Stink bug traps may increase damage to tomato fruits

The invasive brown marmorated stink bug (Halyomorpha halys) is an important pest of fruits and vegetables. To counter them, some home gardeners use pheromone-baited traps that are designed to attract, trap, and kill them. However, new research from entomologists at the University of Maryland suggests that the traps may actually increase stink bug damage to tomatoes. The research will appear in the April issue of Environmental Entomology.

The researchers asked 15 gardeners to place stink bug traps at the ends of rows of tomatoes, while another group of 14 placed no traps in their gardens. Both groups experienced nearly the same amount of stink bugs on the tomato plants themselves, but the the abundance of stink bugs on the tomato fruits was marginally greater in the gardens with traps, and the fruits sustained significantly more injury than tomato fruits grown in gardens without traps. Furthermore, tomato fruits on plants near the traps housed more stink bugs than tomato fruits on plants that were away from the traps.

"We found no evidence that stink bug traps protected tomatoes from H. halys," the authors wrote, "and it appears that the addition of traps to gardens may increase injury to tomato fruits."

The increased damage may have resulted, in part, because of a phenomenon known as "trap spillover," which can occur when pests arrive in the general vicinity of a trap and rest on vegetation before entering and being captured by the trap.

"This study presents evidence that placement of an attract-and-kill stink bug trap near a plant may actually result in greater abundance of stink bugs on the fruit," the researchers wrote. "Vegetable gardens with traps may sustain more injury than those without traps."