Individual study: Effects of the landscape context on aphid-ant-predator interactions on cherry trees
Stutz S. & Entling M.H. (2011) Effects of the landscape context on aphid-ant-predator interactions on cherry trees. Biological Control, 57, 37-43
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Exclude ants that protect pests
A replicated, controlled study in 2008-2009 near Bern, Switzerland (Stutz & Entling 2011) found fewer earwigs Forficula auricularia (enemies of black cherry aphid Myzus cerasi) on trees with glue barriers to exclude ants (0.2 earwigs/tree) than trees without barriers (2.1 earwigs). More hoverfly (Syrphidae) eggs and larvae were found on trees with than without barriers in mid-May (1.9-3.3 vs. 0.6-2.1 eggs or larvae/twig, respectively) but the opposite occurred in late May-early June (0.0-1.0 vs. 0.6-1.9 eggs or larvae/twig). Barriers reduced the total number of ladybirds (Coccinellidae) counted across the season (late April to early June 2009) but differences between treatments were not consistent across individual sampling dates. Fewer ants (Formicidae) occurred on trees with barriers at all sampling dates (0.0-0.2 ants/twig with barriers vs. 0.7-8.2 ants without barriers) and aphids were also fewer from mid-May to early June (0-25 vs. 90-360 aphids/twig). Wild cherry trees Prunus avium with barriers grew more new wood than trees without barriers. Four-year-old cherry trees were planted at 30 sites in spring 2008 and black cherry aphids were released onto four trees/site in mid-April 2009. A 7 cm-width glue ring was attached around the main stem of two trees and renewed monthly to exclude ants.