Entomopathogenic fungi biomass production and extracellular biosynthesis of silver nanoparticles for bioinsecticide action

Entomopathogenic fungi are microbial agents of insect control in nature. They have been used as biologic strategies to manage insect invasion; however, the challenge is to maintain their shelf life and viability when exposed to high temperatures, ultraviolet radiation, and humidity. Synthesized silver nanoparticles (AgNPs) from fungal extracellular enzymes are an alternative using these microorganisms to obtain nanoparticles with insecticidal action. The present study evaluates the biomass production and the potential to synthesize silver nanoparticles using entomopathogenic fungi isolates. Sixteen isolates of entomopathogenic fungi were used in this study. The fungi pathogenicity and virulence were evaluated using the insect model Tenebrio molitor, at a concentration of 5 × 106 conidia/mL. The fungal biomass was produced in a liquid medium, dried, and weighed. The synthesis of silver nanoparticles was performed with aqueous extracts of the entomopathogenic fungi and silver nitrate solution (1 mM), following characterization by a UV/vis spectrophotometer, mean size, and polydispersity index. The results showed a significant variation in pathogenicity, virulence, and biomass production among the evaluated fungi isolates; however, only one of the isolates did not have the potential to synthesize silver nanoparticles. Pearsons correlation showed significant correlation values only between virulence × biosynthesis potential and biomass production × biosynthesis potential, both with negative values, indicating an inverse correlation. Thus, AgNPs with entomopathogenic fungus extract can produce an innovative bioinsecticide product using a green production process.This work was supported by the Fundação de Amparo à Pesquisa do Estado de Sergipe (FAPITEC), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, #443238/2014-6, #470388/2014-5) and Banco do Nordeste (FUNDECI/2017.0014), the Portuguese Science and Technology Foundation (FCT/MCT), and from European Funds (PRODER/COMPETE) for the project UIDB/04469/2020 (strategic fund), co-financed by FEDER, under the Partnership Agreement PT2020.info:eu-repo/semantics/publishedVersio

Idoneidad de Ephestia kuehniella (Lepidoptera: Pyralidae) y Aleurodicus cocois (Hemiptera: Aleyrodidae) como fuentes de alimento para Ceraeochrysa cornuta (Neuroptera: Chrysopidae)

This study aimed to compare the suitability of Ephestia kuehniella (Zeller, 1879) and Aleurodicus cocois (Curtis, 1846) as food sources for Ceraeochrysa cornuta (Navás, 1925) based on the assessment of the development and reproductive parameters of this predator. For this, E. kuehniella eggs or all developmental stages of A. cocois were used as prey and the effects were evaluated on developmental time, survival, viability, longevity, and fecundity of C. cornuta. Ceraeochrysa cornuta completed its development cycle from larvae to adult in 22 d or in 27 d when it preyed on E. kuehniella or on A. cocois, respectively. This could be explained by longer larval instars for C. cornuta feeding on A. cocois. The larval survival was higher when C. cornuta larvae fed on E. kuehniella than when it fed on A. cocois, increasing progressively from 79.82 % in the first to 97.56 % in the third instar. Although the diets did not influence female longevity, oviposition period and egg viability, the total number of eggs laid per female of C. cornuta was higher when their larvae fed on A. cocois. The results indicate that both E. kuehniella eggs and A. cocois developmental stages are suitable prey for rearing C. cornuta. In addition, this predator showed an outstanding potential for controlling A. cocois.Este estudio tuvo como objetivo comparar la idoneidad de Ephestia kuehniella (Zeller, 1879) y Aleurodicus cocois (Curtis, 1846) como fuentes de alimento para Ceraeochrysa cornuta (Navás, 1925), sobre la base de la evaluación de sus parámetros reproductivos y de desarrollo. Para esto, se utilizaron como presa huevos de E. kuehniella o todas las etapas de desarrollo de A. cocois y se evaluaron sus efectos sobre el tiempo de desarrollo, sobrevivencia, viabilidad, longevidad y fecundidad de este depredador. C. cornuta completó su ciclo de desarrollo de larva a adulto en 22 días y en 27 días cuando se alimenta de E. kuehniella y A. cocois, respectivamente. La supervivencia del período larvario fue mayor cuando las larvas de C. cornuta se alimentaron de E. kuehniella en comparación con A. cocois como fuente de alimento, que aumentó progresivamente del 79,82 % en el primero al 97,56 % en el tercer estadio. Aunque las dietas no influyeron en la longevidad de las hembras de esta especie, el periodo de oviposición y la viabilidad de los huevos, así como el número total de huevos puestos por hembra fueron mayores cuando sus larvas se alimentaron de A. cocois. Los resultados indican que tanto los huevos de E. kuehniella como los estados inmaduros de A. cocois son presas adecuadas para la cría de C. cornuta. Adicionalmente, este depredador podría considerarse como un agente de control biológico promisorio para el manejo de A. cocois

