Parasitoids and refuge plants against aphids
The use of natural enemies is growing as chemical tools are progressively withdrawn from the market
Aphids have become one of the most significant pests in crops cultivated under plastic. For years, this pest has been controlled by applying agrochemicals, but nowadays the progressive withdrawal of available active substances from the market means it is difficult to carry out chemical control of aphids. “The majority of products compatible with auxiliary fauna are no longer available, and those that can still be sold are incompatible with natural enemies. It is necessary for farmers to change their attitude now. They need to start using biological control as soon as possible, which in the short term will be the only viable option,” says Julián Giner, Koppert’s technical director in Almería.
Two important factors must be taken into account in order to carry out successful biological control of aphids in horticultural greenhouse crops: selective release of parasitoids, and the use of refuge plants so that aphid predators have a permanent presence on the farm. Aphid parasitoid releases should be carried out from the beginning of the crop cycle and be continued until it ends.
To perform these releases, Koppert offers APHISCOUT®, a powerful tool containing five different parasitic wasps (Aphidius colemani, Aphidius ervi, Aphelinus abdominalis, Praon volucre, and Ephedrus cerasicola). APHISCOUT® is a biological solution that is highly suited to the biological control of larger aphid species such as Macrosiphum euphorbiae. “When we use APHISCOUT®, we allow five types of natural enemies of aphid to quickly establish themselves on the plant. The result is that the pest is protected by the combined action of all these parasitoids, which complement each other perfectly,” adds Julián Giner. For smaller-sized aphids, Koppert recommends using APHIPAR®.
The biological control strategy for aphids in greenhouses requires conservation agriculture practices. For this reason, parasitic wasp releases should be complemented by the use of refuge plants, with the aim of maintaining a permanent population of natural enemies. Cereal plants such as maize or sorghum can be used; however, Koppert recommends the use of aromatic flowering plants. “Aphid predators feed on pollen, which means we need flowering plants,” explains Julián Giner. Koppert is a pioneer in the use of refuge plants and offers personalized guidance. Koppert’s technical advisors determine which is the most suitable type of plant based on the conditions of the farm. This largely depends on flowering dates.