Semi-wild palm groves reveal agricultural change in the forest region of Guinea

In West Africa, natural regeneration of oil palms (Elaeis guineensis Jacq.) can be favoured by agricultural practices. The structure of palm groves may thus reflect the history of land use. In this study, we examined the connection between biophysical factors, land use and the structure and dynamics of semi-wild palm groves in the village of Nienh, in the forest region of Guinea (Forest Guinea), in order to determine to what extent semi-wild palm groves could be considered as an ecological indicator of the history of regional landscapes. Grove management strategies of farmers were also determined and related to farm characteristics. In Nienh, semi-wild palm groves were found in three cropping systems with differing characteristics in each. Palms were scarce in lowland agricultural areas (8 palms ha(-1) stop), while they were significantly taller (15.8 m on average) and less dense (36 palms ha(-1) stop) in agroforests than in slash-and-burn cropping systems (9.4 m and 55 palms ha(-1) stop respectively). Interviews with farmers showed that it was possible for a farmer to have a global strategy of semi-wild palm grove densification combined with oil palm elimination on a plot scale. The lack of regeneration of palms in agroforests resulted from the almost systematic elimination of young palms by farmers. Conversely, in slash-and-burn cropping systems, young palms were often preserved. As the structure of semi-wild palm groves was partly explained by agricultural practices, it could be used as an ecological indicator of changes in practice in relation to socio-economic context

Methodological progress in on-farm regional agronomic diagnosis. A review

The development of sustainable cropping systems is a key priority for agronomists and crop scientists. A first step involves understanding the relationship between cropping system performance and farmers' practices. To complete this step, a methodological framework entitled Regional Agronomic Diagnosis (RAD) has been developed. During the last ten years, the scope of the regional agronomic diagnosis has been enlarged to include several factors describing crop quality and the environmental impact of cropping systems. Regional agronomic diagnosis has led to several major advances such as ( 1) the assessment of the effect of preceding crop and soil structure on malting barley quality in France and ( 2) the assessment of the effects of ploughing, nematicide use and fertilisers on soil properties in intensive banana plantations in the West Indies. Improvements have also been gained in methodology, particularly by the selection of indicators for assessing the effects of crop management, soil and weather conditions, and data analysis. Finally, regional agronomic diagnosis has been integrated into more general approaches of agricultural development. We review here this methodological progress

La dynamique spatiale de l'économie contemporaine

397 p., fig., ref. bib. : dissem.Ce livre essaie d'éclairer les fondements géographiques du capitalisme industriel moderne. Les auteurs présentent différentes approches des mutations du système productif et leurs effets sur l'organisation territoriale. En empruntant des chemins variés, les chapitres de cet ouvrage sont construits autour des thèmes majeurs du développement économique spatial : l'industrialisation, l'organisation de la production et les activités de services, le rôle des PME, etc. Certains d'entre eux ont une orientation principalement théorique, la plupart combinent les arguments théoriques et empiriques. Livre de recherche, mais aussi guide précieux pour étudiants en sciences sociales géographie, sociologie, urbanisme) et économiques, et pour responsables politiques et économiques

Toxicidade residual de alguns agrotóxicos recomendado na agricultura sobre Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) Residual toxicity of some pesticides recommended for citrus orchards on the predaceous mite Neoseiulus californicus (McGregor) (Acari: phytoseiidae)