Biosynthesis of silver nanoparticles mediated by entomopathogenic fungi: antimicrobial resistance, nanopesticides, and toxicity

Silver nanoparticles are widely used in the biomedical and agri-food fields due to their versatility. The use of biological methods for the synthesis of silver nanoparticles has increased considerably due to their feasibility and high biocompatibility. In general, microorganisms have been widely explored for the production of silver nanoparticles for several applications. The objective of this work was to evaluate the use of entomopathogenic fungi for the biological synthesis of silver nanoparticles, in comparison to the use of other filamentous fungi, and the possibility of using these nanoparticles as antimicrobial agents and for the control of insect pests. In addition, the in vitro methods commonly used to assess the toxicity of these materials are discussed. Several species of filamentous fungi are known to have the ability to form silver nanoparticles, but few studies have been conducted on the potential of entomopathogenic fungi to produce these materials. The investigation of the toxicity of silver nanoparticles is usually carried out in vitro through cytotoxicity/genotoxicity analyses, using well-established methodologies, such as MTT and comet assays, respectively. The use of silver nanoparticles obtained through entomopathogenic fungi against insects is mainly focused on mosquitoes that transmit diseases to humans, with satisfactory results regarding mortality estimates. Entomopathogenic fungi can be employed in the synthesis of silver nanoparticles for potential use in insect control, but there is a need to expand studies on toxicity so to enable their use also in insect control in agriculture.The work was funded by the Coordination for the Improvement of Higher Education Personnel (Capes); Sergipe Agricultural Development Company (Emdagro), the Industrial Biotechnology Program, University Tiradentes, Sergipe Technological Park (SergipeTec), and the Banco do Nordeste.info:eu-repo/semantics/publishedVersio

Physical and chemical characteristics of fruits from different orange canopy/rootstock combinations grown in the brazilian semiarid

The orange trees 'Pera'/lemon 'Cravo' combination has predominated in national territory, and new oranges trees canopies/rootstock combinations citrus have been availability in breeding programs to provide for productive sector. Thus, the objective of this work was to evaluate the physical and chemical characteristics of fruits orange trees from canopy/rootstock different combinations grown in Brazilian semiarid. The experimental design was in randomized blocks, in a factorial scheme with three canopy and four rootstock cultivars, with three replications. The orange trees used were 'Pera', 'Natal' and 'Sincorá', while for the rootstocks the lemon 'Cravo Santa Cruz', the mandarin 'Sunki' Tropical selection, and the citrandarins 'Indio' and 'Riverside'. The results obtained showed that factors acted independently in mass and diameter fruit, seeds number, juice yield, skin luminosity and pulp, chromaticity and hue angle pulp, ºBrix and acids contents. However, it was different in shell thickness, chromaticity and hue angle of the shell and SS/AT ratio. Was possible conclude that 'BRS 002 – Sincorá' presented best results for physical and chemical analysis, and lemon 'Cravo Santa Cruz' and Tangerine 'Sunki' Tropical selection influenced the canopies to the best results of the physical and chemical analysis, respectively. All combinations showed low juice yield.No Brasil, a combinação laranjeira ‘Pera’ e limoeiro ‘Cravo’ têm predominado em todo o território nacional, fazendo com que os programas de melhoramento em citros invistam em medidas para disponibilizar novas combinações ao setor produtivo. Com isso, o objetivo deste trabalho foi avaliar as características físicas e químicas de frutos provenientes de diferentes combinações copa/porta-enxerto de laranjeiras cultivadas no semiárido brasileiro. O delineamento experimental foi em blocos casualizados, em esquema fatorial com três cultivares copa e quatro porta-enxerto, com três repetições. As copas utilizadas foram a ‘Pera’, a ‘Natal’ e a ‘Sincorá’, enquanto para os porta-enxertos foram utilizados o limoeiro 'Cravo Santa Cruz', a tangerineira ‘Sunki’ seleção Tropical, e os citrandarins ‘Indio’ e ‘Riverside’. Os resultados obtidos mostraram que os fatores atuaram de forma independente na massa e diâmetro do fruto, no número de sementes, no rendimento do suco, na luminosidade da casca e da polpa, na cromaticidade e ângulo de matiz da polpa, no ºBrix e nos teores de ácidos. Entretanto, foi diferente na espessura da casca, na cromaticidade e no ângulo de matiz da casca e na relação SS/AT. Foi possível concluir que a ‘BRS 002–Sincorá’ apresentou os melhores resultados para as análises físicas e químicas, e as cultivares porta-enxerto limoeiro ‘Cravo Santa Cruz’ e Tangerineira ‘Sunki’ seleção Tropical influenciaram as copas aos melhores resultados das análises físicas e químicas, respectivamente. Todas as combinações apresentaram baixo rendimento do suco

