The persistence of short‐term cold acclimation in Drosophila melanogaster (Diptera: Drosophilidae)

Daily and seasonal fluctuations in temperature present significant challenges for the survival of many ectothermic species that can be tempered via thermal acclimation. In the present study, we use multiple naturally derived genotypes of Drosophila melanogaster to determine the persistence of beneficial short‐term thermal acclimation on subsequent survival after cold shock. We found that the benefit of short‐term acclimation persisted for 2 h in most genotypes after a rapid cold hardening treatment. Genotype did not directly influence the persistence of short‐term acclimation benefits, indicating that environmental variation may be more important for the persistence of acclimation benefits rather than genetic capacity for acclimation. The present study extends the current understanding of the limits and importance of short‐term acclimation events, providing greater detail on the timing of the loss of short‐term acclimation benefits in a genetically variable natural population.     

Insecticidal activities of essential oil of Callistemon viminalis applied as fumigant and powder against two bruchids

The fumigant and contact toxicity of essential oil (EO) extracted from the leaves of Callistemon viminalis and its aromatized clay powder (ACP) was evaluated against adults of Acanthoscelides obtectus and Callosobruchus maculatus (Coleoptera: Bruchidae). The results obtained for fumigation assays showed that C. maculatus seems to be more susceptible (LC₅₀ = 0.019 μl/cm³) to the vapours of the essential oil than A. obtectus (LC₅₀ = 0.011 μl/cm³) after 12 h exposure. On the other hand, A. obtectus seems to be more susceptible (LD₅₀ = 0.133 μl/g) to the essential oil applied by contact on grains than C. maculatus (LD₅₀ = 0.170 μl/g) after 2 days exposure. The ACP was also very toxic towards the adults of A. obtectus (LD₅₀ = 0.100 μl/g) and C. maculatus (LD₅₀ = 0.098 μl/g) by contact on grains. At the doses of 0.133 μl/g and 0.266 μl/g, mortalities caused by ACP on grains were higher than those caused by the same dose of EO against the two bruchids. It is also established that both the EO and the ACP caused higher inhibition of F₁ progeny production of A. obtectus than that of C. maculatus. The loss of insecticidal activity of the two materials in the course of time has been observed; however, the toxicity of the ACP was more persistent than that of the oil in the course of time when applied on grains. These results suggest that EO from the leaves of C. viminalis can be used as fumigant agent against A. obtectus and C. maculatus. In addition, it could be advisable to use an adsorbent mineral material as carrier of this EO for the prolongation of its insecticidal activity in the course of time.     

Comparing the Environmental Performance of Fluorescent Whitening Agents with Peroxide Bleaching of Mechanical Pulp

The use of fluorescent whitening agents (FWAs) instead of oxidative bleaching agents such as peroxide is an alternative for the bleaching of mechanical pulp. By this approach, the chromophores of the wood components in the pulp are not destroyed chemically but the brightness of the pulp is achieved by increased re-emission of blue light in the range of 400–500 nm. In this study, a typical FWA and peroxide bleaching chemicals are compared with respect to both production and application in the pulp mill. The life-cycle inventory shows that, on the one hand, the production of the FWA leads to higher releases of salts and adsorbable organically bound halogens (AOX) to surface waters and that, on the other hand, significantly less FWA is required in the application step in order to reach the same pulp brightness. The life-cycle impact assessment of the production step is presented in terms of Eco-indicator 95. These results, however, do not cover the environmental fate of various chemicals released to the aquatic environment in the course of the bleaching/whitening step. Therefore, this part is assessed by means of a more detailed investigation of the chemicals' environmental fate in rivers and their aquatic toxicity.     

