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

Lav Sharma,Guilhermina Marques,Rupesh Kumar Singh,Irene Oliveira,Fernando Raimundo,Fátima Gonçalves,Laura Torres

doi:10.3390/pathogens10020137

Abstract

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.

Highlights

Entomopathogenic fungi (EPF) contribute to different ecosystem services
EPF can be considered as indicators of soil health [2] and, apart from assisting services for ecosystem functions, they contribute to the sustainable management of agroecosystems [3,4]
We investigated the chemical properties of soils from Portuguese vine farms, by considering multiple variables such as: percentage of organic matter content (OM), total nitrogen (N), total organic carbon (C), available phosphorus (P), available potassium (K), exchangeable ions such as sodium (Na-ions), magnesium (Mg-ions), potassium (K-ions), and calcium (Ca-ions), pH, degree of base saturation (DBS), total acidity (TA), and effective cation exchange capacity (ECEC or CECe )

Summary

Introduction

Entomopathogenic fungi (EPF) contribute to different ecosystem services. These include nutrient cycling, and regulatory roles, such as pest and plant disease control [1].EPF can be considered as indicators of soil health [2] and, apart from assisting services for ecosystem functions, they contribute to the sustainable management of agroecosystems [3,4]. Entomopathogenic fungi (EPF) contribute to different ecosystem services. These include nutrient cycling, and regulatory roles, such as pest and plant disease control [1]. EPF can be considered as indicators of soil health [2] and, apart from assisting services for ecosystem functions, they contribute to the sustainable management of agroecosystems [3,4]. EPF contribute to plant habitat adaptation against various biotic and abiotic stresses, and provide protection to plants against pathogens and pests [4]. EPF interact with plants as growth promoters, beneficial rhizosphere colonizers, and biofertilizers [5]. These properties highlight their immense importance for environmentally friendly agriculture. The factors that influence their diversity in cultivated soils are of paramount importance and should be thoroughly investigated

Methods

Discussion

Conclusion