Woolly Apple Aphid Generalist Predator Feeding Behavior Assessed through Video Observation in an Apple Orchard
Generalist predators are considered effective biological control agents in many agroecosystems. However, characterizing the behavior of different generalist predator species in realistic field settings is difficult due to challenges associated with directly observing predation events in the field. Here we video recorded woolly apple aphid (Erisoma lanigerum) (Hemiptera: Aphididae) colonies to directly observe the feeding behavior of their generalist predators during the day and night. To observe European earwigs (Forficula auricularia) (Dermaptera: Forficulidae), which are thought to be key woolly apple aphid predators but were not present at our study location, we released earwigs into the study area. Across 1413 h of video recorded over 4 weeks, earwigs made the most attacks on woolly apple aphid colonies, but coccinellid larvae spent more total time attacking because their individual attacks were longer. Antagonistic interactions between predators were rare, and earwigs never antagonized other predators. However, ants commonly antagonized earwigs, and incidence of ant-earwig antagonistic interactions was negatively correlated with earwig-aphid attack rates. Overall, these results suggest that coccinellid larvae and earwigs differ in their feeding behavior in the field, and provide new evidence that ants may hinder aphid biological control by antagonizing earwigs.
KeywordsBiological control Eriosoma lanigerum Forficula auricularia formicidae intraguild predation
We thank assistants Sam Martin and Dayna Dinius. This work was supported by grants from the Washington State Tree Fruit Research Commission, and from USDA National Institute of Food and Agriculture: accession numbers 1014754, 1016563, and award number 2016-38640-25383 through the Western Sustainable Agriculture Research and Education Program under subaward number 200592-445.
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