Agroecological prevention of aphids

Agroecological prevention of aphids

Agroecological prevention of aphids (i.e. preventive management without or with minimal use of synthetic insecticides, focusing on natural balances) is implemented through various combined strategies. Among the main ones, we recall the following.
1. Biodiversity and consociations
One of the fundamental aspects of this strategy consists in planting flowers and plants (such as marigold, fennel, dill, coriander) that attract beneficial insects that are predators of aphids: such as ladybugs, hoverflies, lacewings and earwigs.
These are techniques of consociation between various crops such as, for example, growing carrots next to lettuce or garlic next to roses that help repel aphids.
Furthermore, especially in tree plantations, such as citrus groves, it is necessary to encourage the insertion of hedges and natural borders that provide habitats for natural predators.
2. Cultivate resistant varieties
Furthermore, it is advisable to use varieties of plants that are resistant or tolerant to aphids, which, if available, reduce the vulnerability of the ecosystem.
3. Promote natural balance
Furthermore, contrary to popular belief, it is necessary to avoid the indiscriminate use of insecticides (even organic ones) that always negatively affect the populations of useful predators. For this reason, it is necessary to create an environment that favors the presence of predatory and parasitoid insects, through the introduction, even in the fields, of greater biodiversity.
4. Control fertilization
One of the main factors in controlling aphids and other phytophagous insects is to avoid excess nitrogen: plants that grow with higher contents of synthetic nitrogen products have greater vegetation, with more tender parts (especially leaves) that are perceived even at great distances by aphids (and other phytophagous insects) that attract these insects. For this reason, where it is necessary to intervene, it is necessary to prefer a balanced fertilization based on compost or mature manure and, in any case, with natural fertilization models (increase in legumes, vegetal mulching, associations, rotations, etc.
5. Agronomic techniques
The introduction of agronomic techniques that favor crop rotations, that is, changing crops every season, helps to break the aphid cycle. In this sense, hoeing and mulching also contribute to making the soil less hospitable for harmful insects. Correct irrigation also helps to reduce the populations of phytophagous insects; plants in water stress are more susceptible to attacks.
6. Monitoring and early interventions
A notable contribution to the reduction of phytophagous insects in general is to regularly inspect the crops, especially the young parts of the plants. In the case of small initial outbreaks, they can be removed manually or treated with natural remedies such as nettle maceration or soft potassium soap, also in addition to mineral oils.
Practical examples of these techniques include interspersing lettuce and cabbage with rows of nasturtiums, which attract aphids away from the main crops (they function as “trap plants”) and simultaneously planting wild fennel to attract hoverflies that lay eggs from which voracious aphid larvae emerge. Obviously, there are many examples to report, such as associating rose plants in the rows of vineyards or along tree plantations that are highly susceptible to aphids, such as citrus trees.