RESUMEN
High-throughput sequencing studies have shown that diet or antimicrobial treatments impact animal gut microbiota equilibrium. However, properties related to the gut microbial ecosystem stability, such as resilience, resistance, or functional redundancy, must be better understood. To shed light on these ecological processes, we combined advanced statistical methods with 16â¯S rRNA gene sequencing, functional prediction, and fitness analyses in the gut microbiota of the cockroach Blattella germanica subject to three periodic pulses of the antibiotic (AB) kanamycin (n=512). We first confirmed that AB did not significantly affect cockroaches' biological fitness, and gut microbiota changes were not caused by insect physiology alterations. The sex variable was examined for the first time in this species, and no statistical differences in the gut microbiota diversity or composition were found. The comparison of the gut microbiota dynamics in control and treated populations revealed that (1) AB treatment decreases diversity and completely disrupts the co-occurrence networks between bacteria, significantly altering the gut community structure. (2) Although AB also affected the genetic composition, functional redundancy would explain a smaller effect on the functional potential than on the taxonomic composition. (3) As predicted by Taylor's law, AB generally affected the most abundant taxa to a lesser extent than the less abundant taxa. (4) Taxa follow different trends in response to ABs, highlighting "resistant taxa," which could be critical for community restoration. (5) The gut microbiota recovered faster after the three AB pulses, suggesting that gut microbiota adapts to repeated treatments.
Asunto(s)
Antibacterianos , Bacterias , Blattellidae , Microbioma Gastrointestinal , Kanamicina , ARN Ribosómico 16S , Animales , Microbioma Gastrointestinal/efectos de los fármacos , Antibacterianos/farmacología , ARN Ribosómico 16S/genética , Blattellidae/microbiología , Bacterias/clasificación , Bacterias/genética , Bacterias/efectos de los fármacos , Bacterias/aislamiento & purificación , Kanamicina/farmacología , Masculino , Femenino , Biodiversidad , Cucarachas/microbiología , Cucarachas/efectos de los fármacos , Filogenia , Adaptación Fisiológica , Secuenciación de Nucleótidos de Alto RendimientoRESUMEN
Insect neuropeptides play an essential role in regulating growth, development, reproduction, nerve conduction, metabolism, and behavior in insects; therefore, G protein-coupled receptors of neuropeptides are considered important targets for designing green insecticides. Cockroach-type allatostatins (ASTs) (FGLamides allatostatins) are important insect neuropeptides in Diploptera punctata that inhibit juvenile hormone (JH) synthesis in the corpora allata and affect growth, development, and reproduction of insects. Therefore, the pursuit of novel insecticides targeting the allatostatin receptor (AstR) holds significant importance. Previously, we identified an AST analogue, H17, as a promising candidate for pest control. Herein, we first modeled the 3D structure of AstR in D. punctata (Dippu-AstR) and predicted the binding mode of H17 with Dippu-AstR to study the critical interactions and residues favorable to its bioactivity. Based on this binding mode, we designed and synthesized a series of H17 derivatives and assessed their insecticidal activity against D. punctata. Among them, compound Q6 showed higher insecticidal activity than H17 against D. punctata by inhibiting JH biosynthesis, indicating that Q6 is a potential candidate for a novel insect growth regulator (IGR)-based insecticide. Moreover, Q6 exhibited insecticidal activity against Plutella xylostella, indicating that these AST analogs may have a wider insecticidal spectrum. The underlying mechanisms and molecular conformations mediating the interactions of Q6 with Dippu-AstR were explored to understand its effects on the bioactivity. The present work clarifies how a target-based strategy facilitates the discovery of new peptide mimics with better bioactivity, enabling improved IGR-based insecticide potency in sustainable agriculture.
