2015). The colonization of Bt was affected by metaflumizone. Moreover, both
antagonism and synergism effects were observed based on the time of application
of Bt treatment and concentration of chemical insecticides. When Bt was applied
immediately after chemical insecticides, an antagonistic effect was observed.
Whereas, synergistic activity was detected when Bt was used 12 and 24 h after
treatment at a concentration equal to LC 25 value of chlorantraniliprole, dichlorvos,
and abamectin. The simultaneous use of Bt and chemical insecticides was not
recommended by Amizadeh et al. (2015).
The possibility of simultaneous application of parasitoid wasps and Bt has been
questioned (Sedaratian et al. 2014; Alsaedi et al. 2017). The braconid, Habrobracon
hebetor Say (Hym.: Braconidae) and B. thuringiensis subsp. kurstaki were selected
to control the larval stages of H. armigera (Sedaratian et al. 2014). Prior to the
integration of H. hebetor with Bt, the effect of Bt on the wasp or in general, natural
enemies has to be precisely assessed. Sedaratian et al. (2014) studied some of
biological parameters of H. hebetor parasitizing the Bt-infected H. armigera larvae.
Bt negatively affected the development of H. hebetor wasps, suggesting that risk
assessment is required to evaluate the side effects of Bt on natural enemies. In
another study, the possibility of application of the egg parasitoid, Trichogramma
spp., with a commercial Bt formulation (Biolep®) based on the B. thuringiensis
subsp. kurstaki for the control of tomato leafminer, T. absoluta, was examined under
greenhouse conditions (Alsaedi et al. 2017). Moreover, the effect of this commercialized Bt-based product was assessed against the non-target organism,
Trichogramma spp. Based on greenhouse observations, the infestation rate was
significantly lower in the treatment of the combination of Bt and Trichogramma,
compared to the individual application of these two biological control agents.
Interestingly, Bt had no negative effect on the biological parameters of
Trichogramma spp. (Alsaedi et al. 2017), suggesting the simultaneous application
of these two biological control agents. The combined use of two insect pathogens, Bt
and HaNPV, targeting the first instars of H. armigera larvae with the larval parasitoid, H. hebetor, was evaluated under field conditions (Allahyari et al. 2019).
Synergistic interaction between the applications of insect pathogens with releasing
the larval parasitoid in the control of H. armigera in chickpea field was found.
Therefore, the simultaneous applications of these biological control agents in the
IPM program of H. armigera in chickpea field is suggested.
10.15 Challenges
About five microbial pesticides have been registered in Iran (Karimi et al. 2019).
Biological control by the means of insect pathogens faces different challenges in
Iran. The development of the bio-insecticide mass production, finding a wider
spectrum of activity, improvements in Bt formulation, application strategies, persistence in the environment, preserving shelf-life, effective delivery system to all
agricultural sections in Iran, cost-effective production, registration of microbial
428
A. Khorramnejad et al.
antagonism and synergism effects were observed based on the time of application
of Bt treatment and concentration of chemical insecticides. When Bt was applied
immediately after chemical insecticides, an antagonistic effect was observed.
Whereas, synergistic activity was detected when Bt was used 12 and 24 h after
treatment at a concentration equal to LC 25 value of chlorantraniliprole, dichlorvos,
and abamectin. The simultaneous use of Bt and chemical insecticides was not
recommended by Amizadeh et al. (2015).
The possibility of simultaneous application of parasitoid wasps and Bt has been
questioned (Sedaratian et al. 2014; Alsaedi et al. 2017). The braconid, Habrobracon
hebetor Say (Hym.: Braconidae) and B. thuringiensis subsp. kurstaki were selected
to control the larval stages of H. armigera (Sedaratian et al. 2014). Prior to the
integration of H. hebetor with Bt, the effect of Bt on the wasp or in general, natural
enemies has to be precisely assessed. Sedaratian et al. (2014) studied some of
biological parameters of H. hebetor parasitizing the Bt-infected H. armigera larvae.
Bt negatively affected the development of H. hebetor wasps, suggesting that risk
assessment is required to evaluate the side effects of Bt on natural enemies. In
another study, the possibility of application of the egg parasitoid, Trichogramma
spp., with a commercial Bt formulation (Biolep®) based on the B. thuringiensis
subsp. kurstaki for the control of tomato leafminer, T. absoluta, was examined under
greenhouse conditions (Alsaedi et al. 2017). Moreover, the effect of this commercialized Bt-based product was assessed against the non-target organism,
Trichogramma spp. Based on greenhouse observations, the infestation rate was
significantly lower in the treatment of the combination of Bt and Trichogramma,
compared to the individual application of these two biological control agents.
Interestingly, Bt had no negative effect on the biological parameters of
Trichogramma spp. (Alsaedi et al. 2017), suggesting the simultaneous application
of these two biological control agents. The combined use of two insect pathogens, Bt
and HaNPV, targeting the first instars of H. armigera larvae with the larval parasitoid, H. hebetor, was evaluated under field conditions (Allahyari et al. 2019).
Synergistic interaction between the applications of insect pathogens with releasing
the larval parasitoid in the control of H. armigera in chickpea field was found.
Therefore, the simultaneous applications of these biological control agents in the
IPM program of H. armigera in chickpea field is suggested.
10.15 Challenges
About five microbial pesticides have been registered in Iran (Karimi et al. 2019).
Biological control by the means of insect pathogens faces different challenges in
Iran. The development of the bio-insecticide mass production, finding a wider
spectrum of activity, improvements in Bt formulation, application strategies, persistence in the environment, preserving shelf-life, effective delivery system to all
agricultural sections in Iran, cost-effective production, registration of microbial
428
A. Khorramnejad et al.