Advanced phenology of intraguild predators shifts herbivore host plant preference and performance

1. The abundance of insect herbivores is mediated by interactions with higher and lower trophic levels. This research asks (i) how phenological change across trophic levels affects host plant quality and selection for aphids, and (ii) what higher trophic level mechanisms drive aphid abundance. 2. Ligusticum porteri is a perennial host for the sap-feeding aphid Aphis asclepiadis and intraguild mirid predators (chiefly Lygus hesperus) in Colorado. We used long-term observational data to discover that aphids and mirids respond differently to phenological cues. These unique responses can impact aphid abundance through changes to host plant selection and quality. 3. We used behavioural choice assays to assess how advanced mirid phenology influences aphid host plant selection. More alates landed and reproduced on mirid-free control plants relative to host plants with prior mirid feeding. However, this preference did not correlate with aphid performance when we compared aphid relative growth rates between treatments. This suggests that advanced mirid phenology would impact aphid populations more through host plant choice, rather than reductions in host quality. The addition of mirids to experimental aphid colonies also demonstrated reduced aphid colony growth via predation. 4. We measured plant cues involved in host selection and found differences in volatile composition between plants with prior mirid feeding compared to control plants, providing the potential for aphids to detect enemy-free space using volatile cues.     

Control of the growth of Alicyclobacillus acidoterrestris in industrialized orange juice using rosemary essential oil and nisin

The use of rosemary essential oil (RO) and its combination with nisin (RO+N) in preventing the multiplication of Alicyclobacillus acidoterrestris in orange juice was evaluated. The minimum inhibitory and bactericidal concentrations (MIC and MBC) for RO were both 125 μg ml⁻¹ while RO+N displayed a synergistic effect. The use of RO and RO+N at concentrations of 1, 4 and 8× MIC in orange juice for 96 h was evaluated in terms of their sporicidal effectiveness. With regard to the action against A. acidoterrestris spores, RO at 8× MIC was sporostatic, whereas RO+N at 1× MIC was sporicidal. Morphological changes in the structure of the micro-organism after treatment were also observed by microscopy. Furthermore, flow cytometric analysis showed that most cells were damaged or killed after treatment. In general, the antioxidant activity after addition of RO+N decreased with time. The results demonstrate that using the combination of RO and nisin can prevent the A. acidoterrestris growth in orange juice.     

γ-Lactam-Based Antifungal Compounds against the Wheat Pathogen Zymoseptoria tritici

As new environmentally friendly and effective antifungal agents are deeply needed, efficient ecofriendly strategies were designed to access two series of compounds inspired from natural γ-lactams. Designed compounds were fully characterized and evaluated as antifungal candidates against Zymoseptoria tritici, the main pathogen on wheat crops. The targeted derivatives were prepared from natural resources using green solvents, simple procedures, and limited purification steps. These bio-inspired compounds revealed as good candidates for further development of efficient crop protection products. Indeed, the HIT compounds exhibited IC₅₀ around 1 μg/mL and were more active than the references tebuconazole and bixafen towards some multidrug-resistant strains. Two dozen of derivatives have been obtained for each series and allowed to establish early structure-activity relationships useful for the development of next generation of γ-lactam derivatives with improved efficacy.     

Natural enemies of herbivores maintain their biological control potential under short‐term exposure to future CO2, temperature,and precipitation patterns

Climate change will profoundly alter the physiology and ecology of plants, insect herbivores, and their natural enemies, resulting in strong effects on multitrophic interactions. Yet, manipulative studies that investigate the direct combined impacts of changes in CO₂, temperature, and precipitation on the third trophic level remain rare. Here, we assessed how exposure to elevated CO₂, increased temperature, and decreased precipitation directly affect the performance and predation success of species from four major groups of herbivore natural enemies: an entomopathogenic nematode, a wolf spider, a ladybug, and a parasitoid wasp. A four‐day exposure to future climatic conditions (RCP 8.5), entailing a 28% decrease in precipitation, a 3.4°C raise in temperature, and a 400 ppm increase in CO₂ levels, slightly reduced the survival of entomopathogenic nematodes, but had no effect on the survival of other species. Predation success was not negatively affected in any of the tested species, but it was even increased for wolf spiders and entomopathogenic nematodes. Factorial manipulation of climate variables revealed a positive effect of reduced soil moisture on nematode infectivity, but not of increased temperature or elevated CO₂. These results suggest that natural enemies of herbivores may be well adapted to short‐term changes in climatic conditions. These findings provide mechanistic insights that will inform future efforts to disentangle the complex interplay of biotic and abiotic factors that drive climate‐dependent changes in multitrophic interaction networks.     