Asunto(s)
Proteínas de Insectos , Insecticidas , Neuropéptidos , Peptidomiméticos , Insecticidas/química , Insecticidas/farmacología , Insecticidas/síntesis química , Animales , Neuropéptidos/química , Neuropéptidos/farmacología , Neuropéptidos/metabolismo , Proteínas de Insectos/química , Proteínas de Insectos/metabolismo , Proteínas de Insectos/genética , Peptidomiméticos/química , Peptidomiméticos/farmacología , Peptidomiméticos/síntesis química , Diseño de Fármacos , Hormonas Juveniles/química , Hormonas Juveniles/farmacología , Hormonas Juveniles/metabolismo , Cucarachas/efectos de los fármacos , Cucarachas/químicaRESUMEN
PURPOSE: Allergens present in the feces or frass of cockroaches can cause allergic sensitization in humans. The use of fecal and frass extracts for immunotherapy has been previously investigated but has not yet been fully standardized. Here, we treated cockroaches with ampicillin to produce extracts with reduced amounts of total bacteria. METHODS: We performed targeted high-throughput sequencing of 16S rDNA to compare the microbiomes of ampicillin-treated and untreated (control) cockroaches. RNA-seq was performed to identify differentially expressed genes (DEGs) in ampicillin-treated cockroaches. RESULTS: Analysis of the microbiome revealed that alpha diversity was lower in the ampicillin-treated group than in the control group. Beta diversity analysis indicated that ampicillin treatment altered bacterial composition in the microbiome of cockroaches. Quantitative polymerase chain reaction revealed that almost all bacteria were removed from ampicillin-treated cockroaches. RNA-seq analysis revealed 1,236 DEGs in ampicillin-treated cockroaches (compared to untreated cockroaches). Unlike bacterial composition, the DEGs varied between the two groups. Among major allergens, the expression of Bla g 2 decreased significantly in ampicillin-treated cockroaches (compared to untreated group). CONCLUSIONS: In this study, the reduced level of allergens observed in cockroaches may be related to lower amounts of total bacteria caused by treatment with antibiotics. It is possible to make a protein extract with few bacteria for use in immunotherapy.
Asunto(s)
Alérgenos/aislamiento & purificación , Ampicilina/farmacología , Antibacterianos/farmacología , Ácido Aspártico Endopeptidasas/aislamiento & purificación , Cucarachas/efectos de los fármacos , Microbiota/efectos de los fármacos , Animales , Cucarachas/microbiologíaRESUMEN
<b>Background and Objective:</b> The ethanol extract of noni leaves (<i>Morinda citrifolia</i> L.) can be used as insecticides to control populations of German cockroaches that have been resistant to synthetic insecticides. This study aimed to determine the potency of the ethanol extract of noni leaves to kill and repel German cockroaches and affect the amount of food consumed. <b>Materials and Methods:</b> The methods used in this study were the contact toxicity test, the repellency test and the food consumption test. The noni leaves extract and German cockroach populations were provided in the laboratory. <b>Results:</b> The noni leaves extract concentration of 20% (residue of 3.14 mg cm<sup>2</sup> <sup>1</sup>) was very effective in killing the standard population and effective in killing the field population of German cockroaches. The sub-lethal concentration noni leaves extract of 0.36% (residue 0.056 mg cm<sup>2</sup> <sup>1</sup>) and 1.08% (residue 0.169 mg cm<sup>2</sup> <sup>1</sup>) was very high grade as repellent of German cockroaches. The sub-lethal concentration of noni leaves extract did not inhibit the amount of food consumption in German cockroach populations. <b>Conclusion:</b> Leaves of noni plants can be used as bioinsecticides to control German cockroach populations that have been resistant to commercial insecticides.
Asunto(s)
Agentes de Control Biológico/normas , Cucarachas/efectos de los fármacos , Morinda/metabolismo , Extractos Vegetales/aislamiento & purificación , Animales , Agentes de Control Biológico/farmacología , Agentes de Control Biológico/uso terapéutico , Extractos Vegetales/uso terapéuticoRESUMEN
The functional expression of the cockroach Pameα7 nicotinic acetylcholine receptor subunit has been previously studied, and was found to be able to form a homomeric receptor when expressed in Xenopus laevis oocytes. In this study, we found that the neonicotinoid insecticide imidacloprid is unable to activate the cockroach Pameα7 receptor, although thiacloprid induces low inward currents, suggesting that it is a partial agonist. In addition, the co-application or 5 min pretreatment with 10 µM imidacloprid increased nicotine current amplitudes, while the co-application or 5 min pretreatment with 10 µM thiacloprid decreased nicotine-evoked current amplitudes by 54% and 28%, respectively. This suggesting that these two representatives of neonicotinoid insecticides bind differently to the cockroach Pameα7 receptor. Interestingly, the docking models demonstrate that the orientation and interactions of the two insecticides in the cockroach Pameα7 nAChR binding pocket are very similar. Electrophysiological results have provided evidence to suggest that imidacloprid and thiacloprid could act as modulators of the cockroach Pameα7 receptors.
