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1.
J Econ Entomol ; 115(4): 1069-1075, 2022 08 10.
Artículo en Inglés | MEDLINE | ID: mdl-35766382

RESUMEN

Aboveground and belowground herbivory can alter host quality and trophic interactions. However, little research has explored the impacts of belowground herbivory on plant virus epidemiology. To understand this interaction in sweetpotato, Ipomoea batatas L. (Lam), we studied the impact of herbivory by sweetpotato weevil, Cylas formicarius elegantulus (Summers), to storage roots on vector herbivore, Myzus persicae (Sulzer), the green peach aphid, and Aphis gossypii Glover, the cotton aphid, feeding behavior (M. persicae and A. gossypii) and population dynamics (M. persicae only as A. gossypii does not colonize sweetpotato). In addition, a nonvector herbivore, Chrysodeixis includens (Walker), the soybean looper, weight gain was included for comparison. Infestations of sweetpotato weevil in storage roots reduced C. includens weight gain and M. persicae intrinsic rate of increase (rm), net reproductive rate (Ro), and finite rate of increase (λ) on aboveground portions of the plant. In probing behaviors related to nonpersistent virus spread (30 min trials), M. persicae probed less often, took longer to reach the first pd (potential drop), had shorter II-3 (intracellular subphase sap ingestion) durations, and had fewer archlets on plants infested with C. formicarius elegantulus. Total phloem duration did not differ between treatments, indicating that the lowered performance of M. persicae on infested plants was not due to discrepancies in probing duration. Results were less clear for A. gossypii. Thus, in sweetpotato, belowground herbivory can alter plant virus vector abundance and behavior. Understanding the mechanisms underlying these changes in behavior could improve plant virus vector integrated pest management.


Asunto(s)
Áfidos , Escarabajos , Ipomoea batatas , Virus de Plantas , Gorgojos , Animales , Herbivoria , Dinámica Poblacional , Aumento de Peso
2.
J Econ Entomol ; 114(3): 1159-1165, 2021 06 11.
Artículo en Inglés | MEDLINE | ID: mdl-33822082

RESUMEN

The rice water weevil, Lissorhoptrus oryzophilus Kuschel, is the most important economic pest of rice in the United States with the ability to substantially reduce rice yields. Stem borers, including the Mexican rice borer, Eoreuma loftini (Dyar), are emerging as more consistent pests in Louisiana and Texas, but the relationship between blanked panicles (whiteheads) caused by stem borer feeding and yield loss is not well understood. A series of field trials was conducted in Louisiana from 2019 to 2020 to determine the relative yield loss by manipulating infestations of both pests with selective insecticides. Results indicate losses from L. oryzophilus infestations are greater than those for E. loftini in early planted rice. In contrast, relative yield losses were approximately equal in later planted rice in 2019, in which E. loftini infestations were high. Additive impacts of the root-feeding L. oryzophilus and the stem-feeding E. loftini were not observed in our study. Linear regression revealed that each increase of one whitehead per square meter is associated with a 1.7% loss in yield. Results from ratoon rice suggest that protection from L. oryzophilus in the main crop also improves yield in the second crop. Collectively, results demonstrate the continued need for effective L. oryzophilus management programs to prevent economic losses. Conversely, findings suggest that benefits of E. loftini control may be minimal in many instances. Control of E. loftini is most likely to be economical under conditions where high populations are anticipated such as in late-planted fields or regions that previously had high infestations.


Asunto(s)
Escarabajos , Oryza , Gorgojos , Animales , Louisiana , México , Texas , Agua
3.
BJOG ; 127(2): 208-216, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31529767

