HERITABILITY OF FLIGHT DISTANCE FOR CYDIA-POMONELLA

Cydia pomonella L. (Lepidoptera: Tortricidae) is considered to be rath er sedentary, but some individuals undertake flights of several kilome tres in the field. This paper investigates the genetic influence on th is variability. The flight capacity was measured in the laboratory by a flight mill and its heritability was estimated for two different str ains. The laboratory strain was kept for more than 45 generations and the field strain from Embrach (northern Switzerland) was recently coll ected in the field. The multiple-trait-restricted-maximum-likelihood m ethod was used for the estimation of genetic variances and covariances . A mixed full-sib/half-sib design was applied for the field strain an d a full-sib design for the laboratory strain. The heritability of tot al distance was 0.57 for the field strain and 0.37 for the laboratory strain (both sexes). In addition, a heritability of 0.38 for total dis tance was estimated by parent-offspring regression for the laboratory strain. All three values were significantly different from zero (P < 0 .05) and show that there is a significant additive genetic influence o n flight capacity. The genetic correlations between total distance and other flight traits (total duration, flight velocity, longest flight) were between 0.84 and 1.00 for both strains and suggest that these tr aits actually belong to a single one. High genetic correlations were a lso found between total distance and the morphological traits body wei ght and wing length for the field strain, whereas a negative correlati on was found between total flight distance and body weight for the lab oratory strain. This difference between the two strains was interprete d as a possible trade-off between flight capacity and fecundity.