Invasive Insects in

Urban Forests

Urban forests, the trees that are planted in cities and places where people live, provide millions of dollars in ecosystem services annually to people like you and me. However, we are losing millions of urban trees each year in the US alone, and urban trees on average live 20-30 years less than their counterparts in natural areas. This adds up to fewer ecosystem services and higher costs to replace dying trees.

The biggest threat to the urban forest is damage from introduced, invasive insects. My research explores how characteristics of urban environments, like vegetation, temperature, buildings, and paved surfaces, impact the density of these invasive insects on elm trees. This research can inform how we manage existing trees and where we plant future trees so that they are more resilient to insect attack. Additionally, this research helps us understand how invasive insects interact in urban forest ecosystems.

Publication: Buenrostro J & Hufbauer R (2022). ​​Urban environments have species-specific associations with invasive insects herbivores. Journal of Urban Ecology, 8 (1). https://doi.org/10.1093/jue/juac011

Presentations:

Buenrostro J, Hufbauer R (2022). Invaders in the concrete jungle! Effects of urban environments on exotic elm defoliators. Ornamental Workshop on Insects and Diseases. Raleigh, NC

Buenrostro J, Hufbauer R (2022). Cities, pests, and trees, oh my! A tale of invasive insects in the urban forest. Front Range Student Ecology Symposium, Colorado State University

Buenrostro J, Hufbauer R (2021). Invaders in the concrete jungle: Effects of urban environments on elm defoliators. Entomological Society of America, Annual Meeting. Denver, CO

Buenrostro J, Hufbauer R (2021). Chasing pavements: What causes insect outbreaks on city trees? GradShow, Colorado State University. https://hdl.handle.net/10217/234332


From Buenrostro & Hufbauer (2022)



This research explores how urban environments impact the density of elm leafminer (Fenusa ulmi), elm flea weevil (Orchestes steppensis), and elm leaf beetle (Xanthogaleruca luteola) on elm trees in the urban forest. We found:

  • Elm leafminer density decreased with higher temperatures, suggesting that trees in hotter parts of town are less prone to leafminer herbivory. Leafminer density decreased with greater impervious surface and increased with greater vegetational complexity. We believe this is because elm leafminer overwinters within the soil beneath trees. Leafminer density also increased with greater tree size (DBH), suggesting that larger elms are more prone to leafminer herbivory.

  • Elm flea weevil density increased with more elm trees in the surrounding landscape, suggesting that weevil outbreaks may be more common in areas with lots of elm trees. Weevil density also increased with tree size (DBH), suggesting that larger elms are more prone to weevil herbivory.

  • Elm leaf beetle density increased with higher temperatures, suggesting that trees in hotter parts of town are more prone to beetle herbivory.

  • Both elm leaf beetle and elm flea weevil density decreased with greater leafminer density, suggesting that insect density is mediated by species interactions.