RESUMO
Lutzia mosquitoes (Theobald, 1903) are predaceous during their larval stages, but the adult feeding is not clearly understood, especially in relation to blood feeding. In case these mosquitoes are harmless to humans and related animals, they can be useful in biological control of mosquito vectors of pathogens. Investigating the midgut morphology is a good strategy to understand the feeding behavior of this species. The midgut in Lutzia bigoti Bellardi, 1862 displays two distinct portions, a thin anterior midgut and a more dilated posterior midgut. Digestive cells form a single epithelium in the midgut. These cells have long and packed microvilli at their apex and membrane infoldings at their basal portion, the basal labyrinth. The epithelium is supported by a basal lamina. Regarding their cytoplasm, it is noteworthy the abundance of mitochondria, distributed in an apical-basal fashion, and also a whirl-shaped endoplasmic reticulum in the posterior midgut. Basal cells are also found in the midgut of L. bigoti, resembling regenerative cells. The general organization of L. bigoti's midgut closely resembles that of numerous hematophagous mosquitoes previously documented. However, it diverges due to the presence of a peritrophic matrix even when exclusively fed on sugary solutions. Peculiar aspects of L. bigoti's midgut are discussed and compared to those of other mosquito species.
Assuntos
Culicidae , Comportamento Alimentar , Animais , Comportamento Alimentar/fisiologia , Culicidae/anatomia & histologia , Culicidae/fisiologia , Trato Gastrointestinal/anatomia & histologia , Trato Gastrointestinal/fisiologia , Sistema Digestório/anatomia & histologia , FemininoRESUMO
The growing concern with the decline of pollinators worldwide is centered on honey bees, due to their wide distribution, economic, and ecological importance. This type of concern remained less evident for stingless bees, which are widely distributed in the Neotropics, until recently. Since exposure to agrochemicals has been identified as one of the potential threats to bees, the present systematic review compiled information from toxicological evaluations in stingless bees in Brazil, home to a considerable portion of the existing species. This systematic review was performed considering species, research institutions, scientific journals, metrics, experimental set ups, and agrochemicals. The first article in this topic was published in 2010. Since then, 93 scientific papers were published, which showed that there are few species of stingless bees used for toxicological evaluations and Brazilian institutions lead these evaluations. Only 1.5% of the stingless bees' species that occur in Brazil were assessed through chronic exposure in the larval stage. The Universidade Federal de Viçosa (UFV) is responsible for 37% of the total publications. The main route of exposure was acute, using adults in laboratory conditions. The main group of agrochemicals studied were insecticides, in particular the neonicotinoids. The current results reveal the advances achieved and point out the gaps that still need to be filled considering toxicological evaluations in stingless bees.
Assuntos
Agroquímicos , Abelhas/efeitos dos fármacos , Animais , Brasil , Agroquímicos/toxicidade , Inseticidas/toxicidadeRESUMO
Some mosquitoes, including species of the genus Toxorhynchites, are known for actively preying on other mosquito larvae, making these predators valuable allies in the fight against vector-borne diseases. A comprehensive understanding of the anatomy and physiology of these potential biological control agents is helpful for the development of effective strategies for controlling vector populations. This includes the antennae, a crucial component in the search for hosts, mating, and selection of oviposition sites. This study utilized scanning electron microscopy to characterize the sensilla on the antennae of adult mosquitoes from two species that are exclusively phytophagous, including Toxorhynchites theobaldi and Toxorhynchites violaceus, as well as Lutzia bigoti, which females are allegedly hematophagous. The types of sensilla in each species were compared, and five basic types of antennal sensilla were identified: trichoid, chaetic, coeloconic, basiconic, and ampullacea. The analysis also found that they were morphologically similar across the three species, regardless of feeding habits or sex. The identification and characterization of basic types of antennal sensilla in T. theobaldi, T. violaceus, and L. bigoti suggest that these structures, which play a crucial role in the behavior and ecology, have common functions across different mosquito species, despite differences in feeding habits or sex.
