The formation of magnetite nanoparticles (Fe 3 O 4 -NPs) by electro-oxidation process was studied by in situ and ex situ techniques in chloride electrolytes with and without ethanol. The electrochemical synthesis is characterized by the application of a current disturbance that promotes the oxidation of a low carbon steel electrode in solution to an oxidized state (Fe 2+ ) which is subsequently transformed into magnetite by reactions in solution. The electrochemical synthesis results in a final product of pure and crystalline magnetite nanoparticles (20-40 nm). The presence of ethanol in the electrolyte does not modify the mechanism of magnetite formation but it extends the lifetime of some precursors during electrosynthesis and promotes the formation of low size magnetite nanoparticles. In situ Raman spectroscopy measurements were used in order to identify the precursor species formed prior to the formation of magnetite nanoparticles during the electro-oxidation of the low carbon steel in electrolyte containing chloride and ethanol. It was corroborated that the electrochemical synthesis of magnetite follows the sequence: Fe(OH) 2 → GR(Cl − ) → γ-FeOOH → Fe 3 O 4 , with a redox interaction between Fe(OH) 2 and γ-FeOOH precursors.

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Strawberry is one of the main crops in the state of Guanajuato, Mexico. The main insect pests are: Tetranychus urticae (Koch.), Trialeurodes vaporariorum (Westwood) and, Chaetosiphon fragaefolii (Cockerell). In order to evaluate the impact of different natural enemies on these pests, two treatments were compared. The first treatment (T 1) consisted in pesticide application, the second treatment (T 2) was composed of the liberation of two natural enemies of these insect pests: Chrysoperla carnea (Stephens) and Hippodamia convergens (Guérin-Méneville). Coriander (Coriandrumsativum L.) was planted on the side of the fields where the natural enemies were released. The adults of T. urticae were more abundant in T 1 than T 2 , by contrast,there were lower number of nymphs and adults of Ch. fragaefolii in T 1 ; nymphs and pupae of T. vaporariorum there were not significantly different between treatments. The populations of T. urticae and Ch. fragaefolii followed a similar pattern, appearing since the end of November and reaching a peak in April, whereas the population of T. vaporariorum showed three population peaks (December, February and June). The presence of C. carnea and H. covergens was similar between T. urticaeand T. vaporariorum, but significant and different with respect of Ch. fragaefolii. The average number of T. urticae's eggs per leaf in the treatment with the release of natural enemies was of 130, compared with 1000 eggs/leaf in the conventional treatment. The population of whiteflies was lower in the biological control treatment. There was an effective pest control with the biocontrol treatment.