Asunto(s)
Insecticidas/farmacología , Neonicotinoides/farmacología , Antagonistas Nicotínicos/farmacología , Nitrocompuestos/farmacología , Tiazinas/farmacología , Animales , Cucarachas/efectos de los fármacos , Agonistas Nicotínicos/farmacología , Oocitos/efectos de los fármacos , Oocitos/metabolismo , Técnicas de Placa-Clamp , Receptores Nicotínicos , Xenopus laevisRESUMEN
This study investigated the efficacy of isoflurane in Madagascar hissing cockroaches (Gromphadorhina portentosa). Cockroaches (n = 12) were placed in a 2-L anesthesia chamber with isoflurane initiated at 5% at 2 L/m. Movement of antennae, mandibles, and legs and righting reflex were assessed, with full induction achieved when all responses had ceased for 2 m. Cockroach movement became ataxic on average (±SD) 3.5 ± 0.9 m after isoflurane treatment, and induction occurred on average 18.7 ± 4.4 m after treatment. Loss of righting reflex was the most consistent indication of full induction. Cockroaches fully recovered on average 16.2 ± 5.6 m after removal of isoflurane inhalant. Induction was uneventful, and no mortality or obvious morbidity was observed in treated cockroaches up to 30 d posttreatment. The authors conclude that the use of inhalant isoflurane is both safe and effective for anesthesia of Madagascar hissing cockroaches.
Asunto(s)
Anestésicos por Inhalación/farmacología , Cucarachas/efectos de los fármacos , Isoflurano/farmacología , AnimalesRESUMEN
Understanding the process of resistance development of German cockroach, Blattella germanica (L.), in detail is necessary to potentially delay the development of insecticides resistance by rotation or discontinuation of insecticides at the right time. In this study, we investigated the resistance development of the reared German cockroach to chlorpyrifos (CPF) for 23 generations from susceptible cockroaches. CPF 50% lethal dose (LD50) and resistance ratio of each generation cockroaches were determined. The CPF LD50 to each generation cockroaches was used as the insecticide selection pressure of this generation by topical application. The resistance development curve was depicted according to the CPF LD50 to all 23 generations of cockroaches. As a result, a highly resistant German cockroach cohort to CPF, which the resistance ratio was 21.63, was obtained after 23 generations' selection. During the selection, the cockroaches developed low resistance from F1 to F5, moderate resistance from F6 to F12, and high resistance from F13 to F23. There was a rapid resistance increase every 5-7 generations. The resistance growing showed relatively slow from F1 to F11. The fastest growing phase of the resistance was from F12 to F20, in which accounted for more than 80% of the total resistance increase in 23 generations. The development of resistance to CPF tended to slow down from F21 to F23. These findings may provide a basis for the rational use of insecticides, delaying the development of resistance by rotation or discontinuation.
Asunto(s)
Blattellidae/efectos de los fármacos , Cloropirifos/metabolismo , Cucarachas/efectos de los fármacos , Insecticidas/farmacología , Animales , Resistencia a los Insecticidas/efectos de los fármacos , Dosificación Letal Mediana , Personalidad/efectos de los fármacos , RotaciónRESUMEN
A multitude of factors affect the assemblies of complex microbial communities associated with animal hosts, with implications for community flexibility, resilience, and long-term stability; however, their relative effects have rarely been deduced. Here, we use a tractable lab model to quantify the relative and combined effects of parental transmission (egg case microbiome present/reduced), gut inocula (cockroach versus termite gut provisioned), and varying diets (matched or unmatched with gut inoculum source) on gut microbiota structure of hatchlings of the omnivorous cockroach Shelfordella lateralis using 16S rRNA gene (rDNA) amplicon sequencing. We show that the presence of a preexisting bacterial community via vertical transmission of microbes on egg cases reduces subsequent microbial invasion, suggesting priority effects that allow initial colonizers to take a strong hold and which stabilize the microbiome. However, subsequent inoculation sources more strongly affect ultimate community composition and their ecological networks, with distinct host-taxon-of-origin effects on which bacteria establish. While this is so, communities respond flexibly to specific diets in ways that consequently impact predicted community functions. In conclusion, our findings suggest that inoculations drive communities toward different stable states depending on colonization and extinction events, through ecological host-microbe relations and interactions with other gut bacteria, while diet in parallel shapes the functional capabilities of these microbiomes. These effects may lead to consistent microbial communities that maximize the extended phenotype that the microbiota provides the host, particularly if microbes spend most of their lives in host-associated environments.IMPORTANCE When host fitness is dependent on gut microbiota, microbial community flexibility and reproducibility enhance host fitness by allowing fine-tuned environmental tracking and sufficient stability for host traits to evolve. Our findings lend support to the importance of vertically transmitted early-life microbiota as stabilizers, through interactions with potential colonizers, which may contribute to ensuring that the microbiota aligns within host fitness-enhancing parameters. Subsequent colonizations are driven by microbial composition of the sources available, and we confirm that host-taxon-of-origin affects stable subsequent communities, while communities at the same time retain sufficient flexibility to shift in response to available diets. Microbiome structure is thus the result of the relative impact and combined effects of inocula and fluctuations driven by environment-specific microbial sources and digestive needs. These affect short-term community structure on an ecological time scale but could ultimately shape host species specificities in microbiomes across evolutionary time, if environmental conditions prevail.
