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Bacillus thuringiensis subsp. kurstaki
(Biological insecticide)


Schizomycetes: Eubacteriales


Approved name:

Bacillus thuringiensis subsp. kurstaki.

Other names:



Bacillus thuringiensis is common in soil , insect-rich environments mills and warehouses. Strains that are used in crop protection are selected from those isolated in nature on the basis of their potency in test insect species, spectrum of host insects and the ease with which they can be grown in fermenters.



Produced in controlled fermentor in deep tanks of sterilised nutrient liquid medium. The endotoxins and living spores are harvested as water dispersible liquid concentrates for subsequent formulation.

Target Pests and Crops:

Lepidopteran larvae, particularly the American Bollworm (Hellicoverpa armigera), Pink bollworm (Pectinophera species), spotted bollworm (Erias insulana)diamond back moth (Plutela xylostella (Linnaeus)) and other vegetable pests such as Colorado potato beetle (Leptinotarsa decemlineota (Say)) and forest insects.

Vegetables, fruit, maize, small grain cereals and forests, orchards .


Target Pest

Target Crops

Plutella sylostella, Crocidolomia binotalis, Pieris brassicae


Hellothis armigera

Tomato, Sunflower

Spodoptera litura, H. armigera

Tobacco, Soybean

S. Litura

Beet root

Athlia lugens proxima


Papilio demoieus


Achaea janata


Helicoverpa armigera, Amsacta moorei


Acigona steniellus


Earias vitella


Spoiadea  recurvalis


Phthorimaea operculella


Biological Activity

Mode of action:

Bacillus thuringiensis produces parasporal, proteinaceous, crystal inclusion bodies during sporulation. Upon ingestion, these are insecticidal to larvae of the order Lepidoptera and to both larvae and adults of a few Coleoptera. Once in the insect, the crystal proteins are solubilised and the insect gut proteases convert the original pro-toxin into a combination of up to four smaller toxins. These hydrolysed toxins bind to the insect's midgut cells at high-affinity, specific receptor binding sites where they interfere with the potassium-ion dependent, active amino acid symport mechanism. This disruption causes the formation of large pores that increase the water permeability of the cell membrane. A large uptake of water causes cell swelling and eventual rupture, disintegrating the midgut lining. Different toxins bind to different receptors in different insect species and with varying intensities: this explains species specificities.


The crystal inclusions derived from Btk are generally lepidopteran specific. Because they have to be ingested and then processed within the insect's gut, they are often slow acting (two to forty-eight hours in comparison to conventional chemicals). The toxin results in starvation leading to death; insects not killed by direct action of the toxin may die from bacterial infection over a longer period. Different toxins have different spectra of activity. Different strains and serotypes have been developed by different companies. In addition to producing the endotoxins, many strains of Bt are potent insect pathogens. (Many Bt genes ( Cry IA) have been isolated and used to transform crops, also known as Genetically Modified Crop (GMO) or Transgenic Crop ( Cotton ECH-162, MECH-184, MECH-12)  thereby making them resistant.


Effective against lepidopteran species, however, light instability can cause problems if exposed to high light intensities. Rapidly hydrolysed under even mild alkaline conditions.



Sold as a combination of endotoxin crystals and living bacterial spores. Formulated as a suspension concentrate (SC), a granular bait (GB), a ready to use bait (RB), a suspo-emulsion (SE), a granule (GR), an oil miscible flowable concentrate (oil miscible suspension) (OF), a dispersible powder (DP) and a wettable powder (WP).

Trade Name:

Dipel BL, Delfin WG, Bactin, Bio-Tek, Bio Bit WP, WOCK Biological (Halt-Bt).


Use at rates of 100-300 g active ingredient (a.i.) per hectare ensuring that the crop is well covered with the spray suspension. Apply while larvae are small and repeat every five to seven days if infestations are high. Bt-based sprays can be applied up to the day of harvest.

Product Specification:


All formulations are standardised at a toxin content expressed in terms of international units active against a target pest per mg of product.

Storage conditions and shelf-life:

Do not expose to direct sunlight, and keep in cool conditions. If stored under cool dark conditions, the products remain viable for two years or more.


