Estimating Diabrotica virgifera virgifera damage functions with field trial data: applying an unbalanced nested error component model

Abstract

We apply the double‐nested unbalanced panel data model developed by Antweiler [J. Econometrics 101 (2001) 295] to estimate a damage function for western corn rootworm (Diabrotica virgifera virgifera) using commonly available field data. These data are from experiments collecting maize yields and measures of maize root injury due to rootworm larval feeding for different treatments, with multiple replicates at many locations over several years, which creates nested panel data. The nested panel becomes unbalanced when the number of replicates, locations or years of data differs during the course of the study. We use Antweiler’s (2001) method to estimate damage functions with data from four irrigated locations in northern Italy from 2006 to 2008 and from four dryland locations in the state of Illinois from 2005 to 2007 to predict the expected percentage of yield lost based on the observed node injury scale of Oleson et al. [J. Econ. Entomol. 98 (2005) 1]. Estimated coefficients imply that a one unit difference in the node injury scale is on average associated with a 17.9% yield loss for the Illinois locations and a 2.9% loss for the locations in Italy. We attribute the lower yield loss for the Italian locations to the use of irrigation. Estimated variance components were relatively large, indicating the tremendous variability in losses observed for plots with similar node injury scale differences. Given the large variation in observed yield losses and the large estimated random effects, the damage function is more appropriate for larger‐scale, longer‐term estimates of yield loss from the western corn rootworm rather than for field‐scale estimates. These estimates are the first damage function estimates for the node injury scale in maize and should be considered preliminary, an initial baseline for comparison and refinement as additional data are collected and analysed in the US and Europe.

Field-evolved resistance by western corn rootworm to multipleBacillus thuringiensistoxins in transgenic maize

“…An average of one node of root injury or greater was used as the threshold for classifying fields as having severe rootworm injury, because this criterion is used by the US EPA to classify single-toxin Bt maize as having greater-than-expected feeding injury and because injury to one node of roots (i.e., a ring of ca. 12 roots around the base of the plant) is associated with an average reduction in yield of 17% (15,16). The total number of fields found with severe root injury has increased over time, with three fields identified in 2009 (13), seven fields in 2010 (14), and 15 fields in 2011 ( Fig.…”

“…An average root injury of one node was used as the threshold for classifying fields as having severe rootworm injury because this criterion is used by the US EPA to classify Cry3Bb1 maize as having greater-thanexpected feeding injury (15). Furthermore, this injury is associated with an average reduction in yield of 17% (16).…”

Evidence of Resistance to Cry34/35Ab1 Corn by Western Corn Rootworm (Coleoptera: Chrysomelidae): Root Injury in the Field and Larval Survival in Plant-Based Bioassays

“…The vast majority of yield loss from western corn rootworm arises from feeding of larval rootworm on corn roots, although adult feeding on developing corn ears also may reduce yield (Gray et al 2009). On average, yield is reduced by 15-17% for every node of roots lost to larval feeding by western corn rootworm (Dun et al 2010, Tinsley et al 2013. Management of western corn rootworm has included use of soil-applied insecticides to reduce larval feeding on corn roots, rotation of fields to crops other than corn to kill larvae, and aerial application of insecticides to reduce egg laying by females, and in some cases, to reduce adult feeding on corn ears (Levine and Oloumi-Sadeghi 1991).…”

“…The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is among the most serious pests of corn in the United States and imposes annual economic losses to farmers in excess of $1 billion US, as a result of management costs and lost yield (Gray et al 2009, Dun et al 2010. Larvae from this univoltine species feed on corn roots while adults feed primarily on corn silk, pollen, and developing ears (Meinke et al 2009).…”

Discovery of midgut genes for the RNA interference control of corn rootworm

“…6 and Supplementary Table 4). Dun et al 44 and Tinsley et al 45 estimated that under field conditions, one node of root injury was on average associated with a corn yield loss of approximately 15-18%. Further studies are needed to confirm the efficacy 46 of dvssj1 events under field conditions 47 .…”