Comparison of multiple sticky traps for the monitoring of Bt-susceptible and Bt resistant corn rootworm (Diabrotica spp.) populations

Corn rootworms (Diabrotica spp.) have been a major pest on corn (Zea mays L.) for decades due to the injury they cause on corn roots. Many control tactics have been developed for use against this pest. Corn, producing a toxin from Bacillus thuringiensis Berliner (Bt), is the most common control method currently used. Due to the rootworm’s high degree of adaptability, resistance to corn rootworm-active Bt traits is now showing up in many locations. Monitoring techniques, such as sticky traps and whole plant counts, have been used in the past to scout for this pest, but decision criteria have not been updated in 20 years. This study explored five different yellow sticky traps for their use in effectively monitoring corn rootworm populations. Sticky traps were placed in 12 locations at three different sites. Sites differed in their apparent rootworm susceptibility to Bt hybrids and the hybrid used (Site 1: Refuge hybrid planted in Bt susceptible population, Site 2: Single-trait hybrid with insecticide overlay planted in suspected Bt resistant population, Site 3: Pyramided hybrid planted in suspected Bt resistant population). There was a large difference in the number of corn rootworms captured by each trap. The information gathered by this preliminary study will enable better use of sticky traps in monitoring rootworm populations.