RESUMEN

OBJECTIVE: The objective of this study was to use high-throughput sequencing to describe the vaginal eukaryotic DNA virome in patients undergoing in vitro fertilisation (IVF) to examine associations between the vaginal virome, antibiotic exposure and IVF outcomes. DESIGN: Prospective exploratory study. SETTING: Single academic fertility centre. POPULATION: Subfertile women age 18-43 years undergoing their first IVF cycle with a fresh embryo transfer. METHODS: The primary exposure was prophylactic azithromycin or no azithromycin before IVF. A mid-vaginal swab was obtained at the time of embryo transfer for virome analysis. MAIN OUTCOME MEASURES: The primary outcomes compared between exposure groups were characteristics of vaginal virome and clinical pregnancy rates. Secondary outcomes were virome associations with number of oocytes retrieved, number of blastocysts and implantation rate. RESULTS: Twenty-six women contributed a vaginal swab before embryo transfer. There were no significant differences in IVF outcomes between azithromycin groups. There was no association between viral diversity and clinical pregnancy overall. A higher diversity of herpesviruses and α-papillomaviruses was observed in samples from the azithromycin-treated group compared with the no azithromycin group (P = 0.04). In women that received azithromycin, viral diversity was higher in the group that did not achieve clinical pregnancy compared with those who did (P = 0.06). CONCLUSIONS: We demonstrate that the vaginal eukaryotic virome in women undergoing IVF is associated with antibiotic exposure. Additionally, we demonstrate an inverse trend between viral diversity and pregnancy, with a higher number of viruses detected associated with failure to achieve clinical pregnancy in the azithromycin group. TWEETABLE ABSTRACT: Higher viral diversity is associated with prophylactic antibiotic exposure in subfertile women undergoing IVF.


Asunto(s)
Eucariontes/fisiología , Fertilización In Vitro , Infertilidad/terapia , Microbiota , Vagina/virología , Adulto , Antibacterianos/uso terapéutico , ADN Viral/fisiología , Transferencia de Embrión , Femenino , Herpesviridae , Humanos , Microbiota/genética , Microbiota/inmunología , Papillomaviridae , Embarazo , Estudios Prospectivos , ARN Ribosómico 16S/genética , ARN Ribosómico 16S/inmunología , Análisis de Secuencia de ADN , Vagina/microbiología
4.
J Econ Entomol ; 110(2): 479-486, 2017 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-28334296

RESUMEN

Neonicotinoid seed treatments are widely used in agriculture. In rice, Oryza sativa L., in the southern United States, neonicotinoid seed treatments are used to manage early-season populations of the rice water weevil, Lissorhoptrus oryzophilus Kuschel. In addition to their effects on pests, neonicotinoid seed treatments may benefit crop plants directly by increasing plant growth or altering plant responses to stresses. As part of an effort to assess the overall benefits of thiamethoxam seed treatment in rice, rice emergence, growth, and yield were evaluated. In a growth chamber, rice emergence from the soil was 1-2 d more rapid from treated than untreated seeds. These laboratory results were supported by field experiments that revealed higher stand counts from thiamethoxam-treated plots than from untreated plots. Yields from thiamethoxam treatments were no higher than those from untreated plots under conditions in which weevil larvae were absent, a result inconsistent with the hypothesis that thiamethoxam imparts direct yield benefits. In a series of field experiments conducted to compare the relationship between weevil larval densities and rice yields in plots treated with several rates of thiamethoxam or chlorantraniliprole (another widely used seed treatment insecticide), the relationship between weevil density and yield did not differ markedly among both seed treatments. Overall yields from both seed treatments did not differ significantly, despite more effective control in chlorantraniliprole-treated plots. These results provide strong support for effect of thiamethoxam on early-season growth of rice, but only weak support for its direct effect on rice yields.


Asunto(s)
Control de Insectos , Insecticidas , Nitrocompuestos , Oryza/crecimiento & desarrollo , Oxazinas , Tiazoles , Gorgojos , ortoaminobenzoatos , Animales , Control de Insectos/métodos , Larva/crecimiento & desarrollo , Neonicotinoides , Densidad de Población , Semillas/crecimiento & desarrollo , Tiametoxam , Gorgojos/crecimiento & desarrollo
5.
J Perinatol ; 36(5): 342-6, 2016 05.
Artículo en Inglés | MEDLINE | ID: mdl-26796129

RESUMEN

OBJECTIVE: To determine whether a threshold of a 1-h glucose challenge test (GCT) eliminates the need for a 3-h glucose tolerance test (GTT). STUDY DESIGN: A retrospective cohort of patients undergoing GTT after GCT was ⩾140 mg dl(-1). Gestational diabetes mellitus (GDM) was diagnosed using National Diabetes Data Group (NDDG) and Carpenter-Coustan (CC) criteria. Sensitivity, specificity and predictive values were calculated for 1-h GCT values of 160 to 220 mg dl(-1). RESULT: Of 6218 patients, 988 (15.9%) had an elevated GCT and 753 (12.1%) underwent a GTT. In all, 165 (2.7%) were diagnosed with GDM using NDDG criteria, and 250 (4.0%) by CC criteria. The positive predictive value of a 1-h of GCT ⩾200 mg dl(-1) for GDM was 68.6% by NDDG and 80.0% for GDM by CC criteria. CONCLUSION: Although the predictive value of an elevated 1-h ⩽200 mg dl(-1) for GDM was high, 1 in 3 to 1 in 5 women would be overdiagnosed with GDM if the 3-h GTT was omitted.


