The Spider Webs, an Alternative Strategy to Teach Elasticity

La tela de araña es una estructura sorprendente, sus propiedades físicas y químicas han despertado el interés de muchos científicos alrededor del mundo. En este artículo se propone una metodología alternativa, económica y relativamente simple de aplicar para estimar propiedades elásticas de las telas de arañas. Impulsando un método de enseñanza de la Física con aplicación biológica que permita a los alumnos comprender los conceptos de elasticidad de manera experimental y tangible.The spider web is a surprising structure, its physical and chemical properties have woken up the interest of many scientists around the world. In this article is proposed an alternative, economic and relatively simple methodology to estimate elastic properties of the spider webs. Stimulating a method of education of the Physics with biological application that allows pupils to understand the concepts of elasticity of an experimental and tangible way.Fil: Aguilera Sammaritano, Juan Alberto. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Dual effects of entomopathogenic fungi on control of the pest Lobesia botrana and the pathogenic fungus Eutypella microtheca on grapevine

Background: Entomopathogenic fungi (EPF) are the natural enemies of insect pests. Nevertheless, research on the use of EPF for simultaneous prevention of pest and disease agents on the same crop is limited. In this study, we explored the potential dual effects of three strains of the EPF Metarhizium anisopliae on the control of detrimental agents of Vitis vinifera L., including different developmental stages (larvae, pupae, and adult) of the insect pest Lobesia botrana and the phytopathogenic fungus Eutypella microtheca. Methods: Laboratory pathogenicity trials were performed to examine the effects of the three M. anisopliae strains on the mortality rate of L. botrana. In addition, field trials were conducted to assess the biocontrol potential of one selected M. anisopliae strain on the larval stage of L. botrana. Moreover, inhibitory effects of the three EPF strains on E. microtheca growth were examined in vitro. Results: All the M. anisopliae strains were highly effective, killing all stages of L. botrana as well as inhibiting the growth of E. microtheca. The in vitro mortality of larvae treated with the strains was over 75%, whereas that of treated pupae and adults was over 85%. The three EPF strains showed similar efficacy against larvae and adult stages; nevertheless, pupal mortality was observed to be strain dependent. Mortality of L. botrana larvae ranged from 64 to 91% at field conditions. Inhibition of E. microtheca growth reached 50% in comparison to the control. Conclusions: Our study showed that M. anisopliae strains were highly effective in ensuring control of two different detrimental agents of V. vinifera L., providing new evidence to support the dual effects of entomopathogenic fungi.Fil: Aguilera Sammaritano, Juan Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Católica de la Santísima Concepción; ChileFil: Caballero, Juan Jose. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Biotecnología; ArgentinaFil: Deymié Terzi, María Celina. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rosa, Melisa. Universidad Nacional de San Juan; ArgentinaFil: Vazquez, Fabio. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Biotecnología; ArgentinaFil: Pappano, Delia Beatriz. Universidad Nacional de San Juan; ArgentinaFil: Lechner, Bernardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: González Teuber, Marcia. Universidad Católica de la Santísima Concepción; Chil

The entomopathogenic fungus, Metarhizium anisopliae for the European grapevine moth, Lobesia botrana Den. & Schiff. (Lepidoptera: Tortricidae) and its effect to the phytopathogenic fungus, Botrytis cinerea

The European grapevine moth, Lobesia botrana Den. & Schiff. (Lepidoptera: Tortricidae) and the gray rot fungus(Botrytis cinerea) are two important factors that cause elevated losses of productivity in vineyards globally. TheEuropean grapevine moth is one of the most important pests in vineyards around the world, not only because ofits direct damage to crops, but also due to its association with the gray rot fungus; both organisms are highlydetrimental to the same crop. Currently, there is no effective, economic, and eco-friendly technique that can beapplied for the control of both agents. On the other hand, Metarhizium anisopliae belongs to a diverse group ofentomopathogenic fungi of asexual reproduction and global distribution. Several Metarhizium isolates have beendiscovered causing large epizootics to over 300 insects? species worldwide. In this study, a simple design wasconducted to evaluate the potential of native M. anisopliae isolates as one of biological control agents against L.botrana and as possible growth inhibitors to B. cinerea. Entomopathogenic fungal strains were isolated from aridsoils under vine (Vitis vinifera) culture. Results suggest that the three entomopathogenic strains (CEP413, CEP589,and CEP591) were highly efficient in controlling larval and pupal stages of L. botrana, with mortality rates rangingfrom 81 to 98% (within 4?6 days). Also, growth inhibition over B. cinerea strains resulted in percentages rangedfrom 47 to 64%. Finally, the compatibility of the entomopathogenic strains, with seven commercial fungicides, wasevaluated. The potential of the entomopathogenic fungal strains to act as control agents is discussed.Centro de Estudios Parasitológicos y de Vectore

