Predatory thrips deliver strong results for Florein Gerbera

Gerbera cultivation is well suited to biological control. While the flowers are harvested, the leaves remain for up to three years providing a host plant for natural enemies. But what do you do when a pest outbreak threatens to get out of control? Jelle Zwemstra, crop manager at Florein Gerbera, faced that decision last year. His choices were to intervene with chemicals or invest in predatory thrips to control Echinothrips.

The choice was made to use the natural enemy Franklinothrips vespiformis, also known as predatory thrips. In hindsight, it proved to be the right decision. At the Naaldwijk site, Zwemstra explains the process, together with Biobest IPM advisor Gert-Jan de Vast and his colleague Koen Merkus, who supports advisors worldwide by sharing research insights.

Mesh against moths

More and more gerbera growers are adopting biological crop protection. On the one hand, this aligns with the shift towards more sustainable cultivation. On the other, the possibilities for chemical intervention are becoming increasingly limited. “In ornamentals, relying totally on biological solutions is not easy.” says Zwemstra. “In gerbera production biocontrol is already quite advanced. Everything revolves around biological balance. The advantage with gerbera is that only the flowers are harvested, while the leaves remain in the greenhouse. Insect netting on the ventilation windows is essential to keep moths out. If they enter, caterpillars can become a problem and chemical intervention may be required. Biocontrol solutions are becoming more available, but they are less potent than broad-spectrum chemicals and therefore need to be applied more frequently. Our goal is to disturb the biological balance as little as possible, even when chemical intervention is needed.”

Predatory bug population develops slowly

The predatory bug Dicyphus errans is widely used in gerberas. “This generalist predator is used by many growers against a wide range of pests,” says De Vast. “The population is built up using banker plants. It often takes several months before this predator spreads throughout the entire greenhouse.” In 2024, Florein Gerbera detected Echinothrips (Echinothrips americanus) in one section. A larger and hairier thrips species, it defends itself well and is difficult to control with predatory mites alone. “Working with Biobest, we set up a local trial using predatory thrips Vespiformis-System (Franklinothrips vespiformis) in hotspot areas. We saw clear potential.

Predatory thrips or chemical intervention?

In April 2025, Zwemstra observed a sudden increase of Echinothrips in another section. Planted in mid-2024, these gerbera had gone through the winter using a programme of biological solutions. The thrips had spread throughout the entire section. Severe infestations can turn leaves grey and cause yield losses. “Together with my crop scout, Wouter Mooij from Mooij Crop Protection, I had to decide whether to intervene chemically or fully commit to predatory thrips,” says Zwemstra. “It was not an easy choice. Releasing predatory thrips across the entire greenhouse required a significant investment, but chemical intervention would disrupt the biological balance. As a result, other pests such as whitefly and spider mites would likely resurface. Dicyphus also feeds on those pests. We took the decision to use predatory thrips. It worked 100%. In hindsight, we made the right choice.”

Until 2024, Franklinothrips vespiformis was mainly positioned as a niche product. “With the increase of invasive thrips species, Biobest decided to scale up production,” explains Merkus. “The next question was how many individuals were needed to control Echinothrips.  Our strategy recommends three full-field releases, between early April and late June, combined with weekly additional releases in hotspots. The number of individuals depends on infestation pressure and is determined case by case.”

“The use of predatory thrips delivered very positive results,” says De Vast. “Echinothrips were almost eliminated, giving Dicyphus time to build up a stable population in the greenhouse. That was our ultimate goal. Dicyphus is now present throughout the greenhouse and keeps most pests, including Echinothrips, under control. As the amount of Echinothrips declined, the population of vespiformis also decreased. However, we still spotted one individual this week in a small hotspot.”

Grain pollen to promote parasitoid aphid control

Zwemstra is pleased he gained experience with predatory thrips in 2024. “As we had already seen strong local results, we had confidence in a successful outcome,” he says. With aphid control a major challenge in gerbera cultivation, Florein Gerbera is currently conducting a trial using grain pollen to support populations of lacewings and parasitoids. “The parasitoids develop in the grain pollen and then spread throughout the greenhouse to control the aphids. We are keen to participate in trials, as they are the only way to continue developing as a sector and further strengthen biological control strategies.” At the same time, Zwemstra stresses the importance of having chemical solutions available as a backup, when necessary.

Sustainability in Florein Gerbera’s DNA

Florein Gerbera produces large-flowered and mini gerberas at two locations in Naaldwijk, covering a total of 3.5 hectares. Biological control is a good fit with the company’s ethos of working as sustainably as possible. Sustainability efforts go beyond crop protection. Solar panels and LED lighting, of approximately 240mmol, is enabling year-round production of nearly forty gerbera varieties. The greenhouses are Green Label certified and have three  energy screens optimizing energy savings and preventing light emission. Meanwhile, the air is dehumidified using DryGair systems, and the drain water disinfected through ultrafiltration.

Integrating sustainability into many aspect of its operations, Florein Gerbera combines advanced technologies and environmentally conscious practices to achieve efficient, year-round production while minimizing its ecological footprint.

Source: KAS Magazine, https://www.kasmagazine.nl