Submitted to: Entomological Society of America Annual Meeting North Central Branch
Publication Type: Abstract Only
Publication Acceptance Date: 3/27/2002
Publication Date: N/A
Technical Abstract: Continuous two crop rotation with corn and soybeans in Central Illinois has selected for western corn rootworm (WCR) beetles, Diabrotica virgifera virgifera LeConte, which lay eggs in soybean fields and can damage first year corn. A crop rotation study was initiated in 2001 near Urbana, IL, to determine the effect of cuphea as a new crop for rotation. Cuphea produces a seed with about 75% oil, much of which is commercially desirable lauric acid. Seven rotation treatments were established in a field that was planted to corn in 2000. WCR beetles represented the dominant rootworm in this field (98% of the rootworm beetles collected in emergence cages) and in the area (99% of the rootworm beetles collected on sticky traps). Corn plants averaged root damage ratings of 4.3 (1-6 Iowa scale) for the plots planted to corn this season. Emergence cages in corn plots averaged 50 beetles/ft(2), although few beetles emerged from soybean [0.6/ft(2)] and cuphea plots [1.2/ft(2)]. Sticky traps collected on July 23 indicated that beetles prefer pollinating and silking corn to both soybean and cuphea. As corn matured (August 6-20), more beetles were captured by sticky traps in soybean plots with fewer in corn and the fewest in cuphea. Sticky trap catches suggest that the beetles may lay more eggs in soybean plots and fewer in cuphea plots compared with corn. Egg laying in each crop will be assessed by root damage ratings and beetle emergence as plots rotate from cuphea and soybeans to corn in 2002.