Mesocosm Studies Suggest Climate Change May Release Aedes aegypti (Diptera: Culicidae) Larvae from Cold Inhibition and Enable Year-Round Development in a Desert City.

AbstractGlobal warming trends, human-assisted transport, and urbanization have allowed poleward expansion of many tropical vector species, but the specific mechanisms responsible for thermal mediation of range changes and ecological success of invaders remain poorly understood. Aedes aegypti (Diptera: Culicidae) is a tropical mosquito currently expanding into many higher-latitude regions, including the urban desert region of Maricopa County, Arizona. Here, adult populations virtually disappear in winter and spring and then increase exponentially through summer and fall, indicating that winter conditions remain a barrier to the development of some life stages of A. aegypti. To determine whether cold limits the winter development of A. aegypti larvae in Maricopa County, we surveyed for larval abundance and tested their capacity to develop in ambient and warmed conditions. Aedes aegypti larvae were not observed in artificial aquatic habitats in winter and spring but were abundant in summer and fall, suggesting winter suppression of adults, larvae, or both. Water temperatures in winter months fluctuated strongly; larvae were usually cold paralyzed at night but active during the day. Despite daytime temperatures that allowed activity and achieving similar degree-days as warmed mesocosms, larvae reared under ambient winter conditions were unable to develop to adulthood, perhaps due to repetitive cold damage. However, warming average temperature by 1.7°C allowed many larvae to successfully develop to adults. Because daytime highs in winter will often allow adult flight, it is likely that relatively minor additional winter warming may allow A. aegypti populations to develop and reproduce year-round in Maricopa County.

Seasonal variability in physiology and behavior affect the impact of fungicide exposure on honey bee (Apis mellifera) health.

Honey bee pollination services are of tremendous agricultural and economic importance. Despite this, honey bees and other pollinators face ongoing perils, including population declines due to a variety of environmental stressors. Fungicides may be particularly insidious stressors for pollinators due to their environmental ubiquity and widespread approval for application during crop bloom. The mechanisms by which fungicides affect honey bees are poorly understood and any seasonal variations in their impact are unknown. Here we assess the effects on honey bee colonies of four-week exposure (the approximate duration of the almond pollination season) of a fungicide, Pristine® (25.2% boscalid, 12.8% pyraclostrobin), that has been commonly used for almonds. We exposed colonies to Pristine® in pollen patties placed into the hive, in either summer or fall, and assessed colony brood and worker populations, colony pollen collection and consumption, and worker age of first foraging and longevity. During the summer, Pristine® exposure induced precocious foraging, and reduced worker longevity resulting in smaller colonies. During the fall, Pristine® exposure induced precocious foraging but otherwise had no significant measured effects. During the fall, adult and brood population levels, and pollen consumption and collection, were all much lower, likely due to preparations for winter. Fungicides and other pesticides may often have reduced effects on honey bees during seasons of suppressed colony growth due to bees consuming less pollen and pesticide.

The Influence of Concentration and Temperature on the Membrane Resistance of Ion Exchange Membranes and the Levelised Cost of Hydrogen from Reverse Electrodialysis with Ammonium Bicarbonate.

The ohmic resistances of the anion and cation ion-exchange membranes (IEMs) that constitute a reverse electrodialysis system (RED) are of crucial importance for its performance. In this work, we study the influence of concentration (0.1 M, 0.5 M, 1 M and 2 M) of ammonium bicarbonate solutions on the ohmic resistances of ten commercial IEMs. We also studied the ohmic resistance at elevated temperature 313 K. Measurements have been performed with a direct two-electrode electrochemical impedance spectroscopy (EIS) method. As the ohmic resistance of the IEMs depends linearly on the membrane thickness, we measured the impedance for three different layered thicknesses, and the results were normalised. To gauge the role of the membrane resistances in the use of RED for production of hydrogen by use of waste heat, we used a thermodynamic and an economic model to study the impact of the ohmic resistance of the IEMs on hydrogen production rate, waste heat required, thermochemical conversion efficiency and the levelised cost of hydrogen. The highest performance was achieved with a stack made of FAS30 and CSO Type IEMs, producing hydrogen at 8.48× 10-7 kg mmem-2s-1 with a waste heat requirement of 344 kWh kg-1 hydrogen. This yielded an operating efficiency of 9.7% and a levelised cost of 7.80 € kgH2-1.