Estimating age through female reproductive status of southern green stink bug, Nezara viridula, for timing pest management practices

A trap crop consisting of three border rows of grain sorghum was planted along two sides of an organic tomato crop in North Florida to reduce fruit injury caused by invasive stink bugs (Hemiptera: Pentatomidae). The southern green stink bug, Nezara viridula (L.), the most abundant species, remained in the sorghum when the panicles were in the milk to soft dough stage before infesting the tomato crop. Females were collected and each dissected to count the number of mature eggs in their ovarioles and assess expansion of the spermatheca, indicating their reproductive state. In the tomato and sorghum crop, most females contained fewer than 15 eggs and were apparently pre- or post- reproductive. To determine the age distribution of the field-collected females, we compared their number of mature eggs and spermatheca expansion with the same parameters in females from our defined laboratory population and published studies. Female age can then be monitored via reproductive status to indicate the beginning and end of each oviposition cycle. Since most of the stink bugs aggregate and mate in the trap crop, there may be a discrete period when most of the reproductively active females can be eliminated before they infest the tomato crop.