Spittlebug Cephisus siccifolius damaging eucalypt plants in the State of Bahia, Brazil

Os insetos-praga mais comuns em plantios de eucalipto no Brasil são formigas cortadeiras e lagartas desfolhadoras. Eventualmente, outros insetos como percevejos e cigarrinhas podem danificar essas plantas. O objetivo deste trabalho foi identificar e descrever os sintomas de ataque, em um plantio de eucalipto de 25,77 hectares, no Estado da Bahia, onde 99,3% das árvores tinham sido atacadas pela cigarrinha-de-espuma Cephisus siccifolius (Walker 1851) (Hemiptera: Aphrophoridae). Os danos foram maiores em galhos e folhas. A mortalidade de árvores foi baixa, apesar de se observar 4,7 colônias de cigarrinhas por árvore, com 21,9 ninfas por colônia. O corte das árvores infestadas foi recomendado como controle.Most common pests of eucalyptus plants in Brazil are leaf cutting ants and defoliating caterpillars. Other groups, eventually, feeding on eucalyptus include Heteroptera and cicadas. The objectives of this work were to identify and to describe attack symptoms of Cephisus siccifolius (Walker 1851) (Hemiptera: Aphrophoridae) on eucalyptus trees in a stand of 25.77 hectares in the State of Bahia, Brazil, where 99.3% of them were attacked by this spittlebug. Damage was more severe on branches and leaves. Tree death was, relatively, low while those cut showed 4.7 colonies of this spittlebug with 21.9 nymphs per colony. Cultural control with the removal of trees attacked was recommended

Feromônio sexual sintético do minador-dos-citros em pomares brasileiros de citros

The objective of this work was to determine the best conditions of use of the synthetic sex pheromone of Phyllocnistis citrella Stainton for monitoring this species in citrus groves in northeastern Brazil. Pheromone doses (0.0, 0.1, 1, 10 and 100 µg) and longevity (1, 15, 29, 43 and 57-day-old lures) and trap height (0.5, 1.5 and 2.5 m), color (green, red, and white) and model influence on P. citrella males capture were evaluated. The doses of 10 and 100 µg of the synthetic sex pheromone – a 3:1 blend of (Z,Z,E)-7,11,13-hexadecatrienal and (Z,Z)-7,11-hexadecadienal –  attracted the greatest number of P. citrella males. Traps baited with these two both dosages continued to capture P. citrella males at a comparable rate for over eight weeks in citrus groves. Although there was no significant decrease in activity of both dosages until 57 days of exposure to the environment, the higher dose, as time passed, attracted significantly more P. citrella males than the lower dose. There were no significant differences in male capture in traps with synthetic sex pheromone placed at 1.5 and 2.5 m height, wich had the better results. Trap color and model did not affect male capture.O objetivo deste trabalho foi determinar as melhores condições de uso do feromônio sexual sintético de Phyllocnistis citrella Stainton para o monitoramento dessa espécie em pomares de citros no Nordeste do Brasil. Foram avaliados: doses (0,0, 0,1, 1, 10 e 100 µg), duração (1, 15, 29, 43 e 57 dias de exposição do feromônio sexual sintético), altura de instalação (0,5, 1,5 e 2,5 m), cor (verde, vermelha e branca) e modelo de armadilha na captura de machos de P. citrella. As doses de 10 e 100 µg do feromônio sintético – proporção de 3:1 da mistura de Z,Z,E-7,11,13-hexadecatrienal e (Z,Z)-7,11-hexadecadienal – atraíram o maior número de machos de P. citrella. Armadilhas contendo a mistura feromonal nessas duas doses capturaram machos de P. citrella por mais de oito semanas em pomares de citros. Embora nenhuma das duas doses tenha sofrido decréscimo na atividade por até 57 dias de exposição ao ambiente, com o passar do tempo a maior dose atraiu significativamente mais machos de P. citrella que a menor dose. Não houve diferença significativa na captura de machos nas armadilhas com o feromônio sexual instaladas a 1,5 e 2,5 m de altura, as quais apresentaram os melhores resultados. O modelo e a cor das armadilhas não afetaram a captura dos machos