Good Fruit Grower

March 15

Issue link:

Contents of this Issue


Page 15 of 55

16 40 35 30 25 20 15 March 15, 2013 GOOD FRUIT GROWER 0.5 Harvestmen 0.9 1.3 Ant Assassin bug 1.8 Rove beetle 37.1 28.6 Spider 0 Earwig 5 29.9 10 Carabid beetle ded Percent ofcent Totalthat dation Recor Per predators Pre had eaten codling moth What's eating codling moth? where a small sample of the homogenized predator solution is added to a buffer mix containing a special enzyme that copies DNA, as well as short pieces of DNA called primers, to ensure that only codling moth DNA is amplified. We also add the building blocks needed to create new DNA strands, and a fluorescent dye that allows us to measure the amplified DNA. The mixture is then processed, and amplified DNA assessed by measuring fluorescence. In over 2400 samples collected from seven orchards during a three-year period, we found that about 9% had codling moth DNA in their guts. The majority of the samples showing codling moth predation came from three main groups: carabid ground beetles (Carabidae), the European earwig, and spiders (Araneae). We also found that predation rates varied between the different orchards sampled and were linked to management intensity. Pooling across all seven orchards, we found 8.5% of the ground beetles, 8% of the spiders, and 16% of the earwigs had fed on codling moth. Many prey types These results revealed which predators are likely to be important as biological controls for codling moth, and challenge us to create pest management programs focused on conserving them while continuing to adequately control codling moth and other important pests. We should also remember that these predators are generalists and feed on many prey types, including each other. Feeding on codling moth is just one indicator of their importance, as they are also likely preying on other pests such as leafrollers and wooly apple aphids. Predators, such as ground beetles, may also be particularly important in the newer high-density orchards where codling moth is more likely to overwinter on the ground, since trees in these orchards tend to have smooth bark and thus provide fewer cracks and crevices for the larvae to cocoon. It is clear that biological control alone will not control codling moth to acceptable levels, but these predators can contribute to reducing codling moth population levels. In turn, lower pest pressure will allow mating disruption, softer materials, and possibly fewer cover sprays, to provide more effective controls. Understanding the ecological role of these predator groups will help shape future orchard management programs while enhancing biological control. • This is the fourth article in an eight-part series highlighting results of a five-year Specialty Crop Research Initiative project to enhance biological control of orchard pests. The project involves researchers from Washington State University, Oregon State University, University of California Berkeley, and the U.S. Department of Agriculture in Yakima, Washington.

Articles in this issue

Links on this page

Archives of this issue

view archives of Good Fruit Grower - March 15