1a. Objectives (from AD-416):
Determine the associations of navel orangeworm (NOW) (flight, oviposition, wounding of nuts by larvae and adult moths) with aflatoxigenic fungi Aspergillus flavus and A. parasiticus. Also determine the ability of NOW to vector propagules of A. flavus/A. parasiticus, when nuts become susceptible to infestation by NOW, and compare the vectored fungi with those producing aflatoxins in nuts.
1b. Approach (from AD-416):
Larvae and pupae from nut mummies from the trees and the ground and NOW moths will be collected periodically from commercial pistachio and almond orchards and the insects plated on specific media to determine the levels of contamination. Strains of A. flavus/A. parasiticus isolated from NOW will be compared with those isolated from infected nuts. Pea size and crinkled pistachio (NOW-damaged and non-damaged, stained, and not stained) will be plated periodically to determine their infection by Aspergillus spp. To determine when nuts become susceptible to NOW, we will periodically bag pistachio clusters and almonds with NOW. All the isolates of S, L, and M strains of A. flavus and A. parasiticus will be identified based on previously published research.
3. Progress Report:
This Specific Cooperative Agreement was established to support research objective 2.B of the parent project; reducing insect pest populations and insect damage,reduce the need for post harvest treatment as well as promoting the use of selective rather than broad spectrum insecticides to control navel orange worm. Navel orangeworm damage promotes infestation of pistachios by Aspergillus flavus and Aspergillus parasiticus, producers of aflatoxins. Adults were collected and cultured in order to follow changes in the levels of these two fungi over time. Levels were highest in adults emerging in the Spring and lowest in adults collected in late June and early July. Companion studies in the laboratory confirmed that the navel orangeworm could serve as a vector for these fungi. This information supported registration of a new product to suppress the Aspergillus species that produce aflatoxins, and by reducing damage and aflatoxin contamination, we increase the quality of pistachios and help increase consumption of pistachios in domestic and overseas markets. Additionally, by linking navel orange worm damage and aflatoxin contamination, we increase awareness of the need to control this pest.