Gustavo Ferreira Martins

Bio: Gustavo Ferreira Martins is an academic researcher from Universidade Federal de Viçosa. The author has contributed to research in topics: Aedes aegypti & Midgut. The author has an hindex of 24, co-authored 106 publications receiving 1719 citations. Previous affiliations of Gustavo Ferreira Martins include University of the Azores & Oswaldo Cruz Foundation.

Notes on the spermatheca of Vespidae and Sphecidae (Hymenoptera)

Abstract: The insect spermathecae are the female sperm storage organs. In this study we investigated the spermathecal structure in field captured females of Polistes erytrocephalus, P. similimus, P. versicolor, Mischocyttarus cassununga, M. drewseni, Mischocyttarus sp., Apoica sp. and Zethus miniatus (Vespidae) and Trypoxylon albiatarse, T. lactitarse, Sceliphron sp. and Microstigmus brasiliensis (Sphecidae). Spermathecae were fixed, dehydrated in ethanol and embedded in historesin. Pieces were cleared in xylene for whole mounts. Sections were stained and photographed under a light microscope. In Vespidae the spermatheca consists of a single epithelial layer subdivided into three main regions: globular reservoir, spermathecal duct and spermathecal gland. In Sphecidae the spermathecal duct is long and coiled and the reservoir is narrow. In the spermatheca of M. brasiliensis a globular reservoir is not found. In Vespidae there is a Y-shaped spermathecal gland. In Trypoxylon the gland has two branches while in M. brasiliensis there is only one branch. In Vespidae the spermatheca has a fibrous multi-layered cover surrounding the spermatheca, except for the large extension of the gland. We think that this covering may be correlated with spermatozoa protection. We can conclude that the spermatheca of Trypoxylon was more similar to the spermathecae of Vespidae than M. brasiliensis which does not have the globular reservoir and the spermatozoa are placed in a parallel arrangement.

Changes in the reproductive tract of Melipona quadrifasciata anthidioides (Hymenoptera: Apidae, Meliponini) queen after mating

Abstract: The effect of mating on the morphological features of the female reproductive system of the stingless bee Melipona quadrifasciata anthidioides was investigated as well as the amount of time required for spermatozoa transfer to the spermatheca after mating. Five-day old queens were allowed to mate in the presence of one male. After abandoning the females, the male was analyzed to verify genitalia loss. Fifteen mated queens were obtained and three specimens were dissected in the following periods after mating: 5, 10, 15, 20 and 40 days. For each mated queen analyzed there was another virgin queen used as control. Reproductive systems were extracted with light and scanning electron microscope procedures. Results indicated that mating induced ovarian activity and the increase of the spermatheca wall height. Ovarian activity was asynchronic, but in physogastric queens there was synchronism in oocyte production. Ovarioles in virgin queens were stretched, but after mating an enlargement of the basal portion occurred. Follicle degeneration was frequent and seemed to follow virgin queen aging. Ten minutes after mating we found spermatozoa in the spermatheca. Three hours was the necessary for spermatheca lumen to become filled with spermatozoa.

Isolation, primary culture and morphological characterization of oenocytes from Aedes aegypti pupae.

Abstract: Oenocytes are ectodermic cells that participate in a number of critical physiological roles such as detoxification and lipid storage and metabolism in insects. In light of the lack of information on oenocytes from Aedes aegypti and the potential role of these cells in the biology of this major yellow fever and dengue vector, we developed a protocol to purify and maintain Ae. aegypti pupa oenocytes in primary culture. Ae. aegypti oenocytes were cultured as clustered and as isolated ovoid cells with a smooth surface. Our results demonstrate that these cells remain viable in cell culture for at least two months. We also investigated their morphology in vivo and in vitro using light, confocal, scanning and transmission electron microscopes. This work is the first successful attempt in isolating and maintaining Ae. aegypti oenocytes in culture, and a significant step towards understanding the role of this cell type in this important disease vector. The purification and the development of primary cultures of insect oenocytes will allow future studies of their metabolism in producing and secreting compounds.