Asunto(s)
Diabetes Gestacional/diagnóstico , Prueba de Tolerancia a la Glucosa/métodos , Adulto , Glucemia/análisis , Estudios de Cohortes , Femenino , Humanos , Valor Predictivo de las Pruebas , Embarazo , Reproducibilidad de los Resultados , Estudios Retrospectivos , Sensibilidad y Especificidad , Estados Unidos
6.
J Integr Pest Manag ; 7(1): 7, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-28670487

RESUMEN

The Mexican rice borer, Eoreuma loftini (Dyar), is an invasive pest of rice, Oryza sativa L., in the Gulf Coast region of the United States. This pest also damages sugarcane, Saccharum spp. hybrids; corn, Zea mays L.; and sorghum, Sorghum bicolor (L.) Moench, and feeds on weedy noncrop grasses. Multiple aspects of integrated pest management including use of pheromone traps, manipulation of planting dates, harvest cutting height, stubble management, noncrop host management, soil fertility management, host plant resistance, use of insecticides, and biological control have been studied for Mexican rice borer management. However, the current management strategy in rice primarily relies on the use of chlorantraniliprole insecticide seed treatments. This profile addresses Mexican rice borer biology and management in rice in the United States.


El barrenador mexicano del arroz [Eoreuma loftini (Dyar)] es una plaga invasora de arroz (Oryza sativa L.) en la región de la Costa del Golfo de Estados Unidos. Esta plaga también afecta híbridos de caña de azúcar (Saccharum spp.), maíz (Zea mays L.), sorgo [Sorghum bicolor (L.) Moench), y se alimenta de malezas gramíneas. Múltiples aspectos del manejo integrado de plagas incluyendo el uso de trampas con feromonas, la manipulación de las fechas de siembra, la altura del corte durante la cosecha, el manejo de rastrojos, el manejo de hospederos alternos, el manejo de la fertilidad del suelo, la resistencia de la plantas, el uso de insecticidas y el control biológico han sido estudiados para el manejo del barrenador mexicano del arroz. Sin embargo, la estrategia de actual de manejo en arroz se basa principalmente en el tratamiento químico de la semilla con el uso del insecticida clorantraniliprol. Esta revisión se enfoca en la biología y manejo del barrenador mexicano del arroz en arroz en los Estados Unidos.

7.
Environ Entomol ; 44(3): 757-66, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-26313982

RESUMEN

The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is an invasive pest of sugarcane, Saccharum spp., rice, Oryza sativa L., and other graminaceous crops in the Gulf Coast region of the United States. Traps baited with E. loftini female sex pheromones were used to document establishment and distribution of E. loftini near sugarcane, rice, and noncrop hosts in seven southwest Louisiana parishes from 2009 to 2013. Additional field surveys documented larval infestations in commercial sugarcane and rice. After its initial detection in 2008, no E. loftini were detected in Louisiana in 2009 and only two adults were captured in 2010. Trapping documented range expansion into Cameron, Beauregard, and Jefferson Davis parishes in 2011 and Allen, Acadia, and Vermilion parishes in 2013. During the course of this study, E. loftini expanded its range eastward into Louisiana 120 km from the Texas border (≈22 km/yr). Surveys of larval infestations provided the first record of E. loftini attacking rice and sugarcane in Louisiana. Infestations of E. loftini in rice planted without insecticidal seed treatments in Calcasieu Parish reached damaging levels.


