Toxicity of Hydramethylnon to Leaf-cutting Ant Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae)

Since 2009, when sulfluramid was listed in annex B of the Stockholm Convention’s Persistent Organic Pollutants, effort has been made to search for other active ingredients to use in baits for controlling leaf-cutting ants in Brazil. Considering that active ingredients that inhibit insect cellular respiration have been shown to be effective in controlling ants, the current work aimed at assessing the toxicity of hydramethylnon to Atta sexdens rubropilosa workers. Hydramethylnon was dissolved in acetone and in a solution of acetone + soy oil then incorporated in artificial diet at concentrations of 1 µg/mL, 5 µg/mL, 10 µg/mL, 100 µg/mL, 200 µg/mL and 1000 µg/mL. The treatments where ants were daily fed on the diet containing hydramethylnon at 100 µg/mL, 200 µg/mL and 1000 µg/mL, especially those dissolved in soy oil, exhibited high mortality in comparison to the controls. The data presented here confirms the insecticidal activity of hydramethylnon and highlights the importance of employing soy oil in the formulation of baits to control leaf-cutting ants because it enhances hydramethylnon efficiency

Foraging behavior of leaf cutting ants: How do workers search for their food?

Forager ants search for adequate food sources in nature and, after their discovery, decide whether the source is suitable or not for the colony. However, we asked “How do workers seek out the substrate for cultivation of the symbiontic fungus on which they feed? To answer this question, we evaluated the distance traveled by individual workers in the search of food and the distance traveled to return to the nest, as well as the time and velocity necessary for these activities. The results showed that the distance traveled by the leaf cutting ant, Atta sexdens rubropilosa (Linneus, 1758), in the search of food was greater than the distance traveled to return with the substrate to the colony. On the other hand, the mean time and velocity were similar for food search and return to the colony. These results support the hypothesis of information transfer, according to which the worker needs to return to the nest at the beginning of foraging to transfer information to other workers and thus to establish the process of worker ant foraging. It can be concluded that workers travel large distances in a random manner until finding their substrate, but the return to the nest is efficient considering the shorter distance traveled.

O instituto da delação premiada no processo penal brasileiro

O presente trabalho tem como objetivo analisar o instituto da delação premiada no ordenamento jurídico brasileiro, especialmente em relação ao seu valor probatório e efetividade no combate ao crime organizado. O estudo teve como finalidade principal o exame das origens e evolução da delação por diversos países, bem como toda a previsão normativa do instituto. Dentro do contexto de expansão da criminalidade e da fragilidade do Estado para alcançar os delitos de difícil investigação, tais como os das organizações criminosas, o instituto da delação mostrou-se um bom auxílio para persecução penal. Dessa forma, analisam-se as abordagens doutrinárias sobre o tema e seus diversos dispositivos legais

Flight and Digging Effort in Leaf-cutting Ant Males and Gynes

The nuptial flight and nest digging are high intensity activities which consume body reserves. The flight and digging effort was quantified by measuring the carbohydrate and total lipids content in males and females before and after the nuptial flight, and the queen’s digging effort during the foundation. The digging effort was quantified by experimentally stimulating the queens to dig a nest – one, two or three consecutive times – compared to the queens that did not dig. The colorimetric method was used to determine the soluble carbohydrates and extraction method of immersion was used to determine the total lipids. The results showed significant loss of carbohydrates and total lipids in males and females after the flight. On average the males contained 0.027 mg of soluble carbohydrates before the nuptial flight, and 0.005 mg after the nuptial flight, and the females contained 0.129 mg of soluble carbohydrates before the nuptial flight, and 0.079 mg after the nuptial flight. For the males the percentage of lipids decreased from 5.27±1.07% to 2.60±0.63% and for females from 36.46±4.86% to 32.62% after the nuptial flight. The digging effort of the queen caused a slight reduction in total carbohydrates, it was without digging 0.054 mg, normal digging 0.055 mg, double digging 0.045 mg (decrease of 20,22 %), and triple digging 0.044 mg  (decrease of 20 %) per queen. Based on our results we conclude that the carbohydrate content is the main energetic resource used for the nuptial flight and nest digging, for males and gynes of leaf-cutting ants

