Implementing Biocontrol Measures to Protect Your Aquaponic Crops
In aquaponics, more than in any other cultivation system, the use of synthetic chemical products is to be avoided. Here we explain how to effectively combat plant pathogens while preserving the environment, thanks to biocontrol. Principles of prevention, crop auxiliaries, innovative technologies—master biological and integrated protection and optimize your productions.
Description
While soilless crops techniques limit the proliferation of plant pathogens, notably organisms of soil origin (nematodes, slugs, fungi, bacteria, etc.) or weeds, plant productions in aquaponics still experience their share of bioagressors.
By adopting a virtuous production mode, integrating compartments sensitive to physico-chemical changes in water (aquaculture, bacterial filter), the introduction of pesticides into an aquaponic system, whether of biological origin (plant pyrethrum, essential oils, black soap, etc.) or synthetic, is to be avoided or even prohibited.
Avoiding infestations
Thus, the first step of biocontrol is to limit the introduction and development of pests notably by working in a perfectly isolated and compartmentalized environment: sealed greenhouse, entrance airlock, equipment dedicated to the compartment, partitioning by varieties, etc. It is nevertheless advisable to maintain refuges (nasturtiums, marigolds, etc.) which serve both as sentinel zones to detect pests and especially to preserve prey for auxiliaries, which can turn against your crops if their basic food supply becomes scarce.
Promoting diversification
At the same time, it is recommended to promote a strong biotope around production areas through the use of flower strips, insect shelters, ... This will encourage a diverse ecosystem where pests, predators and pollinators develop, which always eventually find a way into your productions.
Auxiliaries
Certain auxiliaries of cultivation or "biological agents" (mites, micro-wasps, lacewings, macrolophus, ladybugs, fungi, nematodes, bacteria,...) are valuable allies when it comes to regulating pest populations. In the broad sense, crop auxiliaries are living organisms that provide ecosystem services facilitating agricultural production. They replace all or part of the work and inputs provided by the farmer. Insects pollinators (bees, bumblebees,...), for example, ensure plant fertilization and fruiting.
In terms of biological control, other organisms, by their lifestyle, development and/or feeding, are natural enemies of organisms harmful to crop development. Three types are distinguished (Marine MASSON, 2018):
Predators
- The best known among them are ladybugs for their predation on pests such as aphids, psyllids, scale insects, mites, thrips,...
- Also included are hoverflies (small yellow and black flies) whose larvae feed on various species of aphids, larvae or caterpillars.
- The lacewings, easily recognizable by their large transparent veined wings, whose larvae also attack aphids, mites, scale insects or larvae of other insects.
- The ground beetles and rove beetles, which are beetles feeding on eggs or larvae of other beetles, nematodes, mites, caterpillars, aphids, slugs and snails.
Parasitoids
They develop at the expense of hosts for which they are lethal. Many Hymenoptera and micro-hymenopteran parasitoids belong here. The most "famous" are the trichogrammas, which lay their eggs inside those of the box tree moth, the corn borer, grapevine moths, the tomato leafminer and other lepidopterans, quickly causing their death. Other parasitoid wasps help control aphid populations. Aphidius ervi, for example, mummifies the aphid of the tomato.
Parasitic microorganisms
These include nematodes, bacteria, fungi or viruses that cause the death of bioagressors through their development. Notable is the Bacillus thuringiensis, Bacillus thuringiensis, a bacterium that synthesizes a protein crystal with a larvicidal effect on certain beetles, lepidopterans and dipterans.
Chemical mediators
Biocontrol can also use biotechnologies by employing chemical mediators (pheromones and kairomones) to trap pests or disrupt their reproduction. These have a very high specificity of action and do not impact the health of bees and other pollinators (The Deceived Aggressor, Chemical Mediators, n.d.).
Advantages and disadvantages of biocontrol
Despite the complexity of its implementation, which requires specific control as well as precise identification of harmful organisms and their predators or parasites, and although it is often costly, biological control is most often very effective in regulating pest populations.
It also has the advantage of being non-toxic and non-pathogenic to wildlife, humans, and organisms not directly related to the targeted pest (Janelle Hager, 2021). However, it requires regular monitoring (counting pathogens and auxiliaries) to maintain a balance in the prey/predator ratio. For this, it is possible to be assisted by partners such as Koppert or Biobest, whose technicians will plan a release and control plan annually based on productions and adjust it according to the context, the bio-agressors identified, and the effectiveness of the solutions used. It is therefore essential to implement this monitoring of pests and solutions; applications have been developed for this purpose and even automatic detection and counting tools are under development, supported by artificial intelligence for very fine management of biological and integrated protection.
Regulations
In France, the use of natural mechanisms within the framework of integrated pest management against crop enemies is governed by the rural and maritime fishing code. The list of non-native macro-organisms used to protect plants from bio-agressors, exempt from authorization requests for entry into the territory and introduction into the environment, is included in Annex 1 of the decree of 26 February 2015.
In parallel, a list published by service note, updated monthly by the minister responsible for agriculture, lists the biocontrol plant protection products authorized in the territory.
In a rapidly expanding market, many biocontrol actors now offer solutions and training adapted to different needs. Do not hesitate to contact them from the launch of your farm to secure one of the keys to the success of your plant productions.