Asunto(s)
Distribución Animal , Mariposas Nocturnas/fisiología , Oryza , Saccharum , Animales , Control de Insectos , Especies Introducidas , Louisiana , Masculino , Mariposas Nocturnas/efectos de los fármacos , Oryza/crecimiento & desarrollo , Feromonas/farmacología , Saccharum/crecimiento & desarrollo , Atractivos Sexuales/farmacología
8.
BJOG ; 122(4): 545-51, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25515321

RESUMEN

OBJECTIVE: To investigate the risk for preterm birth associated with vaginal infections in pregnancies after a loop electrosurgical excision procedure (LEEP), compared with women with no prior LEEP. DESIGN: Multicentre retrospective cohort study. SETTING: USA. POPULATION: Women with LEEP between 1996 and 2006 were compared with two unexposed groups who had cervical biopsy or Pap test, without any other cervical procedure, in the same calendar year. METHODS: The first pregnancy progressing beyond 20 weeks of gestation in women with prior LEEP was compared with pregnancy in women without LEEP. Stratified analysis according to the presence or the absence of vaginal infection during pregnancy was used to investigate whether the risk for preterm birth differed according to the presence or the absence of infection. The interaction between LEEP and vaginal infection was investigated using multivariable logistic regression with interaction terms, as well as the Mantel-Haenszel test for homogeneity. MAIN OUTCOME MEASURES: Spontaneous preterm birth (<37 and <34 weeks of gestation). RESULTS: Of 1727 patients who met the inclusion criteria, 34.4% (n = 598) underwent LEEP prior to an index pregnancy. There was no increased risk for vaginal infections among women with LEEP compared with women without LEEP. Chlamydia infection and LEEP demonstrated significant interaction, suggesting that the presence of chlamydia infection in women with a history of LEEP augments the risk for preterm birth, compared with women with no history of LEEP. CONCLUSIONS: Vaginal infections during pregnancy in women with a history of LEEP may be associated with an increased risk for preterm birth, compared with women with no history of LEEP.


Asunto(s)
Electrocirugia/efectos adversos , Complicaciones Infecciosas del Embarazo/etiología , Complicaciones Neoplásicas del Embarazo/cirugía , Nacimiento Prematuro/etiología , Displasia del Cuello del Útero/cirugía , Neoplasias del Cuello Uterino/cirugía , Adulto , Femenino , Humanos , Recién Nacido , Prueba de Papanicolaou , Embarazo , Complicaciones Infecciosas del Embarazo/epidemiología , Complicaciones Infecciosas del Embarazo/microbiología , Complicaciones Neoplásicas del Embarazo/epidemiología , Resultado del Embarazo , Estudios Retrospectivos , Factores de Riesgo , Estados Unidos/epidemiología , Displasia del Cuello del Útero/epidemiología , Neoplasias del Cuello Uterino/epidemiología , Frotis Vaginal
9.
Bull Entomol Res ; 103(6): 656-64, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23830057

RESUMEN

The sugarcane borer, Diatraea saccharalis (F.), is a pest of graminaceous crops in the southern USA, including sugarcane, maize, and rice. This study was conducted to investigate the effect of silicon (Si) soil amendments on performance of sugarcane borer, D. saccharalis, on two rice cultivars, Cocodrie and XL723. There was a significant increase in the Si content of rice plants supplemented with calcium silicate as compared to non-treated plants. Soil Si amendment led to lower relative growth rates (RGRs) and reduced boring success of sugarcane borer larvae. Effects of soil Si amendments on borer success and RGR appeared to be more pronounced in 'Cocodrie', the cultivar relatively susceptible to borers, than in the moderately resistant cultivar, XL723. Soil Si amendment may contribute to the management of D. saccharalis through reduced feeding injury and increased exposure to adverse environmental conditions and natural enemies arising from reduced boring success.


Asunto(s)
Fertilizantes/toxicidad , Mariposas Nocturnas/efectos de los fármacos , Oryza , Silicio/toxicidad , Animales , Femenino , Herbivoria/efectos de los fármacos , Larva/efectos de los fármacos , Larva/crecimiento & desarrollo , Masculino , Mariposas Nocturnas/crecimiento & desarrollo , Oryza/metabolismo , Silicio/metabolismo
10.
J Econ Entomol ; 106(1): 181-8, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-23448030

