Development of vegetable farming: a cause of the emergence of insecticide resistance in populations of Anopheles gambiae in urban areas of Benin

<p>Abstract</p> <p>Background</p> <p>A fast development of urban agriculture has recently taken place in many areas in the Republic of Benin. This study aims to assess the rapid expansion of urban agriculture especially, its contribution to the emergence of insecticide resistance in populations of <it>Anopheles gambiae</it>.</p> <p>Methods</p> <p>The protocol was based on the collection of sociological data by interviewing vegetable farmers regarding various agricultural practices and the types of pesticides used. Bioassay tests were performed to assess the susceptibility of malaria vectors to various agricultural insecticides and biochemical analysis were done to characterize molecular status of population of <it>An. gambiae</it>.</p> <p>Results</p> <p>This research showed that:</p> <p>(1) The rapid development of urban agriculture is related to unemployment observed in cities, rural exodus and the search for a balanced diet by urban populations;</p> <p>(2) Urban agriculture increases the farmers' household income and their living standard;</p> <p>(3) At a molecular level, PCR revealed the presence of three sub-species of <it>An. gambiae </it>(<it>An. gambiae s.s., Anopheles melas and Anopheles arabiensis</it>) and two molecular forms (M and S). The <it>kdr </it>west mutation recorded in samples from the three sites and more specifically on the M forms seems to be one of the major resistance mechanisms found in <it>An. gambiae </it>from agricultural areas. Insecticide susceptibility tests conducted during this research revealed a clear pattern of resistance to permethrin (76% mortality rate at Parakou; 23.5% at Porto-Novo and 17% at Cotonou).</p> <p>Conclusion</p> <p>This study confirmed an increase activity of the vegetable farming in urban areas of Benin. This has led to the use of insecticide in an improper manner to control vegetable pests, thus exerting a huge selection pressure on mosquito larval population, which resulted to the emergence of insecticide resistance in malaria vectors.</p

Formation, Structure, and Morphology of Triazole-Based Langmuir-Blodgett Films

The formation, morphology, and structure of two-dimensional Langmuir-Blodgett (LB) assemblies of octadecyltriazole (ODT)-based metal-containing oligomers presenting, in the case of iron, the spin-crossover phenomenon is studied with Brewster angle microscopy, IR dichroism, X-ray diffraction, and atomic force microscopy. Two processes occurring at the air-water interface are confirmed to dominate the mechanism of formation of these LB films, the instability of the coordination polymers at the air-water interface and recoordination of metal ions in the subphase at the interface during the LB deposition process. The Langmuir film allowing the LB film formation is mostly made of ODT. The films do present a lamellar structure in which the ODT molecules are tilted and incorporate coordinated isolated metal ions and oligomers of metal ions. The morphology of the LB films is globally flat but with a rather high roughness resulting from inhomogeneities related to phenomena occurring during the LB film formation. These observations are in agreement with the relative affinity of the metal ions with ODT and the relative stability of the coordination polymers at the air-water interface, which have been determined for the group Cu-Fe-Co-Ni

Conducting Langmuir-Blodgett-Films - a Generalized-Approach of the Homodoping Technique Applied on Amphiphilic Tetracyanoquinodimethane (Tcnq) Salts

Journal URL: http://www.sciencedirect.com/science/journal/1251806

Colloidal Crystals as Templates for Macroporous Carbon Electrodes of Controlled Thickness

Macroporous carbon films were synthesized using colloidal crystals as a template and were characterized using scanning electron microscopy (SEM) and Raman spectroscopy. The colloidal crystals were elaborated by the Langmuir-Blodgett technique and were infiltrated with carbon by a controlled chemical vapor infiltration (CVI) process. After removal of the template, thin free-standing carbon membranes whose thicknesses match perfectly those of the templates were obtained. Their ability to act as electrodes was checked by carrying out cyclic-voltammetry experiments

2,6-Dithienyl-substituted pyrylium salts as precursors of functionalized Langmuir films

Starting from 2,6-dithienyl pyrylium perchlorates, the pyrylation reaction was used to obtain 2,6-dithienyl-4-arylpyrylium salts. These salts yield stable monolayers at the air-water interface. Multilayers can be easily built up and films free of light scattering defects were obtained. Both the solution and the Langmuir-Blodgett films exposed to iodine vapor seem to lead to a molecular complex while, on treatment with FeCl 3, oxidation and formation of oligothiophenes have been detected

Langmuir-Blodgett films based on substituted 1,2-dithiolium-tetracyanoquinodimethane radical anion salt

A new semi-amphiphilic radical-anion salt, 1,2-dithiolium-tetracyanoquinodimethane has been synthesized for developing electroactive LB films. From in situ surface potential and ellipsometric measurements, it has been shown that the monolayer thermodynamic state is crucial for the building up of controlled multilayers

EuroMed agreements and agricultural trade issues

Printed from http://www.inea.it target=NewWindow>www.inea.it (March 2004)Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 , Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal