of biomass, which was indicated to be higher in 1000,000 R <100,000 R <10,000 R,
and close to that of the control system. However, in the case of transferring after
22 days, the 1,000,000 R irradiated system showed a similar increase in the volume
of biomass as observed in the control system. This indicates that damage from
irradiation was recovered after 22 days. The fact the mature biota had high fecundity
means that microorganisms survived under strong irradiation, and these surviving
individuals recovered to increasing conditions again after 22 days.
The microorganisms in the microcosm N-system were not influenced by irradiation stronger than that just after the Fukushima nuclear power plant accident in
Japan. This phenomenon makes sense considering that microorganisms first
appeared on the early Earth, which was exposed to very strong irradiation. It is
important to generate new findings for environmental protection and restoration that
some microorganisms have the ability to resist the influence of strong irradiation.
7.12 Microbial Pesticides
These days, the residues and accumulation of chemical pesticides have become one
of the most serious problems all over the world. At the same time, biological
prevention such as the use of microbial pesticides, which include natural enemies,
is revisited, and, in Europe and the USA, microbial pesticides have already been
made practicable. They are obtained from organisms including plants, bacteria and
other microbes, fungi, nematodes, etc. They are often important components of
integrated pest management (IPM) programs and have received much practical
attention as substitutes for synthetic chemical plant protection products (PPPs).
Microbial pesticides are one of many biological preservation methods, and their
main components are bacteria, fungi, viruses, protozoans, and nematodes, which
may or may not be. These microbial pesticides are considered safer for the environment than chemical pesticides because of their natural origins. Furthermore, not only
natural microbial pesticides but also genetically engineered ones have been developed, and more capitalization has been done. Note, however, that how the microbial
pesticide behaves in nature and what effects will happen have not been made clear.
Therefore, it is very important to make clear the proliferation and decay of microbial
pesticides in natural ecosystems and to obtain the basal information for environmental assessment for the field release of microbial pesticides.
7.12.1 Bacillus thuringiensis subsp. aizawai KH
In this section, we focus on the environmental impact assessment of microbial
pesticides, which constitute the lowest prey species in the microcosmic food chain.
Bacillus thuringiensis subsp. aizawai KH was added at 1, 10, and 100 times the
abundance of indigenous bacteria in the microcosm, as a bacterial pesticide, and its
134
K. Murakami et al.
and close to that of the control system. However, in the case of transferring after
22 days, the 1,000,000 R irradiated system showed a similar increase in the volume
of biomass as observed in the control system. This indicates that damage from
irradiation was recovered after 22 days. The fact the mature biota had high fecundity
means that microorganisms survived under strong irradiation, and these surviving
individuals recovered to increasing conditions again after 22 days.
The microorganisms in the microcosm N-system were not influenced by irradiation stronger than that just after the Fukushima nuclear power plant accident in
Japan. This phenomenon makes sense considering that microorganisms first
appeared on the early Earth, which was exposed to very strong irradiation. It is
important to generate new findings for environmental protection and restoration that
some microorganisms have the ability to resist the influence of strong irradiation.
7.12 Microbial Pesticides
These days, the residues and accumulation of chemical pesticides have become one
of the most serious problems all over the world. At the same time, biological
prevention such as the use of microbial pesticides, which include natural enemies,
is revisited, and, in Europe and the USA, microbial pesticides have already been
made practicable. They are obtained from organisms including plants, bacteria and
other microbes, fungi, nematodes, etc. They are often important components of
integrated pest management (IPM) programs and have received much practical
attention as substitutes for synthetic chemical plant protection products (PPPs).
Microbial pesticides are one of many biological preservation methods, and their
main components are bacteria, fungi, viruses, protozoans, and nematodes, which
may or may not be. These microbial pesticides are considered safer for the environment than chemical pesticides because of their natural origins. Furthermore, not only
natural microbial pesticides but also genetically engineered ones have been developed, and more capitalization has been done. Note, however, that how the microbial
pesticide behaves in nature and what effects will happen have not been made clear.
Therefore, it is very important to make clear the proliferation and decay of microbial
pesticides in natural ecosystems and to obtain the basal information for environmental assessment for the field release of microbial pesticides.
7.12.1 Bacillus thuringiensis subsp. aizawai KH
In this section, we focus on the environmental impact assessment of microbial
pesticides, which constitute the lowest prey species in the microcosmic food chain.
Bacillus thuringiensis subsp. aizawai KH was added at 1, 10, and 100 times the
abundance of indigenous bacteria in the microcosm, as a bacterial pesticide, and its
134
K. Murakami et al.