D3384: A good neighborhood to raise a brood: Tree species diversity decreases oviposition and tree damage

Generalist herbivore host choice patterns are key to understanding both herbivore outbreaks and consequences for plant hosts. Natural systems contain diverse assemblages of plants providing a matrix of potential hosts that herbivores must navigate, yet studies untangling the impact of plant diversity on host choice patterns are rare in forested landscapes. We follow a Brood X periodical cicada mass emergence event in the BiodiversiTREE forest diversity experiment at the Smithsonian Environmental Research Center (SERC) in Edgewater, MD to learn how tree diversity influences cicada oviposition preferences and tree response (flagging). We measure 15 tree species grown in single- and mixed-species plots and find that the tree neighborhood plays an important role in determining oviposition preference and tree flagging responses. Cicadas were twice as likely to oviposit in trees grown in single species plots versus diverse plots. While overall we find a concomitant decrease in tree flagging in diverse plots, we also document that species flag at different rates in response to equal oviposition density. This study creates a richer understanding of the importance of tree context, specifically tree neighborhood diversity, in shaping the ecological impacts of a mass insect emergence event.