Most angiosperms, or flowering plants, need animals to pollinate them. Insects, and particularly bees, do the lion’s share. Because of this, pollinators such as bees are responsible for much biodiversity. However, in urban areas resources, such as flowers and nesting sites, for bees may be limited. In addition, abiotic aspects of urbanization such as pollution and high temperatures, may create conditions that are in hospitable for bees or cause them stress. In our lab we are investigating the effects of urbanization on honey bees and native bees.
The effects of urbanization on honey bee stress and immune function
The western honey bee, Apis mellifera, is of great importance both ecologically and economically, with recent disease instances demonstrating the necessity for a thorough understanding of their health state. Graduate student Holden Appler is trekking around Raleigh collecting bees from feral and managed bee hives to determine if bees from urban, suburban, and rural areas differ in their virus load and immune function. Holden is using laboratory assays to determine how bees are able to encapsulate infectious bodies and how well they respond to stress-inducing pesticide applications. Immunocompetency is the measure of an individual’s ability to resist pathogenic infection, and thus an important component to overall wellness. Certain factors of urbanization such as urban pesticides and heavy metals have been shown to negatively affect the immunocompetency of some insects, while other factors, such urban heat island effect have had varied responses. Oxidative stress may also be influenced by urbanization, particularly associated pollutants. The objective of this research will be to determine how urbanization affects the immune system and ability to withstand oxidative stress for A. mellifera. Bees were collected from feral and managed colonies through an urbanization gradient: urban zone, suburban zone, and rural zone. Additionally, managed hives were strategically placed to maximize the exposure to each urbanization zone. Immunocompetency was evaluated via measuring the encapsulation response, phenol oxidase activity, and antimicrobial turbidity analysis. qPCR was used to determine constitutive and induced response immune activation, as well as the pathogen load for several notable diseases. This research will lead to deeper understanding of the mechanistic impacts of urbanization as they pertain to this highly valued species.
The effects of urbanization on native bee communities
Graduate student April Hamblin will be investigating native be communities to determine how composition changes along urbanization gradients. More importantly she will be investigating why these communities change and what aspects of the urban environment make some species rare and other common. Native bees provide pollination services for crops and wild plants.
Urban areas have many different characteristics that affect insects and plants. One that our lab has investigated is hotter temperatures due to the Urban Heat Island effect. Because of this, we are sampling cooler and hotter sites to monitor bee populations with the following questions in mind:
1. How do environmental factors (temperature, impervious surface, available green space, sunlight, etc.) in urban areas affect bee community structure in Raleigh, NC?
2. Which of these factors is the driving cause of the bee community structure?
We are using bee bowls, small (generally 2-4 oz) plastic cups brightly colored blue, white, and yellow with inflorescence to attract bees. Bee bowls attract bees do to their bright colors. The bees get trapped in soapy water where we can collect and identify them. This is the most effective way to sample bee communities.
This research is at its beginning stages and should evolve once baseline data are collected and monitored. Future aspects of this research may include manipulation of study sites and/or different approaches to analyzing data utilizing GIS and other available resources.