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Summary of Pollinator Health Challenges: A bee’s perspective (Margarita López-Uribe)

Posted: June 9, 2020

Bees are a highly diverse group of pollinators. There are over 20,000 species of bees worldwide, 4,500 in North America, and 437 in Pennsylvania alone. Despite this variety, when people think of bees their minds tend to go to the image of a cute little honey bee living in a huge hive. However, that is not always the case. In this webinar, Dr. Margarita López-Uribe, Assistant Professor of Entomology and an Evolutionary Ecologist dispels two big myths about bees, discusses how human activity has impacted bees throughout their life cycle and provides guidance for how to make our gardens and landscape better for bees.

The first myth she dispels is the myth that all bees are social. According to Dr. López-Uribe only about 10% of bee species are social. Seventy percent of bees are solitary, which consist of one female per nest that builds the nest and collects pollen and nectar. The remaining 20% are cleptoparasitic, meaning that rather than building their own nests these bees will seek out existing nests and usurp them and lay their eggs there. The second myth she examines is that all bees live in hives. About 70% of bees live underground where they build their nests, store their pollen provisions and lay their eggs. Of the bees that live aboveground 20% are wood nesters and 10% live in cavities. These bees can get very creative when building their nests with some even opting to nest in old corn husks.

After busting these myths Dr. López-Uribe goes in-depth on the solitary bee life cycle and the effects of human development and climate change at different points of life. Usually, a solitary bee will go through four distinct stages of development. First, the mother collects pollen and nectar and adds these to a brood cell that she has constructed. She then lays her egg in the provisioning cell. The egg hatches into a larva, which eats the provisions. After the larva stage, they enter the pupa stage until they finally emerge as an adult. The adult bees mate and the female will continue the cycle and spend the remainder of her life building the nest and gathering pollen and nectar for the offspring. Newly emerged females will first find a place to nest. Generally, they will stay close to where they were born because those areas tend to have the materials they need. However, due to human activity nesting spots and resources may not always be available and those available may present their own problems.

Habitat loss, pesticides, diseases, agricultural intensification, and climate change all impact bees at each stage of their life cycle. Urbanization modifies the environment and often makes it more difficult for ground-nesting bees to find a good nesting place. Bees that nest above ground tend to have more opportunities to build nests due to higher availability of habitat. However, above-ground bees also need structures like wood which allow them to make their homes and these may not be abundant in suburban areas with clear green lawns. Dr. López-Uribe suggests that commercially available bee hotels can help support more above ground bee populations by giving them a place to nest. More information about managing a common wood-nesting bee will be given the July 1st webinar: Mason bee management for backyard and orchard pollination.

Soil is very important to ground nesting bees since nest building requires these bees to constantly handle it. Pesticide contaminated soil can have negative health impacts on the adult bees and the eggs. Bees tend to be smaller in areas that use more pesticides. Furthermore, higher amounts of pesticides can make bees weak and lead to higher disease risk. Dr. López-Uribe suggests that a more diverse landscape with different kinds of soil, plant life, habitats, in addition to low pesticide inputs is overall better for bee health compared to landscapes that have less diversity and high pesticide inputs.

In addition to pesticide use, other forms of agricultural land practices also tend to be bad for bee health because the landscapes are usually simple. One way to combat this would be to introduce more landscape variety to the surrounding areas in order to give the bees a more diverse and natural environment. Different species of bees differ in what they need to survive and thrive. Bees need to be able to choose from a diversity of flowering plants, which flower throughout the year, to obtain the right balance of nutrients from the pollen and nectar that they collect (more information will be given on this topic in the June 24th and July 22nd webinars). Different species require different amounts of proteins, lipids, sugars, and other nutrients found in pollen and nectar. Having a variety of plants that produce these nutrients is vital for bees to have a balanced diet.

Climate change is resulting in weather patterns that can greatly affect bee health. For example, bees will use temperature as their primary indicator to emerge from their nests after the winter and start collecting pollen and nectar. However, due to climate change, temperatures are getting warmer at earlier points in the year. This may lead to an event known as phenological mismatch, where the flowering time and the time of bee emergence does not match up. As the bees emerge at earlier times, less flowers have bloomed and thus bees do not have enough food to provision their eggs. This means females will produce fewer offspring, and the population can decline.

The three main points that Dr. López-Uribe would like people to take away from this webinar are first that most bees are solitary and live underground. Second, stressors impact different bee stages in different ways. And finally, the last takeaway is that stressors can impact different bee species in different ways. To learn more about bee diversity, bee management, and more please check out the other scheduled webinars below!

Written by Ashley Moak

Full webinar descriptions and registration information

For additional questions you can contact Dr. López-Uribe at:

lopezuribelab.com
@mmlopezu