South Dakota: Reduced Input Grasshopper Management Saves Dollars for Producers

Damage to crops and rangeland from grasshoppers costs South Dakota farmers thousands of dollars each year. Managing grasshoppers is costly and frequently involves treating large acreages of land with conventional insecticides. Often producers do not treat for grasshoppers on rangeland because it is not cost effective, but this decision results in significant damage to rangeland and adjacent cropland. In response to the grasshopper dilemma, researchers at South Dakota State investigated ways to reduce chemical applications and cost, while reducing grasshopper populations below a level that would cause economic damage.

Studies have focused on treating strips within an infested field, while leaving adjacent strips within the field untreated. In a typical scenario, strips of 25 to 50 percent of a test plot are left untreated, resulting in a decreased insecticide input of 20 and 31 percent, respectively. This has the potential to not only reduce the cost of control but also reduce the amount of insecticide introduced into the environment, which may decrease the impact of chemicals on non-target, beneficial organisms.

For four of five grasshopper species at our study site, control of immature grasshoppers in the strip-treated plots was virtually identical to the control obtained in plots where the entire area was treated. Analysis continues on the effect of this control strategy on beneficial insects.

The impact of this experiment could mean significantly reduced grasshopper management costs, decreased insecticide loads on the environment, and less negative impact on the beneficial insects, while still providing acceptable grasshopper control.