Nutrient concentration and availability vary substantially among composts depending on the materials used and the production process. Composts produced from agricultural operations typically utilize animal wastes such as manures, whereas composts produced in urban areas mainly incorporate food and yard waste. Our objective was to assess how different composts affect nutrient availability and cycling, mostly carbon (C) and nitrogen (N). In a laboratory incubation, we compared three composts derived from cow manure (composted dairy manure solids, vermicompost made from those manure solids, and Black KowTM) and two composts derived from food waste (composted food waste from the UF-IFAS Compost Cooperative and EcoscrapsTM). We used two sandy soils from Gainesville, FL: one from an area under perennial grasses and a second heavily-tilled soil lower in organic matter. Incubations were conducted for eight weeks at 24 and 30 °C, i.e., the annual and July mean soil temperature for the area. The composted and vermicomposted cow manure solids had the greatest CO2 emissions relative to the unamended soils. Soil nitrate was highest with composted food waste, whereas all three cow manure-derived composts resulted in lower soil nitrate compared to the unamended soils. This suggests that N was immobilized with cow manure-derived composts, consistent with the high CO2 emissions measured with these amendments. We found similar results for both soils. Our results indicate a greater potential for food-waste compost as a nutrient source than compost derived primarily from cow manure solids, which could be more beneficial to building soil C.
Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), transmits Candidatus Liberibacter asiaticus (Las), the bacterial pathogen putatively responsible for citrus huanglongbing. Multiple studies have shown psyllids acquire Las more frequently, and are more likely to inoculate susceptible plants, when they acquire Las as nymphs. Understanding the transmission of Las to nymphs is critical to the Las lifecycle. The objective of this study was to determine the transmission Las by female D. citri to their offspring. Two transmission pathways were quantified: horizontal transmission (acquisition of Las via feeding at the oviposition site) and vertical transmission (transovarial). Eggs of individual, infected females were transferred to an uninfected seedling to assess vertical transmission. In a second experiment, horizontal transmission was evaluated by replacing eggs laid by infected females with uninfected nymphs. Nymphs exposed to Las via horizontal transmission of the oviposition site were more likely to acquire Las than from vertical transmission. Las deposited in flush by an infected adult female feeding during oviposition was sufficient for infecting nymphs. Combined results of both experiments suggest that vertical transmission allows Las to spread in low amounts even when infected plant hosts are not available and that inoculation of the oviposition site provides a source of Las to developing nymphs via the plant phloem. These data support the hypothesis that transmission through infected plant material via maternal inoculation is a primary pathway of Las transmission between vector and host.
Purpose This study assessed the impact of flipped classrooms on physician assistant (PA) students' performance and opinions. Methods Students completed quizzes and an opinion survey in Genetics, Human Pathophysiology (HPP), Clinical Medicine (CM) (n = 105) and Physical Exam (PE) (n = 98) courses. Results In Genetics and PE, the quiz scores were significantly higher for flipped classrooms (Genetics 95.00 ± 6.56; PE 83.09 ± 11.47) compared to the traditional lectures (Genetics 90.00 ± 10.53; PE 55.43 ± 16.66). In HPP, students performed better with traditional lectures (86.54 ± 8.82) compared to the flipped classrooms (75.12 ± 8.54). In CM, students' gain score was significantly higher for flipped classrooms (37.85 ± 16.73) than for traditional lectures (20.97 ± 15.55). The opinion surveys showed that the students surveyed preferred traditional lectures over flipped classrooms in Genetics (4.58 ± 0.46 vs. 2.29 ± 0.71) and HPP (4.14 ± 0.35 vs. 2.09 ± 0.53). Conclusion Flipped classrooms improved the quality of learning in courses that deliver a hands-on skill or use case-based scenarios. They may not be an ideal choice for courses that require explanation of intricate scientific concepts.
The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is the most detrimental insect pest of citrus crops due to its role as a vector of Candidatus Liberibacter asiaticus (Las), the bacterial causal agent of huanglongbing, also known as citrus greening disease. Trees infected with Las decline rapidly and fruit production decreases until eventual tree death. Few treatment options for infected trees are available for disease management. A technique called "thermotherapy" is under development to reduce bacterial titers in infected trees; however, the effect of these treatments on the transmission cycle of Las is not known. Field and laboratory assays were conducted to determine whether thermotherapy treatment reduced Las acquisition by D. citri. Trees in the field were treated with a mobile heat treatment system. Potted trees in the laboratory were treated in a steam chamber. We monitored acquisition rates in D. citri following thermal treatment of Las-positive Citrus sinensis (L.) (Rutaceae). Psyllid acquisition and Las titer in thermotherapy-treated trees were compared with untreated Las-positive and untreated Las-negative trees. Our results confirmed the efficacy of whole-tree thermotherapy on Las in potted citrus trees. In contrast, thermotherapy did not significantly reduce plant Las titers or acquisition of Las by D. citri under field conditions. These results suggest that further development of field application methods is needed to determine the utility of thermotherapy as a tool for huanglongbing management.
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