title: Predator Preference for Bt-Fed Spodoptera frugiperda (Lepidoptera: Noctuidae) Prey: Implications for Insect Resistance Management in Bt Maize Seed Blends.
abstract: Understanding indirect, trophic-level effects of genetically engineered plants, expressing insecticidal proteins derived from the bacterium, Bacillus thuringiensis (Bt), is essential to the ecological risk assessment process. In this study, we examine potential indirect, trophic-level effects of Bt-sensitive prey using the predator, Harmonia axyridis (Pallas), feeding upon Spodoptera frugiperda (J.E. Smith) larvae, which had delayed development (lower body mass) following ingestion of Cry1Ab maize leaves. We found no adverse effects on development and survival when H. axyridis larvae were fed S. frugiperda larvae that had fed on Cry1Ab maize tissue. Presence of Cry1Ab in H. axyridis decreased considerably after switching to another diet within 48 h. In a no-choice assay, H. axyridis larvae consumed more Bt-fed S. frugiperda than non-Bt-fed larvae. Preference for S. frugiperda feeding on Bt maize was confirmed in subsequent choice assays with H. axyridis predation on Bt-fed, 1-5-d-old S. frugiperda larvae. We suggest that H. axyridis preferred prey, not based on whether it had fed on Bt or non-Bt maize, but rather on larval mass, and they compensated for the nutritional deficiency of lighter larvae through increased consumption. Pest larvae with variable levels of resistance developing on Bt diet are often stunted versus sensitive larvae developing on non-Bt diet. It is possible that such larvae may be preferentially removed from local field populations. These results may have implications for insect resistance management and may be played out under field conditions where seed blends of Bt and non-Bt hybrids are planted.
authors.affiliation: Institute of Entomology, Biology Centre CAS, Branišovská 31, České Budějovice 370 05, Czech Republic ( svobodova@entu.cas.cz ; habustova@entu.cas.cz ).|Faculty of Science, University of South Bohemia, Branišovská 31, České Budějovice 370 05, Czech Republic.
authors.forename: Z
authors.initials: Z
authors.lastname: Svobodová
authors.affiliation: Department of Entomology, University of Minnesota, 1980 Folwell Ave., St. Paul, MN 55108-6125 ( burkn001@umn.edu ; hutch002@umn.edu ).|Corresponding author, e-mail: burkn001@umn.edu.
authors.forename: E C
authors.initials: EC
authors.lastname: Burkness
authors.affiliation: Institute of Entomology, Biology Centre CAS, Branišovská 31, Ceské Budejovice 370 05, Czech Republic (svobodova@entu.cas.cz; habustova@entu.cas.cz).
authors.forename: O
authors.initials: O
authors.lastname: Skoková Habuštová
authors.affiliation: Department of Entomology, University of Minnesota, 1980 Folwell Ave., St. Paul, MN 55108-6125 (burkn001@umn.edu; hutch002@umn.edu).
authors.forename: W D
authors.initials: WD
authors.lastname: Hutchison
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000145:classification; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism*; D001517:Coleoptera / Q000254:growth & development / Q000502:physiology*; D004731:Endotoxins / Q000378:metabolism*; D020387:Food Chain; D006460:Hemolysin Proteins / Q000378:metabolism*; D007814:Larva / Q000254:growth & development / Q000382:microbiology / Q000502:physiology; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D011235:Predatory Behavior; D018411:Spodoptera / Q000254:growth & development / Q000382:microbiology / Q000502:physiology*; D003313:Zea mays / Q000235:genetics / Q000254:growth & development / Q000502:physiology
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Cry1Ab; fall armyworm; multicolored Asian lady beetle, Harmonia axyridis; resistance management