1a.Objectives (from AD-416):
Investigate the length of persistence of the new soft insecticides in pistachios that target navel orangeworm (Amyelois transitella)and assess spray coverage.
1b.Approach (from AD-416):
Pistachios will be sprayed by commercial cooperators and collected at intervals over a 30-60 day period. These pistachios will be challenged in the lab by infesting them with known numbers of eggs and assessing adult emergence. Samples will be taken from the hull and environment and analyzed to determine insecticide residue, which will be linked to the success of the bioassays. Additional experiments conducted in the field will assess insecticide coverage using sentinel eggs.
This trust agreement was established to support research objective 2.B of the parent project, reducing insect pest populations to decrease the need for post harvest treatment as well as promoting the use of selective rather than broad spectrum insecticides to control navel orangeworm. An ARS scientist at Parlier,California, evaluated the duration of control provided by an aerial application of the pyrethroiid Bifenthrin EC (12 oz/ac), flown over approximately 400 acres on September 15 in Madera County, California. The pistachios were removed at weekly intervals and then challenged with NOW eggs. Bifenthrin EC provided excellent control for 22 days (97.6% mortality) and then protection broke down on day 28 as mortality was reduced to 89.7%. These results are consistent with previous experiments. In a second experiment conducted in Madera County, Voliam Xpress (lambda cyhalothrin + rynaxapyr), was applied to 2 blocks at 10 oz per acre and a mixture of Intrepid (methoxyfenozide, 20 oz) + lambda cyhalothrin, 5 oz) was applied to other blocks. Nuts were removed at approximately weekly intervals and challenged with eggs as late as 39 days after application. In one block mortality by Voliam Xpress was reduced to 87.7% after 35 days while in the second block Voliam Xpress was still quite effective providing 98.3% mortality at 35 days after application. The Intrepid+Lambda Cy combination provided more consistent control. However, this was only a single experiment and more research is needed to determine the relative duration of control of these insecticides. Mention of a commercial product is not an endorsement.