A survey of chemical elicitors and their effectiveness as promoters of plant defense against herbivory by Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae)

Insect herbivores can induce a range of plant defenses. Signal pathways can be activated that result in the production of secondary metabolites. Many of these compounds can reduce insect fitness, deter feeding, and attract beneficial insects. Additionally, organic and inorganic chemicals applied as a foliar spray or soil drench can activate these plant responses. Azelaic acid, benzothiadiazole (BTH), gibberellic acid (GA3), harpin, and jasmonic acid (JA) are thought to mediate plant response to pathogens and herbivores. The effects of these elicitors on the induction of plant defenses were determined by measuring the weight gain of fall armyworm (FAW), Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) on four important crops, cotton, corn, rice, and soybean, treated with elicitors, under greenhouse conditions. JA consistently induced cotton and soybean resistance to FAW. In contrast, azelaic acid, BTH, and harpin treated plant material increased weight gain of FAW, suggesting negative crosstalk between the salicylic acid and JA signaling pathways. No induction of defense was observed in corn and rice, and the lack of spray mixture adhesion to those crops inspired a second experiment in which four adjuvants were co-applied with a reduced rate of JA (0.25X) to corn and cotton. Corn was more responsive to the use of an adjuvant than was cotton. The differential effectiveness of two elicitors, JA and BTH, was investigated on FAW and another noctuid species, the soybean looper (SBL), Chrysodeixis includens (Walker). Weight gain of FAW offered JA-treated soybean was significantly lower than FAW offered non-treated soybean in all trials, whereas growth of SBL was significantly reduced in only one trial. BTH was not effective in reducing weight gain of SBL offered plant material treated at the 1X or 5X rates. BTH reduced weight gain of FAW only in trial 2, at the 5X rate. The findings presented herein provide further support that foliar applications of JA increase resistance to arthropod herbivores, and that this relationship between plant and herbivore could be transitioned to the field, with the ultimate goal of using elicitor-induced defense as a part of an integrated pest management program

Management of Sugarcane Aphid, Melanaphis sacchari (Hemiptera: Aphididae), in Susceptible and Resistant Grain Sorghum

Sugarcane aphid, Melanaphis sacchari (Hemiptera: Aphididiae), was first detected on grain sorghum, Sorghum bicolor, in the United States in 2013. The spread of sugarcane aphid across the sorghum-producing regions of North America necessitated increased understanding of damage by and methods for mitigation of the pest. In response, field experiments were conducted to develop economic thresholds for sugarcane aphid. Grain sorghum yield—aphid population density relationships were used to calculate economic injury levels and economic thresholds. Economic injury levels ranged from 37 and 102 aphids per leaf, and an economic threshold of 40 aphid per leaf was deemed prudent to use across the observed range of hybrid, environmental, and market conditions. Subsequently, a tally-based threshold was considered by evaluating the infestation proportion – aphid density relationship for tallies of >25, >50, and >100 aphids per leaf. Regressions showed a second order polynomial relationship yielded decisions most similar to use of the density-based threshold. The tally threshold required half the time to sample 100 leaves compared to the density-based approach. With increased introduction of grain sorghum hybrids partially resistant to sugarcane aphid, field evaluations of the grain yield–aphid population relationship were conducted across growing seasons, locations, and hybrids believed to vary in aphid susceptibility. These data verified previously established economic injury levels ranging from 27 to 72 aphids per leaf for the most susceptible hybrids. For 47 of the 49 partially resistant hybrid location-years, yield loss attributable to aphid density was not detected under aphid densities up to 352 aphids per leaf. Population doubling time for sugarcane aphid on partially resistant grain sorghum hybrids was approximately two times that of susceptible hybrids. Finally, spray tips were evaluated for canopy penetration and coverage using grower spray equipment and two spray volumes. There were no differences in coverage among spray tips or between spray volumes. When guided by economic thresholds for susceptible hybrids, several configurations of spray equipment and volumes are effective. Overall, sugarcane aphid can be managed with use of partially aphid-resistant hybrids and aphid-susceptible hybrids with addition of insecticides applied with common grower equipment and guided by use of economic thresholds

Nestorian ‘merchant missionaries’ – A model for Christian Chinese migrants

Both the Old and New Testament lay a foundation for the role of migrants in God’s mission, missio Dei. With the unprecedented rise of the Global South to prominence in the world mission enterprise, China is poised to play a major role in fulfilling the Great Commission Mandate. Already Christian Chinese migrants are in many countries, possibly in over 140 countries of the world, including many of the unreached, unengaged people groups. The Nestorians, also called ‘merchant missionaries’, were amongst the first to take the gospel to China. They can serve as a methodological mission model, using some basic biblical principles, to help Christian Chinese migrants today, especially the Wenzhou businessmen, to fulfil their apostolic role in world mission. Sowel die Ou as die Nuwe Testament lê ’n fondament vir die rol van nomades (rondtrekkendes) in God se missie (missio Dei). Met die Globale Suide se ongeëwenaarde toename in prominensie ten opsigte van die onderneming van wêreldsending, is China gereed om ’n hoofrol in die verwesenliking van die Groot Sendingopdrag te vertolk. Chinese Christen nomades is alreeds in 140 lande van die wêreld besig, waarvan baie tussen die onbereikte, onbesette mensegroepe is. Die Nestoriane, of ‘kooplui-sendelinge’, was van die eerste sendelinge wat die evangelie na China geneem het. Hulle voorbeeld kan as ’n sendingmodel dien om Chinese Christen nomades te help, veral die Wenzhou-sakemanne, om hulle apostoliese rol in wêreldsending te vervul

Behind the Tusk: Examining the Phenomenon of African Elephant Poaching through Routine Activities Theory and Focal Concerns Theory

The focus of this study is to provide a comparative analysis of routine activities theory and focal concerns theory as it applies to the phenomena of African elephant poaching. As described by Ellison (2010), routine activities theory requires a capable target, a motivated offender, and a lack of suitable guardian. However, focal concerns theory identifies individuals commit crimes because of the pleasure created from trouble, excitement, smartness, toughness, fate, and autonomy (Forsyth & Marchese, 1993). As the world continues to globalize in market and trade, there is a concern to protect endangered species that are sought after for desired physical characteristics. Using peer-reviewed empirical research, this study will be a comparative analysis examining how well routine activities theory and focal concerns theory are able to explain the phenomenon of elephant poaching in Africa. Through the study of poaching, this will reveal more information about the crime of poaching in Africa and the implications it not only has on protected wildlife, but also on the societal norms of the region. This study expects to find that routine activities theory provides a more thorough and complete explanation for poaching than focal concerns theory, though it is possible neither theory adequately explains the four later identified parameters of poaching

Spectral backtests of forecast distributions with application to risk management

We study a class of backtests for forecast distributions in which the test statistic depends on a spectral transformation that weights exceedance events by a function of the modeled probability level. The weighting scheme is specified by a kernel measure which makes explicit the user’s priorities for model performance. The class of spectral backtests includes tests of unconditional coverage and tests of conditional coverage. We show how the class embeds a wide variety of backtests in the existing literature, and further propose novel variants which are easily implemented, well-sized and have good power. In an empirical application, we backtest forecast distributions for the overnight P&L of ten bank trading portfolios. For some portfolios, test results depend materially on the choice of kernel

A broader elementary education,

Mode of access: Internet