MATING DISRUPTION OF DIAMONDBACK MOTH (LEPIDOPTERA, PLUTELLIDAE) IN CABBAGE - REDUCTION OF MATING AND SUPPRESSION OF LARVAL POPULATIONS

An 8.1-ha field of and-wk-old cabbage within an area of general cabbag e production received a single treatment with 8100 m of a continuous-r ope formulation of a 70:30 mixture of (Z)-11-hexadecenal and (Z)-11-he xadecen-1-ol acetate, two components of the sex pheromone of the femal e diamondback moth, Plutella xylostella (L.). Captures of males in syn thetic pheromone-baited traps, mating of laboratory-reared sentinel fe males, and the mated status of native moths taken from the plots demon strated suppression of mating activity by the pheromone treatment rela tive to that in the control area for 9 wk. Cabbage in this farm was pl anted sequentially. Fifteen insecticide treatments were applied during production of the block of cabbage, planted 13 d before the pheromone -treated cabbage, and 13 applications were made to the adjacent (contr ol) block of cabbage planted 3 d after that in the pheromone plot. Two insecticide treatments were applied to plants in the pheromone-treate d block to control diamondback moth larvae resident at the time of the pheromone application, and one spray was applied to this block 10 wk later at harvest. Cabbage at the extreme perimeter of the pheromone-tr eated area was damaged heavily by diamondback larvae; however, larval and pupal counts throughout most of this plot remained comparable to t hose in the control area. Cabbage at the interior of the pheromone are a was graded as U.S. no. 1 quality. The results indicate that mating d isruption can be used to protect cabbage from diamondback moth if pher omones are applied to areas of at least 8.1 ha with some supplemental application of insecticide.