RELATIONSHIP BETWEEN THE NUMBER OF WILD MALES CAPTURED BY SEX-PHEROMONE TRAP AND THE POPULATION-DENSITY ESTIMATED FROM A MARK-RECAPTURE STUDY IN THE DIAMONDBACK MOTH, PLUTELLA-XYLOSTELLA (L) (LEPIDOPTERA, YPONOMEUTIDAE)

The population density of male Plutella xylostella was estimated from a mark-recapture experiment using sex pheromone traps in small-scale cruciferous vegetable fields: Population density was calculated by the YAMAMURA method. Among five summer and four autumn experiments, the release-recapture data from two autumn experiments were not adequate for mathematical methods of density estimation. The number of wild male moths recaptured per sex pheromone trap (u(o)') showed a significant positive correlation with the estimated wild population density per 100 m(2) (($) over cap U'), the ratio of ($) over cap U'/u(o)' being estimated to be about 16.