Focus: Zoonotic Disease: New Series of Imidazoles Showed Promising Growth Inhibitory and Curative Potential Against Trypanosoma Infection

The Trypanosoma spp. cause animal and human trypanosomiasis characterized with appreciable health and economic burden mostly in developing nations. There is currently no effective therapy for this parasitic disease, due to poor drug efficacy, drug resistance, and unwanted toxicity, etc. Therefore, new anti-Trypanosoma agents are urgently needed. This study explored new series of imidazoles for anti-Trypanosoma properties in vitro and in vivo. The imidazoles showed moderate to strong and specific action against growth of T. congolense. For example, the efficacy of the imidazole compounds to restrict Trypanosoma growth in vitro was ≥ 12-fold specific towards T. congolense relative to the mammalian cells. Additionally, the in vivo study revealed that the imidazoles exhibited promising anti-Trypanosoma efficacy corroborating the in vitro anti-parasite capacity. In particular, three imidazole compounds (C1, C6, and C8) not only cleared the systemic parasite burden but cured infected rats after no death was recorded. On the other hand, the remaining five imidazole compounds (C2, C3, C4, C5, and C7) drastically reduced the systemic parasite load while extending survival time of the infected rats by 14 days as compared with control. Untreated control died 3 days post-infection, while the rats treated with diminazene aceturate were cured comparable to the results obtained for C1, C6, and C8. In conclusion, this is the first study demonstrating the potential of these new series of imidazoles to clear the systemic parasite burden in infected rats. Furthermore, a high selectivity index of imidazoles towards T. congolense in vitro and the oral LD₅₀ in rats support anti-parasite specific action. Together, findings support the anti-parasitic prospects of the new series of imidazole derivatives.     

石蒜属植物的药用和观赏利用前景

石蒜属植物是重要的药用植物,又是一类优良观赏植物,既可用于园林配置,也可用作切花生产或盆栽。综述了石蒜属植物的药用和观赏价值并对其应用前景进行了探讨,为全面开发利用我国这一丰富的野生资源提供了一些理论基础。     

Rapid evolution and ecological host-parasite dynamics

Traditionally, the termination of parasite epidemics has been attributed to ecological causes: namely, the depletion of susceptible hosts as a result of mortality or acquired immunity. Here, we suggest that epidemics can also end because of rapid host evolution. Focusing on a particular host–parasite system, Daphnia dentifera and its parasite Metschnikowia bicuspidata , we show that Daphnia from lakes with recent epidemics were more resistant to infection and had less variance in susceptibility than Daphnia from lakes without recent epidemics. However, our studies revealed little evidence for genetic variation in infectivity or virulence in Metschnikowia . Incorporating the observed genetic variation in host susceptibility into an epidemiological model parameterized for this system reveals that rapid evolution can explain the termination of epidemics on time scales matching what occurs in lake populations. Thus, not only does our study provide rare evidence for parasite-mediated selection in natural populations, it also suggests that rapid evolution has important effects on short-term host–parasite dynamics.     

天然产物类药物的合成生物学研究

结构复杂多样的天然产物是现代药物的重要组成部分和新药发现的重要源泉。建立在基因工程及代谢工程、合成化学、基因组学、系统生物学等学科基础上的合成生物学研究对于结构复杂的天然产物类药物研究有特殊的意义。核心是通过在发酵友好、高效的微生物中设计、构建目标化合物的生物合成途径,经系统地调控和优化由重组微生物发酵生产来源稀缺的天然产物类药物或前体。该方法是不远的将来解决来源、成本与环境、资源协调问题最好的途径之一,也是解决海洋天然产物或特殊生境微生物药物面临的如何持续供应化合物这一个瓶颈问题的最佳选择。该文将对天然产物类药物合成生物学研究涉及的主要策略和重要进展进行阐述。