Search

Abstract: By baiting soil samples with larvae of Galleria mellonella detailed surveys of the occurrences of entomopathogenic fungi were conducted over two consecutive years in the soil of an organically farmed field (17.1ha) and the associated hedgerow. Samples were collected at specific points (at distances of 25m) based on Geographical Information Systems (GIS) and sample point coordinates were relocated by Global Positioning System (GPS). In the agricultural field soil Beauveria bassiana was the most common fungus while Paecilomyces fumosoroseus was most common in soil from the hedgerow. Significant clustering of B. bassiana in the agricultural field was found in one of the two years. High and low densities of B. bassiana were subsequently confirmed within selected areas by reducing distances between sample points. The results demonstrated the suitability of the sampling method for identifying distribution patterns of soil borne entomopathogenic fungi and the importance of large sample sizes to describe local biodiversity of the fungi in the soil environment. [Copyright &y& Elsevier]

A method for baiting soil samples with Delia floralis larvae was developed, and a systematic survey was conducted on soils from northern Norway for insect pathogenic fungi, using D. floralis and Galleria mellonella larvae as bait. The occurrence of insect pathogenic fungi in soils from arable fields and adjacent field margins of conventionally and organically managed farms was compared. The study showed a significantly higher occurrence of insect pathogenic fungi in soils from arable fields of organically managed farms. No significant differences in the occurrence of insect pathogenic fungi were, however, found between the field margins of the two cropping systems. Fungal species identified in the study were Beauveria bassiana, Fusarium merismoides, Metarhizium anisopliae and Tolypocladium cylindrosporum. T. cylindrosporum was found more frequently when using D. floralis as the bait insect than when using G. mellonella. [Copyright &y& Elsevier]

Establishment, persistence and local dispersal of the entomopathogenic fungi Metarhizium anisopliae (ESALQ1037) and M. robertsii (ESALQ1426) (Ascomycota: Hypocreales) were investigated in the soil and rhizosphere following soil drench application in strawberries between 2012 and 2013 at a single location in Inconfidentes, Minas Gerais, Brazil. Metarhizium spp. isolates (n = 108) were collected using selective agar media and insect bait methods, and characterized by sequence analyses of the 5’–end of the translation elongation factor 1-α and the MzFG543igs intergenic region and by multilocus simple sequence repeat analysis. Both applied fungal isolates were frequently recovered from bulk soil and rhizosphere samples of the treated plots, suggesting that they were able to establish and disperse within the soil. Persistence within the soil and strawberry rhizosphere for both fungal isolates was observed up to 12 months after application with frequencies of 25% of haplotypes similar to isolate ESALQ1037 and 87.5% of haplotypes similar to isolate ESALQ1426, respectively. Overall, M. robertsii was the most abundant species in the agroecosystem studied representing 77.8% of the isolates recovered across all sample dates. [ABSTRACT FROM AUTHOR]

Abstract: In a field experiment, we evaluated effects of three different organic white cabbage-cropping systems (O1, O2, O3) on the cabbage root fly, Delia radicum, and its egg predators and pupal parasitoids over 3 years. The three systems all complied with regulations for organic production, but varied in external nutrient input and N-recycling, and were compared to a conventionally farmed control. One organic system (O3) included an intercropped strip of green manure between crop rows. Oviposition by D. radicum was generally not reduced in organic cropping systems. However, higher pupae/egg ratios were observed in the conventional compared to all organic systems, indicating that immature survival from oviposition to pupation was reduced under all the three organic farming practices. In organic system O2 most small coleopteran predators were recorded, but predation on fly eggs was not significantly higher in organic treatments. Pupal parasitization rates ranged from 26.5% to 59.5%, but no significant differences among farming systems were found. Although reduced D. radicum survival could not be attributed solely to natural enemies, the results indicated that organic farming practices in general contribute to the suppression of belowground pests in cabbage production. [Copyright &y& Elsevier]