In March 2026, the Botanical Garden introduced a new method of biological pest control to combat mealybugs in its greenhouses. Rather than using chemical sprays, the garden now employs natural predators — predatory ladybirds — which actively seek out and consume the pests.
A new step in plant protection
In March 2026, we implemented a significant change in the protection of plants in our greenhouses by introducing biological control against mealybugs for the first time. Specifically, we introduced predatory ladybirds, which are natural enemies of these pests and thus can effectively regulate their population.
Pests in greenhouses and methods of control
Greenhouse crops are commonly affected by a variety of pests, including mealybugs, spider mites, whiteflies, scale insects, thrips, nematodes and aphids. The traditional method of controlling these pests is spraying with chemicals, collectively referred to as pesticides. These can be divided into contact agents, which only act upon direct contact with the pest, and systemic agents, which are absorbed by the plant and then act as the insect feeds. However, the range of active ingredients is limited today and their use is strictly regulated in terms of their impact on the environment and human health.
Furthermore, a long-standing issue with chemical control methods is that pests develop resistance to the substances used. In our case, there was a significant overpopulation of mealybugs that no longer responded to commonly used products. Chemical control, therefore, ceased to be an effective tool and another solution had to be found.
Predatory ladybirds as a natural ally
Predatory ladybirds are a natural and effective way of controlling this pest. They actively seek out mealybugs and consume both larvae and adults. The larvae are particularly important in terms of effectiveness, as they are voracious eaters and are often camouflaged by a whitish waxy coating that makes them resemble mealybugs. Female predatory ladybirds lay their eggs directly in mealybug egg clusters, ensuring that the larvae have a food source close by. A ladybird larva goes through three instars and consumes more than 250 mealybugs during that time, as well as aphids. After pupating, the adults emerge in 7–10 days and can live for up to two months. Ideally, a stable population of ladybirds will establish itself in the greenhouse, continuing to reproduce and ensuring long-term pest control without the need for repeated interventions. However, these activity of these predators is dependent on the environment, particularly temperature, which should not drop below approximately 16 °C for extended periods. Therefore, in cooler greenhouses, the need to reintroduce ladybirds in subsequent seasons cannot be ruled out.
What will change after reducing chemical use?
It is also important to note that the chemical protection used up to now suppressed the presence of other pests as well as mealybugs, and that regular spraying kept spider mites, thrips, whiteflies and aphids at low levels. Once removed from the protection system, these pest groups may begin to overpopulate gradually. In such cases, a targeted response will be necessary, expanding biological control to include additional specialised predators such as predatory mites or parasitic wasps, thereby gradually building a comprehensive plant protection system
Advantages and limitations of biological control
Biological control offers clear advantages, particularly in terms of its environmental friendliness and long-term sustainability. Unlike chemical products, it does not burden the environment with toxic substances; instead, it makes use of the natural relationships between organisms. However, it requires more knowledge, regular monitoring and careful management of environmental conditions. Predators are living organisms whose activity can be significantly affected by changes in temperature or humidity, and their deployment can be costly, particularly if populations need to be restocked repeatedly.
A long-term process
The transition to biological control should not be viewed as a one-time solution, but rather as a long-term process aimed at establishing a sustainable balance between plants, pests and their natural predators. This approach represents a modern and responsible way to grow plants in greenhouses.
Photo: Hana Ondrušková
Masaryk University is restoring over 500 hectares of endangered wetlands within the agricultural landscape of South Moravia. As well as supporting biodiversity and improving conditions for protected species, the ‘LIFE in Salt Marshes’ project will now also focus on improving the quality of water flowing...
On Saturday, March 21, 2026, 200 students aged 9-18 visited the University Campus in Bohunice as part of the MjUNI Children's University program. Lecturers from the Faculty of Science and the Faculty of Sports Studies prepared a rich interactive program.
