Influence of thermoperiod and photoperiod on reproductive diapause in Bruchidius atrolineatus (Pic) (Coleoptera, Bruchidae)

Abstract Bruchidius atrolineatus (Pic) is a common pest infesting cowpea seeds ( Vigna unguiculata Walp) in Africa. In the Sahelian zone, the adults are in reproductive diapause during the dry season. Diapause induction depends on the climatic conditions during embryonic and post-embryonic development. A strain of B. atrolineatus originating from the Niamey (13^oN) was reared in different thermoperiodic and photoperiodic conditions. In the thermoperiodic regime 40:25^oC, in continuous darkness, induction of diapause was dependent on the duration of the thermophase. Photoperiod could also influence diapause induction but the response depended on the temperature. When the beetles were reared in conditions of LD 12:12 h, 40:25^oC, for seven generations, the proportion of diapausing adults decreased and their sensitivity to photoperiod increased. In LD 14:10 h, 40:25^CC, the proportion of diapausing adults remained high regardless of the photoperiod. In these conditions, the first emerging adults were sexually active and were used for selection of a strain with a low incidence of diapause. After twelve generations, the proportion of diapausing beetles was lower than 5%. The responses of this selected strain to photo- and thermoperiods were reduced. The sensitivity of B. atrolineatus to photoperiod and thermoperiod could be controlled by genetic systems as observed in other insect species.     

Solid–Liquid Equilibrium of Maltitol Aqueous Solutions—Implications on the Crystallization Behavior and Process

The solubility of maltitol in pure water and industrial syrup was measured in a temperature range from 10 to 90 °C. Maltitol is highly soluble in water, and this yields high viscosity values for the saturated aqueous solutions at different temperatures. In addition, solubility of maltitol in ethanol/water mixtures was followed at 30, 35, 45, and 55 °C. Results show that maltitol solubility is highly dependent on water content in the solvent mixture. Moreover, it increases monotonically with temperature. The logarithm of viscosity changes linearly against the mole fraction of maltitol in the aqueous solutions up to saturation. The saturated solutions showed a Newtonian behavior in a temperature range from 20 to 90 °C. Maltitol is also characterized in supersaturated solutions by a narrow metastable zone, which slightly increases as temperature is raised. The density of aqueous solutions of maltitol was measured as a function of molality up to saturation at 20 °C, and results show that density can be correlated with concentration according to a linear relation. The obtained results were used to explain maltitol crystallization, which exhibits a high nucleation rate and a slow growth leading to small size crystals.     

Using management to address vegetation stress related to land‐use and climate change

While disturbances such as fire, cutting, and grazing can be an important part of the conservation of natural lands, some adjustments to management designed to mimic natural disturbance may be necessary with ongoing and projected climate change. Stressed vegetation that is incapable of regeneration will be difficult to maintain if adults are experiencing mortality, and/or if their early life‐history stages depend on disturbance. A variety of active management strategies employing disturbance are suggested, including resisting, accommodating, or directing vegetation change by manipulating management intensity and frequency. Particularly if land‐use change is the main cause of vegetation stress, amelioration of these problems using management may help vegetation resist change (e.g. strategic timing of water release if a water control structure is available). Managers could direct succession by using management to push vegetation toward a new state. Despite the historical effects of management, some vegetation change will not be controllable as climates shift, and managers may have to accept some of these changes. Nevertheless, proactive measures may help managers achieve important conservation goals in the future.     

Response of three lotic assemblages to riparian and catchment‐scale land use: implications for designing catchment monitoring programmes

1. Although many studies have focussed on the effects of catchment land use on lotic systems, the importance of broad (catchment) and fine (segment/reach) scale effects on stream assemblages remain poorly understood. 2. Nine biological metrics for macrophytes (498 sites), benthic macroinvertebrates (491) and fish (478) of lowland and mountain streams in four ecoregions of France and Germany were related to catchment and riparian buffer land use using partial Redundancy Analysis and Boosted Regression Trees (BRTs). 3. Lotic fauna was better correlated (mean max., r = 0.450) than flora (r = 0.277) to both scales of land use: the strongest correlations were noted for mountain streams. BRTs revealed strong non‐linear relationships between mountain assemblage metrics and land use. Correlations increased with increasing buffer lengths, suggesting the importance of near‐stream land use on biotic assemblages. 4. Several metrics changed markedly between 10–20% (mountain ecoregions) and 40–45% (lowland) of arable land use, irrespective of the buffer size. At mountain sites with >10% catchment arable land use, metric values differed between sites with <30% and sites with >30% forest in the near‐stream riparian area. 5. These findings support the role of riparian land use in catchment management; however, differences between mountain and lowland ecoregions support the need for ecoregion‐specific management.     

