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Redbanded shield bug

The redbanded shield bug (RBSB) is a pest of many summer legume crops. It reduces crop yield and quality by feeding on developing seeds with its piercing-sucking mouthparts.

Scientific name

Piezodorus hybneri

Description

Adults

  • RBSB adults are 8–10mm long, shield-shaped and pale green.
  • Females have a pink (not red) band across the shoulders and pink lines along their sides.
  • Males have an off-white band across the shoulders and pale yellow lines along their sides.

Eggs

  • Females lay a very distinctive twin row raft containing 15–40 eggs. Eggs are dark, elliptical (in cross section), and ringed by small spines.

Nymphs

  • Newly hatched nymphs are orange with black markings
  • Larger nymphs are pale green with dark-red and brown markings in the centre of the back.
  • Late autumn nymphs may turn a pale pinkish-brown.

May be confused with

RBSB adults are similar in shape to green vegetable bugs (GVB), but are smaller and paler. GVB adults do not have the pink, white or yellow bands.

Distribution and habitat

Widespread across Australia.

Hosts

Attacks all summer and winter pulses (except chickpea), and is also a pest in cotton and many horticultural crops.

Damage

RBSB typically invades at flowering, but legume crops are at greatest risk during late podding (when seeds are well-developed), and remain at risk until pods are hard (i.e. close to harvest).

Symptoms of damage are similar to that of the green vegetable bug (GVB), but overall, RBSB do only about ¾ of the damage of GVB.

Life cycle

  • Eggs take 4–5 days to hatch.
  • RBSB has has nymphal stages.
  • Total development time (eggs to adult) is 18–35 days depending on temperature.

Monitoring and thresholds

Beatsheeting is the preferred sampling method for nymphs and adults. Visually look for the distinctive twin-row egg rafts that indicate RBSB presence.

Podsucking bugs other than GVB are converted to GVB equivalents, and decisions are made based on the GVB thresholds. An online calculator for mungbean and edible soybean is available at the Beatsheet.

Natural enemies

  • Spiders, ants and predatory bugs are major predators of RBSB, particularly of eggs and young nymphs, with mortality sometimes exceeding 90%.
  • Eggs may be parasitised by the tiny wasp Trissolcus basalis.
  • Adults are infrequently parasitised by the recently introduced tachinid fly, Trichopoda giamocellii.

Control

No insecticides are specifically registered against RBSB in Australia. Trials have shown that not all pesticides registered against GVB are effective against RBSB i.e. synthetic pyrethroids (e.g. deltamethrin) and the organophosphate trichlorfon give poor RBSB control.

Further information