Asunto(s)
Bacterias/genética , Cucarachas/microbiología , Dieta , Microbiota/genética , Animales , Antiinfecciosos/farmacología , Bacterias/clasificación , Bacterias/efectos de los fármacos , Bacterias/patogenicidad , Cucarachas/efectos de los fármacos , Especificidad del Huésped , Transmisión Vertical de Enfermedad Infecciosa , Microbiota/fisiología , Óvulo/efectos de los fármacos , Óvulo/microbiología , Filogenia , ARN Ribosómico 16SRESUMEN
The use of chemical insecticides has had many adverse effects. This study reports a novel perspective on the application of insect-based compounds to repel and eradicate other insects in a controlled environment. In this work, defense fluid was shown to be a repellent and insecticide against termites and cockroaches and was analyzed using gas chromatography-mass spectrometry (GC-MS). Globitermes sulphureus extract at 20 mg/ml showed the highest repellency for seven days against Macrotermes gilvus and for thirty days against Periplaneta americana. In terms of toxicity, G. sulphureus extract had a low LC50 compared to M. carbonarius extract against M. gilvus. Gas chromatography-mass spectrometry analysis of the M. carbonarius extract indicated the presence of six insecticidal and two repellent compounds in the extract, whereas the G. sulphureus extract contained five insecticidal and three repellent compounds. The most obvious finding was that G. sulphureus defense fluid had higher potential as a natural repellent and termiticide than the M. carbonarius extract. Both defense fluids can play a role as alternatives in the search for new, sustainable, natural repellents and termiticides. Our results demonstrate the potential use of termite defense fluid for pest management, providing repellent and insecticidal activities comparable to those of other green repellent and termiticidal commercial products.
Asunto(s)
Repelentes de Insectos/farmacología , Isópteros/química , Animales , Cucarachas/efectos de los fármacos , Cromatografía de Gases y Espectrometría de Masas , Repelentes de Insectos/química , Insecticidas/química , Insecticidas/farmacologíaRESUMEN
The global detection of ciprofloxacin and atrazine in soil is linked to intensive anthropogenic activities in agriculture and inadvertent discharge of industrial wastes to the environment. Nauphoeta cinerea is a terrestrial insect with cosmopolitan distribution and great environmental function. The current study probed the neurobehavioral and cellular responses of N. cinerea singly and jointly exposed to atrazine (1.0 and 0.5 µg g-1 feed) and ciprofloxacin (0.5 and 0.25 µg g-1 feed) for 63 days. Results demonstrated that the reductions in the body rotation, maximum speed, turn angle, path efficiency, distance traveled, episodes, and time of mobility induced by atrazine or ciprofloxacin per se was exacerbated in the co-exposure group. The altered exploratory and locomotor in insects singly and jointly exposed to ciprofloxacin and atrazine were verified by track plots and heat maps. Furthermore, we observed a decrease in acetylcholinesterase and anti-oxidative enzyme activities with concomitant elevation in the levels of lipid peroxidation, nitric oxide, and reactive oxygen and nitrogen species were significantly intensified in the midgut, hemolymph, and head of insects co-exposed to ciprofloxacin and atrazine. In conclusion, exposure to binary mixtures of ciprofloxacin and atrazine elicited greater locomotor and exploratory deficits than upon exposure to the individual compound by inhibiting acetylcholinesterase activity and induction of oxido-inflammatory stress responses in the insects. N. cinerea may be a usable model insect for checking contaminants of ecological risks.
