Damage and control of stink bugs on autumn soybean in Kagoshima Prefecture.

Abstract

Effects of the planting period on the damage caused by stink bugs and of insecticidal control programs against those bugs in autumn soybeans were examined in Osumi district, Kagoshima Prefecture. Three species of stink bugs, Piezodorus hvbneri GMELIN, Riptortus civatus THUNBERG and Nezara viridula SCOTT were recognized as being injurious to the soybean crop. P. hvbneri and R. clavatus appeared from mid-August to November, throughout the pod-setting stages of the crops, but N. viridula was detected after lateSeptember. Soybeans were planted at five different times from mid-June to early-August and harvested in November, depending on the planting time. The earliest (June 19) and the latest (August 1) planted soybeans experienced the most serious damage caused by stink bugs. It appeared that the earliest planting was attacked by the bugs during the longest period from bloom to maturation, while the latest planting tended to be exposed to a concentrated attack by the bugs, especially by N. viridula in the early period of the podsetting stage. Insecticides were applied after the pod-setting stages of soybean plants. Results of field spraying experiments revealed that two applications in the early period reduced the damage to a considerable degree.