Navel Orangeworm in Southern Central Valley Walnuts: Source, Seasonal Abundance, and Impact of Mating
Commodity Protection and Quality
2013 Annual Report
1a.Objectives (from AD-416):
1) Characterize seasonal abundance of navel orangeworm in southern Central Valley walnuts, and compare these data with codling moth abundance and walnut infestation by these two pests.
2) Estimate the relative contribution of residents and immigrants to navel orangeworm populations in orchards in this region.
3) Examine the impact of mating disruption on reproduction and damage of navel orangeworm in the southern Central Valley.
1b.Approach (from AD-416):
For objectives 1 & 2, female-baited and oviposition traps will be used to compare abundance of navel orangeworm males and eggs, respectively, between the center and edges of walnut orchards with historically high damage, and also to compare these codling moth and navel orangeworm abundance with infestation by these pests in harvest samples. For objective 3, mating disruption for navel orangeworm will be applied to orchard with historically high damage. Impact of mating disruption will be assessed based on the ability of males to locate live females in traps, oviposition by females, and infestation at harvest by navel orangeworm.
Progress was made to support Objective 2F determine abundance and evaluate monitoring methods for navel orangeworm in walnuts in the parent project. The navel orangeworm is considered the principal insect pest of almonds and pistachios in California, but generally of secondary importance in walnuts. In the former nut crops, however, there is a gradient of navel orangeworm abundance and damage, with less damage in the northern part of California and more to the south. Efficacy of mating disruption for navel orangeworm has been demonstrated in almonds, but separate examination of mating disruption in walnuts is needed due to a very different canopy structure compared to almonds. Research was initiated in spring 2013 and is still on ongoing.