Based on the literature, many studies as master thesis, PhD dissertation and projects
have been performed in Iran and focused on the discovery of new Bt strains with
potent pesticidal activity. The final aim of all these studies is to introduce an
appropriate candidate for the development of future Bt-based products. While so
far, only a few of these candidates have been developed as Bt-based bio-insecticides
(Karimi et al. 2019). Indeed, more considerations have to be given to bio-insecticide
production in order to develop the microbial pest control. Definitely, innovative
production techniques, optimization of mass production protocols, assessment of
product quality and quantity, preserved shelf-life and high biological activity are
required for the commercialization of bio-insecticides based on Bt. Undoubtedly,
financial support and simplification of microbial insecticide registration lead to the
development of bio-insecticide production. Finally, the consistency of microbial
agents’ effectiveness and low prices of commercialized bio-insecticides encourage
the farmers to substitute Bt-based products for chemicals.
Bt has been predominantly isolated from soils of different regions of Iran. In
different studies, B. thuringiensis subsp. kurstaki was reported as the most abundant
Bt serovar, although it highly depended on the geographical region and the environment where sampling was carried out. The bipyramidal crystalline inclusions
were commonly observed in different Bt screening projects. Due to the economic
and environmental benefits, several companies produce Bt-based insecticides. The
bacterial formulations registered as bio-insecticides in Iran are mainly based on
B. thuringiensis subsp. kurstaki following by B. thuringiensis subsp. israelensis.
Different kinds of formulations are used in Iran for bacterial production, including
suspension concentrates, wettable powders and granular formulations.
B. thuringiensis synthetic genes were transferred into different plants, mainly
rice, cotton, potato, sugar beet, alfalfa, maize and date with the aim of developing
transgenic plants with enhanced resistance to insects. Although GM crops
expressing cry genes have been considered as the successful substitute for
chemicals, risk assessments are performed before their deployment.
Overall, the screening and characterization studies performed in Iran have introduced native Bt strains with high potential for controlling agricultural, household
and medical insect pests. These Bt strains are appropriate candidates for application
as commercialized biocontrol agents. The complementary research is certainly
necessary under laboratory, greenhouse, semi-field and field conditions for evaluating the efficiency of Bt products and Bt crops. The effect of Bt products and Bt crops
has to be assessed on non-target organisms (i.e. parasitoids, predators and pollinators). Optimization of mass production, fermentation, and formulation is critical for
development of successful commercial products for us in biological control and
providing a healthier environment.
Acknowledgement We are deeply grateful to Dr. Mark Goettel for his valuable comments and
improvement of the text. Ayda Khorramnejad acknowledges Dr. Yolanda Bel, Dr. Baltasar Escriche
and Dr. Patricia Hernández-Martínez for their supports and thoughtful comments on the manuscript.
10 Progress on the Bacterium Bacillus thuringiensis and Its. . .
431
have been performed in Iran and focused on the discovery of new Bt strains with
potent pesticidal activity. The final aim of all these studies is to introduce an
appropriate candidate for the development of future Bt-based products. While so
far, only a few of these candidates have been developed as Bt-based bio-insecticides
(Karimi et al. 2019). Indeed, more considerations have to be given to bio-insecticide
production in order to develop the microbial pest control. Definitely, innovative
production techniques, optimization of mass production protocols, assessment of
product quality and quantity, preserved shelf-life and high biological activity are
required for the commercialization of bio-insecticides based on Bt. Undoubtedly,
financial support and simplification of microbial insecticide registration lead to the
development of bio-insecticide production. Finally, the consistency of microbial
agents’ effectiveness and low prices of commercialized bio-insecticides encourage
the farmers to substitute Bt-based products for chemicals.
Bt has been predominantly isolated from soils of different regions of Iran. In
different studies, B. thuringiensis subsp. kurstaki was reported as the most abundant
Bt serovar, although it highly depended on the geographical region and the environment where sampling was carried out. The bipyramidal crystalline inclusions
were commonly observed in different Bt screening projects. Due to the economic
and environmental benefits, several companies produce Bt-based insecticides. The
bacterial formulations registered as bio-insecticides in Iran are mainly based on
B. thuringiensis subsp. kurstaki following by B. thuringiensis subsp. israelensis.
Different kinds of formulations are used in Iran for bacterial production, including
suspension concentrates, wettable powders and granular formulations.
B. thuringiensis synthetic genes were transferred into different plants, mainly
rice, cotton, potato, sugar beet, alfalfa, maize and date with the aim of developing
transgenic plants with enhanced resistance to insects. Although GM crops
expressing cry genes have been considered as the successful substitute for
chemicals, risk assessments are performed before their deployment.
Overall, the screening and characterization studies performed in Iran have introduced native Bt strains with high potential for controlling agricultural, household
and medical insect pests. These Bt strains are appropriate candidates for application
as commercialized biocontrol agents. The complementary research is certainly
necessary under laboratory, greenhouse, semi-field and field conditions for evaluating the efficiency of Bt products and Bt crops. The effect of Bt products and Bt crops
has to be assessed on non-target organisms (i.e. parasitoids, predators and pollinators). Optimization of mass production, fermentation, and formulation is critical for
development of successful commercial products for us in biological control and
providing a healthier environment.
Acknowledgement We are deeply grateful to Dr. Mark Goettel for his valuable comments and
improvement of the text. Ayda Khorramnejad acknowledges Dr. Yolanda Bel, Dr. Baltasar Escriche
and Dr. Patricia Hernández-Martínez for their supports and thoughtful comments on the manuscript.
10 Progress on the Bacterium Bacillus thuringiensis and Its. . .
431