Novaluron impairs the silk gland and productive performance of silkworm Bombyx mori (Lepidoptera: Bombycidae) larvae.

This study investigates the effects of the insect growth regulator Novaluron on the silk gland (SG) and silk cocoon production in a nontarget insect, the silkworm Bombyx mori, which is a model research insect among Lepidoptera and of great economic importance for the commercial production of silk threads. Larvae were segregated into experimental groups: the control group (CG) and the treatment group (TG), which was exposed to a Novaluron concentration of 0.15 mL/L. Following exposure, we analyzed the cytotoxic effects on the epithelial cells of the anterior, middle and posterior regions of the SG of B. mori larvae in the 3rd, 4th, and 5th instars, as well as the quality of the cocoons from larvae in the 5th instar. Cytotoxic effects were observed in the TG, such as the dilation of cells, emission of cytoplasmic protrusions, extreme rarefaction of the cytoplasm and nuclei, dilation of the endoplasmic reticulum, intracellular and intercellular spaces, spacing between the epithelial cells and the basal lamina and detachment of some cells towards the lumen of the SG, and decreased protein in the lumen, with faults in its composition. In addition, we verified ultrastructural changes in the production of fibers and silk cocoons, including a reduction in the weight of the cocoons constructed by both males and females in the TG and the construction of defective cocoons. Novaluron exposure impairs the SG and may affect the physiological functions of this organ; additionally, it compromises the quality of silk cocoons, potentially causing serious damage to sericulture.

Negative impact of Novaluron on the nontarget insect Bombyx mori (Lepidoptera: Bombycidae).

Due to increased use of agrochemicals and growing concerns about ecotoxicology, the development of new insecticides, moving away from those with neurotoxic and broad spectrum effects towards insecticides that are safer for the environment and nontarget beneficial species, has been a research priority. Novaluron stands out among these newer insecticides, is an insect growth regulator that is used for the control of insect pests in crops grown close to mulberry plantations. Mulberry serves as food for the silkworm Bombyx mori, which is a nontarget insect of great economic importance to silk production. We investigated the lethal and sublethal effects of Novaluron on the development of B. mori. Larvae were segregated into experimental groups: the control groups (CGs) and the treatment groups (TGs), which were treated with the Novaluron concentration of 0.15 mL/L. Following exposure, we analyzed: larval mortality, changes in the insect life cicle and cytotoxic effects on the midgut cells. This is the first report about the Novaluron's effects on B.mori. We detected rupture in the integument, complete cessation of feeding, late development, incomplete ecdysis and production of defective cocoons. After 240 h of exposure, there was 100% mortality in TG larvae exposed in the 3rd instar and 20% mortality from larvae exposed in the 5th instar. Cytotoxic effects was observed, such as dilation of cells, emission of cytoplasmic protrusions, extreme rarefaction of the cytoplasm and nuclei, dilation of the endoplasmic reticulum in addition to changes in mitochondria, the presence of large digestive vacuoles and intercellular spaces and the presence of active caspase. Novaluron exposure impairs the midgut and may affect the physiological functions of this organ. Novaluron additionally compromises several phases of insect development, indicating the importance of toxicology studies that utilize different life stages of nontarget species to evaluate the safe use of insecticides.

Ampullae infection of the malpighian tubules of Bombyx mori by Alphabaculovirus / Infecção de células da ampola dos túbulos de malpighi de Bombyx mori pelo Alphabaculovirus