Association of red coloration with senescence of sugar maple leaves in autumn

We evaluated the association of red coloration with senescence in sugar maple (Acer saccharum Marsh.) leaves by assessing differences in leaf retention strength and the progression of the abscission layer through the vascular bundle of green, yellow, and red leaves of 14 mature open-grown trees in October 2002. Computer image analysis confirmed visual categorization of leaves as predominantly green, yellow or red, and chemical quantification of leaf pigment concentrations verified that leaf color reflected underlying differences in leaf biochemistry. Significantly lower chlorophyll concentrations within red and yellow leaves indicated that senescence was more advanced in leaves from these color categories relative to green leaves. Among leaf types, only red leaves contained high concentrations of anthocyanins. There were significant differences in leaf retention capacity among color categories, with the petioles of green leaves being the most firmly attached to twigs, followed by red and then yellow leaves. Microscopic analysis indicated that yellow leaves had the most advanced extension of the abscission layer through the vasculature, with green and red leaves having significantly less abscission layer progression than yellow. A more limited progression of the abscission layer through vascular bundles may be evidence of delayed leaf senescence that could extend resorption of mobile leaf constituents. Together, results from this study suggest an association between leaf anthocyanin content and functional delays in senescence.     

Differences of ecological functions inside and outside the wetland nature reserves in Sanjiang Plain, China

Conservation effectiveness of wetland nature reserves is determined by both the management intensity inside the reserves and the hydrological status outside the reserves. Therefore, differences of ecological functions inside and outside the reserves are an integrated indictor for assessing conservation effectiveness. Based on the land use map created from Landsat-TM satellite image and 1:50000 Digital Elevation Model (DEM) data in the study area, the catchments that belong to the wetland reserves were determined as their hydrological sensitive zones by SWAT (Soil and Water Assessment Tool) hydrological model. The ecological function indices of wetland reserves and their corresponding hydrological sensitive zones were calculated through expert consultation and value assessment on wetland ecosystem service functions. The results showed that the ecological functions of national wetland reserves were better than those of local reserves in general. However, the wetland ecological functions of hydrological sensitive zones of the former were not always better than those of the latter. Meanwhile, clustering analysis showed that the wetland ecological functions of several adjacent reserves in Nongjiang-Bielahonghe watershed were similar. But correlation analysis found that there existed a remarkable positive correlation between the wetland ecological function indices of local reserves and their hydrological sensitive zones.     

Alternative biofacies model for dysaerobic communities

An abundant calcareous fauna has been discovered in the oxygen minimum zone (OMZ; < 0.5 ml/l O₂) off central California at oxygen concentrations considerably less than those predicted by previous ecological models. Analysis of box core samples and bottom photographs has revealed a distinct depth zonation of echinoderms. Asteroids and ophiuroids are most abundant along the upper and lower edges of the OMZ, respectively, whereas echinoids are found near the core of this zone where oxygen levels are as low as 0.3 ml/l O₂. As these heart urchins are very abundant (14/m²), they represent a potentially significant component of the fossil record of OMZ's. Locally these urchins are capable of disturbing over 90% of near surface sediment. The core of the OMZ is inhabited by hermit crabs that actively transport and recycle gastropod shells. This 'biotransport' results in an accumulation of potentially preservable, non-endemic. hard-bodied organisms which may lead to misinterpretation of paleo-oxygenation conditions. We propose an alternative to the Rhoads & Morse (1971, Lethaia 4 ) biofacies model for open-ocean, dysaerobic environments which consists of: (1) a zone devoid of maeroinvertebrates. characterized by laminated sediments (<0.1 ml/l O₂); (2) a zone dominated by small (1–2 mm) soft-bodied infauca which exhibits moderate disturbance of laminae due to bioturbation (0.1–0.3 ml/l O₂); and (3) a zone inhabited by an abundant calcareous fauna characterized by highly bioturbated sediments (>0.3 ml/l O₂).