Submitted to: Journal of Entomological Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/30/1996
Publication Date: N/A
Interpretive Summary: The cabbage looper and diamondback moth are serious pests of cabbage and often occur simultaneously in the same field. Mating disruption is a promising technology for control of diamondback moth, but growers still must rely on pesticides for control of cabbage looper. Scientists at the Center for Medical, Agricultural, and Vetnariary Entomology, Gainesville, FL, investigated the possibility of controlling both pests by evaporating a blend of the species' pheromones simultaneously from Shin-Etsu 'rope' dispensers. Mating by cabbage looper was almost completely suppressed for 2.5 months, and mating by diamondback moth was suppressed for almost 2 months. Cabbage looper larval populations were too low to determine efficacy of the pheromone treatment on this pest, but diamondback moth larval populations were reduced below a composite action spray threshold of 0.3 larva per plant for ca. 60 days. One application of pesticide quickly reduced the diamondback larval count below the spray threshold, and no further pesticide applications were required. These results suggest that control of cabbage looper and diamondback moth in cabbage is possible using mating disruption technology. Adoption of mating disruption for control of these pests in cabbage would result in significant reductions in the number and frequency of conventional pesticide applications, improve food and worker safety, and reduce the chances for pesticide resistance in these pests.
Technical Abstract: Experiments were conducted in commercial plantings of cabbage in spring 1994 and 1995 to evaluate the efficacy of a blend of pheromones for diamondback moth (DBM), Plutella xylostella (Linnaeus), and cabbage looper (CL), Trichoplusia ni (Hubner), for disrupting mating when dispensed simultaneously from Yoto-con-S 'rope' dispensers. A 12.1 ha cabbage field was treated with pheromone in 1994 using a blend of (Z)-11-hexadecenal, (Z)-11-hexadecen-1-ol acetate, and (Z)-11-hexadecanol in a 49:50:1 ratio for DBM and (Z)-7-dodecen-1-ol acetate and (Z)-7-dodecen-1-ol in a 98:2 ratio for CL. The test was repeated in 1995 using a 10.1 ha cabbage field. In 1995, 24.6 ha of cabbage also were treated with a blend of DBM-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 planted. Captures of DBM and CL males in traps baited with synthetic pheromones and mating by laboratory-reared sentinel females in pheromone-treated fields were significantly reduced for 7-9 wk post-treatment relative to control areas. Larval infestation data on cabbage were insufficient to establish the effect, if any, of the DBM/CL combination pheromone treatment on CL control. In 1995, the DBM pheromone only and the DBM/CL combination pheromone effectively suppressed DBM larval numbers below the composite economic action threshold of 0.3 larva per cabbage plant for ca. 60 days. A single application of pesticide quickly reduced the DBM larval count below the action threshold in the pheromone-treated cabbage, and no further pesticide applications were required. The correspondent control field was sprayed 7 times with pesticides for control of DBM.