Two ways of estimating the damage done by stink bugs to the soybean pods were compared: the direct counting of flat loculi (FL), which gives a percentage of damage and an index called Percentual Index of Pod Damage (PIPD). The PIPD is obtained by classifying the pods in three categories (flat, intermediate and sound) and applying the formula PIPD = 1/2 (percentage of intermediate pods) + percentage of flat pods. The FL and PIPD are highly correlated (r > 0.96). The use of the PIPD is recommended since it is easier to obtain. Three ways of sampling were compared: a) Twenty pods from five plants; b) Ten pods from ten plants; c) Five pods from twenty plants. It was demonstrated that it is more advantageous to use less pods per plant and more plants per plot.
soybean; Glycine max (L.) Merrill; stink bugs; Pentatomidae; pod damage index; sampling; insect resistance; soybean breeding