RESUMEN

Effects of treatment of rice seeds with an anthranilic diamide, chlorantraniliprole, and a neonicotinoid, thiamethoxam, on egg laying and first instar survival in rice water weevil, Lissorhoptrus oryzophilus Kuschel, were examined under greenhouse conditions. Exposure of adult weevils to rice (6-7 leaf stage) grown from seeds treated with chlorantraniliprole and thiamethoxam resulted in reduction in numbers of eggs and first instars. The low egg numbers by adults exposed to chlorantraniliprole-treated plants was confirmed as a sublethal effect on adults: adult survival was not impacted after 4 d of feeding on foliage from chlorantraniliprole-treated plants but the number of eggs laid by these weevils was reduced when released on untreated plants. Furthermore, a comparison of first instar emergence from chlorantraniliprole-treated plants and from untreated plants infested with weevils previously exposed to this chemical suggested that chlorantraniliprole was also reducing egg or first instar survival. In contrast, adults that fed on foliage from thiamethoxam-treated plants showed increased mortality. Possible sublethal effects of thiamethoxam on the number of eggs laid by adults were investigated by infesting untreated plants with weevils that survived exposure to thiamethoxam via foliar feeding (7 microg active ingredient/seed). Prior exposure to thiamethoxam through adult feeding reduced egg numbers. However, potential larvicidal or ovicidal effects of thiamethoxam seed treatments could not be detected in this study because of low first instar emergence from both thiamethoxam-treated plants and from untreated plants infested with weevils previously exposed to this chemical. These experiments revealed that the two seed treatments accomplish weevil control in different ways.


Asunto(s)
Insecticidas/toxicidad , Nitrocompuestos/toxicidad , Oviparidad/efectos de los fármacos , Oxazinas/toxicidad , Tiazoles/toxicidad , Gorgojos/efectos de los fármacos , ortoaminobenzoatos/toxicidad , Animales , Conducta Alimentaria/efectos de los fármacos , Femenino , Insecticidas/administración & dosificación , Larva , Masculino , Neonicotinoides , Nitrocompuestos/administración & dosificación , Oryza , Oxazinas/administración & dosificación , Tiametoxam , Tiazoles/administración & dosificación , ortoaminobenzoatos/administración & dosificación
11.
Placenta ; 34(1): 14-9, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23199792

RESUMEN

INTRODUCTION: Markers of placental dysfunction are used for risk prediction of adverse obstetric outcomes including preeclampsia and growth restriction. Although medically indicated preterm birth is often distinguished from spontaneous preterm birth, we hypothesize that similar placental dysfunction may underlay all preterm birth. We aimed to investigate whether first trimester placental protein 13 (PP-13), pregnancy associated plasma protein A (PAPP-A) and uterine artery pulsatility index, with maternal characteristics could be used to predict all preterm birth. METHODS: Prospective cohort study of singleton gestations between 11 and 14 weeks who underwent serum measurement of PP-13, PAPP-A, and measurement of uterine artery Doppler pulsatility index. Primary outcomes were preterm birth (PTB) at less than 37 and 33 weeks. Analysis performed both including and excluding preeclampsia to assess the utility of the predictors for all types of preterm birth. Predictive models assembled using logistic regression with each predictor alone and in combination, along with maternal characteristics. Predictive utility of models was assessed using receiver operating curve (ROC) analysis and sensitivities for fixed false positive values. RESULTS: Of 471 women, PTB occurred in 12.5% and early PTB (<33 weeks) occurred in 4.7%. PP-13 was decreased in PTB <37 weeks. PAPP-A was decreased in a dose-response pattern for PTB at <37 weeks and <33 weeks. Uterine artery pulsatility index was increased in early PTB. All patterns of predictors remained the same whether patients with preeclampsia were excluded or included suggesting predictive utility for all causes of PTB. Predictive models all demonstrated good predictive ability with ROC ≥ 0.90. CONCLUSIONS: PP-13, PAPP-A, and uterine artery Doppler pulsatility index obtained in the first trimester are good predictors of all types of preterm birth, both indicated and spontaneous. Models including first trimester markers combined with maternal characteristics demonstrated good predictive ability and could be investigated for application of targeted prophylactic strategies.


