Year 1 (2006) Summary

Since wireworms have a 4-5 year life cycle, fields that were planted to potatoes in the 2005 season were also sampled in addition to the 2006 potato fields at each of the 5 farms. Adult beetles of the wireworms were sampled with pitfall traps, white sticky traps and pheromone ground traps for two invasive species from Europe (Agriotes lineatus and A. obscurus) which have a reputation for causing more consistent damage to tubers and other crops than the other local wireworm species. Wireworm larvae were sampled with underground bait traps of germinating grain.

Several different species of wireworms were obtained at the 5 farms, but efforts for species-level identification and confirmation focused on the two invasive species due to their economic importance in British Columbia and Washington State over the past several decades. In 2005 the known distribution of these two species in Oregon consisted of only a few nurseries and ports near the Columbia River which were reported in a survey by the Oregon Department of Agriculture (ODA). One of the project farms in this same area near the Columbia River had A. lineatus adults in the pheromone traps. Another farm about 15 miles south of this area also had A. lineatus in the pheromone traps, and this was a new county record of this invasive species that was reported to the ODA.

Although species-level identity of the other wireworm species was not confirmed in most cases, the extent of overall wireworm damage relative to overall wireworm and adult numbers in a given field was recorded. As for the flea beetles, numbers of wireworms were not always associated with the extent of wireworm damage in a given field. Wireworm damage in general was not as prevalent as flea beetle damage among project participants.

Pitfall traps and white sticky traps trapped very few wireworm adults, but the pheromone traps and larval bait traps were useful for wireworm monitoring and should be continued in project fields where wireworms are a concern. As was done for the flea beetles, a wireworm damage rating system was developed for consistent diagnoses, and discussions with the growers provided them with information about how to tell that damage apart from the damage of other insect and other tuber skin problems.

Future work
Since the wireworms are less of a priority for most of the farms, we do not have any experiments planned to generate information about specific management tactics. We will, however, continue to monitor the farms to track the potential spread of the two invasive species. We will also look into monitoring source areas of wireworms on the farms and track the extent of their damage in the potato fields. This information will also result in IPM recommendations that will be discussed and summarized in the same way as those for the flea beetles.