Microbial Diversity in Honeybees

Charles Wick, David Wick

• Editorial: CRC Press
• Año: 2021
• ISBN:
  9781000377125
• Edición: 1
• Categoría: Ciencias biológicas
• Categoría: Botánica

Honeybees are an important link in our food chain because they are major pollinators of food crops. In recent years, honeybee populations have declined precipitously perhaps due to changes in their microbiome. This book describes and identifies the bee microbiome using a proteomics technology. Chapters include the detection and identification of microbes found in honeybees collected around the United States. This book contains new data and illustrates the rich diversity of microbes as collected by honeybees. It is a must read for everyone concerned about the honeybee and working in the industry.

1 Microbe Diversity in Honeybees

Pollinators compose two main groups: commercial beekeepers and hobbyists. Naturally, there is gradation between these two groups – some hobbyists have extensive operations that start to look like commercial operations. Pollinators provide bees to pollinate important food sources; among the largest of these efforts is the pollination of the almond crop in California in the spring. Most of the pollinators are trucked to California for this purpose. Once finished with the almonds, they are moved to other areas to pollinate apples and other fruit crops and then on to the next crop that is in bloom. Moving the bees from one site or region to another has been done for many years, and beekeepers can be thanked for this important contribution to agriculture and the food we enjoy. A question or at least a consideration has been “what is the microflora environment where the bees are working or what is the microflora where they will be working?” A possible concern is that the bees might pick up an unwanted microbe along the way. Likewise, it would be good to know if the bees picked up an unwanted microbe from one region before traveling to another. This reference book should help provide a microbial baseline from which to compare one region to another and one honeybee group with another.

Honey producers and packers face similar questions about the normal microbe environment. It could be expected that honey which comes from bees would reflect the naturally found microbes in their product; indeed the unique flavor of some honey may reflect the unique background associated with honey production. With nearly 40 million pounds of honey produced each year, the question of naturally occurring microbes, regions, and national averages for microbes becomes important. Particularly in light that often the demand for honey in the United States is greater than the supply. Honey imported from outside can be expected to have evidence of a different microflora and this information could be useful in checking the origin and contents labels.

The book in organized into chapters that represent the major microbes and groups of microbes collected by honeybees and should provide a useful reference to beekeepers, commercial beekeepers and hobbyists alike to provide the microflora, the natural microflora, that honeybees collect while working.

Foraging honeybees collect nectar and pollen and a wide variety of microbes. This book focuses on these microbes which can be divided into three main groups – bacteria, viruses and fungi. Although this grouping leaves out other thingssuch as organelles and plasmids, we can be sure that they too are being collected by the honeybees and will be analyzed and included in the listing of microbes as technology and interest permit. One very nice feature of the mass spectrometry proteomics/ABOid (MSP/ABOid) method of detection and identification is that it is not necessary to resample since the results are saved as a computer file, and the file needs to be re-analyzed at the appropriate time when the software is updated as discussed in Chapter 2 (Mass Spectrometry Proteomics/ABOid).

The MSP/ABOidmethod of microbe detection and identification utilize the genomic information available in the DNA or RNA of each microbe. This information is simplified by determining the sequence of the nucleotides in each microbe and using this information in turn to classify and identify each microbe. Nearly 254,000 prokaryotes (bacteria), 41,500 viruses, 12,100 eukaryotes (fungi, plants), 16,500 organelles and 22,000 plasmids are sequenced. The current list of sequenced microbes is available from the U.S. National Library of Medicine.

It is important to know that some of these sequenced microbes are not fully sequenced or complete. This missing sequence information may be important to make an identification. As a result, where possible, only complete sequences are used. This reduces the number microbes available for identification, as there are presently ~18,000 bacteria, ~72 fungi and ~36,000 viruses which are fully or completely sequenced. This gives us 54,072 microbes to utilize. Data groups used in this book represent a portion of these microbes. It is also important to know that as new sequences are completed, they can be easily added to existing data groups and existing data files reexamined producing “new” results from old files.

