Entomo

Agriculture, Ecosystems and Environment 113 (2006) 336–341
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Occurrence and distribution of soil borne entomopathogenic
fungi within a single organic agroecosystem
Nicolai V. Meyling *, Jørgen Eilenberg
Department of Ecology, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
Received 10 December 2004; received inrevised form 14 October 2005; accepted 24 October 2005
Available online 20 December 2005

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 (17.1 ha) and the associated hedgerow. Samples were collected at specific
points (atdistances of 25 m) 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.
Highand 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.
# 2005 Elsevier B.V.All rights reserved.
Keywords: Entomopathogenic fungi; Beauveria bassiana; Galleria bait method; GIS; GPS; SADIE; Sustainable agriculture

1. Introduction
Microbial assemblages in agricultural soils are important
for ecosystem services in sustainable agricultural systems,
including pest control (Altieri, 1999). High populations of
beneficial soil borne organisms are characteristics of healthysoils (Magdoff, 2001). The soil environment constitutes an
important reservoir for a diversity of entomopathogenic
fungi, which can contribute significantly to the regulation of
insect populations (Keller and Zimmerman, 1989). Many
species belonging to Hypocreales (Ascomycota) inhabit the
soil for a significant part of their life cycle at northern
latitudes. Of these, Beauveria spp.,Metarhizium anisopliae
(Metschnikoff) Sorokin and Paecilomyces spp. are especially common (Keller and Zimmerman, 1989). Conversion
from conventional to organic farming generally increases
the diversity and activity of soil microorganisms over time
¨
(Mader et al., 2002). There is evidence for higher population
* Corresponding author. Tel.: +45 3528 2666; fax: +45 3528 2670.
E-mail address:nvm@kvl.dk (N.V. Meyling).
0167-8809/$ – see front matter # 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.agee.2005.10.011

levels of entomopathogenic fungi in soils of organically
farmed fields as opposed to conventionally farmed fields in
Norway (Klingen et al., 2002).
Knowledge of local species composition and distribution
is important if the indigenous populations of entomopathogenicfungi in the soil are to be managed in ways to facilitate
the control of pest insect populations within the agroecosystem. Most studies of the occurrence and biodiversity of
entomopathogenic fungi in soils have focused on differences
in species composition between areas defined by habitat
types (e.g. arable soils, semi-natural habitats, etc.) on
regional or national scales, where severallocalities with
similar types of habitat have been considered together
¨
(Steenberg, 1995; Vanninen, 1996; Bidochka et al., 1998;
Klingen et al., 2002; Keller et al., 2003). In most of these
previous studies, relatively few soil samples were collected
arbitrarily at each locality and at a single time point only.
In the present study, the occurrence and spatial
distribution of entomopathogenic...