Distribution Of Entomopathogenic Fungi Research Articles

Correlation of fruit tree rhizosphere soils with entomopathogenic fungi

AbstractEntomopathogenic fungi are microorganisms that control the density of host insects in nature; they are being studied as environmentally friendly alternatives to chemical insecticides for controlling insect pests. The main habitat of entomopathogenic fungi is soil, and the correlation between the distribution of entomopathogenic fungi and the physicochemical characteristics of soils planted with different trees, including vine (outdoor, greenhouse, and greenhouse shine musket), apple, peach, and pear, were analyzed. The entomopathogenic fungi of the genera Beauveria, Metarhizium, and Purpureocillium investigated in this study were all found in soil samples from vine‐greenhouse, apple, and peach trees. Purpureocillium and Beauveria abundances were positively correlated with soil properties; however, Metarhizium abundances were not correlated with soil properties. The Metarhizium isolates discovered in this study showed pathogenicity to cotton aphids (an agricultural pest) and can be employed as sources for biological studies in the future. This study provides data on the diversity and abundance of entomopathogenic fungi related with soil properties, as well as the molecular, biological, and insecticidal characteristics of Metarhizium isolates.

Effect of Soil Chemical Properties on the Occurrence and Distribution of Entomopathogenic Fungi in Portuguese Grapevine Fields.

Entomopathogenic fungi (EPF) contribute to different ecosystem services. However, factors affecting their natural occurrences in soil remain poorly understood. In a previous study, 81 soil samples were subjected to insect baiting using Galleria mellonella and Tenebrio molitor to isolate EPF from Portuguese vine farms. Here, soils yielding any of the four common EPF, i.e., Beauveria bassiana, Purpureocillium lilacinum, Metarhizium robertsii, and Clonostachys rosea f. rosea, were correlated with their chemical properties. Beauveria bassiana was negatively affected by higher available P (p = 0.02), exchangeable K-ions (p = 0.016) and positively affected by higher soil pH_H2O (p = 0.021). High exchangeable K-ions inhibited P. lilacinum (p = 0.011) and promoted C. rosea f. rosea (p = 0.03). Moreover, high available K also suppressed P. lilacinum (p = 0.027). Metarhizium robertsii was inhibited by higher organic matter content (p = 0.009), higher C:N (p = 0.017), total N (p = 0.007), and exchangeable Mg-ions (p = 0.026), and promoted by higher exchangeable Na-ions (p = 0.003). Nonetheless, mean comparisons and principal component analysis suggested that higher soil pH and exchangeable Ca-ions have contrasting effects on EPF occurrences, as they promote B. bassiana and inhibit M. robertsii. Herbicides did not seem to affect EPF presence. Overall, this study is among the first reports on the effects of soil chemistry on EPF other than Metarhizium, and will facilitate biological pest management approaches.

Abundancia y distribución de hongos entomopatógenos en diferentes localidades y ambientes del sur de Tamaulipas


 
 
 Con el fin de generar un registro de los hongos entomopatógenos con el potencial para el control de insectos plaga en el área agrícola del estado de Tamaulipas. En este estudio se cuantificó la abundancia y determinó la distribución de los hongos entomopatógenos en diferentes localidades y ambientes del sur de Tamaulipas, México. En 2016, los hongos entomopatógenos fueron recolectados en la Brecha de Corpus Christi, Villa Cuauhtémoc, Esteros y Miradores. En cada localidad se seleccionaron los siguientes ambientes: parcelas cultivadas con gramíneas (sorgo y maíz), fabáceas (soya, frijol y jícama), árboles frutales (limón, papaya, litche, mango y naranja), hortalizas (cebolla, chile, tomate y acelga) y parcelas sin cultivar (ambiente natural). En cada ambiente se recolectaron muestras de suelo. Posteriormente, en el suelo recolectado, se trampearon a los hongos entomopatógenos con larvas de Tenebrio molitor L. En total, se recolectaron 134 aislados de los géneros: Beauveria sp., Lecanicillium sp., Metarhizium sp., Paecilomyces sp., Trichoderma sp. e Isaria sp. De los cuales, Beauveria sp. presentó la mayor abundancia y distribución. Mientras que, los otros géneros fueron recolectados en localidades y ambientes específicos. Este resultado indica la posibilidad de que los géneros de los hongos encontrados estén fuertemente adaptados a los factores bióticos y abióticos del ambiente.
 
