ABSTRACT
Background & objectives: Recently, the use of biodegradable and environment friendly plant-based bioinsecticides has received a great deal of attention from researchers to control insect disease vectors. The aim of this research is to determine the larvicidal efficacy of Ruta graveolens essential oil against third instar larvae of two species of mosquito (Culex pipiens and Culiseta longiareolata) and a biological model Drosophila melanogaster. Methods: Culiseta longiareolata and Culex pipiens larvae were collected from untreated areas located in Tebessa and Drosophila melanogaster, the wild strain collected from rotten apples in the Tebessa region. Ruta graveolens essential oil has been tested at different concentrations between 2.5µL/mL and 140µL/mL against third instar larvae of the three species under standard laboratory conditions according to the recommendations from the Word Health Organization. The effects were examined on mortality, growth and the main components (proteins, carbohydrates, lipids). Results: The essential oil showed larvicidal activity with LC50 and LC90 values (10.85µL/mL, 70.95µL/mL and 39.41µL/mL), (26.5µL/mL, 144.5µL/mL and 89.57µL/mL) against third instar larvae of Drosophila melanogaster, Culex pipiens and Culiseta longiareolata respectively. In addition, it disrupted the growth and several morphological malformations were observed. It also affected growth and the main components (proteins, carbohydrates, lipids). Interpretation & conclusion: The essential oil affected growth and energy reserves for all three species. The results indicated that the essential oil of Ruta graveolens has good potential as a source of natural larvicides.
ABSTRACT
Background & objectives: The quality of breeding sites is reflected through the pupal productivity and the life history traits of Aedes mosquitoes. Using nutrient reserves and pupal productivity of Aedes as indicators, the larval habitats including sewage drains were characterized to highlight the habitat expansion and vector management. Methods: The pupae and adults collected from the containers and sewage drains were characterized in terms of biomass and nutrient reserves and the data were subjected to three way factorial ANOVA. Discriminant function analyses were performed to highlight the differences among the habitats for sustenance of Aedes mosquitoes. Results: Survey of larval habitats from the study area revealed significant differences (P<0.05) in the pupal productivity of Aedes among the habitats and months. Despite sewage drains being comparatively less utilized for breeding, the pupae were of higher biomass with corresponding adults having longer wings in contrast to other habitats. The nutrient reserve of the adults emerging from pupae of sewage drains was significantly higher (P<0.05), compared to other habitats, as reflected through the discriminant function analysis. Interpretation & conclusions: The present results showed that for both Ae. aegypti and Ae. albopictus, sewage drains were equally congenial habitat as were plastic, porcelain and earthen habitats. Availability of Aedes immature in sewage drains poses increased risk of dengue, and thus vector control programme should consider inclusion of sewage drains as breeding habitat of dengue vector mosquitoes.
ABSTRACT
Background: determination of water velocity for optimum fish growth is fundamental since its duration and intensity can interfere with the metabolic preference for some biochemical paths, resulting in the use of specific substrates for fish growth. Objective: the purpose of this study was to assess the metabolic adjustments of juvenile matrinxã (Brycon amazonicus) reared under various sustained swimming conditions (SS). Methods: fish were subjected to SS for 90 days at five swimming speeds: 0.0 (control), 1.0, 1.5, 2.0, and 2.5 Body Length per second (BL/s). At the end of the experimental period, fish were euthanized; samples of blood, liver, white-muscle, red-muscle and ventral muscle were collected and metabolite concentrations were evaluated. Results: fish reared between 1.0-1.5 BL/s increased the hepatosomatic index (HSI) while those swimming at velocities higher than 1.5 BL/s showed diminished HSI and visceral fat. Fish under moderate swimming utilized visceral fat to supply energy for red muscle contractions while white muscle of fish swimming at higher speeds used carbon backbones from amino acids plus visceral fat. Conclusion: sustained swimming between 1.0-1.5 BL/s enhanced the intermediary metabolism of B. amazonicus, improving fish performance. Future studies linking macronutrient dietary levels and SS should allow adjusting rearing conditions under SS to optimize growth versus metabolic performance.
