Bean pod sucking bug
Riptorus linearis ()
Heteroptera: Coreidae
R. linearis belongs to the family Coreidae (leaf-footed bugs) and is reported in many tropical and subtropical countries of Asia.
Host plants and damage
R. linearis is a pest on Leguminosae, but also found pecking on rice. Primary hosts are Phaseolus (beans), Vigna unguiculata (cowpea), Glycine max (soybean), and V. radiata (mung bean).
Plant growth stages affected
Flowering and fruiting stages are attacked by R. linearis.
Affected plant parts
Both, nymph and adults attack Fruits/pods, and seeds.
Symptoms
Pods and seeds attacked by R. linearis show spots and discoloration.
Morphology & biology
Nymphs undergo five instars before entering the adult stage.
Adults are 13-15 mm in length and have laterally a yellow band from head to abdomen. Antennae are 4-segmented.
Species in the family Coreidae are separated from those in Alydidae by differences in width and length of their heads relative to the pronotum. Alydids, commonly called broadheaded bugs, have a head that is nearly as wide as and as long as the pronotum.
Monitoring
Adult bugs preferentially colonize larger, more mature plants. Thus, early-planted crops may be especially prone to attack. Numbers are also highest on plants during bloom and fruit set.
The tendency of these bugs to aggregate in sheltered locations can be used for monitoring. Look on undersides of leaves and on pods for both, nymph and adults.
Pest management
Chemical Control
Several synthetic insecticides are reported to control R. linearis effective.
If insecticides are to be applied when blossoms are present, it is advisable to use insecticides with little residual activity.