More than a third of Dutch gerbera growers now work with a new biological control agent, the predatory bug Dicyphus Errans. At the Strawberry Day event, Wouter Mooij of Mooij Gewasbescherming discussed the success of this innovation in gerbera cultivation. He also elaborated on what strawberry growers can learn from it, and which new challenges are emerging now that Dicyphus Errans is proving successful. In the transition from chemical to more biological diseases and pests control the rule often is: three steps forward, one step back.
Wouter Mooij at the Strawberry Day 2025
Importance banker plant
As the predatory bug is not yet commercially available, growers working with the predatory bug grow banker plants in the greenhouse on which they cultivate the biological control agent themselves. Dicyphus errans thrives on Verbascum thapsus.
The use of high-quality supplementary food with Artemia (dead brine shrimp cysts) or Ephestia (sterilized eggs of meal moths) also helps to build a sufficiently high population. Wouter knows of examples where plants host 200 predatory bugs, ready to combat pests. The idea to use the predatory bug was adopted from Canada, where it is already used in vegetable crops, among others.
In recent years, experience with the predatory bug has been gained in the Netherlands, first in the WUR's greenhouse. Practical use soon followed. A lot was learned in two years, Wouter shared. From one grower in 2022, practical use expanded to five growers in 2023, and by 2024, the predatory bug was widely used.
Banker plants in gerbera cultivation, at Gerbera United during Kom in de Kas 2024
Family Macrolophus
Dicyphus errans is related to the predatory bug Macrolophus. That pest is used in tomatoes, for example, to control whitefly. The menu of Dicyphus errans includes whitefly, spider mites, and echinotrips. Unlike Macrolophus, this newer predatory bug in the Netherlands sucks less on the plant and does not cause flower damage. This is important, especially in a gerbera crop where flowers are sold, not fruits.
The new predatory bug already lives outdoors in the Netherlands and can withstand lower temperatures. This winter, the predatory bug will also be used on a large scale in lighted crops.
More pesticides in IPM system cause vulnerability
However, what Wouter has noticed is that with the reduction of chemical control, sooner or later, echinotrips or soft scales emerge in the crop. A tricky point here is that in gerbera cultivation, various blocks alternate, and the greenhouse is never really empty. As a result, pests, including whitefly, secretly remain present anyway, and pest pressure increases when conditions are right.
A general observation Wouter shared at the end of his presentation is that there are many pests to be reckoned with. Solutions are found to control them, however as the number of biological controllers increases the system also becomes more vulnerable. If there does need to be one intervention, there are many critters to reckon with. "The outbreak of one pest can topple the IPM system," he says.
For more information:
Mooij Gewasbescherming
[email protected]
www.erikmooij.nl/