Submitted to: International Conference on Methyl Bromide Alternatives and Emissions Reductions
Publication Type: Proceedings
Publication Acceptance Date: 9/21/2010
Publication Date: 11/1/2010
Citation: Burks, C.S. 2010. Mating disruption for navel orangeworm in Central California: Year 3. International Conference on Methyl Bromide Alternatives and Emissions Reductions. November 2-5, 2010, Orlando, Florida. 52:1-4.
Interpretive Summary: A three-year, replicated block study was conducted in western Fresno County, California, examining the effect of mating disruption on navel orangeworm reproduction and damage in almonds. The study site was in a different region of California from a previously published study, and involved different growing conditions and a wider diversity of growers and pest control advisors. Fertility of navel orangeworm females did not differ between control and treatment plots during an initial baseline year in which no mating disruption was applied, but was significantly reduced in mating disruption plots in two subsequent years. A significant reduction of almond damage was demonstrated between the first (baseline) and second (treatment) year. The navel orangeworm is the most important insect pest of California’s $2.5 billion-a-year almond industry. Demonstration of efficacy of mating disruption in diverse parts of the state’s almond growing region will accelerate adoption of this technology, thereby reducing the use of insecticides with greater negative impact on non-target organisms.
Technical Abstract: The effect of mating disruption on the navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), was examined during a three-year study conducted in 336 ha of commercial almonds in Fresno County (west central San Joaquin Valley). In the first year, pre-treatment (mating disruption) levels of navel orangeworm were determined. In the second two years, the impact of mating disruption with high-volume timed aerosol dispensers was compared between replicated treatment and control plots. Treatment impacts were monitoring using male moths caught in traps baited with virgin females, eggs in egg traps, and harvest damage. Mating disruption almost completely eliminated the capture of males in sticky traps baited with unmated females as a pheromone source; there was also lower capture of males in traps in adjacent untreated control plots. There were significantly fewer eggs in the treatment than in control plots in the second and third (treatment) years, but not in the initial (baseline) year when the mating disruption treatment was not applied. There was small but statistically significant reduction in damage to the first four varieties harvested (Nonpareil, Wood Colony, Padre, and Butte), and a significant and large reduction in damage to Monterey. While harvest data are still being gathered for the third year of the study, these data indicate that mating disruption can be efficacious in a wider variety of conditions than heretofore demonstrated, and may offer more practical protection of later varieties in which late insecticide treatment can conflict with harvest of earlier varieties.