How do monocultures influence bee health?
Posted: August 2, 2014
Monoculture crop plantings in agricultural environments tend to decrease local floral diversity and abundance. This, in turn, may negatively affect local bee species populations that rely on diverse floral resources. Additionally, insecticides used regularly on conventionally managed farms could harm bee populations. This year, I am conducting a comprehensive study to measure the growth, health, and reproductive output of bumble bee colonies that nest near large-scale pumpkin farms. Bumble bees are important pollinators of cucurbit crops, such as pumpkins; therefore, by placing bumble bee colonies on pumpkin farms, I can test whether pumpkin floral resources are sufficient for supporting bumble bee populations, or if the monoculture-cropping practice negatively influences bumble bees.
I am utilizing a variety of different measures to model how the local landscape, land-use practices, and bumble bee foraging behavior relate to bumble bee health and development. I am collecting pollen from pumpkin flowers to determine its nutritional value; I will compare this value to the optimal nutritional requirements for bumble bees which I have determined in previous work. I am collecting pollen from the corbiculae of bumble bee foragers to determine the diversity of pollen collected, which would indicate if bumble bees are truly restricted to foraging on pumpkin or if they are obtaining floral resources from outside the farm. I will also measure the nutritional value of pollen being returned to the colony. Every week, I am counting the number of adult bees, larvae and pupae as measures of colony growth and number of males and future queens as a measure of reproductive output. Finally, by taking samples of bees from each colony, I will measure their disease-infection levels and quantify expression of key genes related to immunocompetence. Finally, I will use GIS data to measure the diversity of the landscape surrounding each farm site to determine how landscape complexity at a large scale may affect the measure of colony health.
This NAPPC-funded project is one of the only studies conducted to holistically determine how bumble bee colony populations are affected by agricultural land use practices. Because of some delay, we placed the colonies in the fields in early July. But this study will expose if and how monoculture crop plantings and/or the availability of late season floral resources influences our important native pollinators.
—Anthony, 26 July 2014