Response of Cydia pomonella to selection on mobility: laboratory evaluation and field verification

1. The codling moth Cydia pomonella (L.), largely regarded as a sedentary s pecies, shows great variation in flight capacity among individuals in the l aboratory, as has been reported for tethered flight. The occurrence of indi viduals with the ability to fly over long distances is considered ecologica lly significant for the colonisation of new habitats in response to deterio rating environmental conditions. The work reported here was designed to inv estigate the importance of the genetic component in regulating dispersal in C. pomonella. 2. Bi-directional selection on mobility measured by actograph was carried o ut in the laboratory. Both male and female codling moths responded signific antly to the upward and downward selections. Divergence between the two sel ected strains occurred after one generation of selection and increased as f urther selections continued. The realised heritabilities for mobility were estimated as 0.43 in males and 0.29 in females when averaged from the two s election directions. 3. The dispersal capacity of the selected mobile and sedentary strains was verified by mark-release-recapture experiments in the field, though only th e released male moths were captured effectively. Flight distances by males differed significantly between the two strains, with the mobile strain show ing a greater dispersal capacity than the sedentary strain. 4. This study demonstrated a positive correlation between mobility measured by actograph and field dispersal capacity in the codling moth. Furthermore , it provides the first experimental data to show field performances of dif ferent genotypes in insect dispersal.