Canopy Closure,Competition, and the Endangered Dusky Gopher Frog

Abstract: A major challenge facing wildlife biologists is understanding why some species go extinct while others persist in the same habitat. To address this question, we investigated whether tree canopy closure over ponds affects growth and survival of rare and common tadpoles within ponds and mediates competitive interactions among species. We conducted 2 experiments to test whether canopy closure and competition may have contributed to the decline of the endangered dusky gopher frog (Rana sevosa), but allowed the persistence of the southern leopard frog (R. sphenocephala). We explored the response of both species to canopy closure in single-species and mixed- (1:1) species treatments of identical total tadpole density. An experiment using aquatic enclosures in temporary ponds showed that canopy closure reduced tadpole growth approximately 20% for both species. Survival of dusky gopher frog tadpoles was higher in mixed-species enclosures than in single-species enclosures. In a complementary experiment using artificial ponds, dusky gopher frogs had lower survival to metamorphosis, reduced size at metamorphosis, and produced a lower total biomass of metamorphosed juveniles in shaded ponds. Southern leopard frogs exhibited reduced body size at metamorphosis only when shaded. These studies suggest that pond canopy closure, not larval competition, may be contributing to the decline of the dusky gopher frog. The different responses to canopy closure suggest a potential mechanism for the loss of dusky gopher frogs and the persistence of southern leopard frogs. Removal of trees from historically open-canopy ponds may help facilitate the recovery of dusky gopher frogs and benefit similar species.     

均匀设计超声波提取豆粕异黄酮的研究

本该采用均匀设计方法试验优化技术,进行超声波循环提取豆粕异黄酮的多因素复杂试验,通过应用统计分析软件SPSS处理试验数据,得出多因素回归方程,求出最佳试验条件,并通过试验进行验证．     

Optimal biocatalyst loading in a fixed bed

The optimal distribution of biocatalyst in a fixed bed operating at steady state was determined to minimize the length of the bed for a fixed conversion of 95%. The distribution in terms of the biocatalyst loading on an inert support depends upon the axial distance from the bed entrance (continuous solution) as well as a set of dimensionless parameters that reflect the bed geometry, the bulk flow, reaction kinetics and diffusional characteristics. A mathematical model of the system with the following features was used to obtain the results: (1) convective mass transfer and dispersion in the bulk phase; (2) mass transfer from the bulk phase to the surface of the catalyst particle; and (3) simultaneous diffusion and chemical reaction in the catalyst particle with Michaelis–Menton kinetics and a reliable diffusion model (Zhao and DeLancey in Biotechnol Bioeng 64:434–441, 1999, 2000). The solution to the mathematical model was obtained with Mathematica utilizing the Runge Kutta 4–5 method. The dimensionless length resulting from the continuous solution was compared with the optimal length restricted to a uniform or constant cell loading across the entire bed. The maximum difference in the dimensionless length between the continuous and uniform solutions was determined to be 6.5%. The model was applied to published conversion data for the continuous production of ethanol that included cell loading (Taylor et al. in Biotechnol Prog 15:740–751, 2002). The data indicated a minimum production cost at a catalyst loading within 10% of the optimum predicted by the mathematical model. The production rate versus cell loading in most cases displayed a sufficiently broad optimum that the same (non-optimal) rate could be obtained at a significantly smaller loading such as a rate at 80% loading being equal to the rate at 20% loading. These results are particularly important because of the renewed interest in ethanol production (Novozymes and BBI International, Fuel ethanol: a technological evolution, 2004).     

Spatio-temporal variation in post-recovery dynamics in a large Peregrine Falcon (Falco peregrinus) population in the Jura mountains 2000–2020†

After spectacular population crashes in the 1960 and 1970s, Peregrine Falcon Falco peregrinus populations recovered worldwide, and in the 2000s many study populations were back to normal. However, post-recovery trends have been documented less well. We combined three long-term population studies covering the entire Jura mountain range (16 304 km²) to examine spatio-temporal variation in population dynamics during 2000–2020 in 420 known nesting sites in five regions: Ain, Jura and Doubs in France, and Jura Sud and Jura Nord in Switzerland. Every year about 60% of all sites were surveyed at least once, and this proportion increased over time. We used Bayesian occupancy modelling to investigate site persistence and colonization probabilities and correct status and trend estimates for bias due to non-random site coverage. Based on the average of two models correcting for preferential sampling, we estimated that population size peaked in 2002 (Jura), 2005 (Doubs), 2007 (Ain, Jura Nord) and in 2007 for the Jura as a whole. Thereafter, the population declined significantly in four regions and in the Jura as a whole, with the strongest decline found in the Jura Nord ( –38%, 95% credible interval –34%/–41%) during 2007–2020. Thus, we found considerable spatial heterogeneity in post-recovery trends and widespread post-recovery declines. Reasons for the latter may include Eagle Owl Bubo bubo predation, illegal persecution and human disturbance. Our results illustrate how quickly positive population trends may be reversed, such that continuous long-term monitoring even for species seemingly ‘out of danger’ remains invaluable. Our study also emphasizes the importance of correcting for both coverage bias in general and preferential sampling in particular when assessing population trends in studies where not every territory can be surveyed in all years.     

