Search results for "INSECTICIDES"

Determination of five pesticide residues in oranges by matrix solid-phase dispersion and liquid chromatography to estimate daily intake of consumers.

2001

Abstract Residues of benzoylphenylurea insecticides (diflubenzuron, hexaflumuron, and flufenuxuron), carboxamide acaricides (hexythiazox), and carbamate insecticides (benfuracarb) were determined in 150 orange fruit samples from September 1998 to June 1999, to estimate exposure of the Valencian population to oranges contaminated with these newly developed pesticides. The method for monitoring these residues is based on matrix solid-phase dispersion and liquid chromatography with UV or atmospheric pressure chemical ionization/mass spectrometry (APCI/MS) detection. Orange samples representing 11 varieties were collected from an agricultural cooperative and examined for the 5 pesticides. In 74…

Matrix solid-phase dispersion microextraction and determination by high-performance liquid chromatography with UV detection of pesticide residues in …

1999

A multiresidue method based on matrix solid-phase dispersion (MSPD) microextraction was studied to determine the carbamate, benfuracarb, and urea insecticides, diflubenzuron, flufenoxuron hexaflumuron and hexythiazox, used in control of citrus pests. Optimisation of different parameters, such as the type of solid support for matrix dispersion, elution solvents and the clean-up step were carried out. The method used 0.5 g of orange sample, C8 bonded silica as MSPD sorbent and dichloromethane as eluting solvent. Recoveries, at spiked concentrations below the maximum residue levels established by Spanish Government, were between 74 and 84% with relative standard deviations ranging from 2 to 4%…

Evaluation of a solid-phase extraction system for determining pesticide residues in milk.

1993

Abstract A simple and rapid procedure based on reversed solid-phase extraction with octadecylsilica was developed for determining chlorinated pesticide residues in milk. The need for an agent that breaks the fat globules was first investigated and the method variables were optimized on whole homogenized milk (3.6% fat content). Recovery experiments performed for 26 organochlorine pesticides at levels of 3–40 μg/l gave > 80% recoveries for all the compounds. The method was validated and evaluated by comparison with two widely used liquid-liquid extraction methods. The performance was checked by analysis of a certified standard with natural low endogenous levels (CMR 187) and different kinds …

Pre-invasion history and demography shape the genetic variation in the insecticide resistance-related acetylcholinesterase 2 gene in the invasive Col…

2012

Abstract Background Invasive pest species offers a unique opportunity to study the effects of genetic architecture, demography and selection on patterns of genetic variability. Invasive Colorado potato beetle (Leptinotarsa decemlineata) populations have experienced a rapid range expansion and intense selection by insecticides. By comparing native and invasive beetle populations, we studied the origins of organophosphate (OP) resistance-associated mutations in the acetylcholinesterase 2 (AChE2) gene, and the role of selection and demography on its genetic variability. Results Analysis of three Mexican, two US and five European populations yielded a total of 49 haplotypes. Contrary to the exp…

Genotoxicity of six pesticides by Salmonella mutagenicity test and SOS chromotest.

1997

Abstract Two in vitro tests (Ames test and SOS chromotest), one for bacterial mutagenicity and one for primary DNA damage, were assayed to determine the genotoxic activity of 6 pesticides (atrazine, captafol, captan, chlorpyrifosmethyl, molinate and tetrachlorvinphos). Assays were carried out both in the absence and presence of S9 fractions of liver homogenate from rat (Sprague–Dawley) pretreated with Aroclor 1254. Captan and captafol were genotoxic on both the Ames test and the SOS chromotest. Comparisons with mutagenesis data in Salmonella indicated that the SOS assay detected as genotoxic the pesticides that were mutagenic on the Salmonella test. Non-genotoxic effects were not detected i…

Proposed use of spatial mortality assessments as part of the pesticide evaluation scheme for vector control

2013

Background: The WHO Pesticide Evaluation Scheme to evaluate the efficacy of insecticides does not include the testing of a lethal effect at a distance. A tool was developed to evaluate the spatial mortality of an insecticide product against adult mosquitoes at a distance under laboratory and field conditions. Operational implications are discussed. Methods: Insecticide paint, Inesfly 5A IGR (TM), containing two organophosphates (OPs): chlorpyrifos and diazinon, and one insect growth regulator (IGR): pyriproxyfen, was the product tested. Laboratory tests were performed using "distance boxes" with surfaces treated with one layer of control or insecticide paint at a dose of 1 kg/6 sq m. Field …

Eficacia di alcuni insetticidi su Phyllocnistis citrella Stainton (Lep.: Gracillariidae) ed effetti collaterali sui suoi antagonisti naturali.

1997

Esterase isoenzymes and insecticide resistance in Frankliniella occidentalis populations from the south-east region of Spain.

2008

BACKGROUND:Frankliniella occidentalis (Pergande) is among the most important crop pests in the south-east region of Spain; its increasing resistance to insecticides constitutes a serious problem, and understanding the mechanisms involved is therefore of great interest. To this end, F. occidentalis populations, collected from the field at different locations in south-east Spain, were studied in terms of total esterase activity and esterase isoenzyme pattern. RESULTS: Individual thrips extracts were analysed by native polyacrylamide gel electrophoresis (PAGE) and stained for esterase activity with the model substrate α-naphthyl acetate. Significant correlations were found between resistance t…

Effects of halofenozide (RH-0345) on cuticular hydrocarbons of mosquito larvae of Culex pipiens

2011

Poster; Insect cuticular hydrocarbons are known to have a protection and a pheromonal role. Quantitative changes in the cuticular hydrocarbons of Diptera occur over time and were used in a preliminary attempt to age-grade of mosquitoes. Halofenozide (RH-0345) is an insect growth regulator belonging to the class of non-steroidal ecdysone agonists. In a previous study, halofenozide was found to be effective against larvae of Culex pipiens L. (Diptera: Culicidae) and exerted its toxicity primarily by the induction of a precocious lethal molting (Boudjelida et al., 2005). In this study, newly molted 4th instar larvae of C. pipiens were exposed to halofenozide (23% EC) for 24 h at LC50 (12.58 µg…

Nuevos fármacos inspirados en Annonáceas

2014

Los metabolitos secundarios activos (MSA) juegan un papel importante en el descubrimiento de nuevos medicamentos. Moléculas naturales con esqueletos complejos, tales como las estatinas aisladas de Aspergillus terreus, o las acetogeninas específicas de la familia Annonaceae, no hubieran podido ser inventadas en ningún laboratorio. Los MSA aislados en Annonaceae, especialmente las acetogeninas y los alcaloides isoquinoleínicos, pueden ser considerados como fuente constante de inspiración para químicos, farmacólogos y para todos los investigadores interesados en el descubrimiento de una nueva familia de medicamentos. Active secondary metabolites (ASM) play a highly significant role in the drug…