|Burks, Charles - Chuck|
Submitted to: Almond Industry Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/21/2005
Publication Date: 12/7/2005
Citation: Burks, C.S., Higbee, B.S., Brandl, D.G. 2005. Mating disruption for suppression of navel orangeworm damage in almonds. Almond Industry Conference Proceedings, December 7-8, Modesto, California. p. 1-10.
Interpretive Summary: The navel orangeworm is a highly destructive pest of California’s almond, pistachio, and walnut crops, collectively worth $2.1 billion in 2003. Compared to residual insecticides, mating disruption has less impact on non-target species including predators and parasites. Previous research has shown that mating disruption with the principle pheromone component can significantly reduce damage in almonds when the navel orangeworm is relatively abundant. The objective of this study was to compare the effects of the older single-component formulation and two newer multi-component formulations on navel orangeworm reproductive biology and damage to almonds. Under conditions of low abundance each of the mating disruption compounds completely prevented male capture in pheromone traps and female mating in assays, but under conditions of high abundance a significantly smaller proportion of females were mated with both of the newer formulations compared to the older one, and one of the newer formulations performed better than the other. Under conditions of high navel orangeworm abundance each of the mating disruption formulations significantly reduced navel orangeworm damage to almonds and the old single component formulation had numerically lower damage than the multiple component formulations, whereas under conditions of low abundance only the newer formulations had significantly lower damage. These findings will facilitate the development of mating disruption for reduction of navel orangeworm damage in almonds for multi-crop area wide control programs.
Technical Abstract: We compared the effects of newer multi-component NOW mating disruption formulations with the previously-used single component formulation and an untreated control, and compared these materials with methoxyfenozide, used in buffer areas surrounding the 40-acre treatment plots, in four almond and three pistachio ranches of 640 acres each. We examined effects of the mating disruption formulations on male counts in pheromone traps, mating status in females, and oviposition on egg traps in both crops, whereas effects of these material on NOW damage at harvest is presented for Nonpareil almonds only. Each of the mating disruption treatments provided near-complete shutdown of pheromone traps and mating assays in almonds, whereas the higher NOW abundance in pistachios allowed comparison of treatment effects on male orientation and female mating status. The pheromone trap capture in untreated control plots in pistachios was in all cases significantly different and of 2-3 orders of magnitude greater than that in any of the mating disruption treatment plots, whereas no significant differences could be demonstrated between male counts in flight traps. Mating of females recovered from assays in pistachios over the entire season ranged from 73 to 92%, whereas those recovered from mating disruption treatment plots ranged from 4 to 19%. There was a significant difference in proportion of females mated between each of the treatments. Oviposition traps gave more variable results. There were significantly fewer eggs in some treatment plots compared to untreated controls in pistachios in the first flight but not in the second flight, and in almonds the overall mean of eggs in the untreated control plot was greater than that in the treatment plot. In an orchard in with high NOW activity (18% NOW damage in control plot), damage was significantly reduced in all mating disruption treatment plots as well as all methoxyfenozide-treated buffer areas. Damage was reduced in some mating disruption treatments in two of the three orchards with low NOW activity (0.7-1.8% damage in untreated controls).