Five organophosphorus pesticides (dichlorvos, diazinon, malathion, methyl parathion and coumaphos) were extracted from propolis by matrix solid-phase dispersion (MSPD) extraction using octadecylsilica (C18, 1.0 g) as dispersant material. The kind of solvent elution (acetonitrile or ethyl acetate), volume (8 mL and 15 mL), and adsorbent used to clean-up the extracts (graphitized carbon, florisil™ and silica) were optimized using fortified propolis samples (5.0 μg g(-1)). Recovery was determined by gas chromatography with mass spectrometric detection in selected ion monitoring mode (GC/MS-SIM) and statistical analysis was done to determine better extraction conditions. Relatively high recovery and lower relative standard deviation values (3.1-14.6%) were obtained when analytes were eluted with ethyl acetate from the MSPD column. Diazinon, malathion, methyl parathion, and coumaphos show recoveries of 72.7%, 84.6%, 62.6%, and 78.3%, respectively. In contrast, the recovery for dichlorvos was 53.8%. Additional adsorbents tested for clean-up and increase in solvent elution did not affect recoveries positively and caused a high background in chromatograms. Thus, final conditions were 1 mL of sample, 1 g C18 and 8 mL of ethyl acetate.

Two bioassays were conducted in parallel to assess the effects of cattle treated with either 1% ivermectin (IVM) or 3.15% IVM (dosed at 0.2 and 0.63 mg kg-1, respectively) on reproduction and survival of Onthophagus landolti Harold. Adult beetles were exposed 10 days to faeces of treated cattle starting at: one day before treatment (controls), 3, 6, 14, 28 and 35 days post-treatment. Adult survival of O. landolti was not affected by either of the two treatments. Faecal residues of 1% IVM almost completely suppressed fecundity of beetles at 3, 6 and 14 days post-treatment (dPT), and reduced fecundity of O. landolti at 28 dPT ( 38.3%), relative to controls. Meanwhile, IVM residues after treatment with 3.15% IVM almost completely suppressed fecundity of beetles at 3, 6, 14 and 28 dPT, and reduced fecundity of O. landolti at 35 dPT (80.9%), relative to controls. Larval survival was significantly reduced only at 3 dPT with 1% IVM. Meanwhile, treatment with 3.15% IVM significantly reduced larval survival at 6, 14 and 28 dPT. Larval mortality was recorded only in L-I and L-II instars. Moreover, in both bioassays, most of the L-I and L-II specimens that survived showed signs of toxicity. In conclusion, residual IVM in cattle faeces after treatment with injectable IVM has a detrimental effect on the fecundity of adult O. landolti up to 4 weeks post-treatment and on the subsequent larval survival.

A novel hybrid polymer was developed and evaluated as a sorbent for the matrix solid-phase dispersion (MSPD) extraction of pesticides. The hybrid polymer was synthesized by the sol-gel method and by free radical polymerization. The chemical structure of the resulting hybrid polymer (SiO 2 -PVI) was confirmed by Fourier transform infrared spectroscopy (FT-IR). Thermal analyses suggest that the polymer consists of an organic/inorganic ratio of 28:72 wt/wt%. Scanning electron microscopy (SEM) and elemental analysis (EDS) revealed particle aggregates and a rough surface and suggested that the polymer is primarily composed of SiO 2 . The obtained pore size was appropriate for use in a solid-phase extraction support. X-ray photoelectron spectroscopy (XPS) was used to assess the surface composition of the hybrid polymer and indicated the presence of C, N, O, and Si. The material was tested for extraction of five selected organophosphorus pesticides (OPPs) in propolis using gas chromatography-mass spectrometry (GC/MS). In experiments performed in triplicate at 1.0 μg mL −1 , pesticide recovery was in the range of 81-122 %. In addition, the sorbent hybrid polymer (SiO 2 -PVI) demonstrated good repeatability (RSD≤11 %), on the same order as C18 (commercial sorbent) when tested under the same conditions. These results suggest that SiO 2 -PVI hybrid polymer is a good sorptive material that is comparable to the commercially utilized C18 and can be used in MSPD for the extraction of organophosphorus pesticides.

The legume Leucaena leucocephala (Leucaena) is widely used to supplement forage in silvopastoral livestock systems in Latin America. Little is known about its possible effects on the cow reproductive dynamic. The aim was to evaluate the effect of Leucaena foliage intake on re-establishment of ovarian activity and estrus behavior in early postpartum (7-90 days) cows. Twenty-four multiparous Bos taurus × Bos indicus cows were divided into two homogenous groups and assigned to one of two treatments: a silvopastoral system (SS, n = 12), consisting of an association of Cynodon nlemfuensis grass and L. leucocephala; and a control system (CS, n = 12), consisting of C. nlemfuensis alone. Intake of Leucaena in the SS ranged from 3.80 to 6.43 kg DM/cow/day. Plasma mimosine concentrations ranged from 1270 to 1530 μg/mL, and those for 2,3-dihydroxypyridine (DHP) from 147 to 729 μg/mL. No 3,4-DHP was detected in plasma. No difference (P > 0.05) between treatments was observed for the number of cows exhibiting small, medium, or dominant follicles, or estrus behavior. The number of cows which re-established ovarian cyclicity (n = 6) was lower (P < 0.05) in the SS than in the CS (n = 9). Corpus luteum lifespan was longer (P < 0.05) in the SS than in the CS. Intake of Leucaena affected the number of cows exhibiting ovarian cyclicity and extended corpus luteum life, but did not affect follicular development and estrus behavior.

Novel hybrid TiO2particles were developed and assessed as an adsorbent for solid phase extraction (SPE) of organophosphorus pesticides (fensulfothion, parathion methyl, coumaphos, and diazinon) from spiked water. The sol-gel method was used to synthesize TiO2particles, which were coated with free-radical polystyrene (PS) and poly(3-chloro-2-hydroxypropyl methacrylate) (PClHPMA) polymers. Particle structures were determined via Fourier transform infrared spectroscopy to confirm that the polymers were successfully anchored to the TiO2particles. Thermogravimetric analysis was conducted to determine organic and inorganic matter in TiO2-PS and TiO2-PClHPMA particles showing results of 20 : 80 wt/wt% and 23 : 77 wt/wt%, respectively. SEM-EDS and X-ray diffraction test were conducted to determine the morphology and semielemental composition of the particles showing amorphous characteristics. By observing the contact angle, particles coated with PClHPMA were determined to be more hydrophilic than TiO2-PS particles. The pore size distributions obtained from the N2adsorption-desorption isotherms were 0.150 and 0.168 cm3g−1. The specific surface area (BET) was 239.9 m2g−1for TiO2-PS and 225.7 m2g−1for TiO2-PClHPMA. The synthesized particles showed relatively high yields of adsorption in SPE. The pesticide recoveries obtained by high performance liquid chromatography ranged from 6 to 26% for TiO2-PClHPMA and 44 to 92% for TiO2-PS.