Asunto(s)
Biomarcadores/análisis , Análisis Químico de la Sangre , Primer Trimestre del Embarazo/sangre , Nacimiento Prematuro/sangre , Nacimiento Prematuro/diagnóstico por imagen , Ultrasonografía Prenatal , Adulto , Biomarcadores/sangre , Estudios de Cohortes , Femenino , Humanos , Recién Nacido , Embarazo , Pronóstico , Factores de Riesgo , Adulto Joven
12.
J Econ Entomol ; 102(5): 1837-45, 2009 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-19886448

RESUMEN

The rice water weevil, Lissorhoptrus oryzophilus Kuschel, is the most widely distributed and destructive early season insect pest of rice, Oryza sativa L., in the United States. Economic losses result primarily from feeding by the larval stage of this insect on the roots of flooded rice plants. Prior studies suggest that infestations of rice water weevil larvae are more severe at low plant densities. Moreover, because feeding by the rice water weevil reduces rice plant tillering, a process particularly important to yield at low seeding rates, infestations by weevil larvae may have a greater impact on rice yields when rice is seeded at low rates. In total, six experiments were conducted over a 3-yr period in Louisiana and Missouri to investigate the impacts of rice seeding rate on levels of infestations by, and yield losses from, the rice water weevil. An inverse relationship between seeding rate and densities of rice water weevil larvae and pupae on a per area basis was found in two of the six experiments. Furthermore, in two of the three experiments conducted with 'Bengal' (a susceptible cultivar) in Louisiana, percentages of yield loss were significantly higher at lower seeding rates than at higher seeding rates. Overall, these results indicate that rice sown at low rates is more vulnerable to infestation by rice water weevils and more susceptible to yield losses from weevil injury. The significance of these findings in light of recent trends toward the use of lower seeding rates in drill-seeded rice is discussed.


Asunto(s)
Productos Agrícolas/economía , Productos Agrícolas/parasitología , Oryza/fisiología , Oryza/parasitología , Semillas/fisiología , Gorgojos/fisiología , Animales , Insecticidas/farmacología , Larva , Pupa , Estaciones del Año , Estados Unidos , Gorgojos/efectos de los fármacos , Gorgojos/crecimiento & desarrollo
13.
Environ Entomol ; 38(4): 1174-81, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19689897

RESUMEN

Rice, Oryza sativa, is the most important staple food for a significant portion of the world's population. Despite the importance of rice, however, induced resistance to insects has not been thoroughly studied in rice; in fact, to our knowledge, direct induced resistance after injury by chewing insects has not been shown in rice. We conducted a series of experiments designed to characterize direct induced resistance in rice after feeding by larvae of the fall armyworm (Spodoptera frugiperda J. E. Smith) and application of jasmonic acid. Weight gains and relative growth rates of fall armyworm larvae were lower when fed leaves from plants previously damaged by armyworms than when fed leaves from undamaged plants. This response was stronger at a systemic spatial scale; that is, the induced resistance was stronger in newly emerged leaves not present at the time plants were damaged than in damaged leaves themselves. Armyworm growth rates were also reduced on foliage from plants treated with jasmonic acid, a hormone known to mediate plant responses to wounding. The response to injury by armyworm larvae and to exogenous jasmonic acid was stronger in transgenic rice plants in which levels of salicylic acid (a signaling molecule that inhibits jasmonic acid) were suppressed. These results show the existence of a direct induced resistance response in rice and suggest that this response to injury by a chewing insect may be mediated by jasmonic acid.


Asunto(s)
Ciclopentanos/metabolismo , Interacciones Huésped-Parásitos , Oryza/inmunología , Oxilipinas/metabolismo , Ácido Salicílico/metabolismo , Spodoptera/fisiología , Animales , Larva/fisiología , Oryza/genética , Oryza/metabolismo , Plantas Modificadas Genéticamente/inmunología , Plantas Modificadas Genéticamente/metabolismo
14.
J Econ Entomol ; 99(6): 2030-7, 2006 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17195670

RESUMEN

Nitrogen fertilizer was applied to rice, Oryza sativa L., before permanent flood to determine the interaction between rice and the rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), through a series of experiments conducted over a 3-yr period in Texas and Louisiana. Both absolute and relative percentage of yield loss because of L. oryzophilus feeding was not affected by fertilizer rates in the Texas experiment. Absolute yield loss increased with nitrogen rates in 2001 and 2002 in the Louisiana experiment; however, percentage of yield loss was not affected. This finding suggests that nitrogen rate does not affect tolerance of rice to L. oryzophilus injury. In the Texas experiment, differences were detected for ratoon crop yield among nitrogen rates and insecticide that were applied at preflood on the main crop, indicating a carryover of fertilizer and insecticide effects from the main to the ratoon crop. L. oryzophilus populations tended to increase with nitrogen fertilizer in the Louisiana experiment. Our results show that farmers should not increase preflood nitrogen fertilizer to increase tolerance of rice to L. oryzophilus injury.