 

Distribution of Entomopathogenic Fungi in Cultivated and Noncultivated Soils in Southern Tamaulipas, Mexico

Distribution of Entomopathogenic Fungi in Cultivated and Noncultivated Soils in Southern Tamaulipas, Mexico

Occurrence of entomopathogenic fungi in tejocote (Crataegus mexicana) orchard soils and their pathogenicity against Rhagoletis pomonella.

To determine the abundance and diversity of entomopathogenic fungi in tejocote orchard soils and evaluate their ability to infect Rhagoletis pomonella Walsh., the main pest of tejocote. Surveys were made in two locations in Mexico state and two in Puebla state. Soil from selected locations was baited for entomopathogenic fungi with Galleria mellonella (L.). All isolates were identified morphologically to genus level and to species level using Bloc and elongation factor 1-α gene sequence information, respectively; Beauveria bassiana ((Bals.-Criv.) Vuill.), B. pseudobassiana (S.A. Rehner & Humber) and Metarhizium robertsii (J.F. Bisch., Rehner & Humber) were found, with B. bassiana being the most abundant and widely distributed. Pathogenicity of five selected B. bassiana isolates and three M. robertsii isolates was evaluated against larvae and pupae of R. pomonella. All isolates infected larvae resulting in an average mortality of 35%. Pupae were not susceptible; however, adults emerging from inoculated pupae did die due to infection. At least three species of entomopathogenic fungi are present in the soil from tejocote orchards, with B. bassiana being the most abundant and widely distributed. Rhagoletis pomonella larvae were more susceptible to infection than pupae. Our study has produced new information about the distribution of entomopathogenic fungi in cultivated soils from this region of North America, contributing to a better understanding of their natural occurrence and underpinning the development of biological control approaches.

Distribution and characterisation of entomopathogenic fungi from Korean soils

We investigated the occurrence of entomopathogenic fungi in 1080 soil samples representing multiple locations and conditions in Korea. Entomopathogenic fungi were isolated from soils using a selective medium containing dodine and antibiotics. Following an initial identification based on morphology, the fungal isolates were more precisely identified by the sequence of their nuclear ribosomal RNA (rRNA) internal transcribed spacer (ITS) regions. As a result, entomopathogenic fungi were found to occur in 32% (342 isolates) of the soil samples studied. The most abundant species were Beauveria spp. (125 isolates) and Metarhizium spp. (82 isolates). Entomopathogenic fungi were more often recovered from natural mountain and riparian soils than from agricultural habitats. The pathogenicity of isolated fungi was evaluated by using wax moth Galleria mellonella L. (Lepidoptera: Pyralidae) larvae. It was determined that 60% (207 isolates) of the isolates were pathogenic using this model. These entomopathogenic fungi may, therefore, have potential use against a variety of agricultural pests. This is the first study of the isolation and distribution of entomopathogenic fungi in representative sampling locations throughout Korea.

Occurrence and diversity of entomopathogenic fungi in cultivated and uncultivated soils in Pakistan

AbstractThe distribution of entomopathogenic fungi in various geographical areas of Punjab, Pakistan, is poorly understood. The present study was planned to explore the occurrence and diversity of entomopathogenic fungi from soils collected from cultivated and non‐cultivated habitats. The detailed survey of different habitats (crop fields, fruits, vegetables, forests) was conducted to collect soil samples and the associated fungi were isolated using Galleria bait method. Among 210 soil samples, 168 fungal isolates were recovered and identified, with 98 from forests, 32 from vegetables, 30 from field crops and 8 from fruits. The major entomopathogenic fungi recovered from these samples were Beauveria bassiana, Metarhizium anisopliae, Paecilomyces lilacinus, B. brongniartii, P. chlamydosporia and Lecanicillium attenuatum. The diversity of entomopathogenic fungi was greater in soil samples from forests compared to crop fields, vegetables and fruits, respectively. The geographical attributes (altitude, longitude, latitude) greatly influenced the occurrence of entomopathogenic fungi with the highest number of isolates found from >600 m altitude, 33°–34′N latitude, and 73°74′E longitude from soil samples. The results of the surveys clearly indicated that the entomopathogenic fungi are distributed in the soils which may be used in successful IPM programs in future.

