Solutions of glycerol and water provide a convenient and inexpensive system to control the relative humidity (RH) in small controlled-environment chambers. The relationship between the specific gravity (SG) of a glycerol-water solution and its equilibrium RH is described by the equation SG = [-0.189 (RH) + 19.9]0.0806. Gas can be humidified by bubbling it through jars containing solutions of glycerol-water with the desired equilibrium RH. The effects of flow rate, volume of solution, temperature, and pressure on the equilibrium RH are discussed.
Context Abandonment of extensively managed meadows is an ongoing global challenge in recent decades, particularly in mountain regions, and directly affects plant diversity. However, the extent to which plant diversity further affects associated insect pollinators or herbivores is little investigated. Objectives We focused on the effects of abandonment of mountain meadows on species richness and assemblages of bumblebees, bugs and grasshoppers. Specifically, we investigated the influence of vegetation cover, flower cover, plant richness and surrounding landscape on the three insect groups.Methods Species richness, abundance and species assemblages of bumblebees, bugs and grasshoppers were surveyed in one Swiss and two Austrian regions: three meadows which had been abandoned for 15-60 years, and three extensively managed meadows (mown once a year, no use of fertilizers). We surveyed bumblebees and bugs by sweep net, and grasshoppers using the time-effective soundscape approach. Results Bumblebee species richness and abundance were significantly higher in managed meadows, whereas bug and grasshopper richness and abundance showed no differences between both management types. Managed and abandoned meadows harboured significantly different species assemblages of bugs and grasshoppers, but not of bumblebees. Increasing flower cover and plant richness increased bumblebee
123Landscape Ecol (2017) 32:1937-1951 DOI 10.1007 richness, but correlated negatively with richness of bugs. Surrounding open landscape positively affected bugs. Caelifera positively correlated with surrounding forest cover and negatively with vegetation cover. Vegetation cover positively affected Ensifera. Conclusions Abandoned and extensively managed meadows are important habitat types for the conservation of the three insect groups, thus suggesting the maintenance of both habitat types within mountain landscapes.
The navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), is the primary insect pest of almonds, Prunus amygdalus Batsch (Rosaceae), and pistachios, Pistacia vera L. (Anacardiaceae), in California, USA. Abundance of A. transitella was compared between these crops by examining total and infested mummy nuts collected in trees and on the ground between January and March in 2003 and 2004, and by examining the number of males captured in sticky traps baited with virgin females as a pheromone source during the subsequent growing seasons. There was an 8–9‐fold greater density of total mummies (potential hosts) in pistachios compared to almonds. The proportion of mummies infested was not significantly different between the crops in 2003, but significantly more almond than pistachio mummies were infested in 2004. In 2003, the average density of infested mummies per hectare was greater in pistachios than in almonds, but in 2004 the converse was true. Examination of meteorological data did not suggest an explanation for more live A. transitella per infested mummy in almonds in 2004. The number of males captured in pistachios was consistently greater than the number captured in almonds, particularly during the second flight in June and July. The number of males captured in sticky traps in the summer was more strongly associated with the total mummy density in the sanitation survey of the previous winter than with the density of infested mummies. We conclude that the overall density of mummy nuts serving as potential oviposition sites prior to the next year's crop has a greater impact on the abundance of A. transitella during the growing season and subsequent harvest than does the density of infested mummies. The implications for the ecology and management of this pest species are discussed.
We propose a treatment strategy combining an initial disinfestation treatment with one of three protective treatments as an alternative for chemical fumigation of almonds and raisins for control of postharvest insect populations. Initial disinfestation treatments using low oxygen controlled atmosphere (0.4% O2) were designed to disinfest product of field populations of pyralid moths; navel orangeworm, Amyelois transitella (Walker), in almonds and raisin moth, Cadra figulilella (Gregson), in raisins. The protective treatments were cold storage (10 degrees C), controlled atmosphere (5% O2) storage, and application of the Indianmeal moth granulosis virus, and were designed to prevent establishment of Indianmeal moth, Plodia interpunctella (Hübner). The initial disinfestation treatment was effective against laboratory populations of navel orangeworm and raisin moth. Efficacy of protective treatments was determined by exposure of commodities to laboratory Indianmeal moth populations at levels far higher than those found in commercial storage facilities. All three protective treatments prevented development of damaging Indianmeal moth populations as measured by pheromone trap catches and evaluation of product samples. Quality analysis by commercial laboratories showed that overall product quality for all protective treatments was maintained at levels acceptable by industry standards.
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