Honey Bees Struggle to Find Enough Good Bacteria

Modern monoculture farming, commercial forestry and even well-intentioned gardeners could be making it harder for honey bees to store food and fight off diseases, a new study suggests.

Phylum-level distributions of bacterial community, determined by Illumina MiSeq sequencing of bee bread from 20 hives, organized by location (on an east-west axis left to right)

Human changes to the landscape, such as large areas of monoculture grassland for livestock grazing, and coniferous forests for timber production, is affecting the diversity of the ‘microbiome’ associated with the long-term food supply of honey bees.

Scientists at Lancaster University examined the mix of bacteria, known as a microbiome, of bee bread. They found that the bee bread within hives close to agriculturally improved grasslands, made up of single grass varieties, and those near coniferous woodland contained lower bacterial diversity than hives near habitats with more plant variety such as broadleaf woodland, rough grasslands and coastal landscapes.

Bees use a diverse community of bacteria to turn fresh pollen into a long-term food store. They need a range of bacteria to help them fight off infectious diseases, and also the bacteria can act as a preservative for bee bread within hives. Without a diverse microbiome the bee bread can be more vulnerable to mold, causing a food shortage for the hive.

The researchers discovered that some of the bacteria present within bee bread, such as bifidobacterium and lactobacilli, are the same ‘good bacteria’ found in some brands of bioactive yogurt. Bees pick up different strains of bacteria from plants when they are foraging for food and this is transferred to bee bread within the hive.

Lancaster’s Dr Philip Donkersley, lead author of the study, which is published in the open access journal Ecology and Evolution, said: “We are showing that even in a small geographical area there is a huge variance in bee bread microbiome. This is almost certainly because bee bread has a variable composition made up of pollen from different plants.

“It is traditionally thought that monocultures, such as grazing land and timber forests, were bad for pollinators due to a lack of food continuance through the year. However, our study suggests land use change may also be having an indirect detrimental effect on the microbiota of bee bread.

“Since nutrition derived from bee bread and the microbiome therein directly affects the health of bees we therefore believe this demonstrates an indirect link between landscape composition and bee fitness.”

In addition, hives located near urban landscapes also demonstrated lower diversity in the microbiome of bee bread. Gardeners trying to help bees by growing a range of pollinator-friendly flowers from around the world may need to consider that non-native species may not be as good for bees as native UK plants.

Native bees, their forage plants and the bacteria located within have evolved together and the bacteria bees pick up from non-native plants may be less likely to be beneficial to the hive.

Dr. Donkersley thinks that “Decreased bacterial diversity in bee breads near urban environments suggests that the increased range of non-native plants in gardens could be impacting bees’ ability to get diverse microbiota.” But perhaps there is something else in urban environments reducing the microbiome availability, such as air pollution. It would be interesting to compare microbiome composition of bee bread from different urban environments that varied in their native vs. introduced plant diversity.

The work is reported in the paper ‘Bacterial communities associated with honeybee food stores are correlated with land use’. http://dx.doi.org/10.1002/ece3.3999