The structure of this book is divided according to areas of interest. The first chapter discusses the honeybee. Without this discussion we would not know the unique place that this insect plays in the collections of microbes. The chapter continues with a discussion of exactly what is a microbe and how are they classified or sorted so they can be distinguished from each other, and a brief discussion on how the honeybee collects. This discussion helps us understand the honeybees’ collection of microbes.

How we detect and identify microbes is discussed in Chapter 2. Utilizing the Mass Spectrometry Proteomic/ABOid method is presented and why it was selected as the identification method of choice as well as how it works is discussed.

Chapter 3 discusses the honeybee (Apis). This chapter also has information on the detection and identification of three other species of sequenced honeybees of the genus Apis.

Each of following chapters presents the various groups of microbes as they occur in nature and collected by honeybees. The national average was determined as well as averages for five regions: California region, Florida region, Idaho region, Iowa region and the Montana region. Chapters 4 (Bee Gut Microbes), 5 (Coronaviruses), 6 (Bacteria), 7 (Fungi), 8 (Nosema), 9 (Viruses) and 10 (Water) are about the different microbe groups collected by the honeybees.

Other questions are also important in understanding this collection of microbe information, and they are addressed first, such as ‘What are microbes and where do we find them?’

1.1 About Honeybees

In the United States, the species of honeybee that is universally managed is the Western honeybee Apis mellifera. The general organization of the honeybee hive is a queen bee, a large number of female worker bees (40,000–100,000) and a few drones depending on the strength of the colony.

A bee colony follows an annual cycle that begins in the spring and ends in the winter. It starts with a rapid expansion of the brood as soon as pollen is available for feeding the larvae. Breeding accelerates towards May producing an abundance of harvesting bees that are synced with the nectar. There is some variation among regions and some variation among commercial hives as the nectar cycles vary.

It is the activity in the spring that gains attention as to collection of microbes. As the climate warms and is moist, the population of microbes can be expected to increase accordingly. It would be interesting to follow the microbe population over a few seasons and years to develop a pattern of microbes seen in bee populations.

1.2 What Is a Microbe?

In the “Tree of Life” there are three principal branches, namely eukaryotes, prokaryotes, and viruses. Two of these (prokaryotes and viruses) are small organisms and generally not visible to the naked eye. These are referred to as microorganisms, or microbes. They are the microscopic organisms and exist as either single-celled or as a colony of cells. They may have been the first forms of life on Earth.

Ancients, as long ago as the sixth-century BC, suspected microbial life but had no direct way to observe it. The invention of the microscope by Antonie van Leeuwenhoek in 1670 changed this, and with the invention of the electron microscope in the 1930s it was possible to observe both bacteria and viruses.

Microorganisms include all unicellular organisms and so are extremely diverse – there may be trillions of different kinds of microbes. They occupy a niche and live in almost every known habitat. They are known to work together as symbiotes, where a bacterium can provide enzymes to a plant or a fungus and have other complex associations found everywhere.

Microbes can be both helpful and hurtful causing fermentation for good uses and plagues (bad uses) in about equal abundance. Microbes are important and it is essential that they are studied, and more than that it is essential that we are able to detect and identify them.

1.2.1 BACTERIA

Bacteria have been around for a long time and may represent some of the first organized life on Earth. Unlike the cells of animals, fungi and other eukaryotes, bacteria cells do not contain a nucleus or for that matter other “membrane-bound” organelles and belong to the prokaryotes. Following the discovery of DNA/RNA and the resulting ability to group or classify living things by their relationships due to similar DNA/RNA, bacteria were grouped and then regrouped as technology improved. Today, prokaryotes are divided into two kingdoms: the bacteria and the archaea. The kingdom of bacteria contains over 260,000 species that have been sequenced. The kingdom of archaea has over 5,000 species that have been sequenced.

