Basic HTML Version
Molecular Plant Breeding 2012, Vol.3, No.7, 63
-
79
http://mpb.sophiapublisher.com
64
fungi are important among all the biological control
agents due to its broad host range, route of
pathogenicity and its ability to control sap sucking
pests such as mosquitoes and aphids (Butt, 2002; Qazi
and Khachatourians, 2005; Thomas and Read, 2007;
Fan et al., 2007) as well as pests with chewing
mouthparts (Hajek and St. Leger, 1994; de Faria and
Wraight, 2007).
This review will help us understand entomopatho-
genic fungal virulence and present the most recent
improvements and achievements in the relevant field.
This will help us determine how to improve the
virulence of entomopathogenic fungi to shorten the
killing time of pest.
1 Entomopathogenic Fungi (EPF)
Entomopathogenic fungi (EPF) are widely distributed
with both restricted and wide host ranges which have
different biocontrol potentials against arthropods
insects and plant pathogenic fungi. Entomopathogenic
fungi were among the first organisms to be used for
the biological control of pests. More than 700 species
of fungi from around 90 genera are pathogenic to
insects (Khachatourians and Sohail, 2008). Most EPF
species are from the fungal divisions
Ascomycota
and
Zygomycota
. The
ascomycete
fungi were previously
divided into two groups, the
Ascomycota
and the
Deuteromycota
(Table 1). The Fungi Imperfecti of
Deuteromycota
was known for having no sexual stage
was known called as. But later on, cultural and
molecular studies have demonstrated that some of
these ―imperfect fungi‖ (formally class Hyphomycetes
in the Deuteromycota) were in fact anamorphs (asexual
forms) of the Ascomycota within the order Hypocreales,
and Clavicipitaceae family (Fukatzu, 1997; Hodge,
2003; Krasnoff, 1995; Shimazu, 1998). Within the
Zygomycota, the most entomopathogenic species are
in the order Entomophthorales (Roy et al., 2006).
These fungi nutritionally may be saprotrophs that
colonize the rhizosphere and phyllosphere, endophytic
saprotrophs, hemibiotrophic, necrotrophic of plants,
entomopathogenic or mycoparasitic and some of them
have adopted more than one econutritional mode.
2 Life cycle of entomopathogenic fungi
The life cycle of EPF is composed of the spore which
geminates into mycelia and the mycelia in turnproduce
spores (spore–mycelia–spore phases). The life cycle
of most entomopathogenic fungi consist of two phases:
a normal mycelia growth phase mostly outside the
host body and a yeast like budding phase mostly in the
hemocoel of host. The yeast-like, dimorphic mode of
growth in
Beauveria bassiana
was described by Alves
et al (2002); and the production of oblong blastospore-
like propagules in
M. flavoviride
was described by
Fargues et al (2002). The life cycle of
M. anisopliae
under liquid culture conditions has also been
described (Uribe and Khachatourians, 2008).
Table 1 Classification of entomopathogenic fungi (Roy et al., 2006)
Division
Class
Order
Family
Genus
Zygomycota
Zygomycetes
Entomophthorales
Entomophthoraceae
Entomophaga
Entomophthora
Erynia
Eryniopsis
Furia
Massospora
Strongwellsea
Pandora
Tarichium
Zoophthora
Neozygitaceae
Neozygites
Ascomycota
Sordariomycetes
Hypocreales
Clavicipitaceae
Beauveriaa
Cordyceps
Cordycepioideus
Lecanicilliuma
Metarhiziuma
Nomuraea