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At least 1,063 records · Page 59Linked to original sources
PubMed2003

Determination of amitraz in canine plasma by solid-phase microextraction-gas chromatography with thermionic specific detection.

A simple and rapid analytical method is presented for the determination of amitraz in canine plasma samples using solid-phase microextraction (SPME) and gas chromatography with thermionic specific detection (GC-TSD). The best conditions for the SPME procedure were: direct extraction on a polydimethlysiloxane (PDMS) fiber with 100-microm film thickness; 400 &microl of sample plasma matrix modified with 4 ml sodium borate solution (0.01 mol l(-1), pH 6.5); extraction temperature 70 degrees C, with stirring at 2500 rpm for 45 min. The method was linear between 20 and 400 ng ml(-1) with regression coefficients corresponding to 0.998 and coefficient of the variation of the points of the calibration curve lower than 15%. The lowest limit of quantification (LOQ) for amitraz in plasma was 20 ng ml(-1). This LOQ was determined as the lowest concentration on the calibration curve in which the coefficient of variation was lower than 15%. The proposed method was applied to determine amitraz concentrations in canine plasma to look for toxicity after treatment with amitraz in a dipping bath.

Animals↗
PubMed2000

Experimental and molecular genetic analysis of the impact of pyrethroid and non-pyrethroid insecticide impregnated bednets for mosquito control in an area of pyrethroid resistance.

Experimental huts in Côte d'Ivoire were used to evaluate the pyrethroid alpha-cypermethrin, the non-ester pyrethroid etofenprox, the organophosphate pirimiphos-methyl and the carbamate carbosulfan on bednets against pyrethroid-resistant Anopheles gambiae Giles. To test for selection for the resistance gene by the treated nets, A. gambiae collected live or dead from the huts were kept and analysed for the presence of the kdr gene using a new polymerase chain reaction followed by sequence-specific oligonucleotide probing (PCR-SSOP) for kdr-genotyping. Deliberately holed bednets freshly treated with pirimiphos-methyl or carbosulfan caused over 90% kill of A. gambiae s.s. and Culex spp. However, the mortality with alpha-cypermethrin or etofenprox treated nets was similar to that with untreated nets. Bloodfeeding of A. gambiae s.s. on the sleepers under the nets was only significantly reduced by alpha-cypermethrin and carbosulfan. Tests of the residual activity of the bednets after seven months showed that pirimiphos-methyl had lost its efficacy while carbosulfan still performed well. Once again the pyrethroid treated nets gave similar results to the untreated nets. Selection for the kdr-allele by alpha-cypermethrin and etofenprox, but not by carbosulfan, was indicated by PCR-SSOP genotyping of mosquitoes. Thus carbamates such as carbosulfan, or organophosphates of longer persistence than pirimiphos-methyl and of low mammalian toxicity, would seem to be a promising alternative to be used on bednets, particularly in areas of pyrethroid resistance.

Adult↗
PubMed2004

Chemical basis for the antifeedant activity of natural hydroxamic acids and related compounds.

Natural hydroxamic acids and related compounds derived from the 1,4-benzoxazin-3-one structure show antifeedant activity against the aphid Rhopalosiphum padi. This antifeeding activity is based on the electrophilic character of the hydroxamic acid function, the opening of the hemiacetal function and the lipophilic character of the molecule. In addition, the antifeedant activity of the aqueous extracts of different tissues of Acanthus mollis (Acanthaceae) was determined. The activity observed is attributed to the presence of 2,4-dihydroxy-1,4-benzoxazin-3-one in the extracts.

Acanthaceae↗
PubMed2002

Synthesis of mayolene-16 and mayolene-18: larval defensive lipids from the European cabbage butterfly.

A tandem Wittig approach has been employed for the synthesis of both (11S,9Z,12Z,15Z)- and (11R,9Z,12Z,15Z)-hydroxyoctadeca-9,12,15-trienoic acid (11-hydroxylinolenic acid, 11-HLA) from (R)-glyceraldehyde acetonide. From (11R)-HLA we have prepared the corresponding palmitic acid and stearic acid esters, mayolene-16 (1) and mayolene-18 (2), insect defensive compounds recently identified from Pieris rapae larvae. In addition, we describe the synthesis of three macrocyclic oligomers (24-26) derived from (11R)-HLA.

Animals↗
PubMed2001

Comparative effectiveness of an integrated pest management system and other control tactics for managing the spider mite Tetranychus ludeni (Acari: Tetranychidae) on eggplant.

The effect of an integrated pest management (IPM) package, host plant resistance, Chrysoperla carnea predation and neem oil were evaluated against the spider mite Tetranychus ludeni on eggplant (Solanum melongena L.) fields in 1996 and 1997, by estimating the mite population density and yield levels. Compared with the IPM package (Panruti local, C. carnea plus neem oil), the standard (susceptible) eggplant variety (MDU1) grown by farmers and treated with an acaricide (dicofol) had significantly higher mite densities. The predator C. carnea was recorded in significantly lower numbers in plots with the standard variety compared to a resistant variety (panruti local) with the full IPM package. Eggplant yield level and crop value were highest in the IPM-treated plots followed by Panruti local plus C. carnea. The standard variety treated with an acaricide had the lowest yield and value. These results indicated the usefulness of host plant resistance complemented by biorational control agents, such as C. carnea and neem oil, that these are suitable components in an IPM programme for managing the spider mite in endemic areas.

Animals↗
PubMed2004

Oviposition deterrents in larval frass of four Ostrinia species fed on an artificial diet.

Behavioral bioassays have shown that volatile oviposition-deterring chemicals are present in the frass of Ostrinia zealis, O. furnacalis, O. scapulalis, and O. latipennis larvae fed on an artificial diet. These chemicals were extractable with acetone, and could be partitioned into a polar lipid fraction. This fraction mainly included palmitic, stearic, oleic, linoleic, and linolenic acids. No significant differences among the four Ostrinia species were found in the amount and composition of these free fatty acids. A mixture of the five authentic fatty acids of the composition found in the larval frass of O. zealis exhibited significant oviposition-deterring effects on all four species.

Animal Feed↗
PubMed1999

Rapid preconcentration method for the determination of azadirachtin-A and -B, nimbin and salannin in neem oil samples by using graphitised carbon solid phase extraction.

A simple and rapid method involving solid phase extraction and liquid chromatography for the determination of azadirachtin-A and -B, nimbin and salannin at nanogram levels in neem oil samples is presented. The neem oil samples are defatted and the compounds of interest extracted by mixing the sample with hexane and passing the hexane solution through a graphitised carbon black column. After washing the column with 2 ml of hexane, azadirachtin-A and -B, nimbin and salannin are eluted with 5 ml of acetonitrile and quantified using HPLC with UV detection. The recoveries of azadirachtin-A and -B, nimbin and salannin in fortified oil samples were 97.4-104.7%. The upper limit of quantification is up to 100 micrograms ml-1 without any additional clean-up and with little interference from lipids during the analysis by HPLC. The method was successfully applied to various neem oil samples collected from different locations in India.

Antiviral Agents↗