Managing the evolution of Bacillus thuringiensis resistance in natural populations of the European corn borer, Ostrinia nubilalis: host plant, host race and pherotype of adult males at aggregation sites.
The European corn borer (ECB) consists of at least two, genetically differentiated host races: one feeding on maize, the other feeding on mugwort and hop. It is unclear to what extent individuals feeding on these, or other host plants, contribute to natural ECB populations. The mechanisms underlying the genetic differentiation between both races are not well understood; they may include sexual attraction via different pheromone blends (E or Z) and differences in the location of mating sites. We caught adult males with traps baited with the E or the Z blend at hop, maize, and 'mixed' sites. We determined their probable host race by allozyme-based genetic assignment, and the photosynthetic type of their host plant by stable carbon isotope analysis. Most individuals caught in Z traps had emerged from a C(4)-type plant and belonged to the maize race, whereas most individuals caught in E traps had emerged from C(3)-type plants and were but weakly differentiated from the hop-mugwort race, suggesting a strong, though not absolute, correspondence between host plant, host race and pherotype. We also found that although spatial segregation may contribute to genetic isolation between host races, moths of both host races may be present at a given location. Regarding the management of Bacillus thuringiensis (Bt) maize, our results indicate that, at least at the present study sites, it is unlikely that any wild or cultivated C(3)-type plant species could be a source of susceptible individuals that would mate randomly with Bt-resistant Z-C(4) moths emerging from Bt-maize fields.
Unité Génétique Microbienne et Environnement, Institut National de la Recherche Agronomique La Minière, 78285 Guyancourt, France.
Arnaud
A
Bontemps
Denis
D
Bourguet
Laurent
L
Pélozuelo
Marie-Thérèse
MT
Bethenod
Sergine
S
Ponsard
D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics*; D000818:Animals; D001413:Bacillus thuringiensis / Q000737:chemistry*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000633:toxicity*; D001427:Bacterial Toxins / Q000633:toxicity*; D005075:Biological Evolution; D002247:Carbon Isotopes; D004351:Drug Resistance / Q000187:drug effects / Q000235:genetics*; D004731:Endotoxins / Q000633:toxicity*; D006460:Hemolysin Proteins; D027582:Humulus; D007527:Isoenzymes; D008297:Male; D009036:Moths / Q000187:drug effects / Q000235:genetics / Q000382:microbiology*; D010572:Pest Control, Biological / Q000379:methods; D030821:Plants, Genetically Modified; D012641:Selection, Genetic; D013045:Species Specificity; D003313:Zea mays
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D002247:Carbon Isotopes; D004731:Endotoxins; D006460:Hemolysin Proteins; D007527:Isoenzymes; C030956:insecticidal crystal protein, Bacillus Thuringiensis