Host range expansion in Plutella xylostella (Lepidoptera: Plutellidae)

Whether or not an insect herbivore can expand its host range depends on the behavior of both larvae and egg-laying females. The diamondback moth, Plutella xylostella, specializes on cruciferous crops, but in Kenya this insect was also found infesting peas. Strains from Kenya that have been reared on cabbage and pea, respectively, were examined to determine the relative importance of certain cues in acceptance of a new host. Larvae and egg-laying females of the pea strain accept both cabbage and pea as a host, and surprisingly, there is a small percentage of the cabbage strain that accepts pea as a host. Oviposition behavior and fecundity are influenced by the presence of these host plants, but effects are stronger in the cabbage strain. Comparisons between ovipositional preference and larval behavior and development are made to provide a basis for investigations into genetic mechanisms underlying host acceptance.