Do not use in combination with broad spectrum biocides such as chlorothalonil. Compatible with a wide range of acaricides, insecticides, fungicides, stickers, spreaders and wetters. Do not use water with a pH above 8.0.

Environmental impact and non-target toxicity:

Btk has a short persistence owing to its sensitivity to UV. light. No adverse effects have been recorded in approved field use and none are anticipated. Btk should not be used near water-courses, however no adverse effect have been observed on birds, fishes and honeybees.

Indian literature:

·         Babu, B.R. and Krishnayya, P.V. 1998. Bioinsecticides to mitigate the load of quinalphos against cauliflower caterpillars. Pesticide Research Journal. 10: (2), 231-234 .

·         Balikai, R.A. and Sattigi, H.N. 2000. Management of sunflower head borer by using bioinsecticide alone and in combination with insecticide. Agricultural Science Digest. 20: (2), 110-111.

·         Banuprakash, K.G., Govindan, R. and Devaiah, M.C. 2000. Survivability of Bacillus thuringiensis var kurstaki H3a3b in different ecosystems and its pathogenicity to silkworm Bombyx mori L. Environment and Ecology. 18: (3), 718-721.

·         Biradar, A.P., Balikai, R.A., Nandihalli, B.S. and Jagginavar, S.B. 1996. Efficacy of bioinsecticides in the management of Helicoverpa armigera (Hubner) on sunflower. Advances in Agricultural Research in India. 5: 70-74 .

·         Biswas, S., Kumar, Ashok., Upadhyay, K.D. and Kumar, A. 1996. Effect of sub-lethal concentration of Dipel on the post embryonic development of Spilosoma obliqua. Indian Journal of Entomology. 58: (4), 359-363.

·         Biswas, S., Upadhyay, K.D. and Dubey, R.K. 1996. Effect of dipel (Bacillus thuringiensis var. kurstaki) on different larval instars of Spilosoma obliqua Walker. Annals of Plant Protection Sciences. 4: (2), 165-166.

·         Biswas, S., Upadhyay, K.D. and Kumar, A. 1994. Bio-efficacy of various Bacillus thuringiensis formulations and dosages against hairy caterpillar, Spilosoma (Diacrisia) obliqua. Journal of Ecotoxicology and Environmental Monitoring. 4: 3-4, 185-188.

·         Biswas, S., Upadhyay, K.D., Ashok, Kumar. and Kumar, A. 1996. Efficacy of some insecticides alone and in combination with Dipel (a bacterial formulation) against Spilosoma obliqua Walker Zeitschrift fur Angewandte Zoologie. 81: (2), 227-235.

·         Bora, R.S., Murty, M.G., Shenbagarathai, R., Sekar, Vaithilingam., Singh Bora, R. and Sekar,V. 1994.Introduction of a Lepidoptera-specific insecticidal crystal protein gene of Bacillus thuringiensis subsp. kurstaki by conjugal transfer into a Bacillus megaterium strain that persists in the cotton phyllosphere. Applied and Environmental Microbiology. 60: (1), 214-222.

·         Borah, M. and Basit, A. 1996. Effect of certain insecticides on the emergence of Trichogramma japonicum Ashmead. Journal of the Agricultural Science Society of North East-India. 9: (2), 224-225.

·         Burges, H.D. and Jones, K A. 1989. Formulation of bacteria, viruses and protozoa to control insects, in Formulation of Microbial Biopesticides: Beneficial Microorganisms, Nematodes and Seed Treatments, H D Burges (ed.), 33-127, Kluwer Academic, Dordecht, the Netherlands.

·         Butter, N.S., Battu, G.S., Kular, J.S., Singh, T.H. and Brar, J.S. 1995. Integrated use of Bacillus thuringiensis Berliner with some insecticides for the management of bollworms on cotton. Journal of Entomological Research. 19: (3), 255-263.

·         Chandra, Ajanta., Kaushik, N.C., Gupta, G.P. and Chandra, A. 1999. Studies of Bacillus thuringiensis on growth and development of Helicoverpa armigera Hubner. Annals of Plant Protection Sciences. 7: (2) , 154-158.

