Good Fruit Grower

May 1

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FRUITGRADING EQUIPMENT Distributors: Fruittek Sumas WA 98295 U.S. Packaging Systems Inc. Temple NH 03084 VAN WAMEL BV Energieweg 1 - P.O. Box 4, 6658 ZG Beneden-Leeuwen Holland Phone: +31(0)487 592944 Fax: +31(0)487 592970 E-mail: perfect@vanwamel.nl Website: www.vanwamel.nl Tel. 877 826 3427 www.fruittek.com Tel. 603 566 9736 www.uspackagingsystems.com Kelly Archer, lab technician at the ARS in Yakima, prepares ground-up spiders for PCR analysis to detect if they had eaten codling moths. first noticed spiders in the organic blocks, but he now sees them in the conventional blocks also. In the organic, the trees are full of webs. "You walk through the orchard, and the webs hit you in the face," he said. "It's a big difference from how it used to be." Live samples Spiders develop through one generation per year and overwinter in either an immature stage or as eggs. Miliczky said, typically, the highest populations are found in August and September although some species are abundant earlier in the summer. Live spiders that Miliczky collects for gut-content analysis are put in an ice chest, and kept frozen at the research lab until they can be analyzed, so they don't con- tinue to digest what they've eaten. The spiders are ground up individually, and the homogenates are analyzed in a PCR (polymerase chain reaction) machine that amplifies codling moth DNA. Sixteen different species of spiders have been analyzed, of which seven species had eaten codling moth. Overall, 10 percent of the spiders analyzed so far had codling moth in their guts, but the percentage varies greatly by species. For example, 50 percent of the Holoena nedra had eaten codling moth. Holoena nedra is a fairly large funnel web spider that spins its webs on large tree limbs. It sits at the back of the web ready to pounce on anything that is caught. Other species that had fed on codling moth are: Phidippus, Antradiatus, Trochosa, Cheiracanthium, Paenius, and Teganaria. Unruh said the study suggests that more selective pest management programs, incorporating granulosis virus, mating disruption, or attract-and-kill strategies, could increase the role of spiders and other beneficial insects in controlling pests. Although laboratory assays have shown that some of the newer pesticides, particularly Delegate (spinetoram), can be toxic to spiders, they tend to be less disruptive than the older pesticides, Unruh said. Altacor (rynaxypyr) had no negative effect on the spiders tested. "We have all these things that can potentially assist in the control of codling moth, and the more sustainable our management system, the more likely that's going to be the case," he said. Also working on the project are lab technicians Kelly Archer, Linda Ray, and Aaron Etherington. Funding for the project has been received from the Washington Tree Fruit Research Commission and from a federal Specialty Crop Research Initiative grant. • 18 MAY 1, 2012 GOOD FRUIT GROWER www.goodfruit.com photo By geraldine warner

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