Asunto(s)
Escarabajos/parasitología , Fertilizantes , Nitrógeno/metabolismo , Oryza/crecimiento & desarrollo , Agua , Animales , Productos Agrícolas , Oryza/metabolismo
15.
J Econ Entomol ; 97(6): 1935-42, 2004 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-15666748

RESUMEN

The impact of a herbicide-tolerant rice, Oryza sativa L., variety was assessed for its resistance to rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), and its place in current integrated pest management (IPM) programs. Greenhouse experiments were conducted to evaluate the resistance of a glufosinate-tolerant rice variety and its glufosinate-susceptible parent line Bengal to the rice water weevil in the presence and absence of glufosinate applications. The LC50 dose-response and behavioral effects of glufosinate on adult rice water weevils also were studied. Field studies investigated the impacts of glufosinate-tolerant rice on rice water weevil management in the presence and absence of glufosinate under early and delayed flood conditions. Greenhouse studies demonstrated that in the absence of glufosinate, oviposition was 30% higher on the glufosinate-tolerant rice line than on Bengal rice or on glufosinate-tolerant line treated with recommended rates of commercially formulated glufosinate. Applications of glufosinate to glufosinate-tolerant rice resulted in a 20% reduction in rice water weevil larval densities compared with nontreated glufosinate-tolerant rice. The LC50 of glufosinate against adult rice water weevil was nearly 2 times the concentration recommended for application to glufosinate-tolerant rice. There was no difference in the amount of leaf area consumed by adult rice water weevils on glufosinate-treated and nontreated foliage. The absence of direct toxicity of glufosinate to rice water weevil at recommended glufosinate use rates and lack of behavioral effects suggest that the reduction in rice water weevil densities observed after glufosinate applications resulted from herbicide-induced plant resistance. Field experiments showed that neither rice variety nor herbicide use affected larval densities; however, delaying flood and applying insecticide effectively reduced numbers of rice water weevil larvae.


Asunto(s)
Aminobutiratos/farmacología , Herbicidas/farmacología , Control de Insectos , Oryza/efectos de los fármacos , Gorgojos , Tolerancia a Medicamentos , Oryza/genética , Enfermedades de las Plantas , Plantas Modificadas Genéticamente/efectos de los fármacos
16.
Bull Entomol Res ; 92(2): 177-84, 2002 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-12020377

RESUMEN

For most plant species, tolerance to many types of herbivory increases as plants age, but the applicability of this pattern to root herbivory has not been tested. Injury to roots of rice plants by larvae of the rice water weevil, Lissorhoptrus oryzophilus Kuschel, causes severe reductions in yields in the United States. It is generally thought that young rice plants, because their root systems are smaller, are less tolerant than older plants of root feeding by L. oryzophilus. Field experiments were conducted to test this hypothesis. Plots of rice (4.7 to 6.5 m2) were established and subjected to natural infestations of L. oryzophilus larvae. A soil insecticide was applied to plots at different times during the tillering phase of rice in order to manipulate the timing of weevil infestation. The impact of these treatments (timings of insecticide applications) was assessed by comparing relationships between yield loss and larval pressure for each treatment using analysis of covariance. Yield losses ranged from 13% to over 40% in plots not treated with insecticide. Patterns of yield losses from plots treated with insecticide at different times were best explained by the hypothesis that yield loss is determined both by the age of plants infested and by the size of larvae infesting plants. Young plants appear to be less tolerant than older plants, and feeding by large larvae appears to be more deleterious than feeding by smaller larvae. Management practices that delay infestation of rice by L. oryzophilus until plants are older may be an important component of management programmes for this pest.