Alphabaculovirus is a genus of the entomopathogenic virus, whose species Bombyx mori nucleopolyhedrovirus (BmNPV) infects the silkworm, Bombyx mori, which is an important insect in the sericulture industry. A geographic isolate of BmNPV was identified in the state of Paraná, Brazil. It was infecting B. mori larvae and various organs and target tissues were identified, however, there was no information about the infection of Malpighian tubules (MT). The MT comprises the excretory system of B. mori and acts in the elimination of toxic substances and in hydroelectrolytic homeostasis. Thus, the present study examined the susceptibility and cytopathology of B. mori MT to BmNPV. To this end, hybrid fifth instar larvae were inoculated with a virus suspension at different days post-inoculation (dpi). MT segments were collected and divided into the ampullae, proximal, medial and distal regions. These were processed for light microscopy and transmission electron analysis. The MT regions revealed differences in susceptibility to BmNPV and the ampullae in its transition area was infected from the sixth dpi; the other regions did not reveal any evidence of infection. The transition area of the ampullae has not been previously described in Lepidoptera and its cytopathology revealed a hypertrophic nucleus with viroplasm, followed by the formation and development of viral polyhedra, which are common characteristics of infections by Alphabaculovirus. Thus, infection of the ampullae of the MT of B. mori by BmNPV, together with other known targets, compromises the metabolic balance of the insect, which results in consequences for silk production and damage to the sericulture sector.

Alphabaculovirus é um gênero de vírus entomopatogênico, cuja espécie Bombyx mori nucleopolyhedrovirus (BmNPV) infecta o bicho-da-seda, Bombyx mori, inseto importante na indústria sericícola. Um isolado geográfico do BmNPV foi identificado no estado do Paraná, Brasil, infectando lagartas de B. mori e vários órgãos e tecidos alvos foram identificados; entretanto, não há informações sobre a infecção do túbulo de Malpighi (TM). O TM compõe o sistema excretor de B. mori, atuando na eliminação de substâncias tóxicas e na homeostase hidroeletrolítica. Assim, o presente estudo, analisou a susceptibilidade e a citopatologia do TM de B. mori ao BmNPV. Para tanto, lagartas híbridas de 5° instar foram inoculadas com uma suspensão viral e em diferentes dias pós-inoculação (dpi), segmentos do TM foram coletados e subdivididos nas regiões da ampola, proximal, média e distal; sendo processados para análises em microscopias de luz e eletrônica de transmissão. As regiões do TM revelaram diferenças na susceptibilidade ao BmNPV e a ampola, na sua área de transição, foi infectada a partir do 6° dpi, já as demais regiões não revelaram quaisquer indícios de infecção. A área de transição da ampola, ainda não havia sido descrita em lepidópteros e sua citopatologia revelou núcleo hipertrófico com viroplasma, seguido da formação e desenvolvimento dos poliedros virais, características comuns das infecções pelo Alphabaculovirus. Assim, a infecção da ampola do TM de B. mori ao BmNPV, somada a de outros alvos conhecidos, compromete o equilíbrio metabólico do inseto, com consequências na produção de seda e prejuízos ao setor sericícola.

Mulberry leaves treated with bordeaux mixture protect silkworm caterpillars against fungal and viral diseases / Folhas de amoreira tratadas com calda bordalesa protegem lagartas de bicho-da-seda contra doenças fúngicas e virais

The bordeaux mixture is used as a natural agricultural fungicide, and its application in sericulture can benefit the production of silkworm cocoons, Bombyx mori (Lepidoptera: Bombycidae). The aim of this study was to verify whether the bordeaux mixture exerts a protective effect in B. mori against fungal and viral diseases. This experiment was performed during two seasons, autumn and spring, in which 7,500 caterpillars were used at the beginning of the third instar and divided into five groups, with three repetitions of 500 individuals each. In the three groups, the caterpillars were fed leaves of Mulberry (Morus spp.) that were enriched with an aqueous bordeaux mixture solution at concentrations of 5, 10 and 20%. One group was fed exclusively mulberry leaves (control), and another was fed leaves that were moistened with water. Fungal contamination was evaluated in the integumentary surface of the insect and the mulberry leaves in the bed of creation by checking the number of colony-forming units (CFU). In the analysis of viral contamination, 20 caterpillars from each group at the beginning of the fifth instar were inoculated with 10 μl of a suspension of Bombyx mori nucleopolyhedrovirus (BmNPV). Daily, from the second to the ninth day after inoculation (dai), two caterpillars of each group were anesthetized and formalin-fixed 7% for microscopic processing and viral cytopathology analysis. A completely randomized design was used, and the CFU were compared by Tukey test with 5% significance. The results showed a decrease of 55.1% in CFU present on the mulberry leaves in the fall, when the 5% bordeaux mixture solution was used. There was no significant difference between the groups based on the bordeaux mixture in this period.[...](AU)

