Agriculture Reference
In-Depth Information
Table 12.1
Nematophagous fungi and their taxonomic positions (Nordbring-Hertz et al.
2006
)
Infection structure
Species
Taxonomic classification
Adhesive nets
Arthrobotrys oligospora
Deuteromycetes
A. conoides
A. musiformis
A. superba Duddingtonia flagrans
Adhesive branches
Monacrosporium gephyropagum
Deuteromycetes
Adhesive knobs
M. ellipsosporum
Deuteromycetes
M. haptotylum
Constricting rings
A. dactyloides
Deuteromycetes
A. brochopaga
Adhesive knobs and
adhesive spores
Nematoctonus concurrens
Basidiomycetes
Adhesive spores
N. leiosporus Drechmeria coniospora
Hirsutella rhossoliensis
Basidiomycetes
Deuteromycetes
Ingested spores
Harposporium anguillulae
Deuteromycetes
Zoospores
Catenaria anguillulae
Chytridiomycetes
Oomycetes
Haptoglossa dickii
Adhesive hyphae
Stylopage hadra Cystopage cladospora
Zygomycetes
Toxic droplets
Pleurotus ostreatus
Basidiomycetes
Appressoria
Pochonia chlamydosporia
Deuteromycetes
adhesive stalks or unstalked knobs, non-constricting rings as well as constricting
rings.
The nematode-trapping fungi generally grow as saprophytic phase, growing
in the form of simple vegetative mycelium and switching over to parasitic phase
through induction of specific hyphal traps stimulated by nematodes. During the
parasitic phase, these specialized morphological structures, i.e., traps of nematode-
trapping fungi, infect and parasitize nematodes (Duddington
1951
; Barron
1977
;
Scholler et al.
1999
; Ahren et al.
2004
) and therefore are important from biological
control point of view (Dong et al.
2004
).
The majority of nematode-trapping fungi are hyphomycetes, placed within the
Orbiliales (Ascomycetes) based on morphological or molecular studies. The genus
Nematoctonus
whose teleomorph belongs to the genus
Hohenbuehelia
(Basidiomy-
cetes), shows an interlink between nematode-trapping fungi and endoparasitic fungi
which possess both adhesive traps and adhesive spores to kill the nematodes. Since
the pioneer work done by Drechsler (
1937
) and Haard (
1968
), nematode-trapping
fungi have been classified in a number of genera based on morphology of conidia
(size, shape and septa) and conidiophores (branching, modifications of the apex).
Traditional taxonomic concepts were mainly based on the morphology of conidia
and conidiophores, irrespective of trapping devices formed by them. This has led
to a situation where species with diverse types of trapping devices have been as-
signed to one genus, while others with similar trapping devices can be found in
different genera (Glockling and Dick
1994
; Liu and Zhang
1994
,
2003
; Zhang et al.
1996a
,
b
). With the advancement of molecular technology, traditional generic clas-
sification based on the morphology of conidial characters, was challenged and justi-
fied by the molecular data. Phylogenies based on rDNA sequences have indicated