Asunto(s)
Atrazina , Ciprofloxacina , Cucarachas/efectos de los fármacos , Contaminantes Ambientales/toxicidad , Acetilcolinesterasa/metabolismo , Animales , Atrazina/toxicidad , Ciprofloxacina/toxicidad , Cucarachas/metabolismo , Peroxidación de Lípido , Estrés OxidativoRESUMEN
The development of new models to study diabetes in invertebrates is important to ensure adherence to the 3R's principle and to expedite knowledge of the complex molecular events underlying glucose toxicity. Streptozotocin (STZ)-an alkylating and highly toxic agent that has tropism to mammalian beta cells-is used as a model of type 1 diabetes in rodents, but little is known about STZ effects in insects. Here, the cockroach; Nauphoeta cinerea was used to determine the acute toxicity of 74 and 740 nmol of STZ injection per cockroach. STZ increased the glucose content, mRNA expression of glucose transporter 1 (GLUT1) and markers of oxidative stress in the head. Fat body glycogen, insect survival, acetylcholinesterase activity, triglyceride content and viable cells in head homogenate were reduced, which may indicate a disruption in glucose utilization by the head and fat body of insects after injection of 74 and 740 nmol STZ per nymph. The glutathione S-transferase (GST) activity and reduced glutathione levels (GSH) were increased, possibly via activation of nuclear factor erythroid 2 related factor as a compensatory response against the increase in reactive oxygen species. Our data present the potential for metabolic disruption in N. cinerea by glucose analogues and opens paths for the study of brain energy metabolism in insects. We further phylogenetically demonstrated conservation between N. cinerea glucose transporter 1 and the GLUT of other insects in the Neoptera infra-class.
Asunto(s)
Encéfalo/metabolismo , Cucarachas/metabolismo , Proteínas Facilitadoras del Transporte de la Glucosa/metabolismo , Glucosa/metabolismo , Estrés Oxidativo , Filogenia , Estreptozocina/farmacología , Animales , Antibióticos Antineoplásicos/farmacología , Encéfalo/efectos de los fármacos , Cucarachas/efectos de los fármacos , Cucarachas/genética , Proteínas Facilitadoras del Transporte de la Glucosa/genética , Glutatión/metabolismo , Glutatión Transferasa/metabolismoRESUMEN
Rhinella schneideri is a common toad found in South America, whose paratoid toxic secretion has never been explored as an insecticide. In order to evaluate its insecticidal potential, Nauphoeta cinerea cockroaches were used as an experimental model in biochemical, physiological and behavioral procedures. Lethality assays with Rhinella schneideri paratoid secretion (RSPS) determined the LD50 value after 24 h (58.07µg/g) and 48 h exposure (44.07 µg/g) (R2 = 0.882 and 0.954, respectively). Acetylcholinesterase activity (AChE) after RSPS at its highest dose promoted an enzyme inhibition of 40%, a similar effect observed with neostigmine administration (p < 0.001, n= 5). Insect locomotion recordings revealed that RSPS decreased the distance traveled by up to 37% with a concomitant 85% increase in immobile episodes (p < 0.001, n = 36). RSPS added to in vivo cockroach semi-isolated heart preparation promoted an irreversible and dose dependent decrease in heart rate, showing a complete failure after 30 min recording (p < 0.001, n ≥ 6). In addition, RSPS into nerve-muscle preparations induced a dose-dependent neuromuscular blockade, reaching a total blockage at 70 min at the highest dose applied (p < 0.001, n ≥ 6). The effect of RSPS on spontaneous sensorial action potentials was characterized by an increase in the number of spikes 61% (p < 0.01). Meanwhile, there was 42% decrease in the mean area of those potentials (p < 0.05, n ≥ 6). The results obtained here highlight the potential insecticidal relevance of RSPS and its potential biotechnological application.
