Biopesticides: Has their time come?

Abstract

The increased tempo of developments in biopesticides is closely related to the growing awareness and emphasis on integrated pest management (IPM) and sustainable agriculture. Several economic forecasting sources predict a growth rate for the biopesticide industry at 10 to 15% per annum over the next 10 years in contrast to a 1 to 2% growth rate for synthetic chemical pesticides.

The greatest opportunity for biopesticides is in the insect pest management arena. This paper discusses several types of bioinsecticides that may have significant economic impact in the coming years.     

东非地区的海洋保护区：它们取得了多大的成功?

本文探讨了东非地区海洋保护区(MPA)及其所包含的珊瑚礁的管理。这一地区包括科摩罗、肯尼亚、马达加斯加、毛里求斯、莫桑比克、坦桑尼亚以及塞舌尔。     

Where artisanal mines and forest meet: Socio‐economic and environmental impacts in the Congo Basin

While mineral exploitation can provide significant income and employment, it may negatively impact the environment, being ultimately detrimental to livelihoods in the long term. The consequences of mining are of concern in high value forest ecosystems such as the Sangha Tri‐National (TNS) landscape covering Cameroon, the Central African Republic and Republic of the Congo. This paper captures the socio‐economic and environmental impacts of small‐scale mining in the TNS. Using structured questionnaires, consultations and observation, diamonds and gold were found to contribute directly to the livelihoods of at least 5% of the landscape's population. Although up to eight income‐generating strategies are used, mining contributes on average to 65% of total income and is used mainly to meet basic needs. A gold miner's average income is US$ 3.10 a day, and a diamond miner earns US$ 3.08, making them slightly wealthier than an average Cameroonian and three times wealthier than an average non‐miner in the TNS. Environmental impacts were temporary, low impact and of limited scale. However, with mining likely to increase in the near future, an increasing population and miners' low environmental awareness, measures are needed to ensure and reinforce the positive impact of artisanal mining on livelihoods and maintain its low environmental footprint in the TNS landscape.     

Open waste burning in Cameroonian cities: an environmental impact analysis

Lack of technology and efficient management of solid waste coupled with poverty have motivated most developing countries to sort for cheap waste disposal methods with negative consequences on the environment. Open burning at waste dumps causes serious toxicological impacts. Most organic solid waste excluding plastics when burned cause considerably little environmental pollution. However, non-stoichiometric combustion of waste plastics produces significant amounts of various aliphatic and aromatic compounds, acidic gases, dust and smoke. These products pollute the air, water and soil generating significant health problems with related socioeconomic impacts on human, animals and plants. Some of these pollutants are toxic and/or carcinogenic, form acid-rain and influence climate change. Critical discourse and research on environmental toxicology resulting from air pollution with related health risk and impacts have been catalysed by the enactment of major environmental regulations and increased awareness. The new clean air act amendment of 1990 is estimated to require about $25billion annually for its implementation in the United States, indicating the gravity of the pollution problem. Understanding, controlling and mitigating the impacts of chemical pollution from multiple sources related to open burning of plastics is complex. This paper uses content analysis of relevant literature and field observations to analyse, evaluate and identify characteristic pollutants including their transmission potentials, sources and impacts on human health with the assessment, prevention and management of related risk. An affordable technology-based approach applied within a bottom-up management strategy to prevent and control pollution offers a sustainable solution underpinned by resource and energy recovery from waste.     

Horizontal Mixing in the Shallow Palic Lake Caused by Steady and Unsteady Winds

Horizontal mixing in shallow lakes plays a significant role in sustaining sound life-supporting processes by facilitating homogenization of water in terms of suspended and dissolved matter. A simple method for the quantification of mixing has been outlined in order to establish a reliable basis of comparison; subsequently, it has been applied to the following studied cases. Mixing has been studied by numerical experiments through the case of the shallow Palic Lake. The mathematical formulation of the applied numerical model is described in detail. In the following, the significance of each current driving force influencing the flow patterns has been analyzed. Wind forcing has by far outweighed other forces. Because of this, focus has been put on the influence of wind action on mixing. The intensity of mixing, induced by characteristic steady winds, has been compared with that produced by unsteady winds. Results at the end of both 30- and 60-day wind forcing periods are presented. They suggest that large-scale circulations dominate the mixing processes. Consequently, a steady wind inducing favorable, far-reaching circulations may result in outstanding mixing in a short period of time. In the long run, however, unsteady winds produce more intensive mixing.     