Effects of Diafenthiuron in Toxic Baits on Colonies of Leaf-cutting ants (Hymenoptera: Formicidae)

Dianfenthiuron is a pre-insecticide that can be activated by photolysis, and may be a promising formicide. This study evaluated the effect of diafenthiuron after photolysis in colonies of Atta sexdens rubropilosa Forel, 1908. The experiment was conducted in a completely randomized design with five treatments and five replications: control (no active ingredient), sulfluramid (standard formicide), diafenthiuron (no exposure to UV), diafenthiuron (2h exposure to UV) and diafenthiuron (6h exposure to UV). Toxic baits were applied at a rate of 0.5 g per colony, and we observed the transport and incorporation of the baits into the colonies. A grading scale was used (0 to 4) to measure the cutting of Acalypha L. (Euphorbiaceae) leaves by workers at 2, 7, 14 and 21 days after application (DAA) and we also measured the garden mass (fungus + adult + brood) at 21 DAA in order to check for growth of the fungus culture. Total loading and incorporation occurred one hour after application of the baits. Colonies that received sulfluramid did not transport leaves at 2 DAA. Workers that received baits with D2h showed an average of 20% transport and 55% incorporation of leaves at 21 DAA. The grading scale indicated that treatments D2h and D6h had the lowest averages, 0.80 and 2.00, respectively. The treatments D2h and D6h reduced cutting of leaves and fungus garden mass, but did not kill the colonies of A. sexdens rubropilosa

Action mode of fipronil and sulfluramid in baits on Acromyrmex crassispinus (Forel, 1909) (Hymenoptera: Formicidae) in laboratory conditions

The leaf-cutting ants (LCAs) of the genus Atta Fabricius, 1804 and Acromyrmex Mayr, 1865 (Hymenoptera: Formicidae) are major pests in forest plantations, agriculture and livestock. Toxic baits with the active ingredients fipronil and sulfluramid are the main method to manage these insects. The internal hygiene of the ant colony needs to be considered to carry out chemical control of LCA. The baits must act as a true ´Trojan horse´ deceiving the toxic action during the moment of transport. The objective was to evaluate fipronil and sulfluramid in toxic baits against Acromyrmex crassispinus (Forel, 1909) (Hymenoptera: Formicidae) in the laboratory. The action was observed in the first hours after application. The pick-up of the bait with fipronil was more heterogeneous and more random than that with the sulfluramid. Individuals of A. crassispinus stopped cutting leaves after four and seven days after application (DAA) of fipronil and sulfluramid baits, respectively. The foraging activity tended to zero over time with the sulfluramid bait, but a low carry of leaves was observed on the 11th DAA with the fipronil bait. The fipronil and sulfluramid baits, in laboratory conditions, were toxic and efficient to the ant A. crassispinus. The lethal action of fipronil was faster, an undesired aspect in the management of social insects. A control method that simulates the mythical ´Trojan horse´ on LCAs nests is desirable.Fil: Sabattini, Julian Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; ArgentinaFil: Zanuncio, Jose C.. Universidade Federal de Viçosa; BrasilFil: Camargo, Roberto S.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Forti, Luiz C.. Universidade Estadual Paulista Julio de Mesquita Filho; Brasi