Asunto(s)
Venenos de Anfibios/farmacología , Bufo marinus/metabolismo , Inhibidores de la Colinesterasa/farmacología , Cucarachas/efectos de los fármacos , Insecticidas/farmacología , Unión Neuromuscular/efectos de los fármacos , Glándula Parótida/metabolismo , Acetilcolinesterasa/metabolismo , Venenos de Anfibios/metabolismo , Animales , Inhibidores de la Colinesterasa/metabolismo , Cucarachas/enzimología , Relación Dosis-Respuesta a Droga , Femenino , Proteínas de Insectos/antagonistas & inhibidores , Proteínas de Insectos/metabolismo , Insecticidas/metabolismo , Dosificación Letal Mediana , Locomoción/efectos de los fármacos , Masculino , Unión Neuromuscular/enzimología , Vías SecretorasRESUMEN
Many relevant aspects of mammal's cardiac physiology have been mainly investigated in insect models such as Drosophila melanogaster and Periplaneta americana. Cardiac function has been poorly studied in the cockroach Gromphadorhina portentosa, which has some advantages for experimental purposes such as an easier culture, bigger organs and a robust physiology. On the other hand, the study of cardiac physiology in insects has been largely improved since the arrival of digital imaging technologies for recording purposes. In the present work, we introduce a methodology of video recording coupled to an isotonic transducer for a three-dimensional analysis of the heart and intracardiac valves of G. portentosa. We used this methodology for assessing the physiological responses of the cockroach heart upon the application of different cholinergic neurotransmitters (acetylcholine, nicotine and muscarine). We recorded in detail the relationship between intracardiac valves movement, hemolymph flow, diastole and systole. Acetylcholine and nicotine induced a biphasic effect on the cardiac frequency. Acetylcholine increased the diastolic opening. Nicotine at high concentration caused paralysis. Muscarine induced no major effects. These findings suggest a combined action of cholinergic agonists for a finely tuned the cardiac frequency, intracardiac valves function and cardiac cycle.
Asunto(s)
Acetilcolina/farmacología , Agonistas Colinérgicos/farmacología , Cucarachas/efectos de los fármacos , Cucarachas/fisiología , Animales , Corazón/efectos de los fármacos , Corazón/fisiología , Imagenología Tridimensional/métodos , Grabación en Video/métodosRESUMEN
Jaburetox is a recombinant peptide derived from one of the Canavalia ensiformis urease isoforms. This peptide induces several toxic effects on insects of different orders, including interference on muscle contractility in cockroaches, modulation of UDP-N-acetylglucosamine pyrophosphorylase (UAP) and nitric oxide synthase (NOS) activities in the central nervous system of triatomines, as well as activation of the immune system in Rhodnius prolixus. When injected, the peptide is lethal for R. prolixus and Triatoma infestans. Here, we evaluated Jaburetox toxicity to Nauphoeta cinerea cockroaches, exploring the effects on the central nervous system through the activities of UAP, NOS, acid phosphatases (ACP), and acetylcholinesterase (AChE). The results indicated that N. cinerea is not susceptible to the lethal effect of the peptide. Moreover, both in vivo and in vitro treatments with Jaburetox inhibited NOS activity, without modifying the protein levels. No alterations on ACP activity were observed. In addition, the enzyme activity of UAP only had its activity affected at 18 hr after injection. The peptide increased the AChE activity, suggesting a mechanism involved in overcoming the toxic effects. In conclusion, our findings indicate that Jaburetox affects the nitrinergic signaling as well as the AChE and UAP activities and establishes N. cinerea as a Jaburetox-resistant model for future comparative studies.
Asunto(s)
Cucarachas/efectos de los fármacos , Cucarachas/enzimología , Proteínas de Plantas/toxicidad , Ureasa/toxicidad , Acetilcolinesterasa/efectos de los fármacos , Fosfatasa Ácida/efectos de los fármacos , Animales , Sistema Nervioso Central/efectos de los fármacos , Femenino , Masculino , Óxido Nítrico Sintasa/efectos de los fármacos , Nucleotidiltransferasas/efectos de los fármacos , Proteínas Recombinantes/toxicidadRESUMEN
OBJECTIVE: Monosodium glutamate (MSG) is a food additive that has been shown to be toxic to rodents at high concentrations. The available studies in Drosophila melanogaster suggest that MSG toxicity depends on concentration and gender, thus the safety of MSG as a food enhancer still requires further investigation. We have documented impaired locomotor activity and altered oxidative stress markers in cockroaches co-exposed to methylmercury and monosodium glutamate (MSG). We herein examined the susceptibility of Nauphoeta cinerea to high and low concentrations (4% and 1%) of MSG, while monitoring the activities of acetylcholinesterase (AChE), as well as markers of oxidative stress and antioxidant activity over 30 days. RESULTS: There was no significant alteration in the parameters assessed at 1% MSG while 4% MSG caused an increase in the activity of reactive oxygen and nitrogen species, with a corresponding reduction in the activities of acetylcholinesterase, glutathione-S-transferase and catalase, suggesting the capacity of MSG to alter redox homeostasis in Nauphoeta cinerea.
