11.4.1 Mode of Action of Bacillus thuringiensis
B. thuringiensis produces protein crystals during spore formation, which is responsible for lysis of gut cells when consumed by susceptible insects (Chandler et al.
2011). B. thuringiensis produces crystalline protein (cry and cyt). When cry protein
is ingested by the larva, delta-endotoxins are activated in the gut of the insects which
has alkaline pH (9.0 to 11.0). The proteins are attached to the gut receptor site, create
pores in the midgut cells (Kumar 2012). Bt toxin causes paralysis of the midgut, cell
lysis results in the release of gut contents into the hemocoel of the insect, disrupting
the pH balance and finally death of specific target pest (Betz et al. 2000; Zhu et al.
2000; Darboux et al. 2001) (Fig. 11.1).
Table 11.1 List of Bacillus thuringiensis subspecies and its toxin used against various pests
Bacillus thuringiensis
subspecies
Toxin
class
Prototoxin size
(K Da)
Target insect
Bt subsp. Berliner
Cry I
130–140
Lepidoptera
Bt subsp. Kurstaki
Cry I
130–140
Lepidoptera
Bt subsp. kurstaki
Cry II
71
Lepidoptera,
Diptera
Bt subsp. aizawai
Cry I
135
Lepidoptera
Bt subsp. tenebrionis
Cry III
66-73
Coleoptera
Bt subsp. israelensis
Cry IV
68
Diptera
Table 11.2 List of Bacillus thuringiensis based pesticides commercially available to control
various pests
Bacteria used
Target pests
Trade name
Bacillus
popilliae
Japanese beetle grubs
Doom, Japidemic, Milky Spore Disease,
Grub Attack
B. sphaericus
Mosquito larvae
Sphericide, VectoLex
B. thuringiensis
subsp. aizawai
Lepidopterans
Certan
B. thuringiensis
subsp.
israelensis
Mosquito, blackflies and
fungus gnats
Bacticide, Summit Bactimos, Bacto PowerBti, Biodart M, Larvect50, Deltafix,
Biovectra Spicbiob, VectoBac, Vectocid
B. thuringiensis
subsp. kurstaki
Lepidopteran larvae
Abtec Btk, Agni, Bioasp, BioDart, Bactur,
Biobit, Bioworm, Biolep, B.T.Killer,
Caterpilin, Cezar, CID, Deflin, DiPel,
Dipole, Gold Btk, Halt, JasBT, KavachBt,
KrishiBio, Prasar, Lipel, Mahastra,
Minchu, Neelstaki
B. thuringiensis
subsp.
tenebrionis
Colorado potato beetle, stored
pests, coleopteran adults and
larvae
Foil, M-one, M-track, Novardo, Trident
B. thuringiensis
subsp. Galleriae
Lepidopteran larvae,
bollworms, Diamondback
moth
Spicturin
Source: Usta (2013)
11 Biopesticides for Pest Management
243
B. thuringiensis produces protein crystals during spore formation, which is responsible for lysis of gut cells when consumed by susceptible insects (Chandler et al.
2011). B. thuringiensis produces crystalline protein (cry and cyt). When cry protein
is ingested by the larva, delta-endotoxins are activated in the gut of the insects which
has alkaline pH (9.0 to 11.0). The proteins are attached to the gut receptor site, create
pores in the midgut cells (Kumar 2012). Bt toxin causes paralysis of the midgut, cell
lysis results in the release of gut contents into the hemocoel of the insect, disrupting
the pH balance and finally death of specific target pest (Betz et al. 2000; Zhu et al.
2000; Darboux et al. 2001) (Fig. 11.1).
Table 11.1 List of Bacillus thuringiensis subspecies and its toxin used against various pests
Bacillus thuringiensis
subspecies
Toxin
class
Prototoxin size
(K Da)
Target insect
Bt subsp. Berliner
Cry I
130–140
Lepidoptera
Bt subsp. Kurstaki
Cry I
130–140
Lepidoptera
Bt subsp. kurstaki
Cry II
71
Lepidoptera,
Diptera
Bt subsp. aizawai
Cry I
135
Lepidoptera
Bt subsp. tenebrionis
Cry III
66-73
Coleoptera
Bt subsp. israelensis
Cry IV
68
Diptera
Table 11.2 List of Bacillus thuringiensis based pesticides commercially available to control
various pests
Bacteria used
Target pests
Trade name
Bacillus
popilliae
Japanese beetle grubs
Doom, Japidemic, Milky Spore Disease,
Grub Attack
B. sphaericus
Mosquito larvae
Sphericide, VectoLex
B. thuringiensis
subsp. aizawai
Lepidopterans
Certan
B. thuringiensis
subsp.
israelensis
Mosquito, blackflies and
fungus gnats
Bacticide, Summit Bactimos, Bacto PowerBti, Biodart M, Larvect50, Deltafix,
Biovectra Spicbiob, VectoBac, Vectocid
B. thuringiensis
subsp. kurstaki
Lepidopteran larvae
Abtec Btk, Agni, Bioasp, BioDart, Bactur,
Biobit, Bioworm, Biolep, B.T.Killer,
Caterpilin, Cezar, CID, Deflin, DiPel,
Dipole, Gold Btk, Halt, JasBT, KavachBt,
KrishiBio, Prasar, Lipel, Mahastra,
Minchu, Neelstaki
B. thuringiensis
subsp.
tenebrionis
Colorado potato beetle, stored
pests, coleopteran adults and
larvae
Foil, M-one, M-track, Novardo, Trident
B. thuringiensis
subsp. Galleriae
Lepidopteran larvae,
bollworms, Diamondback
moth
Spicturin
Source: Usta (2013)
11 Biopesticides for Pest Management
243