Profile

The green rice bug is a bug that mainly attacks legumes, but also numerous vegetable, fruit and arable crops, as well as ornamental shrubs and plants. It causes sucking damage to fruits, resulting in mottling, corking and deformation.

Biology

The females of the green rice bug lay their first yellowish and later red colored eggs in clutches on the underside of the leaf. The larvae that hatch from these eggs pass through five, very variably colored stages. They usually stay in groups on the plants, where they suck mainly on fruits, but also on leaves, just like the adults.

In autumn they leave their host plants to look for overwintering quarters (e.g. ground litter, buildings). In Europe, only one to a maximum of four (in warmer areas) generations are formed. In regions with an average temperature below 5 °C in January and an average lowest annual temperature below -3 °C, the green rice bug cannot survive the winter.

Host plants

The green rice bug can feed on a wide variety of plant species from all cultivated areas. Its main host plants are legumes (including soybean), but it also likes to visit vegetable, fruit and arable crops as well as ornamental shrubs and plants. Annual, herbaceous crops in particular are attacked especially at the time of fruit and seed formation.

Distribution

In Europe, the green rice bug was initially distributed only in the Mediterranean region. However, due to climate warming, it is increasingly spreading towards the north. Until 2015, only individual animals could be detected in Austria. Since then, however, numerous larvae and adults have been detected in home gardens and glass houses, especially in urban regions (Vienna and Graz), indicating temporary reproduction of the bugs.

So far, no economically relevant damage to outdoor crops has been recorded in Austria, but the green rice bug has appeared more frequently in urban allotments and community gardens in recent years (late summer). The green rice bug has also caused damage to vegetables in protected cultivation.

The mortality rate of the animals in winter has so far prevented a permanent existence of the bug populations in Austria, however, due to the increasingly milder winters, the further development of the species must be observed. Furthermore, successful overwintering in protected areas (for example, construction parts in heated glass houses) cannot be ruled out.

Strong reproduction can be observed in years with dry-hot summer conditions.

Prevention and control

• Regular plant inspections to detect affected individual plants as early as possible and to remove eggs or larvae by collecting them.
• To prevent the bugs from flying into the greenhouse, close-meshed (1-1.5 mm) insect screens can be attached to the vents.
• Egg parasitoids (ichneumon wasp Trissolcus basalis) and endoparasites (caterpillar fly Trichopoda pennipes) are described as natural antagonists. However, these are not commercially available in Austria.
• Direct control with approved insecticides against sucking insects is possible, but difficult because usually no sufficient effect can be achieved against the adult bugs.

Online registration platform

This year, in cooperation with the Chambers of Agriculture, we are carrying out Austria-wide monitoring, especially in soybean, vegetable soybean, bush bean and other legumes. Recently, this monitoring has been supplemented by an online reporting platform: Reports on the green rice bug | Warning service - vegetables .

Here, farmers and private individuals can report findings of the green rice bug, indicating the date of discovery, the location, the affected crops and the observed developmental stages. With these data, we want to learn more information about the distribution and seasonal development of the bug in Austria. Thus, it may be possible to clarify in which regions adults or nymphs are active from when and for how long, over which period eggs are laid, which crops are mainly affected or how many generations actually occur.

Links

Informationen des CABI invasive species compendium: Datasheet Nezara viridula

Informationen des LTZ Augustenberg

Services

Plant Health Services