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Acetilcolinesterasa/efectos de los fármacos , Conducta Animal/efectos de los fármacos , Catalasa/efectos de los fármacos , Cucarachas/efectos de los fármacos , Glutatión Transferasa/efectos de los fármacos , Locomoción/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Glutamato de Sodio/farmacología , Animales , Glutamato de Sodio/administración & dosificaciónRESUMEN
Nanomaterials have become increasingly important in medicine, manufacturing, and consumer products. A fundamental understanding of the effects of nanoparticles (NPs) and their interactions with biomolecules and organismal systems has yet to be achieved. In this chapter, we firstly provide a brief review of the interactions between nanoparticles and biological systems. We then provide an example by describing a novel method to assess the effects of NPs on biological systems, using insects as a model. Nanoparticles were injected into the central nervous system of the discoid cockroach (Blaberus discoidalis). It was found that insects became hyperactive compared to negative control (water injections). Our method could provide a generic method of assessing nanoparticles toxicity.
Asunto(s)
Cucarachas/fisiología , Actividad Motora/efectos de los fármacos , Nanopartículas/toxicidad , Animales , Sistema Nervioso Central/química , Sistema Nervioso Central/efectos de los fármacos , Sistema Nervioso Central/fisiología , Cucarachas/efectos de los fármacos , Femenino , Masculino , Modelos Animales , Nanopartículas/administración & dosificaciónRESUMEN
Toxicity profiles of four aliphatic (α-pinene, cyclononanone, limonene, nerolidol), four aromatic (ß-thujaplicin, carvacrol, eugenol, tropolone) essential oil components (EOCs), and permethrin were investigated against three strains of German cockroach, Blattella germanica (L.). The strains include a susceptible strain (S), and two multi-resistant strains - strains D and E. Also, a synergism bioassay, using piperonyl butoxide (PBO) was conducted. The most toxic EOCs were aromatic EOCs carvacrol, eugenol, and tropolone, followed by aliphatic EOC limonene; all had LD50 values of <0.7 mg/µl. Four of the EOCs were equally toxic against all the strains, with carvacrol being the most toxic, followed by eugenol, tropolone, and α-pinene. The other four EOCs were more toxic against strain S than against the two resistant strains. Permethrin was significantly more toxic to strain S (LD50 = 0.056 µg/µl) compared with the resistant strains (D = 2.138 µg/µl, E = 1.730 µg/µl). Toxicity of aliphatic EOCs correlated positively with their molecular weight against strain E only, whereas both molecular weight and vapor pressure of aromatic EOCs correlated significantly with toxicity in all strains. Strain D exhibited the greatest resistance (RR of 6.7) to EOCs, and synergism to the aliphatic EOC cyclononanone. Clear synergism with PBO was observed in permethrin against resistant strains, but not in all of the EOCs, suggesting multiple resistance mechanisms in the resistant cockroaches. These findings give insight on the potential of EOCs to be incorporated as parts of an IPM approach to managing insecticide resistant German cockroaches.
Asunto(s)
Blattellidae/efectos de los fármacos , Cucarachas/efectos de los fármacos , Insecticidas/farmacología , Aceites Volátiles , Animales , Resistencia a los Insecticidas/efectos de los fármacos , Permetrina , Butóxido de PiperoniloRESUMEN
Vinylcyclohexene (VCH) is an environmental contaminant well known for its ovotoxicant effects in several organisms. However, the mechanisms underlying the toxicity of VCH as well as its harmful effects toward other organs are until unclear. In this work, we assess some endpoint signals of toxicity induced by volatilized VCH exposure using nymphs of the lobster cockroach Nauphoeta cinerea. Nymphs were exposed to VCH via inhalation for 70 days. The levels of volatilized VCH were quantified by headspace gas chromatography and the concentration varied between 3.41 and 7.03â¯nmol/µl. VCH inhalation caused a reduction of 35% in the survival rate of the exposed animals. Nymphs exposed to volatilized VCH for 35 and 70 days had a reduction in the body weight gain of 1.8- and 2.6-fold, respectively with a reduction in dissected head, fat body, and maturing reproductive organs. The exposure did not change water consumption, excepting on the 20th day (with a 3-fold change) and decreased the food intake significantly. Regarding biochemical markers, we found that the activity of GST from the dissected organs was increased by volatilized VCH after both 35 and 70 days of exposure. The fat body presented the most prominent GST activity especially after 35 days of exposure with 1.6-fold higher than the control group. Exposure also caused an increase in RS levels in the fat body of 1.35-fold and 1.47-fold after 35 and 70 days, respectively and did not affect the activity of the AChE from the head. Our findings support the harmful impact of volatilized VCH inhalation, highlighting the cockroach N.cinerea as a valuable insect model to investigate environmental toxicants.
