Horacio Heinzen

Toxicity of Piper aduncum L. (Piperales: Piperaceae) from the Amazon forest for the cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

The mortality of 14-21-day-old Rhipicephalus (Boophilus) microplus larvae, and the mortality and fertility of groups of engorged adult females exposed to different concentrations of hexane, ethyl acetate and ethanol extracts of spiked pepper (Piper aduncum) were evaluated, using a completely randomized design with five treatment groups, two control groups, and two replicates for the larvae and five replicates for the adult females. Similar methodology was used to investigate the toxicity of the essential oil hydro-distillate (94.84% dillapiole) obtained from the P. aduncum crude hexane extract. The LC(50) of the hexane extract was 9.30 mg ml(-1) for larvae and the reproduction reduction ranged from 12.48% to 54.22%, while 0.1mg/ml(-1) of the essential oil induced 100% mortality in larvae. Literature reports on natural products active against R. microplus were listed and compared with the results presented here. These results indicate that P. aduncum extracts, and particularly its essential oil, are potential alternative control agents for R. microplus.

Comparison of extraction solvents and conditions for herbicide residues in milled rice with liquid chromatography-diode array detection analysis (LC-DAD)

Different extraction procedures and clean-up methods were compared in order to develop a sample preparation procedure for the multi-residue analysis of six post-emergence herbicides (metsulfuron methyl, bensulfuron methyl, pyrazosulfuron ethyl, bentazone, bispyribac sodium and cyhalofop butyl) in rice grains followed by liquid chromatography-diode array detection (LC-DAD). Optimum results were obtained dispersing milled rice grain in water, followed by the addition of 1% acetic acid in acetonitrile, MgSO4 and sodium acetate as a modification of the quick, easy, cheap, effective, rugged and safe (QuEChERS) method but no primary and secondary amine (PSA) sorbent was added due to the acidic nature of the herbicides. The method was further expanded to other post-emergence herbicides (quinclorac, clomazone and propanil). Except for quinclorac, which cannot be analysed with this method, the recoveries of the other eight herbicides were in the range 73–111%, with relative standard deviations lower than 12%. Limits of detection (LODs) ranged from 0.03 to 0.08 mg kg−1. A single analyst can extract twelve samples in 4 h. The method presented here allows the simultaneous residue determination of the most common post-emergence herbicides employed in cultivating rice. It is simple, rapid, sensitive, and can be applied routinely to polished rice grain herbicide residue analysis.

Acaricidal activity of Palicourea marcgravii, a species from the Amazon forest, on cattle tick Rhipicephalus (Boophilus) microplus

Leaves of Palicourea marcgravii were extracted successively with hexane, ethyl acetate and ethanol in order to evaluate their acaricidal activity on larvae and adult stages of the cattle tick Rhipicephalus (Boophilus) microplus. The ethyl acetate extract showed the highest bioactivity of the tested extracts, which contained 0.12% monofluoroacetic acid. On engorged female, the ethyl acetate extract showed a lethal concentration 50% - LC(50)=30.08 mg ml(-1), inhibitory concentration 50% - IC(50)=5.79 mg ml(-1) and lethal time 50% - LT(50)=4.72 days; 100% reproduction was controlled at concentrations of 50 mg ml(-1) and on larvae the ethyl acetate extract showed a LC(50)=2.46 mg ml(-1). No alkaloids were detected in any of the extracts. This is the first report on the acaricidal activity of P. marcgravii extracts against R. microplus as well as the acaricidal properties of a plant species containing monofluoroacetic acid.

Antifeedant activity of citrus waste wax and its fractions against the dry wood termite, Cryptotermes brevis

Abstract The wood protective action of citrus wax, a waste from the citrus industry that is a mixture of citrus fruit epicuticular waxes and essential oils, was evaluated against the termite Cryptotermes brevis Walker (Isoptera: Kalotermitidae). The antifeedant index (AI) of the total wax and fractions was calculated. The total citrus wax exhibited an AI50 value of 24.69 mg/cm3, the wax after hydrodistillation showed the strongest antifeedant property (AI50 11.68 mg/cm3). Fractionation of the wax and gas chromatography—mass spectrometric analysis allowed the identification of coumarins and furancoumarins as the active compounds. These results suggest the potential use of these industrial residues as a natural approach to termite control.

Critical Revision and Development Perspectives of Herbicide Residues Analysis in Agro Ecosystems

Veronica Cesio1, Lucia Pareja1, Silvina Niell1, Lucia Geis Asteggiante1, Bernardo Bocking2, Claudio Garcia3, Grisel Fernandez4, Amadeo R. Fernandez-Alba5 and Horacio Heinzen1 1Farmacognosia y Productos Naturales, Facultad de Quimica UDELAR General Flores 2124, Montevideo 11800, 2Donistar S.C, Col. Rubio, Salto, 3INIA Las Brujas, Las Brujas, Canelones, 4Malherbologia EEMAC, Facultad de Agronomia, UDELAR Km366 Ruta 3 Paysandu, 5 Grupo de Investigacion de Laboratorio de Residuos de Plaguicidas, Almeria, Universidad de Almeria, Canada de San Urbano s/n, Almeria 1,2,3,4Uruguay 5Spain