Establishing Attractive Cover Crops for Beneficial Insects
Establish crops known as intermediate crops for their ability to attract beneficials, in a logic of biological control by conservation or pollination of crops.
Authors:
| Julien Halska | INRA | Dijon (21) |
| Régis Wartelle | Regional Chamber of Agriculture of Picardy | Amiens (80) |
| Grégory Véricel | INRA | Auzeville (31) |
| Marie-Hélène Bernicot | INRA | Bretenière (21) |
Presentation
Characterization of the technique
Description of the technique:
The interest of the intermediate crop is all the greater as it can develop and flower. It is therefore recommended to sow it early and to choose short-cycle species. Mixtures of species are recommended because they present longer flowering periods, different flower types, and varied colors.
Example of implementation:
After harvesting a winter soft wheat crop, sow buckwheat (for example early August) at 35 kg/ha with a conventional seed drill (row sowing). Buckwheat attracts many beneficials such as hoverflies or bees because it is one of the first species to flower and will be destroyed by frost in November (variable depending on climatic context). Sow the following crop in spring, for example a spring pea.
Details on the technique:
One of the Arvalis experiments in the CASDAR Interapi trials is that it is necessary to sow as early as possible to ensure flowering at a time when pollinators are still active, and that depending on the species chosen, the risk of bolting can be very high (mustard, buckwheat…).
No information on the destruction method, which however very likely influences beneficial insect populations.
Main crops between which attractive intermediate crops for beneficials can be grown
Garlic, Beet, Durum wheat winter, Durum wheat spring, Soft wheat winter, Soft wheat spring, Carrot, Hemp, Forage cabbage, Cauliflower autumn and winter, Cauliflower summer, Rapeseed winter, Rapeseed spring, Einkorn, Small spelt, Spelt, Bean, Green bean, Lettuce, Spring white lupin, Spring blue lupin, Alfalfa, Sweet corn, Silage maize, Grain maize, Melon, Millet, Autumn turnip, Summer turnip, Rocket, Onion, Barley winter, Barley spring, Poppy (corn poppy), Pea, Leek, Chickpea, Potato, Grassland, Perennial ryegrass, Italian ryegrass, Rice, Soybean, Grain sorghum, Tobacco, Industrial Tomato ...
Main or intermediate crops
Diploid oat, Oat winter, Oat spring, Camelina, Flax fiber winter, Flax fiber spring, Flax seed winter, Flax seed spring, Sweet white lupin winter, Foxtail millet, Radish, Rye winter, Rye spring, Sorghum silage, Sunflower, Triticale winter, Triticale spring ...
Attractive plants
White mustard, or melilot attract hoverflies: spring mustard, winter mustard, white or yellow melilot...
Legumes attract many beneficials, including predatory bugs: winter faba bean, spring faba bean, Vetch, Lentil, Winter pea, spring pea, Sainfoin, White clover, Alexandrian clover, Micheli clover, Persian clover, Crimson clover, Purple clover, Common Vetch. They also attract some predators of the soil (Centipedes, ground beetles).
Other crops also have an attraction power on pollinators in general (high nectariferous power): buckwheat, fenugreek, nyjer or phacelia...
Application of the technique to...
Implementation period During the intercrop period
Spatial scale of implementation Plot
All crops: Easily generalizable, possibilities vary depending on the duration of the intercrop period.
All soil types: Easily generalizable, choice of species and varieties to be adapted to the soil.
All climatic contexts: Easily generalizable, choice of species and varieties to be adapted to the local climate.
Regulations
The Nitrate Directive requires soil cover during winter in vulnerable zone, this opportunity can be used to choose a cover attractive to beneficial insects.
The Order of 20 November 2021 relating to the protection of bees and other insects pollinators, specifies that the use of phytosanitary products is prohibited near flowering vegetation during flowering periods. Exceptions apply to products approved by ANSES and those equipped with a "Bee Mention", but their application must imperatively take place at night: within 2 hours before sunset and within 3 hours after sunset.
