Beneficial insects associated with stinging nettle, Urtica dioica Linnaeus, in central Washington State

Beneficial insects (predators, parasitoids, pollinators) associated with stinging nettles, Urtica dioica Linnaeus (Urticaceae), were sampled at three sites in central Washington during spring-summer 2011-2013 using transparent sticky traps attached to upper portions of plants. Large numbers (200-400/trap) of beneficial insects were trapped particularly in June and early July, gradually decreasing thereafter. Phytophagous insects (aphids and leafhoppers) were trapped in much lower numbers (< 20/trap). Predatory bugs, carnivorous flies, parasitic wasps (Pteromalidae, Eulophidae, Trichogrammatidae, Scelionidae) and native bees dominated the trap catches. Predatory bugs were the most abundant beneficial insects trapped in 2 years (2011, 2013) with parasitic wasps dominant in 2012. Minute pirate bugs, Orius spp. (Anthocoridae) were dominant, accounting for > 95% of predatory bugs, peaking in abundance in June or July. Predacious flies were dominated by species of Empididae and Dolichopodidae. Native bees were commonly trapped, especially in 2011 and 2012. The data presented here indicate that stinging nettles in the Yakima Valley of eastern Washington may provide an important habitat for beneficial insects and may have a role to play in enhancing conservation biological control in agricultural crops.