title: Effects of Field History on Corn Root Injury and Adult Abundance of Northern and Western Corn Rootworm (Coleoptera: Chrysomelidae).
abstract: Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), and northern corn rootworm, Diabrotica barberi Smith & Lawrence, are major pests of corn (Zea mays L.). Corn producing Bacillus thuringiensis (Bt) toxins are widely used to manage Diabrotica spp.; however, Bt resistance by D. v. virgifera has led to high levels of feeding injury in the field. We tested whether field history affected root injury and abundance of adult Diabrotica spp. In 2013 and 2014, four types of cornfields were sampled: 1) recently rotated fields, 2) continuous cornfields, 3) fields with a history of injury to Bt corn (past problem fields), and 4) fields with greater than one node of injury to Bt corn at the time of sampling (current problem fields). Data were collected on field history, root injury, and the abundance of adult Diabrotica spp. from each field. Root injury and the abundance of D. v. virgifera were significantly greater in current problem fields compared to the other field types, while D. barberi were significantly more abundant in recently rotated fields. Root injury and the abundance of D. v. virgifera did not differ among recently rotated fields, continuous cornfields, and past problem fields. Analysis of field history showed that recently rotated fields were characterized by significantly less Bt corn, soil-applied insecticides, and years planted to corn continuously. These results suggest that greater cropping practice diversity can reduce management inputs for Diabrotica spp.; however, its effects on resistance evolution remain undetermined.
authors: Department of Entomology, Iowa State University, Ames, IA 50011 (dunbar17@gmail.com; oneal@iastate.edu; aaronjg@iastate.edu) dunbar17@gmail.com.
authors: Mike W
authors: MW
authors: Dunbar
authors: Department of Entomology, Iowa State University, Ames, IA 50011 (dunbar17@gmail.com; oneal@iastate.edu; aaronjg@iastate.edu).
authors: Matthew E
authors: ME
authors: O'Neal
authors: Department of Entomology, Iowa State University, Ames, IA 50011 (dunbar17@gmail.com; oneal@iastate.edu; aaronjg@iastate.edu).
authors: Aaron J
authors: AJ
authors: Gassmann
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000737:chemistry; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000494:pharmacology*; D001517:Coleoptera / Q000254:growth & development / Q000502:physiology*; D000069599:Crop Production / Q000379:methods*; D004731:Endotoxins / Q000494:pharmacology*; D006460:Hemolysin Proteins / Q000494:pharmacology*; D060434:Herbivory; D007305:Insecticide Resistance; D007484:Iowa; D007814:Larva / Q000502:physiology; D010572:Pest Control, Biological; D018517:Plant Roots / Q000502:physiology; D030821:Plants, Genetically Modified / Q000737:chemistry; D011157:Population Dynamics; D013045:Species Specificity; D003313:Zea mays / Q000502:physiology*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Bt corn; Diabrotica barberi; Diabrotica virgifera virgifera; insect resistance management; integrated pest management