Population structure in the small ermine moth Yponomeuta padelus: an estimate of male dispersal

Abstract.

• 1 An extensive investigation was carried out into the structure of a large, effectively continuous population of Yponomeuta padellus Latreille, feeding on hawthorn, Crataegus monogyna, and blackthorn, Prunus spinosa.
• 2 Mark—recapture studies were used to obtain direct estimates of the male dispersal rate, σ, in two successive years.
• 3 Dispersal was found to be extremely localized with respect to the total area of the study population. Estimates of u ranged from a minimum of 2.47 m to a maximum of 12.5 m.
• 4 Limited dispersal could be an important factor governing the genetic differentiation of Y.padellus populations, and its implications for the supposed existence of host races in this species are discussed.