Juliana Andrea Gómez Valderrama

Entomopathogenic fungi of the genus Metarhizium can degrade and penetrate the insect cuticle through the coordinated action of hydrolytic enzymes, mainly lipases, proteases, and chitinases, whose production varies according to the fungal species and fermentation conditions. These enzymes can be generated via submerged fermentation and subsequently employed to enhance the insecticidal activity of fungal conidia. This study aimed to increase protease production from Metarhizium robertsii Mt015 to strengthen biological control agents based solely on fungal biomass. The culture medium composition and physicochemical parameters were optimized using a statistical design approach. Biological activity assays were then performed using Tuta absoluta larvae as the target insect and Beauveria bassiana as the reference control, tested both alone and in combination with the protease extract. Optimization identified wheat bran, casein, and an initial pH of 8–10 as the most influential variables, achieving a 5.5-fold increase in protease activity compared to the basal medium. When the protease extract was combined with B. bassiana conidia, the mortality rate reached 78.2%, significantly higher than the 55.6% achieved with B. bassiana conidia alone. Bliss independence analysis indicated that the observed larval mortality exceeded the additive expectation (Δ = 23.3 percentage points; 95% CI: 16.7–30.0), supporting a synergistic interaction between B. bassiana and the protease extract at 0.68 U/mL. These results demonstrate that enzymatic supplementation markedly improves the insecticidal performance of entomopathogenic fungi, supporting the use of enzyme-enriched formulations as a complementary strategy to strengthen biological control agents and advance the development of next-generation biopesticides.

Esta cartilla es una invitación a conocer el importante papel que tienen los microorganismos en la agricultura. A través de ejemplos sencillos, se muestra cómo pueden ayudar a reducir plagas y enfermedades, cuidar los cultivos, mejorar el crecimiento de las plantas, proteger el suelo y reducir el impacto del cambio climático. Además, se explican estrategias que ayudan a disminuir el uso de productos químicos y a mantener el equilibrio con el medioambiente. Más que un texto técnico, AGROSAVIA, en su misión de contribuir a la producción agrícola sostenible, presenta esta cartilla que busca despertar la curiosidad por aprender nuevas formas de producir más amigables con la naturaleza y con la salud del planeta.

El caucho natural (Hevea brasiliensis) es la base de un sistema productivo promisorio y de gran importancia para el país, que ha generado expectativas no solo alrededor del aumento del mercado, sino también en la consolidación de la industria asociada a la transformación del caucho. Esta importancia da soporte a la necesidad de mejorar la productividad, competitividad y sostenibilidad en los núcleos identificados, particularmente el del “cinturón cacaotero-cauchero de Antioquia-Córdoba”, teniendo en cuenta que estos dos departamentos cuentan con aproximadamente tres millones de hectáreas con aptitud edafoclimática para la producción de caucho natural. Esta aptitud implica la existencia de condiciones que permiten el uso eficiente de los recursos naturales, especialmente el suelo y el agua, a través de un manejo integrado del cultivo que incluye requerimientos edafoclimáticos de la especie, sistemas de siembra, plagas y enfermedades, prácticas culturales y características de la materia prima, entre otros aspectos. El Modelo productivo para el cultivo de caucho natural (Hevea brasiliensis) en el bajo Cauca antioqueño y en el sur de Córdoba busca ser una herramienta de consulta que, a partir del enfoque territorial, facilite la toma de decisiones y la priorización de inversiones por parte de los productores.

Entomopathogenic fungi are important biological control agents of insect pests; however, storage stability is one of the main challenges for their commercialisation. In this study, osmoprotective substances were added to formulation prototypes of a native Beauveria bassiana isolate as a strategy to prolong the efficacy during storage. A three-month accelerated thermo-stability study was conducted as selection criteria. In vitro efficacy (corrected mortality) tests were considered in addition to the microbiological response variables commonly reported in the literature (germination and active ingredient concentration – plate count of colony-forming units). The results allowed to select trehalose as the best osmoprotective substance. This prototype had a lethal concentration (LC₅₀) on Diatraea saccharalis (Lepidoptera: Crambidae) larvae of 2.8×10⁵ conidia mL⁻¹, and its efficacy remained higher than 90% when stored at 6°C and 18°C. Mathematical models were constructed according to efficacy data, the shelf-life of the selected prototype was 36.6 months when stored at 6 ± 2°C, 26.0 months at 18°C, and 5.3 months at 28°C. The obtained results emphasise the importance of shelf-life evaluation based on efficacy data of biological activity in addition to microbiological variables that may not be directly related to efficacy. The current study conclusively demonstrates a relationship between temperature and shelf-life.