Mandibles of Leaf-Cutting Ants: Morphology Related to Food Preference

Feed adaptation is crucial for the ecological success of animals, which explore specific or varied resources according to the suitability of the selected feature. We hypothesized that the mandibles of leaf-cutting ants exhibit a greater degree of specialization because of the specific food preference of some species. The objective of this study was to highlight possible morphological differences between the mandibles of leaf-cutting ants of the genus Atta related to the food preference of the species, i.e., to investigate the morphofunctionality of mandibles in conjunction with a study of the leaf anatomy of plants selected. A detailed description of the mandibles of workers of the grass-cutting ant Atta bisphaerica and of the leaf-cutting ant Atta sexdens rubropilosa was provided, and the anatomy and chemical composition of the plant material foraged by these species were investigated. For morphometric analysis, 50 individuals of each of the four size classes were dissected for removal of the right mandible and one sample of each caste was processed for scanning electron microscopy. The Atta species had a similar mandibular morphology and differences were only observed between species and among castes, demonstrating the clear specialization of workers. Together with the anatomical study of the foraged plant material, the results indicate a high abundance of lignified cells in grasses, permitting to infer that the foraging and processing of these plants can lead to differences in behavioral acts during their preparation and incorporation in the fungus garden. We accept the hypothesis of morphofunctionality in view of the mandibular morphology observed.

Is the initial nest depth adapted to favorable conditions for the incipient colony in leaf-cutting ants?

The nest dug by the leaf-cutter ant queen of the genus Atta is a vertical tunnel interconnected to a small chamber to hold its offspring and the symbiotic fungus. The depth of the initial chamber of the Atta sexdens rubropilosa ranges from 10 to 30 cm below the soil surface. This available information, could it be that the ideal initial nest depth is adapted to favorable conditions for the initial colony? We hypothesized this depth can provide a minimum temperature range with almost constant temperature, leading to the development of symbiotic fungus and brood yet to emerge. To test this hypothesis, laboratory experiments were carried out and the soil temperature was measured at different depths. The colony development at different temperatures was studied in the laboratory and the brood production (number of eggs, larvae, pupae and adults) was measured until the first workers emergency. Additionally, lipid content and the survival of queens at different temperatures were determined. Our results show an suitable temperature range (ranging from 24.82±3.14°C to 24.11±1.30°C) at a depth of 5 to 25 cm from the ground, an ideal brood development at temperatures of 24 and 28 °C, and consequently a reduction in lipid content of the queens at high temperatures, without affecting their survival in the trial period. These results indicate that the depth of the initial chamber excavated by the queen is suitable for the success of the incipient colony

The Impact of Obesity on Pulmonary Function in Adult Women

INTRODUCTION: Obesity can cause deleterious effects on respiratory function and impair health and quality of life. OBJECTIVE: To evaluate the effects of obesity on the pulmonary function of adult women. METHODS: An obese group, constituted of 20 women between 20 and 35 years old with a BMI of 35 - 49.99 kg/m² who were non-smokers and sedentary and had no lung disease were recruited. The non-obese group consisted of 20 women between 20 and 35 years old who were sedentary and non-smokers and had no lung disease and a body mass index between 18.5 and 24.99 kg/m². Spirometry was performed in all subjects. The statistical analysis consisted of parametric or non-parametric tests, depending on the distribution of each variable, considering p < 0.05 to be statistically significant. RESULTS: The obese group presented a mean age of 25.85 ± 3.89 years and a mean BMI of 41.1 ± 3.46 kg/m², and the non-obese group presented a mean age of 23.9 ± 2.97 years and a mean body mass index of 21.91 ± 1.81 kg/m². There were no significant differences between the obese group and the non-obese group as to the age, vital capacity, tidal volume, forced vital capacity, and forced expiratory volume in one second. However, the obese group presented a greater inspiratory reserve volume (2.44 ± 0.47 L vs. 1.87 ± 0.42 L), a lower expiratory reserve volume (0.52 ± 0.32 L vs. 1.15 ± 0.32 L), and a maximal voluntary ventilation (108.5 ± 13.3 L/min vs. 122.6 ± 19.8 L/min) than the non-obese group, respectively. CONCLUSION: The alterations evidenced in the components of the vital capacity (inspiratory reserve volume and expiratory reserve volume) suggest damage to the chest mechanics caused by obesity. These factors probably contributed to a reduction of the maximal voluntary ventilation