Effects on the sustainability of the cropping system
"Environmental" criteria
Effect on air quality: Variable, this practice can lead to a reduction in phytosanitary product consumption, and has little or no impact on greenhouse gas emissions.
Effect on water quality: Since it may reduce pesticide use (variable depending on molecules) and traps phosphorus and atmospheric nitrogen, this practice has a beneficial effect on water quality.
Effect on fossil resource consumption: Establishment and destruction of the cover lead to higher fuel consumption than maintaining bare soil during the intercrop period (except legumes in intercrop which can reduce nitrogen inputs by up to 30 units, corresponding to fossil energy savings via fertilizer production). However, atmospheric carbon storage partially offsets these emissions.
"Agronomic" criteria
Productivity: Careful adaptation of the cover choice to the following crop is necessary. Generally, avoid sowing an intermediate crop from the same botanical family as the following crop. Also beware of possible allelopathic effects. Generally positive effect of intermediate crops based on legumes on following cereals, maize, beets. Generally neutral or slightly negative effect of other species. Also variable depending on destruction conditions of the intermediate crop.
Soil fertility: Nitrogen captured by the cover during its development is gradually released after destruction. Part will be directly available for the following crop. The cover also improves phosphorus and potassium availability for the following crop (element remobilization). Soil structure and organic matter content can also be improved. Moreover, soil cover limits crusting by reducing raindrop impact on soil.
Water stress: Water uptake during cover development can reduce water available in the useful reserve, especially in case of dry winter. Cover destruction must be adapted to soil type and water requirements of the following crop.
Functional biodiversity: Presence of covers favors certain species by providing refuge and food (insects, macro and microfauna of soil, birds, etc.). This effect varies depending on the nature of the cover, for example if it is a nectariferous species or not. Beneficials, pollinators and soil fauna can thus be favored by the presence of the cover, variably depending on the species chosen.
Development of pests
Intermediate crops can have variable effects on pests. They break the cycle of some, but provide habitat and/or food to others (slugs, sawflies, flea beetles, aphids). Avoid choosing intermediate crops hosting pests common to those of main crops (example: crucifers in a rotation with frequent rapeseed).
"Economic" criteria
Operational costs: Depending on the species or mixture chosen, seed cost can vary from €10 to €100/ha.
Mechanization costs: Establishment cost can vary from €0/ha (sowing at harvest under the combine) to €60/ha (no-till sowing). Destruction cost also varies from €0/ha (frost) to €30/ha (mowing + incorporation). Establishment and destruction of the cover lead to higher fuel consumption than maintaining bare soil during the intercrop period.
Margin: Nitrogen released for the following crop generally does not cover the costs related to establishing an intermediate crop. The short-term overall margin will therefore be reduced, however "long-term" effects can be beneficial (improvement of soil structure, erosion limitation, soil life, ...) and contribute to margin improvement. The cover can also be valorized (harvest, forage, ...).
"Social" criteria
Working time: Mechanization time is higher than intercrop without intermediate cover or soil work. It varies depending on establishment and destruction methods compared to an intercrop with soil work (e.g. false seedbed preparation).
Favored or disadvantaged organisms
Disadvantaged pests
This practice can limit the appearance of certain pests, however it is unrealistic to think to disadvantage a wide range of pests without simultaneously favoring others.
The question is therefore to know which cause the most damaging effects and to choose a solution accordingly.
