By 2020, pest insects and spider mites in nine Dutch greenhouse crops will have been controlled organically in 95 percent of the area under cultivation, for example, through the use of ichneumon wasps or predatory mites. In 2016, this was 92 percent, while in 2012, it was 78 percent. The Compendium for the Living Environment (CLO) has listed the CBS figures for the period 2012-2020.
For each of the crops studied, biological control was applied to at least 75 percent of the cultivated area in 2020. By type of pesticide, the percentages with an application are generally lower.
Organic pest control in greenhouse vegetables, top to bottom: strawberries, cucumbers, peppers, and tomatoes
Total horticulture under glass, total pesticides
Across all nine greenhouse horticulture crops, the area with the application of biological control agents increased by 777 hectares to almost 6360 hectares in 2020. That is almost 95 percent of the area. In 2016, it was 92 percent, while in 2012, it was 78 percent.
For vegetable crops, the application of biological control agents in the cultivation of cucumbers, peppers, and tomatoes is 100 percent. Organic pesticides are also used almost everywhere in strawberries under glass, at almost 98 percent. Earlier, this was less than 70 percent.
In flower and ornamental horticulture, (CLO) also sees 100 percent biological control in a crop like roses. With application in chrysanthemums and gerberas also increasing, to over 90 percent, a further increase is only conceivable in potted plants.
Controllers per main group
Four main groups of biological control agents are distinguished for pest control in greenhouse horticulture: A predatory mites and thrips; B parasitic wasps and gall midges; C predatory bugs, lacewings, hoverflies, and predatory beetles and D nematodes. Application varies by group and crop.
Types of biological control agents by group
There is a wide variety of biological control agents on the market that are used against one or more pests. In the graphs accompanying this indicator, three biological control agents are elaborated as examples, the predatory mite Phytoseiulus persimilis, the parasitic wasp Encarsia formosa, and the predatory bug Macrolophus pygmaeus. These control agents are used in the greenhouse cultivation of various crops. Also, these species are stable factors in the variety of pest controls to which new species are regularly added and old species disappear. The publication includes 21 species.
Phytoseiulus persimilis (predatory mite against red spider mite)
By 2020, the predatory mite Phytoseiulus persimilis was an important biological control agent of red spider mites in horticulture under glass, with deployment on almost 52 percent of the area. Compared to 2016 and 2012, the use of the species is steadily increasing. Application is highest in peppers and chrysanthemums at over 90 percent. Also, in cucumbers and roses, this pesticide is applied in three-quarters or more of the area. In tomatoes and pot plants (flowering), the pesticide is not very important, with percentages below 20.
Predatory mite against red spider mite, from top to bottom: strawberries, leafy plants, chrysanthemums, gerberas, cucumbers, peppers, pot plants - blooming, roses, tomatoes.
Encarsia formosa (parasitic wasp against whitefly)
In 2020, the parasitic wasp Encarsia formosa was an important controller of whitefly with a 33 percent deployment rate. Compared to 2016 and 2012, the use of the species is stable. In tomatoes and gerberas, the rate of application is highest at around 80 percent. In cucumbers and roses, we see an application rate of about 45 percent, while the application in potted plants, peppers, and strawberries is limited.
Parasitic wasp Encarsia against whitefly: strawberries, leafy plants, chrysanthemums, gerberas, cucumbers, peppers, pot plants - blooming, roses, tomatoes.
Macrolophus pygmaeus (assassin bug against whitefly)
In 2020, the assassin bug Macrolophus pygmaeus was a major fighter of whitefly with a deployment of almost 37 percent. Compared to 2016 and 2012, the use of the species has increased somewhat. In tomatoes, the application is by far the highest at over 90 percent. In peppers, use increases to over 45 percent. In the other crops, the application of the species is limited or non-existent.
Assassin bug macrolophus against whitefly: strawberries, leafy plants, chrysanthemums, gerberas, cucumbers, peppers, pot plants - blooming, roses, tomatoes
Number of treatments per year
In 2020, it was no longer known in which part of the year pesticides were applied. However, the number of treatments was queried. The frequency of treatments appears to be up to weekly, notes the CLO.