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Bean pod sucking bug (018) Print Fact Sheet

Common Name

Pod sucking bug

Scientific Name

Riptortus species; there are two species, Riptortus serripes and Riptortus linearis.

Distribution

Restricted. Asia, Oceania. Possibly, Australia, Riptortus linearis is recorded from Solomon Islands.

Hosts

Legumes, such as long bean, French bean, soybean, and mung bean. Some species attack Macadamia and sorghum.

Symptoms & Life Cycle

Eggs of Riptortus are laid on bean leaves and those of other plants; usually the eggs are laid singly. They hatch and the nymphs go through five stages. The nymphs are ant mimics (Photos 1&2), meaning they look like large black ants, presumably to protect them from predation. Adults are dark brown and about 20 mm long (Photos 3&4).

Impact

This is a major pest of beans. Both adult and nymphs "sting" the beans in the pods, feeding on the juices in them, so that the beans fail to mature. The pods turn brown, shrivel and die (Photo 5). Severe damage is caused to bean crops, long beans especially, in Pacific island countries.

Detection & Inspection

Look for the large adult bugs on the leaves and under the leaves, 16-18 mm long; look for ant-like nymphs. Look closely for small holes and damaged, shriveled pods.

Management

NATURAL ENEMIES
There are no reports of predators or parasitoids attacking Riptortus in Pacific island countries. However, the reduviids (assassin bugs), mantids (preying mantids), spiders and wasps that are known to attack Leptoglossus (see Fact Sheet no. 165 ) probably attack Riptortus eggs, and prey on nymphs.

CULTURAL CONTROL

Before planting:

During growth:

After harvest

CHEMICAL CONTROL
If infestations reach levels where chemical control is necessary, use sprays of derris, pyrethrum or chilli. If a commercial product is needed, use synthetic pyrethroids or malathion. But note, these pesticides will also kill the natural enemies.


AUTHORS Helen Tsatsia & Grahame Jackson
Photos 1&2 Graham Teakle, Canberra, Australia.

Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.



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