O'Neal M E, Gray M E, Ratcliffe S, Steffey K L
Department of Crop Sciences, University of Illinois, Urbana 61801, USA.
J Econ Entomol. 2001 Feb;94(1):98-105. doi: 10.1603/0022-0493-94.1.98.
Crop rotation for portions of east central Illinois and northern Indiana no longer adequately protects corn (Zea mays L.) roots from western corn rootworm, Diabrotica virgifera virgifera LeConte. Seventeen growers in east central Illinois monitored western corn rootworm adults in soybean (Glycine max L.) fields with unbaited Pherocon AM traps during 1996 and 1997. In the following years (1997 and 1998), growers left untreated strips (no insecticide applied) when these fields were planted with corn. Damage to rotated corn by rootworms was more severe in untreated than in treated strips of rotated corn, ranging from minor root scarring to a full node of roots pruned. Densities of western corn rootworms in soybean fields from 1996 were significantly correlated with root injury to rotated corn the following season. Adult densities from 1997 were not significantly correlated with root injury in 1998, due to heavy precipitation throughout the spring of 1998 and extensive larval mortality. Twenty-eight additional growers volunteered in 1998 to monitor rootworm adults in soybean fields with Pherocon AM traps based on recommendations that resulted from our research efforts in 1996 and 1997. In 1999, these 28 fields were rotated to corn, and rootworm larval injury was measured in untreated strips. Based on 1996-1997 and 1998-1999 data, a regression analysis revealed that 27% of the variation in root injury to rotated corn could be explained by adult density in soybeans the previous season. We propose a sampling plan for soybean fields and a threshold for predicting western corn rootworm larval injury to rotated corn.
伊利诺伊州中东部和印第安纳州北部部分地区的作物轮作，已无法充分保护玉米（Zea mays L.）根系免受西部玉米根虫（Diabrotica virgifera virgifera LeConte）侵害。1996年和1997年，伊利诺伊州中东部的17位种植者，使用未加诱饵的Pherocon AM诱捕器，在大豆（Glycine max L.）田中监测西部玉米根虫成虫。在接下来的年份（1997年和1998年），这些田地种植玉米时，种植者留出了未处理的条带（未施用杀虫剂）。与经过处理的轮作玉米条带相比，未处理条带中根虫对轮作玉米造成的损害更为严重，损害程度从轻微的根系伤痕到整节根系被啃食不等。1996年大豆田中西部玉米根虫的密度，与下一季轮作玉米的根系损伤显著相关。由于1998年春季降水充沛以及幼虫大量死亡，1997年的成虫密度与1998年的根系损伤没有显著相关性。基于我们1996年和1997年的研究成果所提出的建议，另外28位种植者于1998年自愿使用Pherocon AM诱捕器，在大豆田中监测根虫成虫。1999年，这些田地改种玉米，并对未处理条带中的根虫幼虫损伤情况进行了测量。基于1996 - 1997年和1998 - 1999年的数据，回归分析表明，轮作玉米根系损伤变异的27%，可由上一季大豆田中成虫的密度来解释。我们提出了一个针对大豆田的抽样计划，以及一个预测西部玉米根虫对轮作玉米幼虫损伤的阈值。