Background: The fall armywormSpodoptera frugiperdais one of the major pests in maize crops, causing important production losses. The pest has rapidly spread worldwide, generating an urgent need to develop efficient and sustainable strategies for its control. In this work, the potential of integrating nucleopolyhedrovirus- (NPV) and the fungusMetarhizium rileyito controlS. frugiperdalarvae was evaluated under laboratory, greenhouse, and field conditions.Methods: The mortality ofS. frugiperdalarvae was evaluated after the application of NPV andM. rileyialone or in combination using three concentrations (high, medium and low) under laboratory conditions. Then, two greenhouse trials using maize plants were carried out to evaluate the effect of individual or combined applications of NPV andM. rileyionS. frugiperdamortality (first trial) and fresh damage (second trial). Finally, a trial under field conditions was conducted to evaluate the performance of the treatment selected in the greenhouse assay.Results: The combined use of NPV:M. rileyiapplied simultaneously showed an additive effect in laboratory, causing higher larval mortality than the biocontrol agents used separately. This effect was evident in the mixtures using the concentration levels high:medium, medium:medium, and medium:high. Under greenhouse conditions, the use of a 50:50 ratio of the two entomopathogens also caused higher larval mortality and a significantly reduced insect damage to plants. Finally, under field conditions, the individual or sequential application of NPV andM. rileyiusing 100% of their recommended doses, and the simultaneous application of both entomopathogens at 50% of their recommended doses, significantly reduced the recent foliar damage to levels under the threshold for economic losses (30% fresh damage) while the damage reached 43% when control measures were not used.Conclusion: The combined application of NPV andM. rileyi(two biocontrol agents with different mode of action) demonstrated an additive effect that allows to reduce to half their recommended application doses. In this context, the integration of both entomopathogens is a promising strategy to manageS. frugiperda,contributing to improve the economic feasibility of biological control tools for the sustainable fall armyworm management.

Spodoptera ornithogalli (Guenée) (Lepidoptera: Noctuidae) is an important pest in different crops of economic relevance in America. For its control, strategies that include chemicals are usually used; so, the description of entomopathogens would be very useful for the formulation of biopesticides. In this regard, two different baculoviruses affecting S. ornithogalli were isolated in Colombia, with one of them being an NPV and the other a GV. Ultrastructural, molecular, and biological characterization showed that both isolates possess the 38 core genes and are novel species in Baculoviridae, named as Spodoptera ornithogalli nucleopolyhedrovirus (SporNPV) and Spodoptera ornithogalli granulovirus (SporGV). The bioassays carried out in larvae of S. ornithogalli and S. frugiperda showed infectivity in both hosts but being higher in the first. In addition, it was observed that SporGV potentiates the insecticidal action of SporNPV (maximum value in ratio 2.5:97.5). Both viruses are individually infective but coexist in nature, producing mixed infections with a synergistic effect that improves the performance of the NPV and enables the transmission of the GV, which presents a slowly killing phenotype.

Los cambios en las tendencias de consumo, las ventajas competitivas de estas estrategias de manejo, las nuevas regulaciones y los planes gubernamentales han llevado a que cada vez más productores incorporen estas medidas de control dentro de sus esquemas de manejo de plagas y enfermedades. Por lo anterior, la Corporación Colombiana de Investigación Agropecuaria (AGROSAVIA), desde 2008, ha trabajado en el desarrollo y registro del bioplaguicida Erytec® para el manejo del principal insecto plaga de los cultivos de caucho y yuca en América tropical y Colombia, conocido comúnmente como gusano cachón [Erinnyis ello (Lepidoptera:Sphingidae)]. Este bioplaguicida se desarrolló a partir de un aislamiento nativo de granulovirus colectado en el departamento del Meta, Colombia, y presenta una formulación de alta calidad que le confiere ventajas técnicas para el control de la plaga y su uso en estos sistemas productivos.

Erytec® es un bioplaguicida formulado como un polvo mojable para aplicación foliar, desarrollado por AGROSAVIA, cuyo principio activo es el granulovirus de Erinnyis ello, aislamiento colombiano VG010. El producto tiene una concentración mínima de 1 × 109 cuerpos de inclusión por gramo de producto.

Bioproducto desarrollado por AGROSAVIA para el control de la polilla guatemalteca de la papa (Tecia solanivora), en almacenamiento de papa para semilla y papa de consumo; es inocuo para la salud humana y el medio ambiente. Además, reemplaza el uso de insecticidas y no afecta la brotación del tubérculo.