Persistence of azadirachtin A and B in soil: Effects of temperature and microbial activity

Abstract

The persistence of two insecticidally active compounds from the neem tree, azadirachtin A and B, was determined at two different temperatures (15 and 25°C) in the laboratory after application of the commercial neem insecticide, Margosan‐O, to a sandy loam soil. The influence of microbial activity on degradation was also examined by comparing autoclaved and non‐autoclaved soils also at 15 and 25°C. Temperature influenced degradation rates. The DT ₅₀ (time required for 50% disappearance of the initial concentration) for azadirachtin A was 43.9 and 19.8 d for non‐autoclaved soil kept at 15 and 25°C, respectively. The DT ₅₀ for azadirachtin B was 59.2 and 20.8 d for non‐autoclaved soil kept at 15 and 25°C, respectively. Microbial activity was also responsible for faster degradation because DT ₅₀ ’s for autoclaved soil were much longer than for non‐autoclaved soils. DT ₅₀ ‘_s for azadirachtin A in autoclaved soil were 91.2 (15°C) and 31.5 d (25°C). DT50’s for azadirachtin B in autoclaved soil were 115.5 (15°C) and 42.3 d (25°C). Two degradation products of azadirachtin were detected, but were not identified. Higher levels of the two degradation products were detected in non‐autoclaved soil.     

Pesticides in ground water in the united states: Monitoring,modeling, and risks from the U.S. perspective

Abstract

Scientific and regulatory interest in ground water contamination by pesticides increased significantly in 1979. This was prompted by findings of the nematicide 1,2‐dibromo‐3‐chloropropane (DBCP) and the nematicide/insecticide aldicarb (Temik®) in ground water in several states. Since that time, at least 130 pesticides and pesticide metabolites have been detected in ground water in over 150 studies, but detection frequencies are 4–10% nationally. Detection frequencies of pesticides over Health Advisory Levels are generally lower. Screening‐level models and detailed computer simulation models are useful for risk assessments and regulatory decisions. Attenuation Factor, CMLS, PRZM2, GLEAMS, and LEACHM are all useful models.     

Improving food security and safety through use of edible by-products from wild game

Game harvesting in South Africa generally leaves behind edible by-products, which could be a low-cost source of protein for poor people in rural areas. Seven professional and nine recreational hunters were interviewed, a game harvest and trophy hunt attended and literature reviewed, in order to describe the food value chain for game and ways in which edible by-products could be legally channelled into the human food chain, rather than being left in the field for scavengers. Practices of informal vendors (n = 51) were assessed using structured interviews, observation and microbiological analysis. In an experiment, inspected game by-products (shinbones from impala and springbok) were provided to eight informal traders for cooking at an informal market and microbiological analysis was done before and after preparation. The results showed that providing edible by-products to poor consumers appears to be culturally acceptable, affordable, accessible and safe. A crossover from formal to informal marketing is recommended as it would enhance traceability and safety of the product and minimise the risk of poaching. It is suggested that methods should be developed which make the distribution of edible by-products to vulnerable rural communities feasible.     

Efficiency of triggered barriers in dust explosion suppression in galleries

The paper describes large-scale tests of triggered barriers of different design. Main stress was put on examining suitability of the flame detector developed in US Bureau of Mines to work as a trigger for the barriers. It was found that the detector works satisfactorily with the barriers of different design providing a suitable mean to suppress explosions in galleries, either in mines or in other industries.     

Uncertainty in future soil carbon trends at a central U.S. site under an ensemble of GCM scenario climates

This study uses DAYCENT model to investigate the sensitivity of soil organic carbon (SOC) at an intensely cultivated site in the U.S. Midwest under an ensemble of scenario climates predicted by IPCC models. The model ensemble includes three IPCC models (Canadian, French, German), three emission scenarios (B1, A1B, A2) and three time periods (late 20th, mid-21st, late 21st century). DAYCENT shows that SOC at the site would decline by 0.3-2.6 kg m⁻² (5-35%) depending on the models and scenarios from late 20th to mid-21st century despite a larger increase of future net primary production (NPP) than respiration. The future SOC decrease is mostly attributable to harvest loss. The wide spread in future SOC decline rates are in part because SOC decrease (by respiration) is directly proportional to SOC itself. Any uncertainty in absolute SOC in DAYCENT would translate directly into its trend, unlike other variables such as temperature whose trends are independent of their values themselves, contrasting the reliability of SOC trend with temperature change.     

Effects of ecological conditions on lipid composition of the liver and muscles in the daubed shanny, <Emphasis Type="Italic">Leptoclinus maculatus</Emphasis>

A comparative study on the lipid composition of the liver and muscles has been performed in daubed shanny caught in summer (July) in Arctic waters at three different sites (biotopes) along the north-western coast of Spitsbergen. In marine organisms living at high latitudes, lipids play an especially important role, primarily as reserve substances and as a factor influencing adaptation to severe environmental conditions. Since the ecology of daubed shanny is poorly known, the data obtained may be considered novel.     

Using local experts as benchmarks for household local ecological knowledge: Scoring in South African savannas

It is well recognised that local ecological knowledge is an important facet of natural resource management in rural regions of the developing world. However, techniques to assess levels and to integrate it into formal or informal management approaches require further development. In particular, quantitative tools are missing, which would allow more robust analysis of the factors that positively or negatively affect local ecological knowledge and vice versa. This paper reports on a quick assessment approach that provides a quantitative score of generalist local ecological knowledge at the household level. It does so by comparing responses to the knowledge of local people identified as experts within the community. In this way it is both locally constructed and contextualized, and thereby avoids pitfalls of trying to score local ecological knowledge relative to conventional scientific knowledge which frequently cannot account for local constructs. The approach is applied at eight villages throughout the savanna biome in South Africa.     

Synthesis of activated carbon from food waste

Environmental Chemistry Letters - Activated carbon is a&nbsp;material for many adsorption applications, combining low-cost and high-quality properties. Many sources of activated carbon have...