Many herbivorous arthropods, particularly tree pests, are more abundant and damaging in urban than rural areas. Urbanization has many effects on ecosystems but the Urban Heat Island effect, in which cities are 1-12 degrees C hotter than surrounding rural areas, is one of the most pervasive. High urban temperatures should have the important biological effects on ectothermic species, such as insects, and their life histories.  Our hypothesis is that herbivore abundance increases in urban environments because herbivores are physiologically acclimated or adapted to high temperatures and top-down control by natural enemies is reduced. We are currently investigating the effect high urban temperatures on tree pests through two research projects.

The effect of heat on Lecanium scale and their natural enemies on willow oak

This project is being conducted in large part by Phd Student Emily Meineke.  Currently Emily is working to address three primary questions:

1) How do elevated temperatures affect Lecanium scale abundance and survival when isolated from other biotic and abiotic factors.

2) How does heat affect natural enemy communities and their interactions with, and suppression of, Lecanium scale.

3) How do heat and scale insect infestations interact to affect tree health and ecosystem services. View slideshow here.

The effect of heat on arthropod pests of red maple

Red maple is the most widely planted street tree in the Eastern US.  Red maples in cities suffer extraordinary abundance and damage from gloomy scale and maple spider mites.  Currently MS student Adam Dale is working to address two primary questions.

1) How does heat affect the fitness and population growth of maple spidermite.

2) How does heat affect the fitness, abundance and efficacy of maple spider mite predators.

3) How does heat affect gloomy scale abundance and suppression by natural enemies in urban areas.

Funding:

United States Geological Survey, Southeast Climate Science Center. 2011. “Integrating the Effects of Global and Local Climate Change on Wildlife in North America”. PIs: R.R. Dunn, S.D. Frank, N. Haddad, and N. Singh.