Evaluation of Sticky Traps for Monitoring Scolothrips sexmaculatus (Thysanoptera: Thripidae) and Stethorus punctum (Coleoptera: Coccinellidae) as Predators of Spider Mites in California Almonds

Changes in almond production practices have caused sixspotted thrips, Scolothrips sexmaculatus Pergande, and the coccinellid beetle, Stethorus punctum LeConte, to replace phytoseiid mites as the dominant predators of spider mites in California almonds. We conducted a series of field studies to evaluate nine commercially available adhesive traps for S. sexmaculatus and S. punctum and found that the yellow strip trap was the most effective, least expensive, and easy to use. At peak population levels, individual cards routinely caught >1,000 S. sexmaculatus and >100 S. punctum trap−1 week−1. We documented that larger traps collected more S. sexmaculatus, and more S. sexmaculatus per square area, suggesting that the trap surface was attractive. We determined the number of traps needed to have 50, 70, and 90% confidence that the averages of trap captures were within 10, 30, and 50% of the population mean. Two yellow strip traps per orchard provided 90% confidence that trap captures were within 50% of the population mean if there were an average of 16.0 S. sexmaculatus trap−1 week−1 or 7.9 S. punctum trap−1 week−1. Populations required to attain the same levels of confidence using four traps per orchard were 3.9 S. sexmaculatus and 2.9 S. punctum trap−1 week−1. We conclude that use of the yellow strip trap to monitor for natural enemies, in combination with leaf samples for spider mites, has the potential to improve integrated pest management programs for spider mites, and assist future research to understand the biology and phenology of both predator species.

Three-Dimensional Versus Rectangular Sticky Yellow Traps for Western Cherry Fruit Fly (Diptera: Tephritidae)

The most effective traps tested against western cherry fruit fly, Rhagoletis indifferens Curran, have been the Yellow Sticky Strip (YSS) rectangle made of styrene and the three-dimensional yellow Rebell cross made of polypropylene. However, three-dimensional YSS styrene traps have never been tested against this or any other fruit fly. The main objectives of this study were to determine the efficacies of 1) YSS cross, Rebell cross, YSS cylinder, and YSS rectangle traps, 2) Rebell cross versus Rebell rectangle traps, and 3) YSS tent versus YSS rectangle traps for R. indifferens. For 1), the YSS cross caught more flies than the Rebell cross of equivalent surface area and more than a smaller YSS cylinder, but not any more than a YSS rectangle of similar surface area as the YSS cross. For 2), a Rebell cross caught more flies than a rectangle of equivalent surface area made of Rebell panels. For 3), YSS tent and YSS rectangle traps of equivalent surface area did not differ in fly captures. Results suggest that the YSS cross was more effective than the Rebell cross due to its color and that when trap color is highly attractive, three-dimensional shape may be unimportant, whereas it could be when trap color is less attractive. A new trap modeled after the YSS cross, compact but with high trap surface area to increase fly captures, could be an effective option or addition to rectangles for monitoring R. indifferens.