Effects of the emerald ash borer invasion on the community composition of arthropods associated with ash tree boles in Maryland, U.S.A.

Abstract

Emerald ash borer (EAB) Agrilus planipennis Fairmaire is an invasive non-native woodboring beetle that has killed hundreds of millions of ash trees (Fraxinus spp.) in North America. Identifying the arthropod community associated with ash trees has been highlighted as an important research requirement in understanding the wider effects of EAB. We harvested live ash trees infested with EAB at 37 sites in Maryland from 2011 to 2014 and collected a total of 2031 arthropods. All arthropods were identified to order and 94.6% were identified to family or below. The community comprised 13 orders, 60 families and 41 genera, with 28 arthropod species identified. Coleoptera, Diptera, Hymenoptera and Lepidoptera accounted for 98.3% of arthropods collected. Data on changes in richness and diversity over time were fitted to second-order polynomial models, corresponding with a transition in the dominant taxa from woodboring beetles (Cerambycidae) to parasitoids (Braconidae and Eulophidae). This resulted in changes to community composition as the EAB infestation intensified. The findings of the present study provide further evidence of the diversity of arthropods at risk from EAB. Given the number of invasive non-native insects threatening North American forests, establishing what taxa are present is important for predicting the likely broader impacts of these invasions.