Dispersal estimates of codling moth fertilized females in a French farm based on kinship assessments

Abstract: Until now, population dynamics of Lepidoptera pests were mainly inferred from the monitoring of adult males using pheromone traps. Here, we analysed the dynamics of dispersal of codling moth fertilized females, which is more closely connected with the agronomic attacks. The dispersal of the fertilized females was estimated using genetic inferences of full-sibs among their offspring. We collected 6824 larvae using geo-referenced band traps in nine orchards (differing in host-plants and insecticide practices) from an experimental farm (90 ha) for five generations (2003-2006). Heterogeneity in the densities of larvae was mainly explained by inter-generation (twice higher for the diapausing larvae generation) and inter-orchard (50 times higher in untreated apple orchards) differences. A sub-sample of 1064 individuals was genotyped with a set of 13 microsatellite loci for kinship inferences. Three hundred forty pairs of individuals were unambiguously determined as full-sibs. Ninety-six % of the full-sibs were collected within orchards, either on the same tree or on relatively distant trees. The remaining 4% pairs of full-sibs were collected at all the inter-orchard distances (80 to 700 m) including different host-plants. These results confirm the relatively sedentary behaviour of the codling moth females in spite of their ability to disperse over very long distances and to lay their eggs on different host-plants.