Bacteria are widely or rather vastly distributed throughout the world and can be found in nearly every habitat. They are larger than the viruses and smaller than the fungi. Typically, a bacterium can be expected to be in the one- or two-micron range in size and can have many shapes. Considering that there are millions of bacteria cells in a gram of soil or a milliliter of fresh water, it is not surprising to find bacteria collected on honeybees. The only question is how many different types of bacteria are found and what are their names.

Chapter 6 includes details of the bacteria that have been isolated, detected and identified from samples of honeybees.

1.2.2 Fungi

Fungi belong to the kingdom of fungi, which are part of the eukaryotes. Fungi have been around a long time probably dating back 400–500 million years or longer. They are diverse and can be found, much like the bacteria, in every habitual niche. The two phyla of the most interest are the Ascomycota and the Basidiomycota, which are contained within a subkingdom Dikarya, since they may contain the most abundant species of the more than several millions of species of fungi.

Fungi are familiar to most everyone as they are seen as the mushrooms, the fuzz on food and seen in the environment growing on nearly everything. Although they are often thought of as inconspicuous until seen, they are important as major decomposers, producers of antibiotics and in making food.

The Ascomycota are most likely the most abundant fungi in the environment, and as they have both a sexual state and produce ascospores and an asexual stage and produce conidia, they fill the environment with spores. When spores are combined with hypha and other fungi debris, our natural habitat is covered. It is likely it is this material and whatever can be picked up from the Basidiomycota and other fungi the honeybees are collecting. One of the largest and most familiar environmental ascomycota are the Aspergillus species, which includes Aspergillus niger which is the source of the black mold found on most things, including bread.

The fungi are reported in Chapter 7, where the most common fungi are discussed as well as a national average for the more than 200 fungi collected, detected and identified from the honeybee. A detailed list is included in Appendix G.

1.2.3 Viruses

Viruses are smaller than bacteria generally ranging in size from 20 nm to 300 nm. A nanometer is one billionth of a meter. It was not until the 1930s with the invention of the electron microscope that viruses could be imaged. Viruses are referred to as submicroscopic organisms and are known for the feature of replicating only inside other living cells. There has been a debate over the status of “living”, but that is not our concern. We are concerned about where they are found and what is their distribution.

Like bacteria, viruses have been around for a long time and may have been important during the formation of the first life on Earth. It is expected that there are millions and millions of viruses in the environment, maybe even trillions of different species considering their uncanny ability to mutate almost at will as they “react” or accommodate to their environment. It is further expected that viruses inhabit nearly every environmental niche in the world.

Presently there are over 40,000 viruses sequenced and available for use. This has been helpful in classifying and sorting out the relationships between different viruses. This process continues, and many viruses are now named and can be identified by using their sequence as a basis.

Viruses can be expected to be picked up by the honeybee, either directly or indirectly. For honeybees not to pick up a virus would be strange indeed. The question is then “how many different strains and where are they distributed much like the bacteria”.

1.3 Sources of Microbes

The honeybee has many sources in which to pick up a microbe or two. Plants harbor bacteria and fungi and even viruses. Water sources are abundant and water is needed by the honeybees and they can be expected to stop at all sorts of water supplies. Many environmental sources of microbes are available to the honeybee such as farms, other cultivated sites, urban sites, general rural areas, forests and numerous other areas. Other opportunities are also available as the natural microflora is disturbed by weather and weather events. These topics are discussed further.

1.3.1 Plants

Plants both benefit and suffer from microbes. There are many microbes, bacteria and fungi that help plants by providing an abundance of nutrients and minerals by breaking down organic matter. Others benefit the plants by actually making a symbiotic relationship where the microbes fix nitrogen to facilitate water and nutrient uptake and provide sugars, amino acids and other nutrients to the plant. On the negative side, there are many microbes that attack and cause a variety of diseases to cereals, corn, tobacco, tomato and nearly all of our food-producing plants. Likewise, microbes attack trees and other plants. All part of the cycle of breaking down complicated organic matter into simple compounds so they can be used by the complicated organic organisms. It is this proc...