Practicing biological control using Bacillus thuringiensis
1. Presentation
Characterization of the technique
Description of the technique:
Image: Bacillus thuringiensis; author: Dr. Sahay; license (CC BY-SA 3.0)
| Julien Halska | INRA | julien.halska(at)grignon.inra.fr | Dijon (21) |
Spray an insecticidal solution based on Bacillus thuringiensis or Bt (containing the bacteria themselves and/or the toxins that activate it). There are several serotypes with different properties (active on lepidopterans or coleopterans), as well as various commercial products. It is possible to alternate modes of action to prevent resistance development. Intervention must be early (first damage or regional warnings), treatments renewed regularly and in case of rain exceeding 20 mm, and a fine spray applied.
Example of implementation: Against defoliating noctuids of cabbage in Brittany: spray Bt at the recommended dose from the first damage and repeat every 7 to 10 days (and in case of rain exceeding 20 mm) until the end of the sensitive period (end of October).
Implementation period On established crop
Spatial scale of implementation Plot
Application of the technique to...
All crops: Not generalizable
Only authorized uses are possible; see the relevant crops section.
All soil types: Easily generalizable
All climatic contexts: Easily generalizable
Regulation
POSITIVE influence
Several uses are authorized, including in organic agriculture (subject to the use of non-GMO Bt strains). Marketing Authorizations, Organic Farming Specifications
2. Services provided by the technique
3. Effects on the sustainability of the cropping system
"Environmental" criteria
Effect on air quality: Increasing
phytosanitary emissions: DECREASE
GHG emissions: NEUTRAL
Effect on water quality: Increasing
pesticides: DECREASE
Other: No effect (neutral)
Bt-based products are rapidly degraded by light and microorganisms. The risk of transfer to air is very limited.
There is no difference in GHG emissions and fossil energy consumption compared to a non-biological phytosanitary product, except if the number of treatments required is higher.
Biodiversity: link=|alt=green face size 10
Bt-based insecticides are specific to groups of insects and therefore have no effects on species not belonging to that group. Moreover, these products are rapidly degraded by light and microorganisms. Undesirable effects on fauna are thus limited and biodiversity improved compared to the use of chemical insecticides. However, Bt affects species from the same group as the target species (lepidopterans or coleopterans).
"Agronomic" criteria
Productivity: No effect (neutral)
The efficacy of Bt-based products being similar to that of chemical insecticides, no effect on yield is expected when replacing one with the other.
Soil fertility: No effect (neutral)
Generally, no accumulation of Bt is observed as it is naturally present in soils. The bacilli can survive there, but their population is regulated by competition with other species. Effects on microflora and soil fauna are thus probably limited.
Functional biodiversity: Increasing
Increase compared to the use of chemical insecticides due to the rapid degradation and selectivity of Bt-based products. For example, the effect on bees is null to very limited. However, effects are possible on lepidopteran or coleopteran beneficials (trichogramma, ladybugs, etc.).
"Economic" criteria
Operational costs: Increasing
The difference depends on the price gap between chemical programs and Bt-based programs. The latter cost between 20 and 30 euros per hectare per treatment.
Margin: Variable
The cost of Bt-based treatments is relatively low (20 to 30 euros/ha). The margin evolution linked to replacing chemical insecticides with Bt depends on the price ratio between substituted and substituting products, and the number of passes required.
"Social" criteria
Effect on farmer health: Increasing
Risks for the user are reduced because Bt is not toxic to humans. These products carry risk phrases Xi, R36, R41, R43.
4. Organisms favored or disadvantaged
Favored Pests
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Disadvantaged pests
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Favored Beneficials
| Organism | Impact of the technique | Type | Details |
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Disadvantaged beneficials
| Organism | Impact of the technique | Type | Details |
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Favored climatic and physiological accidents
| Organism | Impact of the technique | Details |
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Disadvantaged climatic and physiological accidents
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5. For further information
- Bacillus thuringiensis, alternative and rotation
- -Duchon-Doris J. and Armengaud P. (Philagro)
Phytoma, no. 624-625, Press article, 2009
- Phytosanitary index ACTA
- -ACTA
ACTA, Book, 2017
- Lepidopteran pests in organic vegetables
- -Mazollier C. (GRAB); Oudard E. (SRPV PACA); Bélaird E. (SRPV Centre); Lambion J. (GRAB)
ITAB, Technical brochure, 2001
Book, 2005
6. Keywords
Bioaggressor control method: Biological control
Mode of action: Rescue
Type of strategy regarding pesticide use: Substitution