Asunto(s)
Escarabajos , Oryza/fisiología , Control Biológico de Vectores , Animales , Productos Agrícolas , Oryza/crecimiento & desarrollo , Control Biológico de Vectores/métodos , Densidad de Población
17.
J Econ Entomol ; 94(4): 963-70, 2001 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-11561859

RESUMEN

The rice water weevil, Lissorhoptrus oryzophilus Kuschel, is the most destructive insect pest of rice in the United States and is a particularly severe pest in Louisiana. The current management program for this insect in Louisiana relies heavily on insecticides, most notably the seed treatment fipronil (Icon). Diversification of the management program by incorporation of alternative strategies is needed to improve the effectiveness and long-term stability of the program. In the three experiments reported here, three components of a diversified management program for the rice water weevil in Louisiana--host plant resistance, treatment of seeds with Icon, aid the cultural practice of delayed flooding--were investigated. Comparison of the densities of weevil larvae on the roots of several commercial cultivars indicated that the long-grain cultivar 'Jefferson' was more resistant to infestation by the rice water weevil than the other cultivars. The medium-grain cultivars 'Bengal', 'Earl' and 'Mars' and the long-grain variety 'Cocodrie' were the most susceptible to infestation. Comparison of yield data from untreated plots and plots treated with Icon indicated that the long-grain cultivars Cocodrie, Lemont, and Jefferson were more tolerant of weevil injury than the other cultivars. A 2-wk delay in flooding was associated with yield benefits in plots not treated with Icon. Treatment of seeds with Icon controlled weevils in all three screening experiments. The implications of these results for the development of an integrated management program for the rice water weevil are discussed.


Asunto(s)
Escarabajos , Oryza/fisiología , Control Biológico de Vectores/métodos , Animales
19.
J Chem Ecol ; 22(10): 1767-81, 1996 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-24227107

RESUMEN

Wounding increases the levels and activities of several defense-related proteins in the foliage of the tomato plant,Lycopersicon esculentum Mill. Evidence indicates that two of these responses, the systemic increases in polyphenol oxidase and proteinase inhibitors, are regulated by an octadecanoid-based signalling pathway which includes the wound hormone, jasmonic acid. It is not known whether other responses to wounding are also regulated by this same signalling pathway. In this paper, we show that application of jasmonates (jasmonic acid or its volatile derivative, methyl jasmonate) in low concentrations to foliage of young tomato plants induced, in a dose-dependent manner, the same protein responses-polyphenol oxidase, proteinase inhibitors, lipoxygenase, and peroxidase-as doesHelicoverpa zea Boddie feeding. Application of jasmonic acid to a single leaflet of four-leaf tomato plants induced these four proteins in a spatial pattern nearly identical to that produced by localized feeding ofH. zea. Exogenous jasmonic acid also decreased suitability of foliage for the beet armyworm,Spodoptera exigua Hubner in the laboratory. Based on these results, we conducted an experiment to measure the effects of jasmonic acid spray under field conditions. We provide the first evidence that jasmonic acid spray on field plants induces production of chemical defenses above the levels found in unsprayed controls. Exogenous jasmonic acid sprayed on plants in agricultural plots increased levels of polyphenol oxidase and proteinase inhibitors. Because application of jasmonic acid induces these defensive compounds at low concentrations in a manner similar to natural wounding, it may prove to be a useful tool for stimulating plant resistance to insects in the field.

20.
Am Surg ; 60(12): 946-9, 1994 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-7992971

RESUMEN

A simple rapid technique for cannulating the right atrium during a resuscitative Emergency Department thoracotomy (EDT) for exsanguinating trauma is described. Following the thoracotomy and pericardiotomy, an ordinary Foley urinary bladder balloon catheter is inserted into the right atrial appendage for rapid, large volume normothermic blood and fluid infusion. A method for simplifying this maneuver, as well as the potential complications of over-resuscitation with myocardial distention and fluid overload, myocardial cooling, air embolism, and tricuspid valve occlusion are discussed. We recognize that this technique is radical and applicable to only a limited subset of severely injured patients, for example, victims of non-cardiac penetrating trauma who arrive at the hospital moribund or who arrest in the emergency center.


Asunto(s)
Cateterismo Cardíaco , Resucitación , Toracotomía , Traumatismos Abdominales/cirugía , Adulto , Servicio de Urgencia en Hospital , Atrios Cardíacos , Humanos , Infusiones Parenterales , Masculino , Heridas por Arma de Fuego/cirugía
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