Omnivorous predatory bugs of the family Miridae are feeding on both plant and prey. This is an useful habit for biological control, because this enables us to release these predators preventively at low pest densities or in absence of pests (inoculative biological control). By doing this, predators are ready to control pests as soon as they appear.
The most commonly used and commercially mass-produced species is currently Macrolophus pygmaeus. This predator is successfully used to control whiteflies and other pests in tomato and eggplant. Also gerbera plants are suitable hosts for these bugs.
In a recent project (PT 14941), Wageningen UR Greenhouse Horticulture tested 5 species of mirid predatory bugs. Three of them, were very effective in controlling whiteflies, reducing population more than 90%.
Because mirid predatory bugs are real generalists, they can also contribute to the control of other pests such as leafminers, aphids and spider mites. One of the upcoming pests in ornamentals is Echinothrips. Mirid predatory bugs were, in contrast to predatory mites, able to control this pest very well. Surprisingly, control was even better in the presence of whiteflies. Another advantage of mirid predatory bugs is their relatively long life-span and activity at low temperatures, which make them suitable candidates for pest control in winter gerbera crops.
Hence, using mirid predatory bugs for pest control in gerbera would be a major breakthrough. However, it has been observed that mirid predatory bugs can cause flower damage in some cultivars. The underlying mechanisms for this behaviour are not clear yet. It may also strongly depend on the species of predatory bug, as they vary to the extent that they feed on plant or prey.
More insight in the factors that determine the feeding behaviour of mirid predatory bugs will help us to develop measures that maximise pest control and minimise risks of crop damage. This will be studied in future research.