Effect of epicuticular waxes of fruits on the photodegradation of fenthion

After treatment lipophilic pesticides tend to diffuse by penetrating the epicuticular wax of fruits. In this way, solar radiation only acts on pesticide molecules after passing through the waxes. The effect of epicuticular waxes of three fruits (orange, nectarine, and olive) on the photodegradation of fenthion was studied. The waxes affected the photodegradation process of fenthion. The decay rate of fenthion increased in the presence of orange and nectarine waxes, while it decreased when olive wax was used. In all waxes, the transformation of fenthion produced mainly fenthion sulfoxide and low amounts of fenthion sulfone. In orange wax, 50% of the initial fenthion was transformed into unknown compounds. In nectarine wax, fenthion was degraded stoichiometrically into fenthion sulfoxide and fenthion sulfone. In olive wax, the photodegradation of fenthion yielded about 80% of fenthion sulfoxide.

Persistence and metabolism of fenthion in orange fruit

The persistence and metabolism of fenthion in orange fruit were studied in field conditions. The fenthion was transformed to fenthion sulfoxide and fenthion sulfone. Sunlight photodegradation experiments showed that this transformation is due to the action of sunlight. Residues were found only in the fruit peel. Fenthion showed a rapid degradation rate with a half-life of ca. 6 days. Fenthion sulfoxide was degraded more slowly with a half-life of ca. 14 days and represented the major residue. Fenthion sulfone was present in low quantities.

Residue decay of insecticides applied with mineral oil on clementine fruits

Three insecticides (chlorpyrifos methyl, dimethoate and fenthion) were applied on clementine fruits with and without mineral oil to assess the effect of mineral oil on pesticide residues. In both experiments the residues on the fruits after the last treatment and at harvest time were not significantly different.

Pesticides in the distilled spirits of wine and its byproducts

The fate of eight fungicides (benalaxyl, fenarimol, iprodione, metalaxyl, myclobutanil, procymidone, triadimefon, and vinclozolin) and five insecticides (dimethoate, fenthion, methidathion, parathion methyl, and quinalphos) in wine and its byproducts (cake and lees) during the production of distilled spirits was studied. Among the pesticides studied, only fenthion, quinalphos, and vinclozolin residues were present in the distilled spirits. During wine distillation, respectively 13% and 5% of the initial residues of fenthion and vinclozolin were transferred to the distilled spirit. Low percentages (2% for fenthion and 0.1% for vinclozolin) of these active ingredients (AI) also passed from the lees to the final-distilled spirit, when samples were fortified at 10.1 and 26.1 ppm for fenthion and vinclozolin, respectively. Quinalphos passed only from the lees to the final-distilled spirit in percentages lower than 1% when samples were fortified at the highest concentration (4.6 ppm).

Segurança clínica e eficácia terapêutica de uma nova formulação ectoparasiticida em bovinos natural e experimentalmente infestados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A comparison of three different methodologies for evaluating Rhipicephalus (Boophilus) rnicroplus susceptibility to topical spray compounds

This study aimed to compare three different methodologies (Adult Immersion Tests, field trials with naturally infected animals, and a Stall Test using artificially infested cattle) to evaluate the efficacy of two topical formulations that we administered as whole body sprays (15% Cypermethrin + 30% Chlorpyriphos + 15% Fenthion-Colosso (R) FC 30, Ouro Fino Agronegocios; and 60% Dichlorvos + 20% Chlorpyriphos-Ectofos (R), Vallee Saude Animal Ltd.), against a susceptible strain of Rhipicephalus (Boophilus) microplus. To achieve this objective, two natural infestation trials were conducted, as well as two artificial infestation trials (Stall Tests) and two Adult Immersion Tests (AIT). The AIT results showed that both spray formulations achieved 100% efficacy against R. (B.) micro plus fully engorged females. However, when observing results obtained by field trials (natural infestations) and Stall Tests, none of these topically applied compounds reached 100% efficacy or affected the reproductive capacity of the fully engorged female ticks. Additional studies must be conducted to compare these in vivo methodologies with different in vitro techniques, such as the Larval Packet Test. However, based on results obtained here, we can conclude that depending on the spray formulations used, the AIT can overestimate acaricidal efficacy and values of reproductive efficiency of such compounds against R (B.) micro plus. Specifically, when dealing with spray formulations in the Stall Tests, the period of residual action can increase because these animals are sheltered from contact with environmental factors that might interfere with the efficacy of the products tested. It may be necessary to take in vivo trial results into consideration (such as field trials with naturally infested animals or Stall Tests) to standardize a specific in vitro assay, such as the Adult Immersion Test. (C) 2014 Elsevier B.V. All rights reserved.