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Zac Browning

Publications and source records attributed to Zac Browning.

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Why does bee health matter? The science surrounding honey bee health concerns and what we can do about it

A colony of honey bees is an amazing organism when it is healthy; it is a superorganism in many senses of the word. As with any organism, maintaining a state of health requires cohesiveness and interplay among cells and tissues and, in the case of a honey bee colony, the bees themselves. The individual bees that make up a honey bee colony deliver to the superorganism what it needs: pollen and nectar collected from flowering plants that contain nutrients necessary for growth and survival. Honey bees with access to better and more complete nutrition exhibit improved immune system function and behavioral defenses for fighting off effects of pathogens and pesticides (Evans and Spivak 2010; Mao, Schuler, and Berenbaum 2013; Wahl and Ulm 1983). Sadly, as this story is often told in the headlines, the focus is rarely about what it means for a honey bee colony to be healthy and is instead primarily focused on colony survival rates. Bee colonies are chronically exposed to parasitic mites, viruses, diseases, miticides, pesticides, and poor nutrition, which weaken and make innate defenses insufficient at overcoming these combined stressors. Colonies that are chronically weakened can be even more susceptible to infections and levels of pesticide exposure that might otherwise be innocuous, further promoting a downward spiral of health. Sick and weakened bees diminish the colony’s resiliency, ultimately leading to a breakdown in the social structure, production, efficiency, immunity, and reproduction of the colony, and eventual or sudden colony death.

Report

Mapping large-area landscape suitability for honey bees to assess the influence of land-use change on sustainability of national pollination services

Pollination is a critical ecosystem service affected by various drivers of land-use change, such as policies and programs aimed at land resources, market values for crop commodities, local land-management decisions, and shifts in climate. The United States is the world's most active market for pollination services by honey bees, and the Northern Great Plains provide the majority of bee colonies used to meet the Nation's annual pollination needs. Legislation requiring increased production of biofuel crops, increasing commodity prices for crops of little nutritional value for bees in the Northern Great Plains, and reductions in government programs aimed at promoting land conservation are converging to alter the regional landscape in ways that challenge beekeepers to provide adequate numbers of hives for national pollination services. We developed a spatially explicit model that identifies sites with the potential to support large apiaries based on local-scale land-cover requirements for honey bees. We produced maps of potential apiary locations for North Dakota, a leading producer of honey, based on land-cover maps representing (1) an annual time series compiled from existing operational products and (2) a realistic scenario of land change. We found that existing land-cover products lack sufficient local accuracy to monitor actual changes in landscape suitability for honey bees, but our model proved informative for evaluating effects on suitability under scenarios of land change. The scenario we implemented was aligned with current drivers of land-use change in the Northern Great Plains and highlighted the importance of conservation lands in landscapes intensively and extensively managed for crops.

PLoS ONE