A calda bordalesa é um produto usado como fungicida agrícola natural e sua aplicação em sericicultura pode beneficiar a produção de casulos do bicho-da-seda, Bombyx mori (Lepidoptera: Bombycidae). O objetivo deste estudo foi verificar se a calda bordalesa exerce efeito protetor em B. mori contra doenças fúngicas e virais. O experimento foi realizado em dois períodos sazonais, outono e primavera, sendo utilizadas 7.500 lagartas no início do terceiro instar, divididas em cinco grupos, com três repetições de 500 indivíduos cada. Em três grupos as lagartas foram alimentadas com folhas de amoreira (Morus spp.) enriquecidas com solução aquosa de calda bordalesa nas concentrações de 5, 10 e 20%. Um grupo foi alimentado exclusivamente com folhas de amoreira (controle) e outro com folhas umedecidas apenas com água. A contaminação fúngica foi avaliada na superfície tegumentar do inseto e nas folhas de amoreira presentes na cama de criação, através da verificação do número de unidades formadoras de colônias (UFC). Já na análise da contaminação viral, 20 lagartas de cada grupo, no início do quinto instar, foram inoculadas com 10 μl da suspensão de Bombyx mori nucleopolyhedrovirus (BmNPV). Diariamente, do segundo ao nono dia após a inoculação (dpi), duas lagartas de cada grupo foram anestesiados e fixadas em formol 7%, para o processamento microscópico e análise da citopatologia viral. Foi adotado um delineamento inteiramente casualizado e as médias de UFC foram comparadas por teste de Tukey, com 5% de significância. Os resultados revelaram uma redução de 55,1% nas UFC presentes nas folhas de amoreira no outono, quando foi utilizada a solução 5% de calda bordalesa. Não houve diferença significativa entre os grupos à base de calda bordalesa neste período.[...](AU)

Mulberry leaves treated with bordeaux mixture protect silkworm caterpillars against fungal and viral diseases / Folhas de amoreira tratadas com calda bordalesa protegem lagartas de bicho-da-seda contra doenças fúngicas e virais

The bordeaux mixture is used as a natural agricultural fungicide, and its application in sericulture can benefit the production of silkworm cocoons, Bombyx mori (Lepidoptera: Bombycidae). The aim of this study was to verify whether the bordeaux mixture exerts a protective effect in B. mori against fungal and viral diseases. This experiment was performed during two seasons, autumn and spring, in which 7,500 caterpillars were used at the beginning of the third instar and divided into five groups, with three repetitions of 500 individuals each. In the three groups, the caterpillars were fed leaves of Mulberry (Morus spp.) that were enriched with an aqueous bordeaux mixture solution at concentrations of 5, 10 and 20%. One group was fed exclusively mulberry leaves (control), and another was fed leaves that were moistened with water. Fungal contamination was evaluated in the integumentary surface of the insect and the mulberry leaves in the bed of creation by checking the number of colony-forming units (CFU). In the analysis of viral contamination, 20 caterpillars from each group at the beginning of the fifth instar were inoculated with 10 μl of a suspension of Bombyx mori nucleopolyhedrovirus (BmNPV). Daily, from the second to the ninth day after inoculation (dai), two caterpillars of each group were anesthetized and formalin-fixed 7% for microscopic processing and viral cytopathology analysis. A completely randomized design was used, and the CFU were compared by Tukey test with 5% significance. The results showed a decrease of 55.1% in CFU present on the mulberry leaves in the fall, when the 5% bordeaux mixture solution was used. There was no significant difference between the groups based on the bordeaux mixture in this period.[...]