Control of Bemisia tabaci by entomopathogenic fungi isolated from arid soils in Argentina

Entomopathogenic Hypocreales were isolated from arid soils in Argentina using Tenebrio molitor as bait and tested for their biological performance at 30°C and 45–65% RH. Conidial germination was tested in three vegetable oils (sunflower, olive and maize) at two concentrations (1% and 10%) to evaluate their compatibility for further liquid formulations. According to radial growth and germination results, we selected four isolates to test their pathogenicity against second instar B. tabaci nymphs with the selected oil formulations at 30°C. CEP381 and CEP401 showed the highest radial growth. Isolates CEP381, CEP401, CEP413 and CEP409 (Metarhizium spp.) had similar germination percentages as compared with water control when germinated on either sunflower, olive or maize oils at 10% v/v. The highest mortality of B. tabaci was observed for the isolates CEP381 in sunflower oil and CEP401 in olive oil. Molecular identification of isolates was performed using ITS4–5 primers. All isolates belong to the Metarhizium core group. Tested isolates could grow and infect B. tabaci nymphs at 30°C in some of the vegetable oils as carriers, providing new possibilities for integrated pest management of Bemisia tabaci.Fil: Aguilera Sammaritano, Juan Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Biotecnología; ArgentinaFil: Lopez Lastra, Claudia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Leclerque, Andreas. Hochschule Geisenheim University; AlemaniaFil: Vazquez, Fabio. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Biotecnología; ArgentinaFil: Toro, Maria Eugenia. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Biotecnología; ArgentinaFil: D´Alessandro, Celeste Paola. Universidade de Sao Paulo; BrasilFil: Cuthbertson, Andrew G.S.. Independent Science Advisor; Reino UnidoFil: Lechner, Bernardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; Argentin

Entomopathogenic fungi: Are polisporic isolates more pathogenic than monosporic strains?

Currently only monosporic strains from several entomopathogenic fungi have been selected and used for mass production and bioinsecticide manufacturing worldwide. The main reasons for the use of single spore instead of multispore strains are the attenuated virulence and the contaminants of the same species. In this study, different polisporic isolates and their monosporic combinations were tested against Tenebrio molitor (Linnaeus) larvae as an insect model. Isolates were obtained from arid soils. Four Metarhizium sp. (Metschn.) multisporic isolates (CEP413, CEP589, CEP590 and CEP591) were selected for bioassays. Trials were performed to evaluate mortality on three treatments, Full Polisporic (FP), Partial Polisporic (PP) and Pure Monosporic (PM). Cumulative mortality was measured at day 4 post infection. Sporulation percentage was assessed at day 6 post infection. The highest mortality was found at FP treatment (94%), the lowest mortality at day 4 was found at PM-CEP413 (32%). At day 6 the sporulation percentage was higher on FP (94%) and it was different from the rest of the treatments. To elucidate different polisporic and monosporic combinations to improve their effectiveness, may help to expand the use of bioinsecticides based on entomopathogenic fungi.Centro de Estudios Parasitológicos y de Vectore

Entomopathogenic fungi: Are polisporic isolates more pathogenic than monosporic strains?

Currently only monosporic strains from several entomopathogenic fungi have been selected and used for mass production and bioinsecticide manufacturing worldwide. The main reasons for the use of single spore instead of multispore strains are the attenuated virulence and the contaminants of the same species. In this study, different polisporic isolates and their monosporic combinations were tested against Tenebrio molitor (Linnaeus) larvae as an insect model. Isolates were obtained from arid soils. Four Metarhizium sp. (Metschn.) multisporic isolates (CEP413, CEP589, CEP590 and CEP591) were selected for bioassays. Trials were performed to evaluate mortality on three treatments, Full Polisporic (FP), Partial Polisporic (PP) and Pure Monosporic (PM). Cumulative mortality was measured at day 4 post infection. Sporulation percentage was assessed at day 6 post infection. The highest mortality was found at FP treatment (94%), the lowest mortality at day 4 was found at PM-CEP413 (32%). At day 6 the sporulation percentage was higher on FP (94%) and it was different from the rest of the treatments. To elucidate different polisporic and monosporic combinations to improve their effectiveness, may help to expand the use of bioinsecticides based on entomopathogenic fungi.Centro de Estudios Parasitológicos y de Vectore