Asunto(s)
Cucarachas/efectos de los fármacos , Ciclohexenos/toxicidad , Ninfa/efectos de los fármacos , Administración por Inhalación , Animales , Cucarachas/enzimología , Cuerpo Adiposo/efectos de los fármacos , Cuerpo Adiposo/enzimología , Glutatión Transferasa/metabolismo , Ninfa/enzimología , VolatilizaciónRESUMEN
Standard chemical insecticides present mainly neurotoxic effects and are becoming less and less effective due to insects developing resistance to them. One of the innovative strategies to control insects pests is to find a way to increase the sensitivity of the target sites in the insect nervous system to the applied insecticides. In the presented research, we proposed menthol, a component of essential oils, as a factor increasing the effectiveness of bendiocarb, a carbamate insecticide. The aim of our study was to evaluate the potentiation of the bendiocarb effect by menthol. In toxicity tests performed on Periplaneta americana, menthol (0.1⯵M) accelerated the lethal effect of bendiocarb, primarily in its low concentrations (lower than 0.05â¯mM). In the presence of menthol (1 and 0.1⯵M), the ability of insects to turn back from its dorsal to the normal ventral side was significantly lower than with bendiocarb (1⯵M) alone. We also evaluated the effectiveness of chemicals on the activity of the ventral nerve cord of the cockroach. In this preparation, bendiocarb (1⯵M and higher concentrations) caused an irregular, spontaneous bursts of action potentials. The total nerve activity (including the response to stimulation and spontaneous firing) was much higher when bendiocarb was applied in the presence of menthol (1⯵M). The effect of menthol was similar to the octopamine effect and was abolished by phentolamine, the octopamine receptor antagonist. Our results clearly indicated a strengthening effect of menthol on bendiocarb effectiveness; potentiation occurred through octopamine receptors activation.
Asunto(s)
Carbamatos/farmacología , Cucarachas/efectos de los fármacos , Insecticidas/farmacología , Mentol/farmacología , Aceites Volátiles/química , Fenilcarbamatos/farmacología , Acetilcolinesterasa/metabolismo , Animales , Interacciones Farmacológicas , Resistencia a los InsecticidasRESUMEN
Indoxacarb, a commercialized oxadiazine insecticide, nearly irreversibly blocks open/inactivated, but not resting sodium channels. The structure-activity relationships showed that the substituents at the position of the chiral atom in the oxadiazine ring are very important to the biological activity of oxadiazine insecticide. Here we synthesized a series of tricyclic oxadiazine 4a-methyl ester derivatives. The chiral atom in the oxadiazine ring has been epimerized and substituted with either pyrethric acid or cinnamic acid derivatives. Benzene ring in the tricyclic moiety was substituted with a chlorine, fluorine, or bromine atom, and nitrogen-linked benzene ring was substituted with a trifluoromethyl or trifluoromethoxy group. Toxicity of these compounds against Spodoptera litura F. was evaluated. Diastereoisomers of most toxic compounds J7 and J9 with pyrethric acid moiety were separated by flash column chromatography. The more polar diastereoisomers, J7-L-Rf and J9-L-Rf, and compounds J24 and J26 with cinnamic acid moiety exhibited highest insecticidal activities. We further used Monte Carlo energy minimizations to dock compound J7 and J24 in the NavMs-based homology model of the open cockroach sodium channel. In the low-energy binding modes, the compound interacted with residues in the inner pore and domain interfaces, which previously were proposed to contribute to receptors of pyrethroids and sodium channel blocker insecticides. Our results define compound J7 and J24 as a potentially useful optimized hit for the development of multiple sites sodium channel blocker or modulator.