Personnel from Ohio State University Extension sampled for western corn rootworm adults (WCRA) in soybean fields for the sixth year in a row. The sampling was done using Pherocon AM yellow sticky traps placed in 89 fields in 21 counties. Six traps were placed in the soybeans on metal posts at canopy height and located at least 100 feet from the field edge and evenly spaced in the field. The traps were placed in the field at the end of July and changed weekly for six weeks until the early part of September. Each week the old traps were removed from the posts, the WCRA were counted and recorded and new traps placed on the posts. After each trapping week, the number of beetles collected were summed and divided by the number of days the traps were in the field resulting in the average number of beetles collected per trap per day. Research indicates that catches in soybean of 5 or more beetles/trap/day during any trapping week indicates a potential problem with rootworm in the field the following year.
A summary of the weekly catches of WCR adults per trap per day from the 2003 season is presented in Table 1. Based on the potential treatment level of 5 beetles/trap/day during any trapping week, the trapping data from 2003 had the following results:
One field had an average > 3 beetles/trap/day
Three fields had an average > 2 beetles/trap/day
Twenty-six fields had an average > 1 beetle/trap/day
Fifty-nine fields had an average < 1 beetle/trap/day
None of the fields went over the threshold of 5 beetles/trap/day.
Based on these data, if any of these fields are planted to corn in 2004, a treatment (either insecticide or plant resistance) should not be needed for rootworm. These data do not mean that other fields in a county, that were not sampled, do not need treatment but it does give good information about the fields that were sampled and about the abundance of the beetles this year.
In addition to sampling with the sticky traps, OSU Entomologists sampled soybeans in 8 counties along the Ohio-Indiana border for WCRA the first week of August. Twenty sweeps in 5 places in 3 fields per county were taken and contents of the nets bagged and later counted in the lab. Sweep net samples do not tell us if a field has a high enough WCRA population to warrant treatment the next year, but they do tell us the relative abundance of the beetle population. The number of WCRA per 100 sweeps ranged from 0 to 25 (Figure 1). This is the first year that we have swept for beetles so we cannot compare data from this year with prior years data but if we compare these sweep counts with data from Indiana and Illinois where they may sweep several hundred beetles in some of their problem counties, it does indicate how low our beetle populations were in soybeans this year.
Multi-colored Asian lady beetles were also counted each time the traps were changed and these counts are included in Table 2.
Thanks to the following county agents for their help in conducting this survey:
| County | Agent | County | Agent |
| Allen | C. Young | Miami | H. Watters |
| Auglaize | J. Smith | Morrow | S. Ruhl |
| Butler | S. Bartels | Paulding | J. Lopshire |
| Champaign | B. Ward | Putnam | G. Arnold |
| Crawford | S. Prochaska | Sandusky | M. Koenig |
| Darke | S. Foster | Shelby | R. Bender |
| Defiance | B. Clevenger | Van Wert | A. Kleinschmidt |
| Fulton | G. Lebarge | Williams | F. Chirra |
| Henry | D. Sonnenberg | Wood | A. Sundermeier |
| Mercer | T. Mangen | ||
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