Antecedentes: la determinación de la velocidad del agua para óptimo crecimiento de los peces es importante porque dependiendo de la intensidad y duración, puede interferir sobre la activación de las vías metabólicas, indicando mayor o menor utilización de un determinado substrato energético para el crecimiento. Objetivo: la finalidad de este trabajo fue estudiar los efectos del ejercicio de natación sobre el metabolismo de juveniles de matrinxa (Brycon amazonicus). Métodos: juveniles de B. amazonicus fueron cultivados y condicionados a nadar bajo diferentes velocidades de natación 0,0 (control), 1,0, 1,5, 2,0 y 2,5 longitud total por segundo (LT s-1). Al final del período experimental (90 días), se realizó la eutanasia de los peces y se recolectaron muestras de sangre, tejido hepático, músculo blanco, músculo rojo y músculo ventral para determinar los intermediarios metabólicos. Resultados: peces cultivados en velocidades de natación entre 1,0 y 1,5 LT s-1 presentaron aumento del índice hepasomático (HSI), mientras que los peces que nadaron en velocidades superiores a 1,5 LT s-1 mostraron disminución de los índices HSI y grasa visceral (IGVS). Los peces condicionados a nadar en velocidades moderadas utilizaron lípidos viscerales como fuente de energía para sostener la contracción muscular del músculo rojo. Mientras que los peces que nadaron en las mayores velocidades, el músculo blanco fue más demandado, empleando como combustible, esqueletos de carbono provenientes de los aminoácidos y significativa movilización de grasa visceral. Conclusión: la natación sostenida entre 1,0 - 1,5 LT s-1 mejoró el metabolismo intermediario de B. amazonicus y el desempeño de los peces. Futuros trabajos asociando niveles de macro nutrientes y protocolos de natación moderada pueden permitir ajustes más refinados en la mejoría de las condiciones de cultivo, en la optimización del crecimiento, en la eficiencia alimenticia y en el aumento de la resistencia orgánica a las prácticas de manejo en las pisciculturas.
Antecedentes: a determinação da velocidade da água para o ótimo crescimento dos peixes é importante porque dependendo da intensidade e duração, pode interferir sobre a predominância na ativação de uma ou de outra via metabólica, indicando maior ou menor utilização de um determinado substrato energético e agir no crescimento. Objetivo: o propósito deste trabalho foi estudar os efeitos que o exercício de natação tem sobre o metabolismo de juvenis do peixe Matrinxa, Brycon amazonicus. Métodos: juvenis de B. amazonicus foram criados e condicionados a nadar durante 90 dias em cinco velocidades de natação: 0,0 (controle); 1,0; 1,5; 2,0 e 2,5 comprimentos corporais por segundo (CC s-1). Após termino do período experimental, os peixes foram sacrificados, o sangue, fígado, músculos branco, vermelho e ventral foram coletados para avaliar o perfil metabólico. Resultados: velocidades moderadas de natação entre 1,0 a 1,5 CC s-1 aumentaram o índice hepatosomático (HSI), enquanto que, o condicionamento dos peixes a maiores velocidades diminuiu significativamente o índice HSI e a gordura visceral (IGVS) em relação ao controle. Com respeito às respostas metabólicas, o condicionamento dos peixes em velocidades moderadas mostrou que o fornecimento de energia para sustentar a contração muscular dependeu primariamente dos triglicerídeos provenientes principalmente dos lipídios viscerais, ao passo que, em velocidades maiores, a via gliconeogênica foi a responsável pela manutenção na produção de energia para os músculos locomotivos, a qual aumentou progressivamente em função do catabolismo dos aminoácidos dos músculos locomotivos. Conclusão: a natação sustentada entre 1,0 - 1,5 CC s-1 melhorou o metabolismo intermediário do B. amazonicus o que resultou em melhor desempenho dos peixes. Estudos futuros associando níveis dietéticos de nutrientes com a natação moderada, pode permitir aos peixes ajustes mais refinados na melhoria das condições de criação, na otimização do crescimento, na eficiência alimentar e no aumento da resistência orgânica as praticas de manejo nas pisciculturas.