·         Chari, M.S., Sreedhar,U., Rao, RSN. and Reddy, SAN. 1996. Studies on compatibility of botanical and microbial insecticides to the natural enemies of Spodoptera litura F. Tobacco Research. 22: (1), 32-35.

·         Chitra, S., Narayanan, R.B., Balakrishnan, A., Jayaraman, Kunthala and Jayaraman, K. 1998. A rapid and specific method for the identification of Bacillus thuringiensis strains by indirect immuno fluorescence.Journal of Invertebrate Pathology. 71: (3), 286-287.

·         Das, N.D., Sankar, G.R.M. and Biswas, K.K. 2000. Field evaluation of botanical and biopesticides against pod borer, Helicoverpa armigera on pigeonpea. Annals of Plant Protection Sciences., 8: (2), 233-234.

·         Devasahayam, S. 2000. Evaluation of biopesticides for the management of shoot borer (Conogethes punctiferalis Guen.) on ginger (Zingiber officinale Rosc.)Spices and aromatic plants:-challenges and opportunities in the new century. Contributory papers Centennial conference on spices and aromatic plants, Calicut, Kerala, India 20-23-September, 2000. 276-277. Indian Society for Spices; Calicut; India

·         Devi, P.S.V., Prasad, Y.G. and Rajeswari, B. 1996. Effect of Bacillus thuringiensis var. kurstaki and neem on castor defoliators - Achaea janata (Linnaeus) and Spodoptera litura (Fabricius). Journal of Biological Control. 10: (1-2), 67-71.

·         Dilawari, V.K., Khanna, V., Gupta, V.K., Dhaliwal, H.S.and Dhaliwal, G.S. 1996. Toxicity of Bacillus thuringiensis var. kurstaki delta-endotoxin proteins from HD-1 and HD-73 strains against Plutella xylostella (L).Allelopathy Journal. 3: (2) 267-272.

·         Entwistle, P.F., Cory, J. S., Bailey, M. J.and Higgs, S. (eds.). 1993. Bacillus thuringiensis, on Environmental Biopesticide: Theory and Practice, Wiley, Chichester, UK, 311 pages.

·         Fast, P. and Surges, D (ed.). 1981. The crystal toxin of Bacillus thuringiensis. In Microbial Control of Pests and PlantDiseases 1970-1980. Academic Press, New York.

·         Gaikwad, M.A., Narkhede, S.S. and Borkar, S.L. 1998. Toxicity of different formulation of Bacillus thuringiensis var. kurstaki (Berliner) against Helicoverpa armigera (Hubner). PKV Research Journal. 22: (1), 49-53.

·         Gloriana, A.S., Raja, N. Seshadri, S., Janarthanan, S.and Ignacimuthu, S. 2000. Pathogenicity of entomopathogens, Bacillus thuringiensis subsp. kurstaki and Beauveria bassiana, to the larvae of Spodoptera litura (F.) and Pericallia ricini (F.). Biological Agriculture and Horticulture. 18: (3), 235-242.

·         Gujar, G.T. and Mohan, M. 2000. Effect of Bacillus thuringiensis subspecies kurstaki and its endotoxin CrylAb on growth and development of Helicoverpa armigera Hubner. Pesticide Research Journal. 12: (2), 210-214.

·         Gujar, G.T., Kalia, Vinay., Kumari, Archana., Kalia, V. and Kumari, A. 2000. Bioactivity of Bacillus thuringiensis against the American bollworm, Helicoverpa armigera (Hubner). Annals of Plant Protection Sciences. 8: (2), 125-131.

·         Gujar, G.T., Kumari, Archana., Kalia,Vinay,. Chandrashekar, K., Kumari, A. and Kalia, V. 2000. Spatial and temporal variation in susceptibility of the American bollworm , Helicoverpa armigera (Hubner) to Bacillus thuringiensis var. kurstaki in India.Current Science. 78: (8), 995-1001.