Factors affecting the occurrence of entomopathogenic fungi in soils of Slovakia as revealed using two methods

Soil samples from 901 sampling sites in Slovakia were collected during 2008 and the presence of entomopathogenic fungal species from the order Hypocreales was evaluated. Entomopathogenic fungi were detected in 430 samples by the Galleria mellonella bait method (GBM) and in 627 soil samples using selective medium (SM) containing cycloheximide and dodine. There was a significant difference between the ability of these methods to detect the fungi. Four species were detected by the GBM: Beauveria bassiana (31% of samples), Metarhizium anisopliae (8%), Isaria farinosa (6%), and Isaria fumosorosea (6%). Only three species were detected with SM: B. bassiana (36% of samples), M. anisopliae (37%), and I. fumosorosea (9%). In addition, some samples that were positive using SM were negative with the GBM and vice versa, implying that these methods are not equivalent for the determination of the occurrence and distribution of entomopathogenic fungi. Our results indicated that B. bassiana preferred natural habitats, particularly forests, though it was also frequently detected in other habitats. I. farinosa was strictly limited to forest habitats and I. fumosorosea was most frequently detected in soil samples from hedgerows. M anisopliae was observed primarily in field and meadow samples, and its occurrence was not negatively affected by intensive agriculture. It was most frequently found in lowland soils with a neutral or alkaline pH. Detection of B. bassiana and I. farinosa significantly increased with increasing altitude and decreasing soil pH. Both fungi also preferred soils with high organic content.

Factors affecting the occurrence and distribution of entomopathogenic fungi in natural and cultivated soils

Factors affecting the occurrence and distribution of entomopathogenic fungi in 244 soil samples collected from natural and cultivated areas in Spain were studied using an integrated approach based on univariate and multivariate analyses. Entomopathogenic fungi were isolated from 175 of the 244 (71.7 %) soil samples, with only two species found, Beauveria bassiana and Metarhizium anisopliae. Of the 244 soil samples, 104 yielded B. bassiana (42.6 %), 18 yielded M. anisopliae (7.3 %), and 53 soil samples (21.7 %) harboured both fungi. Log-linear models indicated no significant effect of habitat on the occurrence of B. bassiana, but a strong association between M. anisopliae and soils from cultivated habitats, particularly field crops. Also, irrespective of habitat type, B. bassiana predominated over M. anisopliae in soils with a higher clay content, higher pH, and lower organic matter content. Logistic regression analyses showed that pH and clay content were predictive variables for the occurrence of B. bassiana, whereas organic matter content was the predictive variable for M. anisopliae. Also, latitude and longitude predicted the occurrence of these same species, but in opposite directions. Altitude was found to be predictive for the occurrence of B. bassiana. Using principal component analysis, four factors (1 to 4) accounted for 86 % of the total variance; 32.8, 22.9, 19.6 and 10.4 % of the cumulative variance explained, respectively. Factor 1 was associated with high positive weights for soil clay and silt content and high negative weights for soil sand content. Factor 2 was associated with high positive weights for soil organic matter content and high negative weights for soil pH. Factor 3 was associated with high positive weights for latitude and longitude of the sampled localities and factor 4, had high positive weights only for the altitude. Bi-plot displays representing soil samples were developed for different factor combinations and indicated that, irrespective of geographical location, absence of both fungal species was determined by alkaline sandy soils with low organic matter content, whereas heaviness of soil texture, acidity and increasing organic matter content led to progressively higher percentages of samples harbouring entomopathogenic fungi. These results could aid decision-making as to whether or not a particular cultivated or natural soil is suitable for using entomopathogenic fungi as a pest control measure and for selecting the fungal species best suited to a particular soil.