A mutation in pheromonal communication system of cabbage looper moth,Trichoplusia ni

A mutation that results in a dramatic change in the relative proportions of the pheromone components produced by female cabbage looper moths has been found. The most notable changes involve reduction in the emission rate of the major component [(Z)-7-dodecenyl acetate], near absence of a component [(Z)-5-dodecenyl acetate] that is normally present at about 20% of the major component, and a remarkable ca. 20-fold increase in a trace component [(Z)-9-tetradecenyl acetate]. In spite of the multiplicity of changes in the pheromone blend, a genetic analysis indicates that the condition is controlled by a single autosomal gene. These mutants are ineffective in attracting conspecifics, but do attract another distantly related noctuid moth. These results suggest that the evolutionary process that leads to distinct chemical signals in sibling species may include single gene mutations that lead to major changes in the species-specific blend.