the nematode population, kill the juveniles, prohibit the nematode egg hatching and
also decrease the number of galls (Baghaee and Moghaddam 2015).
These results highlight the importance and the success of Bt in the biological
control of pests under the laboratory conditions. Although the successful application
of Bt is dependent on various factors such as applied dose, weather conditions and
time of application, the efficacy of the desired Bt strain, Bt formulation or Bt crop
has to be clearly determined under greenhouse and field conditions.
B. thuringiensis subsp. israelensis (serotype H14) is commonly used in the
southern part of Iran to control the vectors of malaria, A. dthali, A. fluviatilis and
A. stephensi (Hanafi-Bojd et al. 2006; Shahi et al. 2013). B. thuringiensis subsp.
israelensis H14 effectively controls the dipterans and this success is due to the
expression of insecticidal proteins, Cry4A, Cry4B, Cry11A and Cyt1A, in this
serotype (Höfte and Whiteley 1989; Dulmage et al. 1990). The larvicidal activity
of B. thuringiensis H14 has been studied and indeed demonstrated against Anopheles
dthali and A. fluviatilis. Besides the application of chemical insecticides, these
malaria vectors are being controlled by the utilization of Bt in the mosquitoes
breeding sites in the south part of Iran (Hanafi-Bojd et al. 2006).
The effect of Bt and Azadirachtin individually and in combination against tomato
leaf miner, Tuta absoluta Meyrick (Lep.: Gelechiidae) was evaluated under the field
conditions. Due to the significant reduction in the population of T. absoluta in the
tomato field after treating with Bt and Azadirachtin, the application of these two
insecticides whether alone or in combination, has been strongly recommended by
Nazarpour et al. (2014).
The possibility of simultaneous application of Trichogramma spp. and a commercial Bt formulation (Biolep®) based on the B. thuringiensis subsp. kurstaki for
the control of tomato leafminer, T. absoluta, has been 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., the egg parasitoids of T. absoluta. Based on the greenhouse observations, the
number of mines detected in the treatment of the combination of Bt and
Trichogramma, were significantly lower than the individual application of these
two biological control agents. More importantly, following the application of Bt, no
negative effect was observed on the biological parameters of Trichogramma spp.
(Alsaedi et al. 2017).
10.10 Fermentation Optimization
Due to the importance of Bt in microbial pest control, the appropriate and economic
production of Bt-based bio-insecticides is critical. Therefore, many studies have
investigated optimization of the fermentation conditions. B. thuringiensis strains
have special requirements during the fermentation process. Sporulation and germination of Bt are dependent on the available nutrition. Therefore, investigation of the
nutritional requirements of Bt is of importance in Bt production. A summary of
416
A. Khorramnejad et al.
also decrease the number of galls (Baghaee and Moghaddam 2015).
These results highlight the importance and the success of Bt in the biological
control of pests under the laboratory conditions. Although the successful application
of Bt is dependent on various factors such as applied dose, weather conditions and
time of application, the efficacy of the desired Bt strain, Bt formulation or Bt crop
has to be clearly determined under greenhouse and field conditions.
B. thuringiensis subsp. israelensis (serotype H14) is commonly used in the
southern part of Iran to control the vectors of malaria, A. dthali, A. fluviatilis and
A. stephensi (Hanafi-Bojd et al. 2006; Shahi et al. 2013). B. thuringiensis subsp.
israelensis H14 effectively controls the dipterans and this success is due to the
expression of insecticidal proteins, Cry4A, Cry4B, Cry11A and Cyt1A, in this
serotype (Höfte and Whiteley 1989; Dulmage et al. 1990). The larvicidal activity
of B. thuringiensis H14 has been studied and indeed demonstrated against Anopheles
dthali and A. fluviatilis. Besides the application of chemical insecticides, these
malaria vectors are being controlled by the utilization of Bt in the mosquitoes
breeding sites in the south part of Iran (Hanafi-Bojd et al. 2006).
The effect of Bt and Azadirachtin individually and in combination against tomato
leaf miner, Tuta absoluta Meyrick (Lep.: Gelechiidae) was evaluated under the field
conditions. Due to the significant reduction in the population of T. absoluta in the
tomato field after treating with Bt and Azadirachtin, the application of these two
insecticides whether alone or in combination, has been strongly recommended by
Nazarpour et al. (2014).
The possibility of simultaneous application of Trichogramma spp. and a commercial Bt formulation (Biolep®) based on the B. thuringiensis subsp. kurstaki for
the control of tomato leafminer, T. absoluta, has been 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., the egg parasitoids of T. absoluta. Based on the greenhouse observations, the
number of mines detected in the treatment of the combination of Bt and
Trichogramma, were significantly lower than the individual application of these
two biological control agents. More importantly, following the application of Bt, no
negative effect was observed on the biological parameters of Trichogramma spp.
(Alsaedi et al. 2017).
10.10 Fermentation Optimization
Due to the importance of Bt in microbial pest control, the appropriate and economic
production of Bt-based bio-insecticides is critical. Therefore, many studies have
investigated optimization of the fermentation conditions. B. thuringiensis strains
have special requirements during the fermentation process. Sporulation and germination of Bt are dependent on the available nutrition. Therefore, investigation of the
nutritional requirements of Bt is of importance in Bt production. A summary of
416
A. Khorramnejad et al.