3.4 Direct pest control methods in organic farming
Use of natural enemies
The use of natural enemies (predators and parasitoids) for pest control is one of the ways of biological control. The most used method of biological control is the augmentation method, which aims to increase the population of natural enemies that exist in a given field or to introduce species that are widely distributed in a given area. This method is implemented in several ways:
- 1. cultivation of the natural enemy in the laboratory and its release into the farm
- 2. collecting a natural enemy in another environment and bringing it to the farm where we want to carry out biological control
- 3. purchasing a natural enemy from an authorized supplier/manufacturer of the formulated products called biopesticides
The following requirements are necessary for the successful use of natural enemies:
- An accurate identification of the pest
- An accurate and timely assessment of the threat
- The selection of the optimum natural enemy for the specific conditions; the determination of the optimum time for the first application
- Knowledge of the optimum required ratio between the number of natural enemies and the number of pests
- Knowledge of the manufacturer of the chosen enemy who can guarantee the quality and make the delivery quickly
- Properly prepared storage of the natural enemies from receipt to application
- Existing/previous measures in the crop into which the natural enemy is introduced (nets at ports of entry, application of other pesticides, etc.)
There are a large number of natural enemies that can be used in organic farming. Table 3.5. shows the main species available on the market with their basic characteristics and scope of application (target pests for which they can be used).
| Type of the natural enemy (systematic group) | Species | Packaging | Target pests | Application tips |
|---|---|---|---|---|
| Predatory mites | Neoseiulus cucumeris, Amblyseius swirskii, Phytoseiulus persimilis | Adult mites mixed with inert substance in a bottle or in smaller packets prepared for hanging on plants. | Phytophagous mites (Tetranychus urticae, Panonychus ulmi etc.) | Scatter the mites evenly in the culture on the leaves (depending on the culture 5 - 100 mites/m²) or hang the sachets on the plants. Mites tolerate temperatures up to 40 ° C, but work optimally at temperatures between 25-30 ° C and humidity 40-90%. |
| Macrocheles robustulus | Adult mites mixed with inert substance (vermiculite) | Pests in soil (thrips nymphs, sciarid flies etc.) | Release on the soil | |
| Amblydromalus limonicus | Nymphs and adult mites mixed with inert substance | Thrips, whiteflies | Scatter the mites evenly in the culture on the leaves (depending on the culture 5 - 100 mites/m²) or hang the sachets on the plants. Mites tolerate temperatures up to 40 ° C, but work optimally at temperatures between 25-30 ° C and humidity 40-90%. | |
| Predatory true bugs | Macrolophus pygmaeus, M. caliginosus | Nymphs and adults mixed with woodchips and buckwheat | Thrips (various species) | Scattering of bugs in groups of 75-100 on plant leaves for preventive control. |
| Macrolophus pygmaeus, M. caliginosus | Nymphs and adults mixed with wood chips and/or buckwheat | Thrips, whiteflies, aphids, leaf miner larvae, Tuta absoluta eggs. | Shake from the bottle onto the leaves or into a storage box that hangs on the plants. It works best at temperatures below 20 ° C. | |
| Coccinellids (predators) | Adalia bipunctata, Cryptolaemus montrouzieri, Delphastus catalinae | Depending on the species, larvae and adults mixed with wood chips and/or buckwheat | Depending on the species: aphids, mealybugs, whiteflies…. | Open bottles or packets, place in dispensers that are placed near infected plants. |
| Lacewings (predators) | Chrysoperla spp. | Larvae mixed with buckwheat | Aphids, other pests | Open bottles or packets, place in dispensers that are placed near infected plants. |
| Predatory Diptera | Aphidoletes aphidimyza | Fly pupae in a bottle mixed with organic material | Aphids | Leave the open bottle on the ground or hang it between the plants - flies that come out of the pupa will fly out and lay eggs next to aphid colonies. |
| Parasitoid wasps | Aphelinus abdominalis | Parasitic wasps mummies on the card or in bottles mixed with inert material (buckwheat, wood-chips etc.) | Aphids | Wasps are less mobile, so it is important to distribute the mummies evenly around the infected plants. |
| Aphidius ervi, A. matricariae, A. colemani | Aphids | Distribute the mummies evenly around the infected plants. A. matricariae does not act above 28 ° C and A. colemani and A. ervi above 30 ° C. | ||
| Anagyrus vladimiri | Scale insects | Distribute the mummies evenly around the infected plants. They are most active around 25 ° C and the activity zone is from 13 to 38 ° C. | ||
| Encarsia formosa | Trialeurodes vaporariorum, Bemisia tabaci | Hang cards with mummies on plants. Temperatures above 17 ° C are required to achieve efficiency. | ||
| Eretmocerus eremicus | Trialeurodes vaporariorum, Bemisia tabaci | Also suitable for use in higher temperature conditions. | ||
| Dacnusa sibirica | Adults | Larvae of leaf miner flies | The wasp lays an egg in the miner larva, the wasp larva develops in the mineral larva. | |
| Diglyphus isaea | The wasp paralyzes the miner larva and lays eggs on it, the wasp larva develops in the mine and feeds on the miner larva. | |||
| Entomopathogenic nematodes | Steinernema feltiae, S. carpocapsae, Heterorhabditis bacteriophora … | Nematode (larvae) mixed with inert carrier material | Lepidoptera: Tuta absoluta, Noctuids larvae, Spodoptera spp., cotton bollworm, corn earworm (Helicoverpa sp.), Chrysodeixis chalcites, Agrotis sp., Autographa gamma, Duponchelia fovealis, Cydalima perspectalis, Crambus hortuellus, Chrysoteuchia topiaria, Cydia pomonella, Cydia molesta, Cydia funebrana, Adoxophyes orana, and Synanthedon myopaeformis.
Coleoptera: Leptinotarsa decemlineata, Capnodis tenebrionis, Crioceris asparagi. Diptera: Scatella sp., Tipula sp. Other orders: Nesidiocoris tenuis, Corythucha ciliata, Gryllotalpa gryllotalpa, Neoscapteriscus sp. |
Depending on the target pest, they are poured onto the soil or applied by spraying the trunk and soil around the trunk. Nematodes are susceptible to ultraviolet light (UV): do not use them in direct sunlight; the moisture content of the soil must be kept high for several days after application. When possible, irrigate the crop before and right after application. For foliar application, spray when relative humidity will exceed 75% for several hours post treatment; an adjuvant and/or an anti-desiccant/humectant additive can be beneficial. |