Assuntos
Culicidae , Microscopia Eletrônica de Varredura , Sensilas , Animais , Sensilas/ultraestrutura , Feminino , Culicidae/ultraestrutura , Culicidae/anatomia & histologia , MasculinoRESUMO
The disposal of plastics and metal-derived compounds results in the contamination of the environment with nano/microparticles, leading to the exposure of various organisms to these harmful particles. However, the impacts of these particles on pollinating insects, which provide relevant ecosystem services, are not well understood. The aim of this study was to assess the effects of microscopic particles on the tropical pollinator Partamona helleri (Apinae: Meliponini), specifically evaluating the toxicity of plastic microparticles (polystyrene - PS, and polyethylene terephthalate - PET) and nanoparticles of a metal oxide (titanium dioxide - TiO2) via larval ingestion by bees reared in vitro. The survival rate of P. helleri larvae was not affected by the ingestion of particles of PS (500 ng/bee), PET (500 ng/bee), or TiO2 (10 µg/bee) compared to the non-treated diet (control or diet without the particles). Adults derived from treated larvae had increased body weight compared to the control, and the walking behavior of adults was altered by the ingestion of particles. Adults that ingested PET or TiO2 as larvae tended to rest for a longer time and interact more with other bees than the control. Hemocyte counts also changed, with a shift in the proportion of plasmatocytes and prohemocytes in treated individuals. Our findings suggest that even levels considered low for honey bees of exposure to plastic microparticles or metal nanoparticles can harm the health and behavior of stingless bees.
Assuntos
Ecossistema , Microplásticos , Abelhas , Animais , Plásticos/toxicidade , LarvaRESUMO
The mosquito larval midgut is responsible for acquiring and storing most of the nutrients that will sustain the events of metamorphosis and the insect's adult life. Despite its importance, the basic biology of this larval organ is poorly understood. To help fill this gap, we carried out a comparative morphophysiological investigation of three larval midgut regions (gastric caeca, anterior midgut, and posterior midgut) of phylogenetically distant mosquitoes: Anopheles gambiae (Anopheles albimanus was occasionally used as an alternate), Aedes aegypti, and Toxorhynchites theobaldi. Larvae of Toxorhynchites mosquitoes are predacious, in contrast to the other two species, that are detritivorous. In this work, we show that the larval gut of the three species shares basic histological characteristics, but differ in other aspects. The lipid and carbohydrate metabolism of the An. gambiae larval midgut is different compared with that of Ae. aegypti and Tx. theobaldi. The gastric caecum is the most variable region, with differences probably related to the chemical composition of the diet. The peritrophic matrix is morphologically similar in the three species, and processes involved in the post-embryonic development of the organ, such as cell differentiation and proliferation, were also similar. FMRF-positive enteroendocrine cells are grouped in the posterior midgut of Tx. theobaldi, but individualized in An. gambiae and Ae. aegypti. We hypothesize that Tx. theobaldi larval predation is an ancestral condition in mosquito evolution.
Assuntos
Aedes , Anopheles , Animais , Anopheles/fisiologia , Larva/metabolismo , Sistema Digestório , Células EnteroendócrinasRESUMO
Over the last few decades, agrochemicals have been partially associated with a global reduction in bees' population. Toxicological assessment is therefore crucial for understanding the overall agrochemical risks to stingless bees. Therefore, the lethal and sublethal effects of agrochemicals commonly used in crops (copper sulfate, glyphosate, and spinosad) on the behavior and gut microbiota of the stingless bee, Partamona helleri, were assessed using chronic exposure during the larval stage. When used at the field-recommended rates, both copper sulfate (200 µg of active ingredient/bee; a.i µg bee-1) and spinosad (8.16 a.i µg bee-1) caused a decrease in bee survival, while glyphosate (148 a.i µg bee-1) did not show any significant effects. No significant adverse effects on bee development were observed in any treatment with CuSO4 or glyphosate, but spinosad (0.08 or 0.03 a.i µg bee -1) increased the number of deformed bees and reduced their body mass. Agrochemicals changed the behavior of bees and composition of the gut microbiota of adult bees, and metals such as copper accumulated in the bees' bodies. The response of bees to agrochemicals depends on the class or dose of the ingested compound. In vitro rearing of stingless bees' larvae is a useful tool to elucidate the sublethal effects of agrochemicals.