·         Gupta, G.P., Chandra, Ajanta., Chandra, A., Dhaliwal,G.S (ed.)., Arora, R (ed.)., Randhawa, N.S. (ed.). and Dhawan, A.K. 1998. Food consumption by Helicoverpa armigera (Hubner) larvae intoxicated with Bacillus thuringiensis (Berliner).Ecological agriculture and sustainable development: Volume 1. Proceedings of an International Conference on Ecological Agriculture: Towards Sustainable Development, Chandigarh, India, 15-17 November, 1997. 468-474. Centre for Research in Rural and Industrial Development; Chandigarh; India

·         Gupta, P.R., Babu, RRM., Reddy, P.P. (ed.), Kumar, NKK. (ed.) and Verghese, A. 1998. Management of Helicoverpa armigera on tomato with Trichogramma pretiosum and Bacillus thuringiensis var. kurstaki. Advances in IPM for horticultural crops. Proceedings of the First National Symposium on Pest Management in Horticultural Crops: environmental implications and thrusts, Bangalore, India, 15-17 October 1997. 75-80. Association for Advancement of Pest Management in Horticultural Ecosystems, Indian Institute of Horticultural Research; Bangalore; India

·         Jayanthi, PDK. and Padmavathamma, K. 1996.Cross infectivity and safety of nuclear polyhedrosis virus, Bacillus thuringiensis subsp. kurstaki Berliner and Beauveria bassiana (Balsamo) Vuille to pests of groundnut (Arachis hypogaea Linn.) and their natural enemies. Journal of Entomological Research., 20: (3), 211-215.

·         Jeyakumar, P. and Gupta, G.P. 1999. Impact of UV and white lights on the bio-potency of Bacillus thuringiensis against Helicoverpa armigera Hubner. Annals of Plant Protection Sciences.7: (2), 121-124.

·         Kalia, Shamila., Lall, R.B. and Kalia, S. 2000. Efficacy of three varietal toxins of Bacillus thuringiensis tested against some important forest insect pests of multipurpose forest tree species. Indian Forester. 126: (1), 62-66.

·         Kulat, S.S., Nimbalkar, S.A., Radke, S.G. and Tambe, J. 1999. Evaluation of biopesticides and neem seed extract against Helicoverpa armigera on chickpea. Indian Journal of Entomology. 61: (1), 19-21.

·         Kumar, N.S. and Venkateswerlu, G. 1998. Analysis of 66 KDA toxin from Bacillus thuringiensis subsp. kurstaki reveals differential amino terminal processing of protoxin by endogenous protease(s). Biochemistry and Molecular Biology International. 45: (4), 769-774.

·         Kumar, N.S. and Venkateswerlu, G. 1998. Endogenous protease activated 66-kDa toxin from Bacillus thuringiensis subsp. kurstaki active against Spodoptera littoralis. FEMS Microbiology Letters. 159: (1), 113-120.

·         Kumar, N.S. and Venkateswerlu, G. 1998. Intracellular proteases in sporulated Bacillus thuringiensis subsp. kurstaki and their role in protoxin activation. FEMS Microbiology Letters., 166: (2), 377-382.

·         Kumawat, K.C. and Jheeba, S.S. 1999. Ecofriendly management of gram pod borer, Helicoverpa armigera. Annals of Plant Protection Sciences., 7: (2), 212-214.

·         Latha, E.S., Krishnayya, P.V. and Subbaratnam, G.V. 1996. Effect of Bacillus thuringiensis var. kurstaki Berliner and its additive chemicals on haemolymph constituents of Spodoptera litura (Fab.). Pest Management and Economic Zoology. 4: 1-2, 65-69.

·         Latha, K., Balasubramanian, G., Sundarababu, P.C. and Gopalan, M. 1994. Field evaluation of insecticides alone and in combination against leaffolders and their effect on natural enemies in rice. Pest Management and Economic Zoology. 2: (2), 105-109.

·         Loganathan, M., Babu, P.C.S. and Balasubramanian, G. 2000. Testing of indigenous Bacillus thuringiensis var galleriae against the predatory green lace wing, Chrysoperla carnea. Indian Journal of Entomology. 62: (3), 286-288.

·         Malathi, S., Sriramulu, M. and Babu, T.R. 1999. Evaluation of certain eco-friendly insecticides against lepidopterous pests of cabbage. Indian Journal of Entomology. 61: (2), 127-133.