Influence of biotic and abiotic factors on the persistence of a Beauveria bassiana biopesticide in laboratory and high-rise poultry house settings

Recent studies suggest the potential for use of oil formulations of the entomopathogenic fungus, Beauveria bassiana, as residual sprays for control of house flies in poultry production facilities. The current study investigated the influence of biotic and abiotic factors on biopesticide persistence. We found that flies physically removed and deactivated conidia, with higher fly densities and greater cumulative exposure hastening the decline. Nonetheless, very low densities of viable conidia were still able to cause rapid mortality, suggesting the potential for relatively long re-treatment intervals as fly populations are controlled. Considering abiotic factors, we found that fungal spray treatments remained viable for up to 13 weeks under laboratory conditions. Periodic exposure of flies to the spray residue showed high levels of mortality, with very little decline in mortality rate over time. Equivalent treatments placed in a commercial poultry house showed much more rapid decline. One trial at the end of summer showed conidia to remain viable up to seven weeks. However, repeats during the winter months revealed decay in 1–2 weeks, with fly mortality rates influenced accordingly. The exact reasons for the more rapid decay remain unclear but could be linked to high concentrations of ammonia in the basement areas, especially during winter when ventilation is minimal. The combined data suggest the potential for adaptive treatment regimes with weekly spray intervals in conditions with very high fly populations and/or high ammonia levels, and potentially monthly spray intervals when fly populations and ammonia levels are reduced.     

Environmental monitoring of the biocontrol agent Pantoea agglomerans CPA‐2 applied to citrus fruit at preharvest

The aim of this study was to evaluate the environmental fate and behaviour of the biocontrol product based on Pantoea agglomerans CPA‐2 cells after its release into the field. Three different methods, dilution plating, quantitative real‐time PCR (qPCR) and propidium monoazide combined with qPCR (PMA‐qPCR) were used to track the CPA‐2 population. Populations quantified by qPCR were statistically different compared with those by the PMA‐qPCR and dilution plating methods. In addition, the spray dispersion of the CPA‐2 treatment was evaluated using water‐sensitive papers. A lack of dispersion of the CPA‐2 treatment was observed at distances of 2.5 ± 0.5 m. The presence and persistence of CPA‐2 in the environment were monitored in different areas, by dilution plating and confirmed by conventional PCR. The results showed that CPA‐2 can survive but not proliferate on weed and leaves. The persistence on inert surfaces, such as motorised backpack sprayer, gloves and working clothes, was less than 7 days. In conclusion, PMA‐qPCR was a potential tool for fast and specific monitoring of viable populations of CPA‐2 and it gave valuable information on population behaviour. Moreover, the results demonstrate that CPA‐2 would not present a risk for the environment because of its low establishment, survival and dispersion.     

Reef‐coral refugia in a rapidly changing ocean

This study sought to identify climate‐change thermal‐stress refugia for reef corals in the Indian and Pacific Oceans. A species distribution modeling approach was used to identify refugia for 12 coral species that differed considerably in their local response to thermal stress. We hypothesized that the local response of coral species to thermal stress might be similarly reflected as a regional response to climate change. We assessed the contemporary geographic range of each species and determined their temperature and irradiance preferences using a k‐fold algorithm to randomly select training and evaluation sites. That information was applied to downscaled outputs of global climate models to predict where each species is likely to exist by the year 2100. Our model was run with and without a 1 °C capacity to adapt to the rising ocean temperature. The results show a positive exponential relationship between the current area of habitat that coral species occupy and the predicted area of habitat that they will occupy by 2100. There was considerable decoupling between scales of response, however, and with further ocean warming some ‘winners’ at local scales will likely become ‘losers’ at regional scales. We predicted that nine of the 12 species examined will lose 24–50% of their current habitat. Most reductions are predicted to occur between the latitudes 5–15°, in both hemispheres. Yet when we modeled a 1 °C capacity to adapt, two ubiquitous species, Acropora hyacinthus and Acropora digitifera, were predicted to retain much of their current habitat. By contrast, the thermally tolerant Porites lobata is expected to increase its current distribution by 14%, particularly southward along the east and west coasts of Australia. Five areas were identified as Indian Ocean refugia, and seven areas were identified as Pacific Ocean refugia for reef corals under climate change. All 12 of these reef‐coral refugia deserve high‐conservation status.