O objetivo do trabalho foi avaliar a toxicidade residual de alguns agrotóxicos utilizados em citros sobre Neoseiulus californicus (McGregor) em condições de laboratório. O método de bioensaio adotado foi o de contato residual. Folhas de citros da variedade Pêra, acondicionadas em arenas, foram pulverizadas em torre de Potter. A toxicidade residual dos produtos foi avaliada duas horas e 1; 3; 5; 7; 10; 14 e 21 dias após a aplicação. Em cada arena, foram transferidas dez fêmeas adultas de N. californicus, juntamente com uma quantidade suficiente de Tetranychus urticae, como fonte de alimento. As avaliações de mortalidade foram realizadas 72 horas após a transferência dos ácaros para as arenas. Os agrotóxicos acrinathrin, deltamethrin, dinocap, enxofre, fenpropathrin, óxido de fenbutatin e propargite não causaram mortalidades significativas em adultos de N. californicus. Foram registradas mortalidades de 29,8; 24,0 e 34,1% para ácaros N. californicus expostos a resíduos de duas horas de idade de abamectim, azocyclotin e cyhexatin, respectivamente. Dicofol, pyridaben e chlorfenapyr causaram 100% de mortalidade aos ácaros predadores expostos aos resíduos tóxicos dos acaricidas, com duas horas de idade. Abamectin provocou mortalidade significativa por um período inferior a um dia. Resíduos dos acaricidas azocyclotin, cyhexatin, dicofol, pyridaben e chlorfenapyr provocaram mortalidades significativas por períodos de 1; 1; 10; 10 e 21dias, respectivamente. Os resultados obtidos no presente experimento servem de subsídio para a escolha adequada dos agrotóxicos a serem utilizados em pomares de citros nos quais N. californicus esteja presente ou naqueles em que o predador venha a ser liberado. Esses resultados também servem para a escolha do momento mais favorável para a liberação dos ácaros predadores dessa espécie no campo, após a aplicação de agrotóxicos nos pomares. Estudos conduzidos em condições de campo ainda são necessários para se compreender melhor o efeito desses agrotóxicos sobre o ácaro predador.<br>This study was carried out to evaluate the residual toxicity of some pesticides used in citrus orchards, on Neoseiulus californicus (McGregor) under laboratory conditions. The residual contact bioassay method was adopted. Citrus leaves of the variety "Pêra" were sprayed in a Potter tower. The products' residual toxicity was evaluated at two hours and 1, 3, 5, 7, 10, 14 and 21 days after treatment. Ten adult females of N. californicus were transferred to each arena together with an enough amount of Tetranychus urticae to feed the predator. Mortality evaluations were performed at 72 hours after transferring the predaceous mites to the arenas. The pesticides acrinathrin, deltamethrin, dinocap, sulphur, fenpropathrin, fenbutatin oxide and propargite did not cause significant mortalities to the adults of N. californicus. Abamectim, azocyclotin and cyhexatin caused mortalities of 29.8, 24.0 and 34.1%, respectively, for N. californicus adults exposed to two-hour pesticide residues. Dicofol, pyridaben and chlorfenapyr caused 100% of mortality to the predators exposed to the two-hour acaricide residues. Abamectin provoked significant mortalities for a period shorter than one day. Residues of azocyclotin, cyhexatin, dicofol, pyridaben and chlorfenapyr caused significant mortalities for periods of 1, 1, 10, 10 and 21 days, respectively. The results of this study provided basic information for choosing the adequate pesticides to be used in citrus orchards in which N. californicus is present, or in those the predator will be released. The results are also useful for the decision of the best releasing time for N. californicus in the field, after pesticide applications. Studies carried out in the field are still necessary to understand better the effect of these pesticides under the predaceous mite

Agroecological crop protection in organic farming: Relevance and limits

International audiencePlant protection is one of the major issues in organic farming. Organic crop protection (OCP) strategies often rely on a limited number of methods that provide only partial control of pests and that induce lower yields and economic performances. As a result, farmers hesitate to adopt these strategies and doubts are cast on the ability of organic agriculture to feed the world. This chapter questions how agroecological concepts may contribute to OCP, while taking the different alternative schemes already developed to manage, integrate and design crop protection strategies into account. As demonstrated by a bibliographic analysis, Integrated pest management (IPM) remains the leading paradigm in crop protection. It also provides its foundational basis, giving priority to bioecological processes and alternative techniques to reduce pesticide use. Beyond IPM, agroecology is characterised by a holistic approach and the importance given to the design of a “healthy” agroecosystem. In practice, all these concepts are subject to various interpretations, and organic farming includes a variety of practices, ranging from intensive input substitution to a comprehensive integrated approach. This paper provides key elements for crop protection in OF on the basis of the adaptation of the agroecological crop protection approach. Based on a successful case study of fruit fly management in OF in Reunion Island (France), we highlight three major pillars to design pest management strategies: sanitation, habitat manipulation and conservation biological control. Finally, in the field of crop protection, this paper shows that organic farming can be both a prototype for designing innovations and a source of practices to be extended to other types of agroecosystem