Intercropping Walnut and Tea: Effects on Soil Nutrients, Enzyme Activity, and Microbial Communities.

The practice of intercropping, which involves growing more than one crop simultaneously during the same growing season, is becoming more important for increasing soil quality, land-use efficiency, and subsequently crop productivity. The present study examined changes in soil physicochemical properties, enzymatic activity, and microbial community composition when walnut (Juglans spp.) was intercropped with tea (Camellia sinensis L.) plants in a forest and compared with a walnut and tea monocropping system. The results showed that walnut-tea intercropping improved the soil nutrient profile and enzymatic activity. The soil available nitrogen (AN), available phosphorus (AP), available potassium (AK), organic matter (OM) content, and sucrase activity were significantly boosted in intercropped walnut and tea than in monocropping forests. The interaction between crops further increased bacterial and fungal diversity when compared to monoculture tea forests. Proteobacteria, Bacteroidetes, Firmicutes, Chlamydiae, Rozellomycota, and Zoopagomycota were found in greater abundance in an intercropping pattern than in monoculture walnut and tea forest plantations. The walnut-tea intercropping system also markedly impacted the abundance of several bacterial and fungal operational taxonomic units (OTUs), which were previously shown to support nutrient cycling, prevent diseases, and ameliorate abiotic stress. The results of this study suggest that intercropping walnut with tea increased host fitness and growth by positively influencing soil microbial populations.

Total Phenolic Content and Antioxidant Activity of Mycelial Extracts from the Medicinal Fungus Paecilomyces hepiali (Ascomycetes).

Paecilomyces hepialid, a fungus originating in the Tibetan Plateau, has been used as a substitute for Ophiocordyceps sinensis because the primary chemical compounds and pharmacological effects of P. hepialid are similar to those of O. sinensis. P. hepialid has been developed into a dietary supplement and pharmaceutical products. The antioxidant activity of extracts using 2 solvents (water and ethanol) from mycelia obtained from 2 cultivation modes (solid-state and submerged cultivation) were evaluated in this study. Four strains of P. hepialid obtained from Qinghai, Sichuan, and Yunnan Provinces were included; the total phenolic content and in vitro antioxidant activity of mycelial extracts were compared. The total phenolic content and antioxidant activity of strains were found to be affected by the cultivation mode and extraction solvent. The ethanol extracts of solid-state cultivation of strain 2138, obtained from Sichuan Province, exhibited the highest antioxidant activity. The results showed that different strains might require different cultivation modes and extraction solvents for better antioxidant activity. However, solid-state cultivation and ethanol extraction are generally recommended based on the analyses conducted. Strain 2138 may be a good candidate for the purpose of producing functional foods. The results suggest that strain selection is important when P. hepialid is used to manufacture pharmaceutical products.

Beauveria medogensis sp. nov., a new fungus of the entomopathogenic genus from China.

Beauveria is among the most ubiquitous genera of entomopathogenic fungi throughout the world. A previously unknown species of the genus was recently discovered from a soil sample collected from Tibetan Plateau, China and is here described as new to science, B. medogensis sp. nov. The new species is distinguished from its closest relatives based on both morphological characterization and molecular phylogenetic analyses. Beauveria medogensis is characterized by globose to subglobose conidia, morphologically similar to some other species of in the genus, but was conclusively separated from those species in the phylogenetic analyses including sequences of four nuclear genes (RPB1, RPB2, TEF1 and Bloc). The new species was clustered in the analyses in a single terminal lineage which was grouped with B. australis sequences together as a sister clade to the B. brongniartii terminal clade. Although molecularly closely related, the new species is distinct morphologically from its closest sisters, B. australis and B. brongniartii, in producing globose to subglobose conidia rather than subglobose, broadly ellipsoid to ellipsoid conidia or ellipsoidal to cylindrical conidia. As isolated from a soil sample, the entomopathogenicity of the new species has been confirmed using Helicoverpa armigera and Tenebrio molitor larvae.

Pathogenicity of Beauveria bassiana isolated from Moroccan Argan forests soil against larvae of Ceratitis capitata (Diptera: Tephritidae) in laboratory conditions.

The Mediterranean fruit fly, Ceratitis capitata Wiedemann (Diptera: Tephritidae), is the major tephritid pest in Morocco. This pest survives in Moroccan forests Argania spinosa and continually invades the nearest agricultural areas. Entomopathogenic fungi are an interesting tool for fruit fly control and hold a useful alternative to conventional insecticides. However, primary selection of effective pathogens should be taken in laboratory condition prior to applying them in the field. Here, we used third late instar larvae of C. capitata to investigate the effectiveness of 15 local Beauveria bassiana isolates. Results showed that all isolates were able to infect the larval stage, producing a large mortality rate in puparia ranging from 65 to 95 % and caused significant reduction in adult emergence. The fungal treatments revealed that the mycosis occurred also in adults escaping infection as pupariating larvae. The percentage of mycosed puparia was highest in strain TAM6.2 (95 %) followed by ERS4.16 (90 %), therefore they were the most virulent. Median lethal concentration (LC50) was studied for five isolates at four concentrations ranging from 105 to 108 conidia ml⁻¹. The results showed that the slopes of regression lines for B. bassiana ERS4.16 (slope = 0.386) and TAM6.2 (slope = 0.41) were the most important and had the lowest LC50 values (2.85 × 10³ and 3.16 × 10³ conidia ml⁻¹ respectively). This investigation suggests that the soil of Argan forests contains pathogenic B. bassiana isolates and highlights for the first time their potential as biological control toward C. capitata larval stage in Morocco.