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Showing papers by "Gustavo Ferreira Martins published in 2018"


Journal ArticleDOI
TL;DR: Even at very low concentrations, the spinosad formulation was toxic to the vital organs midgut and Malpighian tubules and adversely affected walking behavior, providing new insights into the debate about the role of bioinsecticides in the mortality of Africanized honey bees.
Abstract: Background The global decline in Apis mellifera colonies is attributed to multiple factors, including pesticides. The bioinsecticide spinosad was initially recognized as safe for non-target organisms; however, its toxicity has been changing this view. Here, we investigated the survival, behavioral changes, and structural changes in the midgut and Malpighian tubules of A. mellifera treated orally with a spinosad formulation. Results The field-recommended concentration of spinosad killed 100% of the bees. The 5% and 50% lethal concentrations (LC5 and LC50 , respectively) of spinosad altered the behavioral activity, reducing the walking distance and velocity, and increased the resting time in comparison to the control. The LC50 caused disorganization of the epithelia of tested organs and induced oxidative stress and cell death. Conclusions The present work provides new insights into the debate about the role of bioinsecticides in the mortality of Africanized honey bees. Even at very low concentrations, the spinosad formulation was toxic to the vital organs midgut and Malpighian tubules and adversely affected walking behavior. This detailed evaluation of the impact of the bioinsecticide on A. mellifera will contribute to the clarification of disturbances probably caused by spinosad formulations, which can be used to develop more sustainable protocols in agriculture. © 2017 Society of Chemical Industry.

38 citations


Journal ArticleDOI
TL;DR: Results showed azadirachtin posed a toxicological hazard to P. helleri queens, similar to imidacloprid, and altered development time, caused deformations, and reduced the size of the queens' reproductive organs.

38 citations


Journal ArticleDOI
TL;DR: The toxicity of the different compounds and behavioral changes in response to them are dependent on the stage of the insect life cycle and the importance of analyzing sublethal effects on the population dynamics of the A. aegypti mosquito is revealed.
Abstract: Background The mosquito Aedes aegypti is intensively controlled because it is a vector of viruses that cause numerous diseases, especially in tropical regions. As a consequence of the indiscriminate use of insecticides, populations from different regions have become resistant to pyrethroids. Here, we analyzed the lethal and sublethal effects of essential oil of Aristolochia trilobata and its major compounds on A. aegypti from susceptible and pyrethroid-resistant populations. Results Our results showed that the toxicity of the different compounds and behavioral changes in response to them are dependent on the stage of the insect life cycle. The monoterpene ρ-cymene caused high mortality in both larvae and adult females of A. aegypti, including those from the pyrethroid-resistant population. The monoterpenes limonene and linalool caused a sublethal effect in the larvae, triggering changes in the swimming pattern. Conclusion This study highlights the potential of the essential oil of A. trilobata and its major compounds ρ-cymene and limonene for the control of A. aegypti and reveals the importance of analyzing sublethal effects on the population dynamics of the A. aegypti mosquito. © 2017 Society of Chemical Industry.

27 citations


Journal ArticleDOI
TL;DR: The inclusion of EPRI in βCD increased its larval toxicity and reduced its human cytotoxicity, while for IVER/βCD no beneficial effect was observed upon inclusion, which has great potential as an insecticide against A. aegypti larvae with high human safety.
Abstract: In the present work, hydrophobic nanoprecipitates (HNPs) of inclusion complexes formed between β-cyclodextrin (βCD) and the avermectins (AVMs) named eprinomectin (EPRI) and ivermectin (IVER) were synthesized and characterized, and their larvicidal activity against Aedes aegypti and human safety against fibroblasts were evaluated. Initially, thermogravimetric analysis/differential thermal analysis data revealed that inclusion increased the thermal stability of AVMs in the presence of βCD. Nuclear magnetic resonance experiments and density functional theory calculations pointed out the inclusion of the benzofuran ring of the two AVMs in the βCD cavity. Isothermal titration calorimetry experiments allowed identification of different binding constants for EPRI/βCD ( Kb = 1060) and βCD/IVER ( Kb = 1700) systems, despite the structural similarity. Dynamic light scattering titrations of AVMs' dimethyl sulfoxide solution in βCD aqueous solution demonstrated that the formed HNPs have lower sizes in the presence of βCD. Finally, the inclusion of EPRI in βCD increased its larval toxicity and reduced its human cytotoxicity, while for IVER/βCD no beneficial effect was observed upon inclusion. These results were rationalized in terms of structural differences between the two molecules. Finally, the EPRI/βCD complex has great potential as an insecticide against A. aegypti larvae with high human safety.

