Commercial trials of pheromone-mediated mating disruption with Isomate-C® to control codling moth in British Columbia apple and pear orchards

Gary J. R. Judd, Mark G. T. Gardiner, Don R. Thomson

Abstract


Pheromone-mediated mating disruption to control codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), was tested in commercial apple and pear orchards in 1991 and 1992 using Isomate-C® dispensers. In 1991, a single treatment of 1000 dispensers/ha released the pheromone, E,E-8,10-dodecadien-1-ol (codlemone), calculated rates of 14.9, 15.2, 16.6 and 17.5 gm/ha from 1 May to 30 September in Kelowna, Summerland, Cawston and Oliver, respectively. At the same four sites, but during the 1-hr dusk flight periods, when most mating occurs, codlemone was released at calculated median rates of 7.6, 8.2, 8.3 and 12.7 mg/ha/h during first brood and 2.4, 23, 4,7 and 53 mg/ha/h during second brood, respectively. Damage in 22 pheromone-treated apple orchards ranged from 0.02 - 6.75%, with a median of 042%, whereas damage in 12 pheromone-treated pear orchards ranged from 0.02 - 6.23%, with a median of 0.87%. Three insecticide-treated apple orchards had a mean of 0.06% damage and one insecticide-treated pear orchard had 4.21% damage. Untreated apple and pear orchards had 56.9 and 2.23% damage, respectively. In pheromone-treated orchards, few male codling moths were caught in Pherocon 1-C wing traps baited with 1 mg of codlemone (x=2.9 moths/trap/orchard/season) compared with identical traps hung in insecticide-treated orchards (x=29.2 moths/trap/orchard/season). Traps baited with 10 mg of codlemone caught codling moths in 96% of the pheromone-treated apple orchards and weekly catches showed seasonal flight patterns similar to those in insecticide-treated orchards. A signifieant linear relationship between mean cumulative catches in traps baited with 10 mg of codlemone during night of tirst-brood moths and damage at harvest, can be used to warn growers if mating disruption is failing and that additional treatment may be needed for the second brood. In 1992, treatment of apple orchards in Cawston with 1000 dispensers/ha as a single application on 1 May, released codlemone at calculated median rates of 13.3 and 4.6 mg/ha/h during first and second brood, respectively. A split application of 650 dispensers on 1 May and an additional 350 on 1 July released codlemone at median rates of 8.7 and 7.8 mg/ha/h during first and second broods, respectively. Damage in 5 orchards with a single pheromone treatment ranged from 0 - 1.52%, and 2 orchards with the split application had 0.08 and 0.97% damage. Damage in an untreated control orchard was 43.5%. Used as described here, pheromone-mediated mating disruption using Isomate-C® is commercially viable in British Columbia.

Key words: Codling moth; mating disruption; Isomate-C; codlemone release rates


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