Economic thresholds – Podsucking bugs in mungbean and soybean

Counting pod sucking bug counts

Green vegetable bugs (GVB) are considered the most important pod sucking bug pest in pulse crops due to their abundance, wide-spread distribution and rate of reproduction, however other species  can still cause severe damage when present in large numbers. A conversion to green vegetable bug equivalents (GVBEQ) allows an assessment of overall potential damage of a mix of bug species compared to the likely damage of GVB.

If no nymphs are present, the adult counts for each species can be converted to GVBEQ by simply multiplying the sample counts by the appropriate conversion factors:

Pod sucking bug species Relative damage conversion factor
Green vegetable bug (GVB): Nezara viridula 1.00 Adult (15 mm)
Brown bean bugs (BBB): Riptortus & Melanacanthus sp. 1.00 Large brown bean bug (<em>Riptortus serripes</em>) female (17 mm)Small brown bean bug (<em>Melanacanthus scutellaris</em>) female (12 mm) - note fuller abdomen and absence of pale patch in scutellum
Redbanded shield bug (RBSB): Piezodorus oceanicus 0.75 Redbanded shield bug (<em>Piezodorus oceanicus</em>) - typical female colouration with pink transverse band and pink perimeter band (10 mm)
Brown shield bug (BSB): Dictyotus caenosus 0.75 Brown stink bug (<em>Dictyotus caenosus</em>) adult (8 mm)

If you have nymphs in your fields, a further conversion to green vegetable bug adult equivalents (GVBAEQ) is required, because bug nymphs are less damaging than adults. Remember to take an adequate number of samples to ensure your counts are representative of what is present in the field.

Photos of a range of life stages of these bugs are available at the Podsucking bugs image gallery.

Action threshold calculator

Note that pulse crops for the edible market have severe penalties for damage, so these thresholds prioritise quality over yield. See the explanation at the end of the calculator for more details.

Spraying before podfill is unlikely to be economically worthwhile.