A calda bordalesa é um produto usado como fungicida agrícola natural e sua aplicação em sericicultura pode beneficiar a produção de casulos do bicho-da-seda, Bombyx mori (Lepidoptera: Bombycidae). O objetivo deste estudo foi verificar se a calda bordalesa exerce efeito protetor em B. mori contra doenças fúngicas e virais. O experimento foi realizado em dois períodos sazonais, outono e primavera, sendo utilizadas 7.500 lagartas no início do terceiro instar, divididas em cinco grupos, com três repetições de 500 indivíduos cada. Em três grupos as lagartas foram alimentadas com folhas de amoreira (Morus spp.) enriquecidas com solução aquosa de calda bordalesa nas concentrações de 5, 10 e 20%. Um grupo foi alimentado exclusivamente com folhas de amoreira (controle) e outro com folhas umedecidas apenas com água. A contaminação fúngica foi avaliada na superfície tegumentar do inseto e nas folhas de amoreira presentes na cama de criação, através da verificação do número de unidades formadoras de colônias (UFC). Já na análise da contaminação viral, 20 lagartas de cada grupo, no início do quinto instar, foram inoculadas com 10 μl da suspensão de Bombyx mori nucleopolyhedrovirus (BmNPV). Diariamente, do segundo ao nono dia após a inoculação (dpi), duas lagartas de cada grupo foram anestesiados e fixadas em formol 7%, para o processamento microscópico e análise da citopatologia viral. Foi adotado um delineamento inteiramente casualizado e as médias de UFC foram comparadas por teste de Tukey, com 5% de significância. Os resultados revelaram uma redução de 55,1% nas UFC presentes nas folhas de amoreira no outono, quando foi utilizada a solução 5% de calda bordalesa. Não houve diferença significativa entre os grupos à base de calda bordalesa neste período.[...]

Análise morfométrica dos neurônios da curvatura gástrica maior glandular de ratos induzidos ao alcoolismo / Morphometric analysis of gastric neurons of the greater curvature glandular of rats induced to alcoholism

Objetivo: analisar os efeitos do álcool sobre a morfometria dos neurônios do plexo mioentérico da curvatura gástricamaior glandular de ratos submetidos à ingestão crônica de álcool. Método: utilizados 14 ratos Wistar, com 90 dias,distribuídos em: Controle (GC, n=7) e Experimental (GE, n=7). O GC recebeu durante 120 dias ração para roedorese água ad libitum, enquanto o GE recebeu ração e aguardente de cana ad libitum, diluída em água em concentraçõescrescentes de 5% até 30%. A curvatura maior do estômago glandular foi submetida à realização de preparados demembrana de acordo com o método de Giemsa. Foram mensurados 40 campos microscópicos de cada animal. Os cálculosestatísticos realizados utilizando-se o software Prisma 2.0, por meio do teste T de Student com nível de significânciade 5%. Resultados: verificou-se que média da área dos neurônios no GC foi de 43,56±2,69 ?m2 e no GE de 56,03±2,16 ?m2. Quando comparados os pesos finais dos dois grupos observamos que os animais experimentais tiveram umaredução de peso corporal de 18,94% em relação aos controles, com p=0.0002. Conclusão: a ingesta crônica de álcoolem ratos aumentou a área neuronal da curvatura maior do estômago glandular

Objective: to analyze the alcohol effects on the neurons? morphology in the myenteric plexus of the greater gastriccurvature of rats? glandular stomach subjected to chronic alcohol ingestion. Method: 14 Wistar rats with 90 days wereused, distributed into two groups: Control Group (CG n=7) and Experimental Group (EG n = 7). CG animals receivedfood and water ad libitum during 120 days, while EG animals received food and sugar cane brandy ad libitum dilutedin water at increasing concentrations from 5% to 30%. The greater gastric curvature of rats, glandular stomach wassubjected to implementation of membrane preparations according to the Giemsa?s method. 40 microscopic s weremeasured for each animal. Statistical calculations were performed using Prism 2.0 software and t-Student test withsignificance level of 5%. Results: it was identified that neurons? average area in CG was 43,56 ± 2,69 ?m2 and 56,03 ±2,16 ?m2 in EG. When comparing both groups? final weights it was observed that experimental animals had a reductionof body weight of 18.94% when compared to the control group, p = 0.0002. Conclusion: chronic alcohol ingestion inrats increased greater gastric curvature neurons of glandular stomach