Control of Sunn pest is mainly based on chemical control in farms which is
widely used in different countries. In recent years, chemical control of Sunn pest
spanned more than 1,500,000 ha in Iran. Chemical insecticides have negatively
affected many beneficial insects, wildlife, waters and causing even more harm to
humans (Javahery 2004). In general, a few parasitoids, predators and pathogens are
known as natural enemies of Sunn pest. However, the scelionid wasp, Trissolcus
grandis (Hymenoptera: Scelionidae), has shown considerable promise due to its
ability to regulate Sunn pest populations in farm (Amir-Maafi 2000; Amir-Maafi and
Parker 2002, 2003). The entomopathogenic fungi have demonstrated a favorable
potential to affect this pest when other natural enemies are not present especially
during its diapause in overwintering sites (El-Bouhssini et al. 2004; Nouri-Aiin et al.
2014). Parker et al. (2000, 2003) collected EPFs on Sunn pest from some parts of
Syria, Turkey, Iran, Uzbekistan, Kazakhstan, Kyrgyz Republic and Russia. The most
common species was B. bassiana, followed by other species such as Verticillium and
Paecilomyces. Skinner et al. (2007) obtained more than 220 isolates of fungi from
the soil of hibernating sites of Sunn pest in Russia, East and central part of Asia. In
addition, Kazemi Yazdi et al. (2011) and Nouri-Aiin et al. (2014) isolated more than
170 strains of different fungal species from overwintering sites of Sunn pest in
various regions of Iran. Some of these isolates preserve in the fungal culture
collection of IRIPP. In other studies, Parsi and Mohammadipour (2017) collected
different isolates of B. bassiana from overwintering areas in the center of Iran. They
collected 510 soil samples and cadavers from overwintering sites of Sunn pest in
Semnan, Qom, Kerman and Markazi provinces in three elevation classes (1900,
2100 and 2300 m), in late summer and winter 2015 and 2016. Their results indicate
that from 250 samples in winter, 50.4% and from 260 samples in summer, 17% had
B. bassiana spores. The result showed more isolates were found at 2300 meters
elevation although some were present at 1900 to 2100 meters.
Furthermore, B. bassiana and M. anisopliae have been subjected to bioassays on
different developmental stages of Sunn pest. Rastegar et al. (2006) evaluated the
virulence of eight Iranian isolates of B. bassiana and also the American GHA isolate
on adult Sunn pest by immersion of insects in spore suspensions. The lowest LC50
was 3.78 Â 10
3 spores ml
À1 and lowest LT50 was 8.55 days with isolate DEBI002
and the highest LC50 (5.06 Â 10
5 spore ml
À1 ) and LT50 (17.96 days) recorded for
DEBI008, respectively. In another work, Bandani and Esmailpour (2006) proved
that an oil formulation of B. bassiana against the Sunn pest increased fungal
virulence. Oil formulation enhances the adhesion of spore to the insect cuticle,
especially epicuticle, through hydrophobic interaction between the spore and cuticle
surface.
A study was conducted by Tork et al. (2008) to determine the virulence and
enzyme production of two isolates of M. anisopliae (4556 and M187) on Sunn pest.
Comparison of the LC50s of these isolates showed that the 4556 isolate, with LC50
of 3.38 Â 10
5 spores ml
À1 , was more virulent than isolate M189, with an LC50 of
7.70 Â 10
5 spores ml
À1 . The assays also demonstrated that enzyme production in the
4556 isolate was more than M198. Therefore, there may be a direct relationship
between enzyme production and virulence, at least with these two isolates. Also,
450
H. Askary et al.
widely used in different countries. In recent years, chemical control of Sunn pest
spanned more than 1,500,000 ha in Iran. Chemical insecticides have negatively
affected many beneficial insects, wildlife, waters and causing even more harm to
humans (Javahery 2004). In general, a few parasitoids, predators and pathogens are
known as natural enemies of Sunn pest. However, the scelionid wasp, Trissolcus
grandis (Hymenoptera: Scelionidae), has shown considerable promise due to its
ability to regulate Sunn pest populations in farm (Amir-Maafi 2000; Amir-Maafi and
Parker 2002, 2003). The entomopathogenic fungi have demonstrated a favorable
potential to affect this pest when other natural enemies are not present especially
during its diapause in overwintering sites (El-Bouhssini et al. 2004; Nouri-Aiin et al.
2014). Parker et al. (2000, 2003) collected EPFs on Sunn pest from some parts of
Syria, Turkey, Iran, Uzbekistan, Kazakhstan, Kyrgyz Republic and Russia. The most
common species was B. bassiana, followed by other species such as Verticillium and
Paecilomyces. Skinner et al. (2007) obtained more than 220 isolates of fungi from
the soil of hibernating sites of Sunn pest in Russia, East and central part of Asia. In
addition, Kazemi Yazdi et al. (2011) and Nouri-Aiin et al. (2014) isolated more than
170 strains of different fungal species from overwintering sites of Sunn pest in
various regions of Iran. Some of these isolates preserve in the fungal culture
collection of IRIPP. In other studies, Parsi and Mohammadipour (2017) collected
different isolates of B. bassiana from overwintering areas in the center of Iran. They
collected 510 soil samples and cadavers from overwintering sites of Sunn pest in
Semnan, Qom, Kerman and Markazi provinces in three elevation classes (1900,
2100 and 2300 m), in late summer and winter 2015 and 2016. Their results indicate
that from 250 samples in winter, 50.4% and from 260 samples in summer, 17% had
B. bassiana spores. The result showed more isolates were found at 2300 meters
elevation although some were present at 1900 to 2100 meters.
Furthermore, B. bassiana and M. anisopliae have been subjected to bioassays on
different developmental stages of Sunn pest. Rastegar et al. (2006) evaluated the
virulence of eight Iranian isolates of B. bassiana and also the American GHA isolate
on adult Sunn pest by immersion of insects in spore suspensions. The lowest LC50
was 3.78 Â 10
3 spores ml
À1 and lowest LT50 was 8.55 days with isolate DEBI002
and the highest LC50 (5.06 Â 10
5 spore ml
À1 ) and LT50 (17.96 days) recorded for
DEBI008, respectively. In another work, Bandani and Esmailpour (2006) proved
that an oil formulation of B. bassiana against the Sunn pest increased fungal
virulence. Oil formulation enhances the adhesion of spore to the insect cuticle,
especially epicuticle, through hydrophobic interaction between the spore and cuticle
surface.
A study was conducted by Tork et al. (2008) to determine the virulence and
enzyme production of two isolates of M. anisopliae (4556 and M187) on Sunn pest.
Comparison of the LC50s of these isolates showed that the 4556 isolate, with LC50
of 3.38 Â 10
5 spores ml
À1 , was more virulent than isolate M189, with an LC50 of
7.70 Â 10
5 spores ml
À1 . The assays also demonstrated that enzyme production in the
4556 isolate was more than M198. Therefore, there may be a direct relationship
between enzyme production and virulence, at least with these two isolates. Also,
450
H. Askary et al.