Supervisory Project Scientist University of California Riverside, California
Wireworms, the soil-dwelling larvae of click beetles, have reemerged as significant pests of cereal crops in the Pacific Northwestern US. The aim of this research study was to improve our knowledge of the biology and ecology of wireworms so more effective IPM can be developed. Specifically, we conducted a large-scale survey to examine the distribution and ecology of wireworm species in PNW cereal fields. This survey revealed 13 different wireworm species, collected from 160 fields distributed across 20 PNW counties. Three species, Limonius infuscatus, L. californicus, and Selatosomus pruininus represented 90% of wireworms collected. The dominant species detected varied across counties, indicating that landscapes and climate factors play a major role in species distribution. We also examined the differences in seasonal population dynamics of the two Limonius species. Our results show that as spring moves into summer L. californicus feeds more aggressively, whereas L. infuscatus is less aggressive and decreases in abundance. These data indicate that IPM needs to be tailored to the species seasonality so more effective control can be achieved. We further investigated whether diverse wireworm communities are more impactful than single species at damaging wheat plants. Our results revealed that wireworms cause higher damage to crops if present as a single species in the field than as a multi-species complex. Limonius californicus and S. pruininus were highly impactful species, while L. infuscatus had reduced impacts. Overall, our results suggest that management of wireworms needs to be tailored to the specific species present in a field
