Diversity of plants in the vegetable garden is beneficial for pest control

A study conducted by the Secretariat of Agriculture, Livestock, Sustainable Production and Irrigation (Seapi) at its State Center for Forestry Diagnosis and Research, in Santa Maria, proved that the cultivation of broad beans, fennel and tagetes on the border of a cabbage garden helps in biological control of predatory insects. The results were published in the technical bulletin “Diversified borders in cabbage cultivation increases the insect community and reduces damage by defoliating beetles”.

“The inclusion of plants of different species in an agricultural environment can favor the abundance of natural enemies, increase competition between herbivores and, therefore, reduce the action of pests. Plants close to crops can serve as a repository for insect predators and parasitoids by providing shelter, oviposition sites, alternative prey and nutritional resources such as pollen and nectar”, explains researcher Rosana Matos de Morais, one of the authors of the publication.

The choice of plants for cultivation in the cabbage border followed specific criteria. “The broad bean has extrafloral nectaries that can offer a food resource for insects even during the vegetative period, and also, as it is a nitrogen-fixing legume, it improves soil conditions. Fennel is an aromatic, from a family of plants that offers very abundant flowering and is accessible to insects. And tagetes is widely recognized for having repellent properties”, details Rosana.

The results demonstrated that the three species were capable of harboring a range of predatory, herbivorous and pollinating arthropods. Fennel stood out for its greater abundance and presence of ladybugs in the larval and adult stages. The broad bean had a large number of aphids that are not pests for cabbage, making it an alternative food source for predators. “In addition, cabbage plants kept within two meters of the border showed less damage caused by defoliating beetles and reduced abundance of cowpea (Diabrotica speciosa), compared to cabbages kept more than 20 meters away from the diverse border”, adds the researcher.

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