| Organism | Impact of the technique | Type |
|---|---|---|
| Tomato fruitworm | MEDIUM | pest, predator or parasite |
| mite | MEDIUM | pest, predator or parasite |
| stem weevil | MEDIUM | pest, predator or parasite |
| terminal bud weevil | MEDIUM | pest, predator or parasite |
| beet leafhopper | MEDIUM | pest, predator or parasite |
| wheat leafhopper | MEDIUM | pest, predator or parasite |
| corn leafhopper | MEDIUM | pest, predator or parasite |
| wheat flower midge | MEDIUM | pest, predator or parasite |
| pea midge | MEDIUM | pest, predator or parasite |
| cockchafer | MEDIUM | pest, predator or parasite |
| slug | MEDIUM | pest, predator or parasite |
| pollen beetle | MEDIUM | pest, predator or parasite |
| cutworm | MEDIUM | pest, predator or parasite |
| aphid | MEDIUM | pest, predator or parasite |
| European corn borer | MEDIUM | pest, predator or parasite |
| house centipedes | MEDIUM | pest, predator or parasite |
| wireworm | MEDIUM | pest, predator or parasite |
| thrips of flax and cereals | MEDIUM | pest, predator or parasite |
| pea thrips | MEDIUM | pest, predator or parasite |
| pea moth | MEDIUM | pest, predator or parasite |
Favored beneficials
| Organism | Impact of the technique | Type | Details |
|---|---|---|---|
| Spiders | MEDIUM | Natural enemies of pests | Beneficials favored by intercrop cultivable species. See bibliography (Attractive plants for beneficials in gardens and green spaces). |
| Predatory and granivorous ground beetles | MEDIUM | Natural enemies of pests | Beneficials favored by intercrop cultivable species. See bibliography (Attractive plants for beneficials in gardens and green spaces). |
| Centipedes | MEDIUM | Natural enemies of pests | |
| Green lacewings and antlions | MEDIUM | Natural enemies of pests | Beneficials favored by intercrop cultivable species. See bibliography (Attractive plants for beneficials in gardens and green spaces). |
| Carnivorous mammals | MEDIUM | Natural enemies of pests | Small mammals Beneficials favored by intercrop cultivable species. See bibliography (Attractive plants for beneficials in gardens and green spaces). |
| Predatory birds | MEDIUM | Natural enemies of pests | Insectivorous and/or granivorous Beneficials favored by intercrop cultivable species. See bibliography (Attractive plants for beneficials in gardens and green spaces). |
| Parasitoids | MEDIUM | Natural enemies of pests | Beneficials favored by intercrop cultivable species. See bibliography (Attractive plants for beneficials in gardens and green spaces). |
| Parasitoids | MEDIUM | Natural enemies of pests | Check the hymenopteran class |
| Predatory or granivorous bugs | MEDIUM | Natural enemies of pests | Including mirids Beneficials favored by intercrop cultivable species. See bibliography (Attractive plants for beneficials in gardens and green spaces). |
| Predatory hoverflies | MEDIUM | Natural enemies of pests | However, it is unrealistic to think to increase only beneficials without also favoring some pests. Focus usefully on the beneficial that seems most appropriate to favor. Beneficials favored by intercrop cultivable species. See bibliography (Attractive plants for beneficials in gardens and green spaces). |
For further information
- Creating a territory reconciling the needs of honey bees and the challenges of sustainable agriculture - members of CASDAR Interapi ITSAP, Website, 2014. CASDAR Interapi restitution conference dealing with the impact of nectariferous intermediate crops on bees: link to summary
- Intermediate crops - Ibis, Technical brochure, 2011. Very comprehensive document on intermediate crops (interest, technical implementation, cost, regulations).
- Attractive plants for beneficials in gardens and green spaces - Regional Federation for Pest Control Poitou-Charentes. Technical brochure, 2010, list of plants favorable to various beneficials.
- Better managing the intercrop for agronomic and environmental benefits - Minette S. (CRA Poitou-Charentes); Blondeau P. (CA Deux-Sèvres); Catala C. (CA Vienne); Bessettes C. (CA Charente); Guerin O. (CA Charente-Maritime) CRA Poitou-Charentes, CA Vienne, CA Deux-Sèvres, CA Charente, CA Charente-Maritime, Technical brochure, 2009.
- Decision support tool on cover crop choice - Arvalis, Website http://www.choix-des-couverts.arvalis-infos.fr/
- Decision support tool for managing nectar resources - members of CASDAR Interapi ITSAP, Website, 2014: site
Appendices
Est complémentaire des leviers
Favorise les auxiliaires
- Spiders
- Predatory and granivorous ground beetles
- Centipedes
- Green lacewings and antlions
- Carnivorous mammals
- Predatory birds
- Parasitoids
- Predatory or granivorous bugs
- Predatory hoverflies
