Oviposition preference of the diamondback moth (Plutella xylostelld) unaffected by the presence of conspecific eggs or Bacillus thuringiensis

Neither toxins from Bacillus thuringiensis Berliner nor conspecific eggs deterred oviposition by the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), in laboratory choice tests. The finding that toxins did not deter oviposition by moths from a susceptible line shows that oviposition preference and larval survival were not associated in this line. Selection for larval resistance to toxins did not significantly alter oviposition preference, which rules out a strong genetic correlation between larval performance and oviposition preference. Failure of conspecific eggs to deter oviposition may not represent lack of association of preference and performance because other evidence suggests that larval performance may not be greatly affected by larval density. These results suggest that the ability of refuges to slow evolution of physiological resistance to B. thuringiensis toxins will not be magnified by an oviposition preference for untreated foliage.