25 citations


Journal ArticleDOI
TL;DR: It is suggested that during the metamorphosis, Malpighian tubules are non-functional until the light-brown-eyed pupae, indicating that A. mellifera may be more vulnerable to toxic compounds at early pupal stages.
Abstract: The honeybee Apis mellifera has ecological and economic importance; however, it experiences a population decline, perhaps due to exposure to toxic compounds, which are excreted by Malpighian tubules. During metamorphosis of A. mellifera, the Malpighian tubules degenerate and are formed de novo. The objective of this work was to verify the cellular events of the Malpighian tubule renewal in the metamorphosis, which are the gradual steps of cell remodeling, determining different cell types and their roles in the excretory activity in A. mellifera. Immunofluorescence and ultrastructural analyses showed that the cells of the larval Malpighian tubules degenerate by apoptosis and autophagy, and the new Malpighian tubules are formed by cell proliferation. The ultrastructure of the cells in the Malpighian tubules suggest that cellular remodeling only occurs from dark-brown-eyed pupae, indicating the onset of excretion activity in pupal Malpighian tubules. In adult forager workers, two cell types occur in the Malpighian tubules, one with ultrastructural features (abundance of mitochondria, vacuoles, microvilli, and narrow basal labyrinth) for primary urine production and another cell type with dilated basal labyrinth, long microvilli, and absence of spherocrystals, which suggest a role in primary urine re-absorpotion. This study suggests that during the metamorphosis, Malpighian tubules are non-functional until the light-brown-eyed pupae, indicating that A. mellifera may be more vulnerable to toxic compounds at early pupal stages. In addition, cell ultrastructure suggests that the Malpighian tubules may be functional from dark-brown-eyed pupae and acquire greater complexity in the forager worker bee.

13 citations


Journal ArticleDOI
TL;DR: The findings showed that the relative number of granulocytes declined with imidacloprid exposure, but the overall capacity of hemocyte responses in terms of total numbers after bacterial infection persisted even after the insecticide exposure.

10 citations


Journal ArticleDOI
TL;DR: The morphological features and total and differential counts of hemocytes in different female classes (newly emerged workers, nurses, foragers, and virgin queens) of the eusocial stingless bee Melipona quadrifasciata suggest that profiles of hemocyte vary according to the caste and age of this eussocial bee.
Abstract: The insect immune system faces various challenges; particularly in social bees, caste system and age polyethism expose individuals to numerous environmental and working conditions However, little is known about how cellular defenses in social bees may be organized to respond to a variety of immune challenges Here, we describe the morphological features and the total and differential counts of hemocytes in different female classes (newly emerged workers, nurses, foragers, and virgin queens) of the eusocial stingless bee Melipona quadrifasciata Granulocytes and prohemocytes were, respectively, the most and the least abundant cells among all classes of females Furthermore, there were more prohemocytes in virgin queens than in foragers The total number of hemocytes was smaller in foragers, whereas the largest number was observed in nurse workers This reduced amount of hemocytes in foragers might allow energy savings to perform colony activities such as foraging and defense Foragers also had the biggest hemocytes (either prohemocytes, granulocytes, or plasmatocytes) in comparison to the other classes of females, which might have arisen as a compensation for the reduction in number of these cells during aging These results suggest that profiles of hemocytes of M quadrifasciata vary according to the caste and age of this eusocial bee

9 citations


Journal ArticleDOI
TL;DR: A seven-year-old girl, treated with methylphenidate, who suffered an atypical femoral neck stress fracture is presented and this case report alerts the clinicians about this rare entity that might be misdiagnosed.
Abstract: Las fracturas por estres afectan, con mayor frecuencia, a personas fisicamente activas con hueso normal y son infrecuentes en los ninos con placa de crecimiento abierta. Aun mas infrecuentes son las fracturas por estres del cuello femoral en la poblacion pediatrica. Sin embargo, constituyen entidades muy importantes debido al riesgo de complicaciones graves, como la necrosis avascular. Se describe el caso de una nina de 7 anos medicada con metilfenidato que sufrio una fractura por estres del cuello del femur atipica. La paciente consulta por dolor inguinal derecho sin limitaciones en las actividades cotidianas. La radiografia muestra una fractura por estres del cuello del femur, que se confirma con tomografia. Se instaura un tratamiento conservador, y la paciente esta asintomatica a las cuatro semanas. Este caso representa una alerta sobre esta infrecuente entidad en la que podrian presentarse errores diagnosticos. Investigaciones recientes tambien sugieren la posible participacion de farmacos, como el metilfenidato, en la desmineralizacion osea, que podria constituir un posible factor de riesgo de fractura. AbstractStress fractures most commonly affect physically active individuals with normal bone, and they are rare in children with open growth plates. Even rarer are femoral neck stress fractures in pediatric age. Nevertheless, they constitute a very important entity due to the risk of severe complications, such as avascular necrosis. A seven-year-old girl, treated with methylphenidate, who suffered an atypical femoral neck stress fracture is presented. Patient complained of right inguinal pain without daily life activity limitations. The radiograph showed a stress femoral neck fracture, confirmed by CT imaging. Conservative treatment was instituted and the patient became asymptomatic after 4 weeks.This case report alerts the clinicians about this rare entity that might be misdiagnosed. Recent research also suggests a possible involvement of drugs, such as methylphenidate, in bone demineralization, which might constitute a possible risk factor for fractures.

5 citations