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Showing 3 results for Guedes


Volume 7, Issue 3 (7-2018)
Abstract

The essential oils of plants are composed of several volatile compounds, which may have different concentrations and may be determinant for their toxicity. Thus, in this work, sublethal and lethal effects of the compounds, geraniol and citronellal on the biochemical and reproductive parameters of Spodoptera frugiperda were investigated. For the geraniol compound the LD30 of 9.42 mg/g and LD50 of 13.65 mg/g was used, while for the citronellal LD30 of 0.06 mg/g and LD50 of 0.08 mg/g. Pure acetone was used in the control. Third instar caterpillars were treated topically in the prothoracic region by applying 1 μl of the respective compounds with a HamiltonTM 50 μl syringe. After 48 h the caterpillars were macerated in sodium phosphate buffer at a ratio of 4 caterpillars / 5 ml of the buffer, the levels of total protein, total sugar, lipid and glycogen were measured. The daily posture was evaluated in order to determine the periods of pre-oviposition, oviposition, post-oviposition and egg quantity. The results showed a reduction in the concentration of proteins and sugars for both compounds and concentrations studied. There was no change in lipid concentration. Citronellal increased the concentration of glycogen for both concentrations. The oviposition period and the number of eggs were reduced. However, there was no difference for the pre-oviposition and post-oviposition periods. Thus, it is inferred that geraniol and citronellal compounds cause alterations in the biochemical parameters that reflect in the reproduction of S. frugiperda.

Volume 19, Issue 1 (1-2017)
Abstract

The mating disruption technique has been widely used for the control of several lepidopteran pests. In the present study, we assessed the efficiency of two formulations of SPLAT Neo, a wax emulsion containing E-11-hexadecenol, with and without the insecticide cypermethrin, in affecting mating disruption of Neoleucinodes elegantalis (Guenée). We also determined the best phenological age or stage of the crop for the application of the pheromone formulation, based on its effectiveness in reducing injuries on tomato fruits. We performed two field trials. The first field trial had three treatments: (1) Areas treated once (30 days after transplanting seedlings) with SPLAT Neo (mating disruption, formulation without cypermethrin); (2) Areas treated once with SPLAT Cida Neo (attract and kill, formulation with cypermethrin), and (3) Control plots, i.e. areas treated with the growers’ pest management procedures, based on pre-scheduled calendar applications of conventional insecticides. The use of SPLAT Neo with and without cypermethrin resulted in a significant season-long reduction of the average number of N. elegantalis eggs throughout the tomato cycle, compared to the control. Areas that received two SPLAT Neo applications had a lower number of males captured by monitoring pheromone traps, a lower number of eggs laid in the field, and significantly lower levels of fruit injury at pre, first, and second tomato harvests. The crop subjected to a single SPLAT Neo application, however, experienced reduction in fruit injury only at the second harvest. Our data suggest that two SPLAT Neo applications promote efficient control of N. elegantalis, resulting in significant reduction of fruit damage in tomato.

Volume 22, Issue 4 (6-2020)
Abstract

The aim of this study was to determine the differences in digit sizes from both pelvic limbs of 169 dairy cows of different genetic groups (Holstein, Jersey, Brown Swiss, and Jersolando), in lactating and non-lactating conditions, and their relation with diseases. Images were taken from the plantar view of the lateral and medial digits, and the length and width of the sole and bulb were then measured. Variables were discarded and factors for analysis were defined. Data were defined according to the highest coefficients and used to discriminate genetic groups and their association with indexes of foot diseases and productive performance. The Chi-square test showed that higher involvement occurred in lactating cows and in the right pelvic limb. Differences among all genetic groups were observed regarding the variables body weight, productive longevity, incidence of foot diseases, and generated factors. The Jersey breed was isolated from the other genetic groups because it presented lower coefficients for all variables; Holstein and Brown Swiss presented the highest morphometric measures of the digits, a higher body weight, and productive longevity, and higher rates of foot diseases. The Jersolando presented intermediate values ​​between those of the two breeds from which it originated. The susceptibility to foot diseases is associated with breed, lactational stage, body weight, and with the morphometric parameters of the digits.

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