Meet My Students  Publications

As a researcher, I am interested in the ecology and evolution of plant-insect interactions. Along with my very hard-working students, I study the feeding ecology and basic biology of insects, the contributions of wild pollinators to agricultural systems, the potential impacts of human activities on insect populations, and various aspects of evolutionary ecology between insects and plants or insects and their parasites.. 

As curator of the State Arboretum of Virginia, I work with skilled colleagues to maintain a diverse plant collection and provide learning opportunities for the public about the diversity of plants and their associations with insects. 


Bumble Bee Population Dynamics
We are looking at various factors, including parasitism, and resource availability, that may play a role in regulating bumble bee populations. Recent research in North America and Europe has indicated that several species of bumble bee have undergone precipitous declines in recent decades, with one, the rusty-patched bumble bee, becoming the first bee species in the continental United States to be placed on the Endangered Species List. Because bumble bees play important roles in both agricultural and wild plant pollination, these declines are of great concern. We use RFID technology to help us understand the risks and opportunities they encounter in the landscape.

Ecosytem Services of Wild Pollinators
Although managed honey bees are commonly placed in agricultural fields for pollination, wild bees provide extensive pollination services on farms, especially on smaller farms in diverse landscapes. In fact, bee species such as the native squash bee, which collects pollen only from squash and pumpkins, are often the dominant pollinator of particular crops even when honey bees are placed on farms for pollination. Understanding how landscape management influences wild bee populations can inform regional and local efforts at maintaining pollinators and the ecoystem services they provide. Management decisions influence floral resources, nesting opportunities, overwintering safety and risk factors such as exposure to pesticides, and all of these factors feed back into pollinator populations and the services they provide.

Evolutionary Ecology of Bees and Parasitoid Flies
While bees are cruising flower patches looking for the most rewarding patches to gather nectar and pollen, conopid flies (Conopidae) are cruising flower patches looking for bees. Conopid flies are parasitoids: their offspring develop in a susceptible host and kill it in order to complete development. My lab looks at the fascinating arms race between parasitoids and their hosts, an interaction that includes grave-digging behavior and host-specific immune system attack. When is it worthwhile to defend yourself? When is it worth the effort of utilizing a poor host? This area of research was initiated in my lab by 2 former students (Rosemary Malfi and Staige Davis) and continues with current student Amber Slatosky.

Mason Bee Population Dynamics
Bees in the genus Osmia nest in linear cavities and are frequently managed for orchard pollination. When people put out bee hotels (structures with horizontal cavities made of drilled wood, hollow bamboo or straws) on their property, they often attract mason bees in the spring and enjoy watching the bees on their daily commute between the nest and the flowers in the yard or orchard. Although most Osmia species are native, two non-native species (O. cornifrons and O. taurus) introduced from Asia have become the most common mason bee species in the mid Atlantic region. At the same time, 6 of the most common native mason bee species have gone on a decades-long decline. Led by Ph.D. student Kate LeCroy, our lab looks to understand not only the population trajectories of mason bee species but the underlying causes for why some decline while others proliferate.