title: Lengthening of insect development on Bt zone results in adult emergence asynchrony: does it influence the effectiveness of the high dose/refuge zone strategy?
abstract: The &#8220;High Dose/Refuge&#8221; strategy (HD/R) is the currently recommended Insect Resistance Management strategy (IRM) to limit resistance development to Bacillus thuringiensis (Bt) plants. This strategy requires planting a &#8220;refuge zone&#8221; composed of  non-Bt plants suitable for the target insect and in close proximity to a &#8220;Bt zone&#8221; expressing a high toxin concentration. One of the main assumptions is that enough susceptible adults mate with resistant insects. However, previous studies have suggested that the high toxin concentration produced by Bt plants induces slower insect development, creating an asynchrony in emergence between the refuge and the Bt zone and leading to assortative mating between adults inside each zone. Here, we develop a deterministic model to estimate the impact of toxin concentration, emergence asynchrony and refuge zone size on the effectiveness of the HD/R strategy. We conclude that emergence asynchrony only affects resistance when toxin concentration is high and resistance is recessive. Resistance develops more rapidly and survival of susceptible insects is higher at lower toxin concentration, but in such situations, resistance is insensitive to emergence asynchrony.
authors.affiliation: Biological Control and Spatial Ecology Laboratory (LUBIES), CP 160/12, Université Libre de Bruxelles, av. FD Roosevelt 50, B-1050 Brussels, Belgium. agryspei@ulb.ac.be
authors.forename: Aiko
authors.initials: A
authors.lastname: Gryspeirt
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Grégoire
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003198:Computer Simulation; D018556:Crops, Agricultural / Q000235:genetics; D004731:Endotoxins / Q000235:genetics / Q000378:metabolism*; D006460:Hemolysin Proteins / Q000235:genetics / Q000378:metabolism*; D007313:Insecta / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D007305:Insecticide Resistance / Q000235:genetics; D007814:Larva / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D008954:Models, Biological; D010572:Pest Control, Biological / Q000379:methods*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D011156:Population Density; D013997:Time Factors
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis