MATING DISRUPTION OF DIAMONDBACK MOTH (LEPIDOPTERA, PLUTELLIDAE) AND CABBAGE-LOOPER (LEPIDOPTERA, NOCTUIDAE) IN CABBAGE USING A BLEND OF PHEROMONES EMITTED FROM THE SAME DISPENSER

Experiments were conducted in commercial plantings cabbage in spring 1 994 and 1995 to evaluate the efficacy of a blend pheromones for diamon dback moth, Plutella xylostella (Linnaeus), and cabbage looper, Tricho plusia ni (Hubner): for disrupting mating when dispensed simultaneousl y from Yoto-con-S(R)'rape' dispensers (Shin-Etsu Chemical Co., Ltd., T okyo, Japan). A 12.1-ha cabbage field was treated with pheromone in 19 94 using a blend of(Z)-11-hexadecenal, (Z)-11-hexadecen-1-ol acetate, and (Z)-11-hexadecanol in a 49:50:1 ratio for diamondback moth and (Z) -7-dodecen-1-ol acetate and (Z)-7-dodecen-1-ol in a 98:2 ratio for cab bage looper. The test was repeated in 1995 using a 10.1-ha cabbage fie ld. In 1995, 24.6 ha of cabbage also were treated with a blend of diam ondback moth-only pheromone: (Z)-11-hexadecenal and (Z)-11-hexadecen-1 -ol acetate in a 50:50 ratio. All pheromone treatments were applied at the rate of 1,000 m rope per ha within 2 wk after the cabbage was pla nted. Captures of diamondback moth and cabbage looper males in traps b aited with synthetic pheromones and mating by laboratory-reared sentin el females in pheromone-treated fields were significantly reduced for 7 to 9 wk post-treatment relative to control areas. Larval infestation data on cabbage were insufficient to establish the effect, if any, of the diamondback moth/cabbage looper combination pheromone treatment o n cabbage looper control. In 1995, the diamondback moth pheromone only and the diamondback moth/cabbage looper combination pheromone effecti vely suppressed diamondback moth larval numbers below the composite ec onomic action threshold of 0.3 larva per cabbage plant for approximate ly 60 days. A single application of pesticide quickly reduced the diam ondback moth larval count below the action threshold in the pheromone- treated cabbage, and no further pesticide applications were required. The correspondent control Geld was sprayed 7 times with pesticides for control diamondback moth.