Health for humans, animals & plants

Natural enemy of the green rice bug detected for the first time

The green rice bug has caused damage to tomatoes, garden beans and berry bushes in private gardens and glasshouses in recent years. We have now detected a natural enemy of this bug, a tiny ichneumon wasp.

In recent years, the non-native green rice bug has caused damage to young shoots, fruits and seeds through its sometimes mass occurrence, especially in private gardens and glasshouses in urban regions (Vienna and Graz). The tree bug, which probably originates from Africa, prefers to suck on solanaceous plants (tomatoes, melanzani, peppers), legumes (soybean, common bean) and berry bushes.

The green rice bug is very resistant, so available pesticides are not effective enough. However, there are natural enemies of the bugs: ichneumon wasps, which lay their eggs in the eggs of the bugs and whose larvae then eat the larvae of the bugs.

We therefore launched a bedbug egg clutch monitoring program in 2021 to investigate the occurrence of native natural antagonists in Austria. In the process, we detected for the first time in Austria the hatchling wasp Trissolcus basalis, which is only 1-2 mm small and preferentially parasitizes the eggs of the green rice bug, but also the eggs of the marbled tree bug. The wasp is thought to have a worldwide distribution; in the course of monitoring, we detected it in eight Viennese municipal districts.

To date, such beneficial insects against exotic bugs are not available in Austria; however, the first detection could be relevant in a possible registration procedure and thus allow their use as an alternative or additional control measure.

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