Life Lines by Dr. Dolittle

Sponsored by the American Physiological Society

What’s the buzz about bees?

MPRWe are excited to share the following interview with Dr. Lizzette Cambron, an NSF Graduate Fellow working in Dr. Kendra Greenlee’s laboratory at North Dakota State University. Dr. Cambron was scheduled to present her research at the 2020 Experimental Biology conference last month in a Comparative and Evolutionary Physiology session hosted by the American Physiological Society. As with many conferences, the meeting was cancelled due to Covid-19.  She has agreed to tell us about her exciting research with bees.

1200px-ARS_Megachile_rotundata

What inspired you to study alfalfa leafcutting bees?

Our lab has a strong collaboration with the local USDA-ARS, so I applied for an internship through my NSF fellowship to work at the USDA-ARS studying the alfalfa leafcutting bees, Megachile rotundata. My internship included a small grant that funded my research project which focused on investigating the role of insulin signaling in insect overwintering. To survive unfavorable conditions like the lack of food and extremely low temperatures that come with winter, insects can go into a developmental dormancy that allows them to survive the winter months. During overwintering, an insect’s metabolism decreases, like turning down a furnace, to slowly use it’s energy reserves which allows it to survive winter. However, the mechanisms signalling and regulating the changes that occur during overwintering are not clearly understood, especially in non-model insects like M. rotundata. This gap of knowledge inspired me to study insulin signaling, which is important for metabolism, in overwintering M. rotundata. Plus I got to work with and learn from alfalfa leafcutting bee experts at the USDA-ARS, which was pretty amazing!

How are these bees different from honey bees?

Megachile rotundata are solitary bees, meaning they do not form hives or communities, producing wax and honey, like honey bees do. That also means there is no caste or queens with M. rotundata. It’s each bee for itself! M. rotundata also have different nesting behaviors than honey bees. In the spring/summer, adult female bees will create brood cells by cutting pieces of leaves and sticking them together with saliva. Then in this brood cell she will provide a food provision and then lay a single egg in the cell. She will continuously create brood cells in a linear fashion, with the final product taking the form of a straw. Unlike honeybees, alfalfa leafcutting bees do not return to care for their offspring. Both bees also have different overwintering strategies. M. rotundata overwinter as prepupae in the brood cells they were laid, whereas in honeybees the queen overwinters in the colony with reduce number of workers. Solitary bees like M. rotundata are also unlikely to sting or be as aggressive as honeybees can be when they are defending their hives.

How might climate change impact gene expression in these bees?

My research used bees that were overwintered in either a constant temperature similar to the farmer’s storage protocols, or in naturally fluctuating temperatures in an alfalfa field. My results found that bees overwintered in different temperature treatments had different genetic expression profiles, meaning they might possibly have different proteins made, which could impact their ability to pollinate. Since these bees use environmental cues like temperature and light for regulating development, the seasonal shifts and changes in temperature extremes that come with climate change will definitely have an impact on gene expression in these bees. Whether that impact will be beneficial or harmful is still unclear.

How might your research inform the agricultural industry?

Farmers use a storage protocol for overwintering these bees that has been shown to be suffer from a high mortality rate. My research informs the agricultural industry that their storage protocols need to change. Bees that are agriculturally managed are showing different genetic expression profiles than bees found in the field. It is not well understood how changes occur during overwintering, and my research closed that gap a little by showing how the insulin signaling pathway changes. By better understanding how overwintering mechanisms are regulated, and how those mechanism respond to temperature, we can work on optimizing storage protocols for better bee survival. Better bee survival can lead to more pollination, which is great for the farmers.

Categories: Comparative Physiology

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