Effect of fatty acids and oils on photodegradation of azadirachtin-A

Azadirachtin-A on exposure to UV-light (254 nm) as a thin film on glass surface gave a isomerised (Z)-2-methylbut-2-enoate product. Half-life of azadirachtin-A as thin film under UV light was found to be 48 min. Azadirachtin-A was irradiated along with saturated and unsaturated fatty acids, and fatty oils under ultra-violet light as thin film. Saturated fatty acid increased the rate of photodegradation of azadirachtin-A, whereas unsaturated fatty acids such as oleic, linoleic and elaidic acid reduced the rate of degradation. Castor, linseed and olive oil accelerated the rate of degradation, whereas neem oil showed no or little change in the rate of degradation of azadirachtin-A. None of these fatty acids and fatty oils were effective in controlling the rate of degradation of azadirachtin-A under UV-light as thin film.     

Low queen mating frequency in the seed-harvester ant Pogonomyrmex (Ephebomyrmex) pima: implications for the evolution of polyandry

The evolution of polyandry is a central problem in the study of insect mating systems, and both material and genetic benefits have been proposed to offset the presumed costs of multiple mating. Although most eusocial Hymenoptera queens mate with just one or occasionally two males, high levels of polyandry are exhibited by several taxa, including seed-harvester ants of the genus Pogonomyrmex. Previous studies of queen mating frequency in Pogonomyrmex have focused on monogynous (one queen per colony) species in the subgenus Pogonomyrmex. We performed a genetic mother–offspring analysis of mating frequency in Pogonomyrmex (Ephebomyrmex) pima, a queen-dimorphic species with dealate and intermorph queens that differ in colony structure (intermorph colonies contain multiple queens). Our results demonstrate that both dealate and intermorph queens of P. (E.) pima are typically single maters, unlike their congeners analyzed thus far. Polyandry appears to be a derived trait in Pogonomyrmex, but comparative tests between P. (E.) pima queen morphs and across the genus provide no evidence that it evolved as an adaptation to increase genetic diversity within colonies or to obtain more sperm, respectively.     

Simplified method for wetland habitat assessment

This article presents a wetland habitat assessment technique (HAT) using birds as indicators of habitat quality. The technique is quick, simple, inexpensive, and lends itself to screening large numbers of wetlands. HAT can provide input to more extensive evaluation techniques. Measures of species diversity and rarity are used to assess the quality of the wetland. By applying the notion of ecologically optimum size, the technique addresses the issue of economic efficiency. Results of field testing HAT on 11 tidally influenced wetlands are presented to illustrate HAT's utility. Application of HAT in a variety of situations is discussed.     

COMPUTER-AIDED PLANNING FOR MULTIPLE-PURPOSE RESERVOIR OPERATING POLICIES1

ABSTRACT: Computer-aided planning (CAP) for multiple-purpose reservoir operations involves use of state-of-the-art simulation and optimization methods, color graphic displays, and interactive computing interfaces. These technologies were integrated into a coherent system that has user-friendly interfaces to help the process of communicating reservoir system operations, solicit planning participant preferences and valuation judgments, and provide understandable feedback of system performance. The CAP system was imbedded in a comprehensive public involvement program that paralleled the reservoir operating policy modeling process, as part of multipurpose reservoir operations planning on the Great Plains Reservoirs in Colorado. Experience with the approach indicates the involved publics can quickly learn of reservoir system limitations and opportunities, and can indeed participate in the operations planning process.     

Fissiparity and population genetics of Coscinasterias calamaria

The effect of asexual reproduction on the population genetics of the fissiparous seastar Coscinasterias calamaria was examined at Rottnest Island and the adjacent mainland, Western Australia, in 1985. Field samples and laboratory observations on growth rate and regeneration showed that fission is common at all 14 sites examined. Electrophoretic analysis of six polymorphic enzymes revealed low genotypic diversity and strong genetic disequilibrium at each site, confirming the highly clonal structure of local populations. Striking variation in clonal composition over distances as short as 50 m emphasizes the very localized subdivision of these populations. In the combined sample from all sites, however, the expected range of multilocus genotypes was found in the proportions expected from random mixing of sexually produced larvae, confirming that clonal diversity results from sexual reproduction. Local genotypic diversity was not correlated with fission, emphasizing the difficulty of determining the short-term roles of asexual and larval recruitment in the maintenance of populations. Subtidal populations, however, appear to have both lower incidence of fission and lower larval recruitment than do intertidal populations.     

Feasibility study of using brine for carbon dioxide capture and storage from fixed sources

A laboratory-scale reactor was developed to evaluate the capture of carbon dioxide (CO2) from a gas into a liquid as an approach to control greenhouse gases emitted from fixed sources. CO2 at 5-50% concentrations was passed through a gas-exchange membrane and transferred into liquid media--tap water or simulated brine. When using water, capture efficiencies exceeded 50% and could be enhanced by adding base (e.g., sodium hydroxide) or the combination of base and carbonic anhydrase, a catalyst that speeds the conversion of CO2 to carbonic acid. The transferred CO2 formed ions, such as bicarbonate or carbonate, depending on the amount of base present. Adding precipitating cations, like Ca++, produced insoluble carbonate salts. Simulated brine proved nearly as efficient as water in absorbing CO2, with less than a 6% reduction in CO2 transferred. The CO2 either dissolved into the brine or formed a mixture of gas and ions. If the chemistry was favorable, carbonate precipitate spontaneously formed. Energy expenditure of pumping brine up and down from subterranean depths was modeled. We conclude that using brine in a gas-exchange membrane system for capturing CO2 from a gas stream to liquid is technically feasible and can be accomplished at a reasonable expenditure of energy.     

EFFECT OF “WHITING” ON OPTICAL PROPERTIES AND TURBIDITY IN OWASCO LAKE,NEW YORK1

ABSTRACT: The effects “whiting” (CaCO₃ precipitate) had on the optical properties and turbidity of the epilimnion of Owasco Lake, New York, were studied during the summer of 1985. Turbidity was partitioned according to “whiting” and non-“whiting” components utilizing a simple acidification procedure. Diffuse light attenuation was partitioned according to the attenuating processes of absorption and scattering. “Whiting” was present most of the summer. Two major “whiting” events occurred that caused major increases in turbidity and the attenuation of light. “Whiting” was the principle regulator of turbidity during the study; it caused increases in light attenuation by increasing light scattering. “Whiting” events can easily be mistaken by the public for phytoplankton blooms.