Determination of growth stage-specific response of soybeans to varying densities of redbanded stink bug, Piezodorus guildinii Westwood, (Hemiptera: Pentatomidae)

The redbanded stink bug (RBSB), Piezodorus guildinii Westwood, (Hemiptera: Pentatomidae) is an emerging pest of soybeans in the southern states of the US.  Studies were conducted with the objective to determine the interaction(s) between the soybean plant and RBSB.

Soybeans at reproductive stages R2, R3, R4, R5 and R6 were infested with field-collected RBSB adults using cylindrical, wire mesh cages.  RBSB densities (0, 1, 2 and 4 RBSB adults/cage) were used and infestations were maintained for 10 days. Controls were established without infestation for all the plant growth stages. Plant physiological response was measured in terms of photosynthetic rate and leaf chlorophyll measurements on uppermost fully expanded leaves on the main stem. At maturity soybeans were harvested and parameters such as numbers of pods, seed weight, seeds per pod and seed quality were recorded.

RBSB infestations during early reproductive stages had no significant effect on the rate of photosynthesis and leaf chlorophyll. However, RBSB infestation at R4 stage significantly reduced the number of fully developed pods indicating vulnerability of soybeans at R4 (full pod) stage to RBSBs. Our results show that RBSB does not alter plant physiology significantly, but has great damage potential due to direct feeding on soybean pods.