaluated in participants according to the different criteria. Multivariate logistic regression analyses were conducted to assess the association between three definitions of MetS with stroke. We found that MetS was significantly associated with higher odds of stroke according to NCEP-ATP III (odds ratio (OR): 1.89, 95% confidence interval (CI) 1.30-2.74), international IDF (OR:1.66, 95% CI: 1.15-2.40) and Iranian IDF (OR:1.48, 95% CI: 1.04-2.09) after adjusted for variables confounders. Furthermore, after adjustment, in receiver operating characteristic (ROC) curve, the AUROC was 0.79 (95% CI = 0.75-0.82), 0.78(95% CI = 0.74-0.82) and 0.78(95% CI = 0.74-0.81) for presence of MetS according to NCEP-ATP III, international IDF and Iranian IDF, respectively. ROC analyses revealed that all of these three criteria for MetS are moderately accurate for the identification of increased stroke risk.In conclusion, our results showed that MetS was associated with increased odds of stroke. Our findings implicate the importance of early identification, treatment, and ultimately prevention of the metabolic syndrome

    Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017

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    A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4% (62.3 (55.1–70.8) million) to 6.4% (58.3 (47.6–70.7) million), but is predicted to remain above the World Health Organization’s Global Nutrition Target of <5% in over half of LMICs by 2025. Prevalence of overweight increased from 5.2% (30 (22.8–38.5) million) in 2000 to 6.0% (55.5 (44.8–67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic

    Adolescent transport and unintentional injuries: a systematic analysis using the Global Burden of Disease Study 2019

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    Background: Globally, transport and unintentional injuries persist as leading preventable causes of mortality and morbidity for adolescents. We sought to report comprehensive trends in injury-related mortality and morbidity for adolescents aged 10–24 years during the past three decades. Methods: Using the Global Burden of Disease, Injuries, and Risk Factors 2019 Study, we analysed mortality and disability-adjusted life-years (DALYs) attributed to transport and unintentional injuries for adolescents in 204 countries. Burden is reported in absolute numbers and age-standardised rates per 100 000 population by sex, age group (10–14, 15–19, and 20–24 years), and sociodemographic index (SDI) with 95% uncertainty intervals (UIs). We report percentage changes in deaths and DALYs between 1990 and 2019. Findings: In 2019, 369 061 deaths (of which 214 337 [58%] were transport related) and 31·1 million DALYs (of which 16·2 million [52%] were transport related) among adolescents aged 10–24 years were caused by transport and unintentional injuries combined. If compared with other causes, transport and unintentional injuries combined accounted for 25% of deaths and 14% of DALYs in 2019, and showed little improvement from 1990 when such injuries accounted for 26% of adolescent deaths and 17% of adolescent DALYs. Throughout adolescence, transport and unintentional injury fatality rates increased by age group. The unintentional injury burden was higher among males than females for all injury types, except for injuries related to fire, heat, and hot substances, or to adverse effects of medical treatment. From 1990 to 2019, global mortality rates declined by 34·4% (from 17·5 to 11·5 per 100 000) for transport injuries, and by 47·7% (from 15·9 to 8·3 per 100 000) for unintentional injuries. However, in low-SDI nations the absolute number of deaths increased (by 80·5% to 42 774 for transport injuries and by 39·4% to 31 961 for unintentional injuries). In the high-SDI quintile in 2010–19, the rate per 100 000 of transport injury DALYs was reduced by 16·7%, from 838 in 2010 to 699 in 2019. This was a substantially slower pace of reduction compared with the 48·5% reduction between 1990 and 2010, from 1626 per 100 000 in 1990 to 838 per 100 000 in 2010. Between 2010 and 2019, the rate of unintentional injury DALYs per 100 000 also remained largely unchanged in high-SDI countries (555 in 2010 vs 554 in 2019; 0·2% reduction). The number and rate of adolescent deaths and DALYs owing to environmental heat and cold exposure increased for the high-SDI quintile during 2010–19. Interpretation: As other causes of mortality are addressed, inadequate progress in reducing transport and unintentional injury mortality as a proportion of adolescent deaths becomes apparent. The relative shift in the burden of injury from high-SDI countries to low and low–middle-SDI countries necessitates focused action, including global donor, government, and industry investment in injury prevention. The persisting burden of DALYs related to transport and unintentional injuries indicates a need to prioritise innovative measures for the primary prevention of adolescent injury. Funding: Bill &amp; Melinda Gates Foundation
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