Mammalian caspases: structure ,a ctivation ,s ubstrates, and functions during apoptosis

Abstract: ■ Abstract Apoptosis is a genetically programmed, morphologically distinct form of cell death that can be triggered by a variety of physiological and pathological stimuli. Studies performed over the past 10 years have demonstrated that proteases play critical roles in initiation and execution of this process. The caspases, a family of cysteine-dependent aspartate-directed proteases, are prominent among the death proteases. Caspases are synthesized as relatively inactive zymogens that become activated by scaffold-mediated transactivation or by cleavage via upstream proteases in an intracellular cascade. Regulation of caspase activation and activity occurs at several different levels: ( a) Zymogen gene transcription is regulated; ( b) antiapoptotic members of the Bcl-2 family and other cellular polypeptides block proximity-induced activation of certain procaspases; and ( c) certain cellular inhibitor of apoptosis proteins (cIAPs) can bind to and inhibit active caspases. Once activated, caspases cleave a variety of intracellular polypeptides, including major structural elements of the cytoplasm and nucleus, components of the DNA repair machinery, and a number of protein kinases. Collectively, these scissions disrupt survival pathways and disassemble important architectural components of the cell, contributing to the stereotypic morphological and biochemical changes that characterize apoptotic cell death.

Principles of Insect Morphology

Abstract: THE author of this book ranks as the foremost American worker on insect morphology. His contributions on the subject are notable for their clarity and originality of thought, and the appearance of a volume, embodying his ideas in comprehensive form, is sure of a hearty welcome. In its preparation, Mr. Snodgrass has incorporated the results of much first-hand study with those of many recent investigators in the same field. He has produced an outstanding book wherein knowledge of facts is combined with that of function and, at the same time, theoretical conceptions of the origins and relationships of organs and parts are not overlooked. Principles of Insect Morphology By R. E. Snodgrass. (McGraw-Hill Publications in the Zoological Sciences.) Pp. ix + 667. (New York and London: McGraw-Hill Book Co., Inc., 1935.) 36s. net.

Effects of neonicotinoids and fipronil on non-target invertebrates

Abstract: We assessed the state of knowledge regarding the effects of large-scale pollution with neonicotinoid insecticides and fipronil on non-target invertebrate species of terrestrial, freshwater and marine environments. A large section of the assessment is dedicated to the state of knowledge on sublethal effects on honeybees (Apis mellifera) because this important pollinator is the most studied non-target invertebrate species. Lepidoptera (butterflies and moths), Lumbricidae (earthworms), Apoidae sensu lato (bumblebees, solitary bees) and the section “other invertebrates” review available studies on the other terrestrial species. The sections on freshwater and marine species are rather short as little is known so far about the impact of neonicotinoid insecticides and fipronil on the diverse invertebrate fauna of these widely exposed habitats. For terrestrial and aquatic invertebrate species, the known effects of neonicotinoid pesticides and fipronil are described ranging from organismal toxicology and behavioural effects to population-level effects. For earthworms, freshwater and marine species, the relation of findings to regulatory risk assessment is described. Neonicotinoid insecticides exhibit very high toxicity to a wide range of invertebrates, particularly insects, and field-realistic exposure is likely to result in both lethal and a broad range of important sublethal impacts. There is a major knowledge gap regarding impacts on the grand majority of invertebrates, many of which perform essential roles enabling healthy ecosystem functioning. The data on the few non-target species on which field tests have been performed are limited by major flaws in the outdated test protocols. Despite large knowledge gaps and uncertainties, enough knowledge exists to conclude that existing levels of pollution with neonicotinoids and fipronil resulting from presently authorized uses frequently exceed the lowest observed adverse effect concentrations and are thus likely to have large-scale and wide ranging negative biological and ecological impacts on a wide range of non-target invertebrates in terrestrial, aquatic, marine and benthic habitats.

Pesticide-Induced Stress in Arthropod Pests for Optimized Integrated Pest Management Programs

Abstract: More than six decades after the onset of wide-scale commercial use of synthetic pesticides and more than fifty years after Rachel Carson's Silent Spring, pesticides, particularly insecticides, arguably remain the most influential pest management tool around the globe. Nevertheless, pesticide use is still a controversial issue and is at the regulatory forefront in most countries. The older generation of insecticide groups has been largely replaced by a plethora of novel molecules that exhibit improved human and environmental safety profiles. However, the use of such compounds is guided by their short-term efficacy; the indirect and subtler effects on their target species, namely arthropod pest species, have been neglected. Curiously, comprehensive risk assessments have increasingly explored effects on nontarget species, contrasting with the majority of efforts focused on the target arthropod pest species. The present review mitigates this shortcoming by hierarchically exploring within an ecotoxicology fram...