Are network indices robust indicators of food web functioning? A Monte Carlo approach

Indices based on network theory are often used to describe food web functioning. These indices take as input food web flows that are estimated based on merging of (scarce) data with linear inverse methods (LIMs). Due to under sampling, most food webs are highly uncertain and can only be quantified within a specific uncertainty range. The linear inverse method (LIM) can estimate food web flows using a variety of techniques, e.g. the parsimonious or minimum norm (MN) solution, which selects one food web, based on a quadratic minimization technique or the Monte Carlo solution where a finitely many random solutions are generated which are then averaged. We use the Monte Carlo approach (MCA) to estimate the values of several indices from four published food webs, the Gulf of Riga for the autumn, summer and spring seasons, and the Takapoto atoll system. We first show that network indices are much better constrained than the uncertain food webs from which they are calculated. Therefore, even in the face of food web uncertainty, they are robust estimators of food web functioning. We then use the MCA-derived network indices to generate cumulative density functions for each index. These serve to compute the probabilities of the MN indices estimates being an extreme solution as compared to the median values. Our findings show that 82% of the MN solutions are smaller than the MCA solutions, and 63% of the network indices are significantly under-estimated.     

Bars to Jars: Bamboo Value Chains in Cameroon

Bamboo is a well know and versatile material, which is a common sight across Cameroon's diverse ecosystems, from dry to humid tropical and Afromontane forests. Its numerous uses range from storage jars to decorating restaurant-bars, beehives to knives, fences, fodder, and fuel. Responding to the paucity of data on species and uses, the value chain for bamboo in Cameroon was analyzed. Based on 171 interviews and field observations, two African indigenous species (alpine Yushania alpina and savannah Oxytenanthera abyssinica) and exotic (Bambusa vulgaris spp.) bamboos were identified as most utilized. They were tracked from major production zones to final consumers. The ecological, socio-economic, institutional, and governance contexts and impacts are described and analyzed. Issues for research, conservation, and development are highlighted. These include the ambiguous regulatory status, the relationship between tenure and management, threats and conservation of African species and options to increase the sustainable livelihoods for stakeholders dependent upon bamboo.     

Atmospheric monitoring of organochlorine pesticides across some West African countries

Most African countries have ratified the Stockholm Convention on persistent organic pollutants (POPs) and are expected to reduce emissions of POPs such as organochlorine pesticides (OCPs) to the atmosphere. Emerging evidence, however, suggests that there are contemporary sources of OCPs in African countries despite the global ban on these products. This study investigated the atmospheric contamination from OCPs in four West African countries—Togo, Benin, Nigeria, and Cameroon—to ascertain the emission levels of OCPs and the characteristic signatures of contamination. Polyurethane foam (PUF) disk passive air samplers (PAS) were deployed in each country for ca. 55 days in 2012 and analyzed for 25 OCPs. Hexachlorocyclohexanes (HCHs) and DDTs constituted the highest burden of atmospheric OCPs in the target countries, at average concentrations of 441 pg m^?3 (range 23–2718) and 403 pg m^?3 (range 91–1880), respectively. Mirex had the lowest concentration, ranged between 0.1 and 3.3 pg m^?3. The concentration of OCPs in rainy season was higher than in dry season in Cameroon, and presupposed inputs from agriculture during the rainy season. The concentrations of ∑25 OCPs in each country were in the following order: Cameroon > Nigeria > Benin > Togo. There was significant evidence, based on chemical signatures of the contamination that DDT, aldrin, chlordane, and endosulfan were recently applied at certain sites in the respective countries.     

An efficient synthesis of bisenols in water extract of waste onion peel ash

Environmental Chemistry Letters - Bisenols and its derivatives are attractive heterocyclic compounds exhibiting a wide range of biological properties, including anticancer, antipyretic and...