Measurement of insecticide uptake and effective fraction in a beneficial insect using solid-phase microextraction

The determination of insecticide uptake in beneficial insects is important for quantifying the doses that are responsible for the toxicological effects and to compare them with the doses that insects may absorb in treated fields. Because of the small size of some beneficial species, the amount of insecticide absorbed may be very low. Herein, we present a method that relies on the sensitivity and specificity of SPME (solid-phase microextraction) as a sampling technique that can be used to measure very small amounts of an organophosphorus insecticide in small insects. In our study, the method was applied to quantify the internal dose and free dissolved fraction of chlorfenvinphos in beneficial parasitoids exposed through a topical application. Up to 0.5 ng of the insecticide could be quantified in these fractions, that is, 10 times less than when using solvent extraction techniques. The penetration and elimination rates of the insecticide in the insect were also determined. The method proved to be suitable to quantify internal doses in parasitoids collected in a treated field.     

Development of polyhydroxyalkanoate/beer spent grain fibers composites for film blowing applications

The high cost, narrow processing window, and poor mechanical properties of polyhydroxyalkanoates hamper their use as films for food packaging applications. We report the preparation, characterization, and film blowing of polyhydroxybutyrate‐valerate (PHBV)/beer spent grain fibers (BSGF) composites. Beer spent grains are by‐products of the beer industry submitted to an acid/caustic treatment and to successive grinding to achieve fibers with typical size of 30 microns. PHBV/BSGF compounds were extruded and successfully subjected to draw down ratios as high as 50. However, processability was lost for BSGF contents above 10 wt%, due to their percolation within the PHBV matrix. Two PHBV/BSGF compounds were processed into blown films. The resulting mechanical, structural, and barrier properties depend on processing parameters and BSGF content. The fully bio‐sourced and compostable PHBV based thin films produced under processing conditions scalable to industrial production show gas and water vapor barrier properties attractive for food packaging applications. POLYM. COMPOS., 36:1859–1865, 2015. © 2014 Society of Plastics Engineers