Assuntos
Agroquímicos , Microbioma Gastrointestinal , Abelhas , Animais , Agroquímicos/farmacologia , Sulfato de Cobre , Larva , Comportamento AnimalRESUMO
There are multifactorial causes for the recent decline in bee populations, which has resulted in compromised pollination and reduced biodiversity. Bees are considered one of the most important non-target insects affected by insecticides used in crop production. In the present study, we investigated the effects of acute oral exposure to spinosad on the survival, food consumption, flight behavior, respiration rate, activity of detoxification enzymes, total antioxidant capacity (TAC), brain morphology, and hemocyte count of Apis mellifera foragers. We tested six different concentrations of spinosad for the first two analyses, followed by LC50 (7.7 mg L-1) for other assays. Spinosad ingestion decreased survival and food consumption. Exposure to spinosad LC50 reduced flight capacity, respiration rate, and superoxide dismutase activity. Furthermore, this concentration increased glutathione S-transferase activity and the TAC of the brain. Notably, exposure to LC50 damaged mushroom bodies, reduced the total hemocyte count and granulocyte number, and increased the number of prohemocytes. These findings imply that the neurotoxin spinosad affects various crucial functions and tissues important for bee performance and that the toxic effects are complex and detrimental to individual homeostasis.
Assuntos
Inseticidas , Abelhas , Animais , Inseticidas/toxicidade , Macrolídeos , Combinação de Medicamentos , Dose Letal MedianaRESUMO
Microplastics (MPs) are widespread pollutants of emerging concern, and the risks associated with their ingestion have been reported in many organisms. Terrestrial environments can be contaminated with MPs, and terrestrial organisms, including arthropods, are predisposed to the risk of ingesting MPs. In the current study, the larvae of the paper wasp Polistes satan were fed two different doses (6 mg or 16 mg at once) of polystyrene MPs (1.43 mm maximum length), and the effects of these treatments on immature development and survival till adult emergence were studied. Ingestion of the two doses resulted in mortality due to impaired defecation prior to pupation. The survival of larvae that ingested 16 mg of MPs was significantly lower than that of the control. The ingestion of 16 mg of MPs also reduced the adult emergence (11.4%) in comparison to the control (44.4%). MPs were not transferred from the larvae to the adults that survived. These findings demonstrate that MP ingestion can be detrimental to P. satan, e.g. larval mortality can decrease colony productivity and thus the worker force, and that MPs can potentially affect natural enemies that occur in crops, such as predatory social wasps.
Assuntos
Vespas , Poluentes Químicos da Água , Animais , Larva , Poliestirenos , Plásticos , Defecação , Microplásticos , Ingestão de Alimentos , Poluentes Químicos da Água/farmacologiaRESUMO
Inclusion complexes (ICs) of 2-hydroxypropyl-ß-cyclodextrin with the essential oil (EO) from Seculo XXI cultivar of Psidium guajava were prepared using kneading (KN) and freeze-drying (FD) methods. The resulting ICs clusters have a nanometric size, with a diameter of approximately 80 and 40 nm for KN and FD, respectively. Complexation efficiency was 80.3% and 50.8% for KN and FD methods, respectively. The larvicidal activity of the EO in DMSO on A. aegypti had LC50 and LC90 values of 51.49 and 64.51 µg mL-1, respectively. For the KN method, the toxicity corresponded to 77.54 and 107.29 µg mL-1 for LC50 and LC90, respectively. FD method demonstrated toxicity at concentrations above 600 µg mL-1. Thus, ICs enable the use of EO in breeding sites for A. aegypti, thus being potential products to be commercially exploited.