Local dispersal of the diamondback moth (Plutella xylostella (L.)) (Lepidoptera: Plutellidae)

Local dispersal of the diamondback moth (Plutella xylostella [L.]) was studied using the mark-recapture technique in commercial cauliflower and broccoli crops in the northern Adelaide plains. Moths were marked with fluorescent powder and released at one or more points within the experimental fields. Recaptures of the marked moths were made with pheromone traps and yellow sticky buckets, the latter being used to study the dispersal of both males and females. Four indices of dispersal ranges were estimated from the recapture data, the average dispersal distance and the distances from the release point within which 95, 99, and 99.9% of the released moths were expected to remain. Separate estimates were obtained for recapture data of males from the pheromone traps, recapture data of males from the yellow sticky buckets, and recapture data of females from the yellow sticky buckets. Overall, the estimated average dispersal distance ranged 14 to 35 m and the 95, 99, and 99.9% distances ranged 40 to 106 m, 63 to 177 m, and 113 to 300 m, respectively. Longer dispersal distances were obtained from the pheromone traps than from the yellow sticky buckets. Data from the yellow sticky buckets revealed similar dispersal ranges of the males and the females. The positions of recapture centers of the two sexes were also largely similar. While the distance ranges of recaptures increased gradually during the experiments, the recapture centers stayed within close vicinity of the release points. Temperature and wind did not appear to influence the dispersal ranges or directions. Implications of the results in the management of diamondback moth are discussed.